Author Topic: What is the cheapest and fastest way to go to the moon or mars  (Read 71313 times)

Offline nec207

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What is the cheapest and fastest way to send people to the moon or mars .  Is that using Falcon ,SLS or going back to the constellation  project that Bush wanted !! I keep reading these anti-SLS or anti-Falcon threads but no clear posts in any of these threads want is the cheapest and fastest way to go to the moon or mars.

I also read that Falcon or constellation  project may be good going to the moon but not mars.

Is it is it possible to go to the moon by 2016 or 2020 using Falcon or constellation  project that Bush wanted if the next president goes for it. Also in cost per pound or ton what is cheaper?

Offline Downix

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Small note, the Constellation Bush asked for was not Ares I/V. As it was implemented by Administrator O'Keefe, Constellation built on the existing Atlas and Delta rockets rather than build a unique NASA-only launch system.  This was scrapped after 18 months of development for an all new, top-down design system which was the Griffin program.  They had already begun engine testing, LAS development, and the crew capsule competition was down to it's last two choices, the Boeing/Northrop capsule and Lockheed/Orbital spaceplane.

The Boeing crew capsule from this program was continued, and now is called the CST-100.  Orbital kept the work from the spaceplane, and calls it Promethius now.

Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.  Atlas and Delta are your best bets there, but you are talking a three or four launch architecture, which would take a month of preparation before your moon mission due in part to the results of the Griffin era Constellation changes.  Before Griffin, the CEV was nothing but a way to and from orbit, with on-orbit systems for going BEO.  As a result, the CEV was lightweight and minimalist.  The current Orion is neither, and handles a lot of jobs itself that were to be left to the mission systems under the O'Keefe era Constellation program.  That does not mean Orion is a bad system, far from it.  It does, however, mean that it is not as flexible, and as a result you need to work around it depending on your mission needs.

Using the original March '05 Boeing CEV, for instance, you could launch it on a normal Atlas V without concern, no need for the Heavy form of the launcher.  You could in three launches run the full moon mission, using one for the CEV itself, one for the lunar lander (Lockheed's design being the simplest/cheapest, as it was a modified Centaur upper stage) and one for the EDS (just a DCSS on a Delta IV Heavy). 

With todays architecture, however, you now have a significantly heavier weight, which did not gain you much more than duration.  Your systems can now run for 6 months without any external addition, great if you're running multi-month missions, overkill if doing an Apollo 11 repeat.  With the older arch, you just flew one more launcher for the additional supplies and systems for multi-month, scale it up or down as needed.

But, combine the current Orion with SLS, you now are up to the original concept, only now you have a single launch for the multi-month stay on the moon.  With the stage 1, without US, you need two launches to handle the mission, one for Orion, one for the lander.  With stage 2, you now can do it all with a single launch.  It's a sweet spot for a moon or mars mission.

Mars missions of course add more complexity, and as a result need more launches regardless of your architecture.  With SLS you gain an advantage that each launch adds little incidental costs, so 3 launches is not much more expensive than 4, something you do not get with a Falcon or EELV launch system.  Using the Shuttle as a baseline, for 2 missions per year, with the Shuttle it costs $3.2 billion, for 5 it cost $3.6 billion.  And the more missions, the better the savings.  This means, for the heavy lift demands of a mars mission, the SLS will come out on top, and the more aggressive your launch schedule is, the better your savings.
« Last Edit: 09/19/2011 07:19 pm by Downix »
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Offline savuporo

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The cheapest and fastest choice starts with figuring out why and who wants to go, where, how often and so on, everything else can only follow from that.

If you want to do reenactments of 60ies stunts, there is no choice but designing authentic costumes, hire a Walter Cronkite lookalike and yes, build a tall rocket.

If you had other goals in mind, whatever these might be, the cheapest and fastest ways may end up being different.
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Offline Robotbeat

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One of the fastest ways to the Moon (not counting using foreign hardware) is probably this approach, here:
http://www.nasa.gov/pdf/65851main_spacehab.pdf

Fastest way to Mars may be a similar approach.
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Offline savuporo

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One of the fastest ways to the Moon (not counting using foreign hardware) is probably this approach, here:
http://www.nasa.gov/pdf/65851main_spacehab.pdf

Fastest way to Mars may be a similar approach.

Probably not, because it also tries to bring people back. Its logically quite a bit cheaper to send people one-way.

This is just to demonstrate again, if you don't specify the reasons for going, its impossible to work out the optimum solutions.
Orion - the first and only manned not-too-deep-space craft

Offline Robotbeat

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One of the fastest ways to the Moon (not counting using foreign hardware) is probably this approach, here:
http://www.nasa.gov/pdf/65851main_spacehab.pdf

Fastest way to Mars may be a similar approach.

Probably not, because it also tries to bring people back. Its logically quite a bit cheaper to send people one-way.

This is just to demonstrate again, if you don't specify the reasons for going, its impossible to work out the optimum solutions.
Did you actually look at all of what is in that pdf? There is one-way payload capabilities shown on page 8 (before the two-way manned capabilities shown on page 9).
« Last Edit: 09/19/2011 09:06 pm by Robotbeat »
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Offline Prober

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What is the cheapest and fastest way to send people to the moon or mars .  Is that using Falcon ,SLS or going back to the constellation  project that Bush wanted !! I keep reading these anti-SLS or anti-Falcon threads but no clear posts in any of these threads want is the cheapest and fastest way to go to the moon or mars.


Everything is in a state of "flux".  No real answers to your questions as we have little real direction.   Many projects come and go, and many don't even get past the paper stage.   

Enjoy reading you find tons of materials avail.

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Offline nec207

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Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.   


What do you mean here.


Quote
Atlas and Delta are your best bets there, but you are talking a three or four launch architecture, which would take a month of preparation before your moon mission due in part to the results of the Griffin era Constellation changes.


But would it be cheaper and could you go to the moon before SLS is built that say go to the moon by 2016?



Quote
Before Griffin, the CEV was nothing but a way to and from orbit, with on-orbit systems for going BEO.  As a result, the CEV was lightweight and minimalist. 

So you are saying CEV is way too small.They need some thing bigger?

Quote
Using the Shuttle as a baseline, for 2 missions per year, with the Shuttle it costs $3.2 billion, for 5 it cost $3.6 billion.


What $3.6 billion for 5 shuttle launch that you can do with 1 SLS launch?

Well SLS or saturn-v is what you will need if you want to go to Mars has Falcon or constellation project I do not think it will get you there.The Falcon or constellation project is not built for that .
« Last Edit: 09/19/2011 09:43 pm by nec207 »

Offline Downix

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Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.   


What do you mean here.
Just that.  SpaceX is LEO-centric, anything further out their performance drops significantly.  That is why the Falcon 9 may deliver ~10 metric tons to LEO, but less than 2 to geo-stationary orbits, while the Atlas V 401 delivers the same ~10 metric tons to LEO, but over twice as much to geo-stationary, it uses a high-energy upper stage, the Centaur.  The Proton, using Blok-DM and Briz-M, uses long-duration capability to similarly deliver a higher payload percentage.
Quote

Quote
Atlas and Delta are your best bets there, but you are talking a three or four launch architecture, which would take a month of preparation before your moon mission due in part to the results of the Griffin era Constellation changes.


But would it be cheaper and could you go to the moon before SLS is built that say go to the moon by 2016?
No, the long pole in the room remains the lander, regardless.  You won't get to the moon any faster than with SLS in that regards, and may even take longer as the SLS has a much larger payload margin.
Quote


Quote
Before Griffin, the CEV was nothing but a way to and from orbit, with on-orbit systems for going BEO.  As a result, the CEV was lightweight and minimalist. 

So you are saying CEV is way too small.They need some thing bigger?
No, I'm saying that the 2005 CEV was a lighter weight craft than Orion is today, with more mission profile options.  Orion is heavy, but for it's planned mission is incredibly well designed, to the point nothing else can touch it.  If you step out of that mission, it's over-built.
Quote
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Using the Shuttle as a baseline, for 2 missions per year, with the Shuttle it costs $3.2 billion, for 5 it cost $3.6 billion.


What $3.6 billion for 5 shuttle launch that you can do with 1 SLS launch?

Well SLS or saturn-v is what you will need if you want to go to Mars has Falcon or constellation project I do not think it will get you there.The Falcon or constellation project is not built for that .
Well, I was speaking cost to operate, not payload, but in effect yes.
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Offline Robotbeat

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Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.   


What do you mean here.
Just that.  SpaceX is LEO-centric, anything further out their performance drops significantly.  That is why the Falcon 9 may deliver ~10 metric tons to LEO, but less than 2 to geo-stationary orbits, while the Atlas V 401 delivers the same ~10 metric tons to LEO, but over twice as much to geo-stationary, it uses a high-energy upper stage, the Centaur.  The Proton, using Blok-DM and Briz-M, uses long-duration capability to similarly deliver a higher payload percentage.
...
More importantly, Proton has lots of stages. Falcon Heavy also is essentially a three-stage vehicle, so would get decent performance to high energy orbits (well, better performance to GTO than anything available today, by far).
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Offline Downix

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Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.   


What do you mean here.
Just that.  SpaceX is LEO-centric, anything further out their performance drops significantly.  That is why the Falcon 9 may deliver ~10 metric tons to LEO, but less than 2 to geo-stationary orbits, while the Atlas V 401 delivers the same ~10 metric tons to LEO, but over twice as much to geo-stationary, it uses a high-energy upper stage, the Centaur.  The Proton, using Blok-DM and Briz-M, uses long-duration capability to similarly deliver a higher payload percentage.
...
More importantly, Proton has lots of stages. Falcon Heavy also is essentially a three-stage vehicle, so would get decent performance to high energy orbits (well, better performance to GTO than anything available today, by far).
Eh, debateable.  Compared to today, yes, but the FH is not available today.  By the time it is available, Delta and Atlas both will have had upgrades which boost their GTO performance to comparable levels.  Remember, FH only is 30% better performance to GTO than Delta IV Heavy as it is now, and there are upgrades for both in the works which can improve their performance to these high energy orbits.  I know other launch vehicles are also either being upgraded, or introduced in the interim as well, so by the time the FH is available, the marketplace will be different than it is today.
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Offline nec207

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Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.   


What do you mean here.
Just that.  SpaceX is LEO-centric, anything further out their performance drops significantly.  That is why the Falcon 9 may deliver ~10 metric tons to LEO, but less than 2 to geo-stationary orbits, while the Atlas V 401 delivers the same ~10 metric tons to LEO, but over twice as much to geo-stationary, it uses a high-energy upper stage, the Centaur.  The Proton, using Blok-DM and Briz-M, uses long-duration capability to similarly deliver a higher payload percentage.
...
More importantly, Proton has lots of stages. Falcon Heavy also is essentially a three-stage vehicle, so would get decent performance to high energy orbits (well, better performance to GTO than anything available today, by far).

When is Falcon Heavy going to be going in service and could they use that to go to the moon ?


Yes but the  Atlas and Delta rockets is going be able to go in service alot faster than SLS?
« Last Edit: 09/19/2011 10:04 pm by nec207 »

Offline nec207

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No, I'm saying that the 2005 CEV was a lighter weight craft than Orion is today, with more mission profile options.  Orion is heavy, but for it's planned mission is incredibly well designed, to the point nothing else can touch it.  If you step out of that mission, it's over-built.


The Orion is way way way too small to be used to go to mars and even going to the moon it is small.

I don't think you want to go to the moon in Orion .

Offline 93143

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Orion is significantly larger than Apollo.  And, just like Apollo, it was designed to be paired with a lander.

If you had the option of riding Warpstar-1, you might not want to go to the moon in Orion.  As it is, I think you're being a bit picky...

It is, of course, much too small for Mars, which is why it's never seriously proposed as a habitat for a Mars transit.  It's only used to get the crew to the spacecraft before it leaves and to return them to Earth after it comes back.

Offline Downix

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Orion is significantly larger than Apollo.  And, just like Apollo, it was designed to be paired with a lander.

If you had the option of riding Warpstar-1, you might not want to go to the moon in Orion.  As it is, I think you're being a bit picky...

It is, of course, much too small for Mars, which is why it's never seriously proposed as a habitat for a Mars transit.  It's only used to get the crew to the spacecraft before it leaves and to return them to Earth after it comes back.
Right, but Orion does offer the ability to be an emergency vehicle should all hell break loose, with enough delta-v to offer a return to earth on its own from LLO.
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Offline Robotbeat

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Can we go to the moon, yes, but not simply nor cheaply.  Falcon is ill suited, due to the lack of both a high energy orbital stage as well as long duration capability.   


What do you mean here.
Just that.  SpaceX is LEO-centric, anything further out their performance drops significantly.  That is why the Falcon 9 may deliver ~10 metric tons to LEO, but less than 2 to geo-stationary orbits, while the Atlas V 401 delivers the same ~10 metric tons to LEO, but over twice as much to geo-stationary, it uses a high-energy upper stage, the Centaur.  The Proton, using Blok-DM and Briz-M, uses long-duration capability to similarly deliver a higher payload percentage.
...
More importantly, Proton has lots of stages. Falcon Heavy also is essentially a three-stage vehicle, so would get decent performance to high energy orbits (well, better performance to GTO than anything available today, by far).

When is Falcon Heavy going to be going in service and could they use that to go to the moon ?


Yes but the  Atlas and Delta rockets is going be able to go in service alot faster than SLS?
FWIW, I'd plan on using current EELVs and Falcon 9s until another launch vehicle has flown successfully.

Falcon Heavy will probably be in service within a few years (first flight no earlier than 2013, more likely somewhere 2014-2016). Delta IV with RS-68A upgrade is essentially already a given at this point. (Current non-RS-68A DIVH can do 13130kg to GTO, versus Falcon Heavy's purported 19000kg, about a 45% increase from 13130kg.) All other upgrades depend on additional funding and are probably most likely going to take longer to field than Falcon Heavy (not counting RL-10C as an upgrade).
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Offline 93143

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Right, but Orion does offer the ability to be an emergency vehicle should all hell break loose, with enough delta-v to offer a return to earth on its own from LLO.

Considering Orion's likely consumables capacity, plus the mention of LLO, I'm going to assume you aren't talking about a Mars mission...

My point was simply that Orion is a bigger and better moonship than the only one anyone has ever actually flown to the moon, and hence the comment that it is "small" for the task does not appear well founded.
« Last Edit: 09/19/2011 10:43 pm by 93143 »

Offline savuporo

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One of the fastest ways to the Moon (not counting using foreign hardware) is probably this approach, here:
http://www.nasa.gov/pdf/65851main_spacehab.pdf

Fastest way to Mars may be a similar approach.

Probably not, because it also tries to bring people back. Its logically quite a bit cheaper to send people one-way.

This is just to demonstrate again, if you don't specify the reasons for going, its impossible to work out the optimum solutions.
Did you actually look at all of what is in that pdf? There is one-way payload capabilities shown on page 8 (before the two-way manned capabilities shown on page 9).

Yes i did, but you did not read my reply. I said, sending people (not cargo) one way, especially sending a single person one way can be obviously done cheaper and sooner.

Once again, without specifying the goal of going, its impossible to perform any useful analysis on the optimum solutions. I am wearing that drum out, just about now ..
« Last Edit: 09/19/2011 10:45 pm by savuporo »
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Offline Robotbeat

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One of the fastest ways to the Moon (not counting using foreign hardware) is probably this approach, here:
http://www.nasa.gov/pdf/65851main_spacehab.pdf

Fastest way to Mars may be a similar approach.

Probably not, because it also tries to bring people back. Its logically quite a bit cheaper to send people one-way.

This is just to demonstrate again, if you don't specify the reasons for going, its impossible to work out the optimum solutions.
Did you actually look at all of what is in that pdf? There is one-way payload capabilities shown on page 8 (before the two-way manned capabilities shown on page 9).

Yes i did, but you did not read my reply. I said, sending people (not cargo) one way, especially sending a single person one way can be obviously done cheaper and sooner.

Once again, without specifying the goal of going, its impossible to perform any useful analysis on the optimum solutions. I am wearing that drum out, just about now ..
The cargo module is pressurized in the example I linked to ( http://is.gd/WDtF2q ); you could use it to send people one-way. I know you had a larger point to prove, but some architectures are more flexible and better at being optimal given almost any sort of goals than other architectures.
« Last Edit: 09/19/2011 11:00 pm by Robotbeat »
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Offline nec207

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well still no one answered if Falcon Heavy could they use that to go to the moon  , or if Atlas and Delta rockets is going be able to go in service alot faster than SLS?

Offline savuporo

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The cargo module is pressurized in the example I linked to ( http://is.gd/WDtF2q ); you could use it to send people one-way. I know you had a larger point to prove, but some architectures are more flexible and better at being optimal given almost any sort of goals than other architectures.
Oh we can pass it back and forth til we are both blue in the face .. the cargo module is not exactly minimally sized for a single human, at 1.5t its way overkill, hence oversized for most cost-optimal launchers. Not sized to fit something like Falcon-1 ..

And we do not know full mission requirements anyway to argue, does the one-way hero need to pack a flag ? pickaxe ? lots of red paint to draw Coca Cola logo on the moon ?

I hope you did get my point.
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Offline Robotbeat

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well still no one answered if Falcon Heavy could they use that to go to the moon  , or if Atlas and Delta rockets is going be able to go in service alot faster than SLS?
Yes and yes.
http://www.nasa.gov/pdf/65851main_spacehab.pdf
Falcon 9 or Falcon Heavy could be used in place of Atlas V and Delta IV... I believe in this particular (LEO assembly) architecture, it could be done with only Falcon 9 or only Atlas V or only Delta IV... The important parts are the spacecraft, not the launch vehicles (which already exist).
« Last Edit: 09/19/2011 11:23 pm by Robotbeat »
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Offline nec207

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well still no one answered if Falcon Heavy could they use that to go to the moon  , or if Atlas and Delta rockets is going be able to go in service alot faster than SLS?
Yes and yes.
http://www.nasa.gov/pdf/65851main_spacehab.pdf
Falcon 9 or Falcon Heavy could be used in place of Atlas V and Delta IV... I believe in this particular (LEO assembly) architecture, it could be done with only Falcon 9 or only Atlas V or only Delta IV... The important parts are the spacecraft, not the launch vehicles (which already exist).

So you think Atlas V and Delta IV could go in service alot faster than SLS?

Yes the spacecraft is important but so is the launch vehicles . We have Orion but we do not have a launch vehicles .

If Atlas V or only Delta IV  can go in service by 2016 than we could go to the moon before SLS goes in service.
« Last Edit: 09/19/2011 11:37 pm by nec207 »

Online mmeijeri

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So you think Atlas V and Delta IV could go in service alot faster than SLS?

They have been in service for years.

Quote
Yes the spacecraft is important but so is the launch vehicles . We have Orion but we do not have a launch vehicles .

We have already launch vehicles, but no spacecraft (no capsule, no lander).

Quote
If Atlas V or only Delta IV  can go in service by 2016 than we could go to the moon before SLS goes in service.

We could if SLS were cancelled so the money could be used for a lander.
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Offline savuporo

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If Atlas V or only Delta IV  can go in service by 2016 than we could go to the moon before SLS goes in service.
This is an incredibly surreal discussion. The EELVs you mention have been in service for years.
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Offline deltaV

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What is the cheapest and fastest way to send people to the moon or mars .
An ordinary coffin on top of a Falcon 9 should work nicely for about $60 million.  :)

Offline savuporo

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What is the cheapest and fastest way to send people to the moon or mars .
An ordinary coffin on top of a Falcon 9 should work nicely for about $60 million.  :)
Exactly, but a Dnepr would probably be enough at far lower price tag. And looking at launch manifests, probably available sooner, too..
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Offline nec207

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So you think Atlas V and Delta IV could go in service alot faster than SLS?
Quote
Yes the spacecraft is important but so is the launch vehicles . We have Orion but we do not have a launch vehicles .

We have already launch vehicles, but no spacecraft (no capsule, no lander).

We have Orion .

Offline nec207

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If Atlas V or only Delta IV  can go in service by 2016 than we could go to the moon before SLS goes in service.
This is an incredibly surreal discussion. The EELVs you mention have been in service for years.

Than why is NASA not doing any thing for the next 10 years than ?

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We have Orion .

Not yet. And you cannot land on the moon without a lander. A lander and a service module are the crucial missing pieces. We already have adequate launch vehicles, with another one on the way, and Dragon could be modified for beyond LEO.
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Than why is NASA not doing any thing for the next 10 years than ?

Because they want to develop SLS + MPCV.
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Offline nec207

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We have Orion .

Not yet. And you cannot land on the moon without a lander. A lander and a service module are the crucial missing pieces. We already have adequate launch vehicles, with another one on the way, and Dragon could be modified for beyond LEO.


So if we have launch vehicles why is NASA not using them .


Why is NASA not working on lander or service module.

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So if we have launch vehicles why is NASA not using them .

Because they want to develop their own.

Quote
Why is NASA not working on lander or service module.

They are working on the service module. It could even have commonality with the lander, as was the plan with Altair. But they have no money to do a lander, especially if they're also working on a crew module and SLS.
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Offline nec207

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Than why is NASA not doing any thing for the next 10 years than ?

Because they want to develop SLS + MPCV.

I still do not know if SLS is going to be cheaper than any of the other launch vehicles .

And even if SLS is going to be cheaper than all the other launch vehicles  in service or going to be in service that is 10 years NASA is not going to do any thing.

That is a slap in the face to the people by NASA.

Offline savuporo

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So if we have launch vehicles why is NASA not using them .
Because of politics. Read some other threads here.
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Offline nec207

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So if we have launch vehicles why is NASA not using them .

Because they want to develop their own.

Quote
Why is NASA not working on lander or service module.

They are working on the service module. It could even have commonality with the lander, as was the plan with Altair. But they have no money to do a lander, especially if they're also working on a crew module and SLS.

Well it depends if NASA can build the service module and MPCV in the next 4 or 5 years or if it is going to take longer.

Offline Robotbeat

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We have Orion .

Not yet. And you cannot land on the moon without a lander. A lander and a service module are the crucial missing pieces. We already have adequate launch vehicles, with another one on the way, and Dragon could be modified for beyond LEO.


So if we have launch vehicles why is NASA not using them .


Why is NASA not working on lander or service module.
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Offline nec207

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So if we have launch vehicles why is NASA not using them .
Because of politics. Read some other threads here.

With out politics getting in way of these threads than may be the people here at this web site and other web sites should sign a petition that 10 years is unacceptable.


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I still do not know if SLS is going to be cheaper than any of the other launch vehicles .

It is certain to be more expensive if you count development costs, as you should. In fact that is precisely why certain influential politicians want it.
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Offline nec207

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I still do not know if SLS is going to be cheaper than any of the other launch vehicles .

It is certain to be more expensive if you count development costs, as you should. In fact that is precisely why certain influential politicians want it.


It may be more expensive to built it but it may be cheaper to put payload in space and the other launch vehicles may be no good  to go to mars.

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It may be more expensive to built it but it may be cheaper to put payload in space

If that were true, then we could depend on commercial competition to find the cheapest solution. The fact that proponents of SLS don't want that suggests they know it would be more expensive.

Quote
and the other launch vehicles may be no good  to go to mars.

They would be good enough.

If you want to go faster, then you'll need to get rid of SLS or get a bigger NASA budget. Both seem unlikely for the next couple of years.
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Offline savuporo

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So if we have launch vehicles why is NASA not using them .
Because of politics. Read some other threads here.

With out politics getting in way of these threads than may be the people here at this web site and other web sites should sign a petition that 10 years is unacceptable.

Oh im sure a lot would. In fact, there are a lot of space advocacy organizations around to help you with your quest. Try SFF, NSS , CSF if you want to organize something.
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Offline nec207

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The commercial competition are not planning to go to mars any time soon.

That me say this again if the SLS is the same or more costly than the apollo program ,space shuttle or project constellation proposed by president Bush that all got slash do to cost. Than it is a knownen fact that SLS is going to get scrapped before the first flight or after 2 or 3 launches.

Only if this brings space cost down or is much cheaper of putting payload into space.It would have to be cheaper than the apollo program ,shuttle program or project constellation if NOT it will be doomed like those programs too.
« Last Edit: 09/20/2011 12:50 am by nec207 »

Online mmeijeri

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The commercial competition are not planning to go to mars any time soon.

Neither is NASA, but even if it were, it still wouldn't be a problem. NASA can buy their launch services to launch the spacecraft and the vast quantities of propellant needed to get to Mars and back. No special capabilities are needed, launching to LEO and/or L1/L2 would be enough, what matters is cost per kg of payload. And that same metric is what counts for commercial development of space, something I'm passionate about. Dramatically lower launch prices ($100-$1,000/kg instead of the $10,000/kg we have today) are the holy grail of space launch and have been for decades. With it, we'll have the entire solar system. Without it we'll have Apollo on Steroids or a lunar ISS at best and yet another cancellation at worst.

Quote
That me say this again if the SLS is the same or more costly than the apollo program ,space shuttle and project constellation proposed by president Bush that all got slash to to cost. Than it is a know fact that SLS is going to get scrapped before the first flight or after 2 or 3 launches.

That seems likely. And from the perspective of someone who passionately wants to see commercial development of space, it is the least bad thing we can hope for. Because after that, maybe we could give competitive procurement another try. Depressing, isn't it?

Quote
Only if this brings space cost down or much cheaper of putting payload intospace.It would have to be cheaper than the apollo program ,shuttle program and project constellation if NOT it will be doomed like those programs too.

Not even its proponents claim it can make space launch radically cheaper.
« Last Edit: 09/20/2011 01:18 am by mmeijeri »
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In response to the question in the original post, the cheapest and fastest way to go to the Moon or Mars is to first go to a "Cis-Lunar Base Camp."  Mountaineers use this approach with great success.  The Moon and Mars are the equivalents of the mountain tops.  Low-Earth orbit equates to the nearest city or town.  Somewhere outside of town, right near the base of the mountain peaks, mountaineers establish base camp.  Space exploration efforts will benefit from establishing the equivalent.  I believe these will be placed in quasi-orbits associated with the L1 or L2 Lagrange points in the Earth-Moon system.

It really won't matter too much whether explorers get themselves and their equipment to the base camps on a large launcher like SLS, or medium launchers like the EELVs, Ariane, Proton, and HLV.  In any case it will take a sequence of launches to assemble the expedition elements at the base camp.  Only after that can the equivalent of the mountain ascent really begin!
« Last Edit: 09/20/2011 12:58 am by sdsds »
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It really won't matter too much whether explorers get themselves and their equipment to the base camps on a large launcher like SLS, or medium launchers like the EELVs, Ariane, Proton, and HLV.

Not from the point of view of technical feasibility, but it will matter greatly from the point of view of doing it in the cheapest and fastest way.
« Last Edit: 09/20/2011 01:20 am by mmeijeri »
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Offline 93143

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nec207, you should be aware that you've wandered into a crowd of anti-SLS posters who are apparently trying to push their opinions on you as facts...

The answers to the questions of "which launcher is cheaper/faster/better for lunar/Mars missions" depend on assumptions about architecture and mission rate.  SLS is expensive if you don't use it much, but as you ramp up it gets cheaper faster than the smaller rockets do.  Remember also that the in-space elements are a substantial part of the cost; it isn't all about the rocket.  One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

So, much as we would like there to be a simple answer, there isn't.
« Last Edit: 09/20/2011 01:54 am by 93143 »

Online mmeijeri

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
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Offline savuporo

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The answers to the questions of "which launcher is cheaper/faster/better for lunar/Mars missions" depend on assumptions about architecture and mission rate. 
Thats exactly what this evil crowd has been trying to hammer home here : if the goal is just to get a human, not necessarily a live one and not necessarily in one piece to lunar surface, then shooting a coffin through TLI on an absolute cheapest rocket possible is the way to go.

The problem with this thread is, still, that the goal of actually "landing people on moon or mars" is not specified, SLS or no SLS.
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Offline 93143

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should.

Yes, it does, even if you allow for propellant transfer.  The objective is not a flags-and-footprints mission; we want to get serious infrastructure out there.  (Or not, but IMO the answer to the thread's question does depend on this.)

Landing a reasonably large payload on Mars with a biconic aeroshell, for instance, takes a bigger rocket than anything we've currently got, simply because of the size of the aeroshell (not to mention its mass).  Also, for a large piece of equipment (say a backhoe, or a surface nuclear plant), the lander (not counting the aeroshell) could very easily exceed the capacity of a current launch vehicle even without propellant...

In fact, landing any human mission on Mars without larger payload fairings than we've currently got is an unsolved problem, and there is no guarantee that we can solve it in a way that works better than just using an HLV (no, fully propulsive EDL doesn't count, not without a detailed trade study backing it).

Say you want to do a fast transit using VASIMR, on the order of the infamous 39-day example - the power plant and engine module will both be quite heavy, and very much the sort of thing you want to launch in as few pieces as possible.

Even a lunar mission benefits in terms of operational simplicity, schedule, and even safety, if you just launch the whole stack in one shot, tank up the EDS at a depot, and go.

You can get around most difficulties (not necessarily all) with some ingenuity and perhaps some handwaving, but to pretend they aren't there, to pretend that an HLV provides no enabling or easing capability for anything we might ever want to do, is not the way to treat a new poster...  as far as I can tell from your posts, you seem to be a commercial cheap lift monomaniac of sorts; you literally don't care how complicated and marginal the BEO architecture gets, so long as it takes a lot of launches to put together.

Quote
As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...

You wouldn't know that from the last two pages of this thread; hence my comment...
« Last Edit: 09/20/2011 03:12 am by 93143 »

Offline savuporo

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The objective is not a flags-and-footprints mission; we want to get serious infrastructure out there.  (Or not, but IMO the answer to the thread's question does depend on this.)
See right there, perfect example of assumptions that people enter the discussions with and fail to check at the door. See, the thread topic is "how to get human(s) to the moon OR mars in the fastest and cheapest way possible" and you start speaking about serious infrastructure.

Yours is a valid and fine goal, i'd be fully behind that, but its got nothing to do with the optimum solution for the question at hand.

I keep ranting about this, as i feel if people would start more seriously articulating the end goals the discussions would be far more fruitful.
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Offline 93143

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That depends on what he means by "go to the moon or mars" (I did acknowledge this).

When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface.  When they said "and on to Mars", I assume the sentiment was similar.

As you say, there can be assumptions wrapped up in these questions.  Our friend the OP earlier expressed the sentiment that Orion, which he and everyone else agreed was too small for a Mars mission by itself, was "small" even for the moon.  Since it is twice the size of Apollo, which did the job, this sentiment cannot be founded on hard requirements; it is a preference only.

...

Besides, I was talking to mmeijeri, who had stated categorically that HLVs do not help at all, even for Mars, if you have propellant transfer (he didn't even say depots).  I don't think even he truly believes that, not as a general statement covering the full subspace of reasonable program objectives and constraints.
« Last Edit: 09/20/2011 03:09 am by 93143 »

Offline nec207

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That seems likely. And from the perspective of someone who passionately wants to see commercial development of space, it is the least bad thing we can hope for. Because after that, maybe we could give competitive procurement another try. Depressing, isn't it?


I`m not sure if that is a bad thing or not. Really if that happance NASA would do one of 2 things one get out of the rocket business and pay the private sector to get in space from now on or come up with other plan that may or may not work and yet back to where we are again.


On the down side NASA would waste 30 years of staggering progress.

Offline luke strawwalker

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I still do not know if SLS is going to be cheaper than any of the other launch vehicles .

It is certain to be more expensive if you count development costs, as you should. In fact that is precisely why certain influential politicians want it.


It may be more expensive to built it but it may be cheaper to put payload in space and the other launch vehicles may be no good  to go to mars.

Mars is SO far out to the right on the schedule as to be off the map, IMHO. 

This is a LARGE part of why everything's so expensive and nothing is getting done. Planning for Mars NOW is rather rediculous, because we can't even REALISTICALLY see when a Mars mission is likely to happen, what the mission mode/hardware would be, and most importantly, HOW TO FUND IT. 

Basing the launcher requirements we're developing NOW on some nebulous idea about "what's going to be required" for a Mars mission in two or three decades is about as foolish as Ford or Chevy worrying about what design changes to their pickup trucks will require in 2030 and incorporating that into the design for next years model...

It's all an expensive guessing game and the problem is, it's impeding progress and costing REAL money, RIGHT NOW, for something that is totally over the horizon and that can only be GUESSED at as to how it will eventually be done or what it will require. 

We should focus on the shorter term goals, keep some flexibility in the design to make upgrades a little easier down the road, and GET ON WITH IT! 

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Offline notsorandom

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
Propellant transfer doesn't solve the problem of Mars EDL. To land humans on the surface of mars the lander needs an entry mass of 100-150mt. The percentage of a Mars lander that is fuel is not above 50 percent meaning that a Falcon Heavy could not lift one dry. In other words the unfueled mass of the lander is still too much for LVs smaller then SLS to launch into LEO. That does not mean that we need the whole 130mt of SLS with propellant transfer, the version without the upper stage may be enough.

Another issue current launcher will have with getting a Mars lander into LEO will be the diameter of the heat shield. The extra fairing diameter of up to 10 or 12 meters will really simplify things compared with the 5m of currently available launchers.

Mars EDL is a huge challenge. With our current technology most of Mars' surface is inaccessible and we can not put more then 1mt on the ground. I'm attaching a presentation on crewed Mars EDL if people are interested.

Offline luke strawwalker

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SLS is expensive if you don't use it much, but as you ramp up it gets cheaper faster than the smaller rockets do.

 

Don't forget to tell him that this is EXACTLY how it's being planned to be used...

SLS isn't going to be used enough to justify the costs of it.  IF it were used MORE, as the basis of a vibrant and ongoing exploration effort, it would make sense...  Even DIRECT'S flightrates/figures proved that... 

At these "one flight every couple years or so" flight/mission rates, it's a total waste.  Something I pointed out in the DIRECT threads when the discussion turned to "how cheap it'd be" flying 8 or more times a year, compared to Cx flying twice a year... BUT of course that ASSUMES that NASA WANTS to fly the thing 8 times a year (which they don't, and didn't, and won't... there's no money for the missions or payloads at the higher flight rate). 

We could do missions every other year using existing EELV's with a few more launches and in-space assembly.  Sure it's more complex and extra launches cost money, but compared to developing and maintaining an HLV capability and its infrastructure and workforce with NO other use or cost sharing, just to fly it every couple or three years?? 

I KNOW EELV-based missions would be cheaper under THOSE circumstances... Not all some of us might hope for, but doable...

Later!  OL JR :)
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Offline savuporo

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When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface.  ..

... while completely failing to articulate any end goals for such antics.

You see, because if all you want is to have a few government employees sitting in a lunar base with no particular purpose and "flying sorties", your optimal mission architectures will still be very significantly different from other types of lunar bases, where you might want to focus on things like industrializing moon, developing key technologies for eventual settlement, or just building a huge theme park for hundreds of wealthy tourist to visit.

The "why" and goals discussion goes a little deeper than how many NASA astronauts and how often. This seems to bother a lot of people ..
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Offline nec207

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The objective is not a flags-and-footprints mission; we want to get serious infrastructure out there.  (Or not, but IMO the answer to the thread's question does depend on this.)
See right there, perfect example of assumptions that people enter the discussions with and fail to check at the door. See, the thread topic is "how to get human(s) to the moon OR mars in the fastest and cheapest way possible" and you start speaking about serious infrastructure.

Yours is a valid and fine goal, i'd be fully behind that, but its got nothing to do with the optimum solution for the question at hand.

I keep ranting about this, as i feel if people would start more seriously articulating the end goals the discussions would be far more fruitful.


I do not have a problem with SLS it looks cool we can get big things in space and think big !! I do fear it may not be the fastest way to get to the moon or mars or will bring same cost down.

I say again if it is the same or more than the apollo program ,shuttle program or project constellation if is doomed like the apollo program ,shuttle program or project constellation.


NASA is not part of the air force or DOD that get all the money and nice toys .NASA gets very little money and and goals change faster than they can test or built it that is the way it is.

If space cost can go down by 50% or more the cost than it is today this would not be a problem and more countries could be going in space than the US,China and Russia.

The holy grail is to bring space cost down.
« Last Edit: 09/20/2011 03:33 am by nec207 »

Offline 93143

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I say again if it is the same or more than the apollo program ,shuttle program or project constellation if is doomed like the apollo program ,shuttle program or project constellation.

Shuttle wasn't cancelled due to costs.  It lasted 30 years, and would have kept right on going if it weren't for the Columbia accident.

SLS looks like it will cost significantly less per year to keep going than the Shuttle did.

SLS isn't going to be used enough to justify the costs of it.

Don't you think that's a little premature?  The very low flight rates you complain of are not "the plan", still less any sort of best-case scenario (as you occasionally catch h8ers on here claiming).  It's certainly possible it will go sour, but it's a bit early to claim it already has...

Positive, as will many of the negative votes when they see the improved schedule and flight rate.

I'm just waiting to see what Phil was talking about...  I haven't missed anything, have I?

When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface.  ..

... while completely failing to articulate any end goals for such antics.

You see, because if all you want is to have a few government employees sitting in a lunar base with no particular purpose and "flying sorties", your optimal mission architectures will still be very significantly different from other types of lunar bases, where you might want to focus on things like industrializing moon, developing key technologies for eventual settlement, or just building a huge theme park for hundreds of wealthy tourist to visit.

The "why" and goals discussion goes a little deeper than how many NASA astronauts and how often. This seems to bother a lot of people ..

You're missing my point.  All I meant was that "go to the moon or mars" can carry the sort of unstated assumptions you're complaining about, and thus it is unjustified to assume it means a minimalistic stunt mission.  Especially when the question seems to have been about launch vehicles specifically.

Also, if we do go back to the moon, I suspect it will have something to do with those polar craters...
« Last Edit: 09/20/2011 03:54 am by 93143 »

Offline nec207

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When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface.  ..

... while completely failing to articulate any end goals for such antics.

You see, because if all you want is to have a few government employees sitting in a lunar base with no particular purpose and "flying sorties", your optimal mission architectures will still be very significantly different from other types of lunar bases, where you might want to focus on things like industrializing moon, developing key technologies for eventual settlement, or just building a huge theme park for hundreds of wealthy tourist to visit.

The "why" and goals discussion goes a little deeper than how many NASA astronauts and how often. This seems to bother a lot of people ..


For the past 50 years progress is staggering do to cost , programs get cut or do not run for long.Ask most people in the 60`s thay would say by 2015 we would have been to every place in the solar system and have moon base and mars base. And by 2050 or less people living on mars and the moon.

The American people have lost interest in space that space would be scfi do to cost .

Some one was saying people have a short attention span they do and for NASA to be this cool thing they cannot and for more than the 3 countries to put people into space they cannot .Why do to cost.

For NASA to run programs that do not turn into like the apollo program , shuttle program , x-programs like x-33 or x-38 or project constellation they cannot do to cost.

No one hear is saying space cost has to come down where your typical American middle class can pay to go in space that would be scfi.But bring space cost down where more than the 3 countries can go in space or NASA can do stuff that does not turn into like the apollo program , shuttle program , x-programs like x-33 or x-38 or project constellation .

I do fear SLS may not be the fastest way to get to the moon or mars or will bring same cost down and turn into like the apollo program , shuttle program , x-programs like x-33 or x-38 or project constellation .
« Last Edit: 09/20/2011 03:59 am by nec207 »

Offline savuporo

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You're missing my point.  All I meant was that "go to the moon or mars" can carry the sort of unstated assumptions you're complaining about, and thus it is unjustified to assume it means a minimalistic stunt mission.  Especially when the question seems to have been about launch vehicles specifically.
Its equally unjustified to assume any other specific space cadet fantasy, like i dont know .. going there do dig out TMA-1 or whatever.

Its especially unjustified to try and shoehorn in a particular end goal specifically tailored to meet a particular yet-to-be-built launch vehicle constraints.

There are lots of launch vehicles in existence that can carry out all sorts of lunar or martian missions, have done so in recent past and will be doing so in near term future. Most of the current ones are very specifically oriented to meet specific scientific goals, but the vehicles launching these are obviously not limited to either minimalistic stunts or grandiose paint-the-moon-red visions.
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Offline savuporo

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For the past 50 years progress is staggering do to cost , programs get cut or do not run for long.Ask most people in the 60`s thay would say by 2015 we would have been to every place in the solar system and have moon base and mars base. And by 2050 or less people living on mars and the moon.

If people "living on the mars and moon by 2050" is your end goal, then the launch vehicle choice to get there soon and fast is about the last thing you want to worry about.

How about trying to figure out how could they actually live there, how would they sustain themselves and who would pay for it ? From there, you can start working backwards trying to identify which technologies and funding sources are we still lacking for this to happen, what are the realistic timescales do obtain these, and so on.
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Offline nec207

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Shuttle wasn't cancelled due to costs.  It lasted 30 years, and would have kept right on going if it weren't for the Columbia accident.

SLS looks like it will cost significantly less per year to keep going than the Shuttle did.

The Shuttle was safe for the first prototype and I`m sue the x-33 would been safer and the next Shuttle or space plane safer yet.

It is PR move that the Shuttle was not safe. That me say this no rocket ,Shuttle or space plane is safe.

And if you think you can go to moon or mars and not have a accident evey 8 years or so you are living in scfi world  , going in space is not safe and never will be for a long time .

Over years to the bugs are worked out and building things that are safer but never be like air plane or a car.

Has for Shuttle it got cut for 3 reasone .

----cost
----MASA admin never like the Shuttle and wanted to go back to apollo program and this was way to do it.
----People in the US lost intrest in space and do to the accident need a PR move to get support for a new project.

Even if the accident never happen it would have not have gone on for too much longer the Shuttle was way over do . And NASA doing LEO people in US lost interest.

« Last Edit: 09/20/2011 04:18 am by nec207 »

Offline Robotbeat

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That depends on what he means by "go to the moon or mars" (I did acknowledge this).

When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface....
None of those things require a larger launch vehicle than we have now, so why accuse those who (correctly) say that current launch vehicles are adequate of being "anti-" whatever?
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Offline Robotbeat

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
Propellant transfer doesn't solve the problem of Mars EDL. To land humans on the surface of mars the lander needs an entry mass of 100-150mt....
That's just plain false.

If you land an empty ascent vehicle beforehand that becomes filled with ISRU-derived propellants, nothing even near 100mT is needed as an entry mass (probably could make do with just 10mT or less landed dry mass at a time...). And besides, 100mT entry mass still requires ballutes or other more difficult EDL technology.

Heck, the Apollo lunar module, which could probably fit 3 in a pinch (after all, Apollo 17 had over 100kg of samples, plus the two astronauts), and had enough delta-v for a Mars ascent vehicle (if not thrust) weighed only about 4 or 5 tons dry and could have considerable weight shaved off if it used modern electronics and batteries and aluminum-lithium alloys

It also depends if you want a crew of 8 (like some of the Mars architectures had) or a smaller crew of 6, 4, or even 2 (say, for the short-stay missions... some crew could stay on orbit, ala Apollo).
« Last Edit: 09/20/2011 04:42 am by Robotbeat »
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Offline 93143

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I do fear SLS may not be the fastest way to get to the moon or mars

The fastest way may not be the best way.  If it can be shown that a sprint mission using existing vehicles would result in an overly constrained architecture (and for Mars at least, this is very likely), it would be better to take a bit more time and get it right.

This also raises the question of why we are going to the moon and Mars; ie: what do we intend to do there?  This does drive the architecture design.

Spacecraft are expensive too, and not just because the launchers are expensive.  Rockets aren't the whole story.

Its especially unjustified to try and shoehorn in a particular end goal specifically tailored to meet a particular yet-to-be-built launch vehicle constraints.

Your bias is showing.  I didn't do any shoehorning; I was responding (I've already told you this, and you didn't listen) to a claim from mmeijeri that an HLV doesn't help if you have prop transfer.  Period.  This is obviously incorrect, since plausible scenarios and goals can be (and have been) laid out that do benefit from an HLV even with prop transfer taken into account.

I didn't say that was necessarily what we were going to do.

But it does seem that in your rush to be broadminded about this, you are ignoring the fact that the manned missions that actually seem worth doing all seem to benefit in some way from an HLV.  Whether this justifies the cost of the HLV is a separate question, but if we could have our pick of rockets at no cost, we would use an HLV for these missions, because it helps with architecture design.

You do realize the OP was talking about manned missions, right?

That depends on what he means by "go to the moon or mars" (I did acknowledge this).

When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface....
None of those things require a larger launch vehicle than we have now, so why accuse those who (correctly) say that current launch vehicles are adequate of being "anti-" whatever?

That depends on your definition of "require".  You could technically do it, but it would help immensely to at least have ACES with the depot option.

Offline savuporo

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That depends on what he means by "go to the moon or mars" (I did acknowledge this).

When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface....
None of those things require a larger launch vehicle than we have now, so why accuse those who (correctly) say that current launch vehicles are adequate of being "anti-" whatever?
Plus, its not even the most cost-optimal or time-optimal way of doing any of these things, for whatever purpose.
The claims around here are that under some circumstances, restrictions and conditions SLS and HLVs in general would start to make sense, but nobody has explained what these constraints would be. Presumably because these would be very contrived indeed.

Launch a caterpillar D9 bulldozer to the moon in one piece ? Even that doesnt need an SLS, you know.
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Offline nec207

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For the past 50 years progress is staggering do to cost , programs get cut or do not run for long.Ask most people in the 60`s thay would say by 2015 we would have been to every place in the solar system and have moon base and mars base. And by 2050 or less people living on mars and the moon.

If people "living on the mars and moon by 2050" is your end goal, then the launch vehicle choice to get there soon and fast is about the last thing you want to worry about.

How about trying to figure out how could they actually live there, how would they sustain themselves and who would pay for it ? From there, you can start working backwards trying to identify which technologies and funding sources are we still lacking for this to happen, what are the realistic timescales do obtain these, and so on.


That not going to happen for a long time .The typical American middle class going in space or to a space station for 5 days will not happen for a long time and for a typical American middle class to live on the moon or mars that is way beyond today's technology.

Not only would space cost have to come down it would have to come down so much a typical person going into space would cost $2,000 and $2,000 a day on space station and that number is way beyond today's technology.


They can bring space cost down where space mining is real or moon base or mars base but not your typical American middle .

If all goes well may be just may be less than 1% of  richest person can go in space for 2 or 3 hours or on a space station for 4 days but that is all.

No one not even the less than 1% of  richest person could go to the moon or mars that alone live there for a month.

It cost lots of money to go in space and to stay up there that only Astronautes can do that the government pay.

Offline savuporo

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And with this last post, this thread has become officially too silly.

It does not appear to be worth taking any further.
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Offline 93143

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The claims around here are that under some circumstances, restrictions and conditions SLS and HLVs in general would start to make sense, but nobody has explained what these constraints would be. Presumably because these would be very contrived indeed.

This is ridiculous.  Nothing but handwaving.  You're the one who has been saying incessantly that we can't define the requirements until we know the goals - and now you're trying to define the requirements without providing so much as a number by way of analysis?

Have you read any of the DIRECT threads?  The DRM 5.0?  Are you aware of the flaws that have been noted in the "Mars For Less" mission plan?  Even "Mars Direct" uses an HLV; the version that uses Falcon Heavy was just painful...

Apparently, according to you, if you can theoretically do something without an HLV, it doesn't "make sense" to use an HLV, no matter how difficult or expensive or dangerous or time-consuming the alternative is.

It's not all about the rocket.

Offline nec207

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That depends on what he means by "go to the moon or mars" (I did acknowledge this).

When Constellation fans said "go back to the moon", they didn't mean "fire someone's ashes into a crater with a Pegasus".  They meant a permanently-manned base, operating in parallel with sortie missions using large pressurized rovers all over the lunar surface....
None of those things require a larger launch vehicle than we have now, so why accuse those who (correctly) say that current launch vehicles are adequate of being "anti-" whatever?
Plus, its not even the most cost-optimal or time-optimal way of doing any of these things, for whatever purpose.
The claims around here are that under some circumstances, restrictions and conditions SLS and HLVs in general would start to make sense, but nobody has explained what these constraints would be. Presumably because these would be very contrived indeed.

Launch a caterpillar D9 bulldozer to the moon in one piece ? Even that doesnt need an SLS, you know.

He is saying SLS or HLV`s are much cheaper at putting lots of tons into space.And much faster than going up many times and than the construction of putting it all together .It is faster and cheaper to send SLS than having to go up 15 or 20 times.

To go to mars or space mining you need SLS from what people say may be not the moon but mars or space mining you need SLS .

Offline nec207

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And with this last post, this thread has become officially too silly.

It does not appear to be worth taking any further.

Stop watching scfi shows and start talking to rocket engineers and you will see why that is not possible with today's technology.

Offline 93143

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He is saying SLS or HLV`s are much cheaper at putting lots of tons into space.

...not necessarily.  It depends on how many tons and what you're comparing it to.

Quote
And much faster than going up many times and than the construction of putting it all together .It is faster and cheaper to send SLS than having to go up 15 or 20 times.

You're stating it too simply.  15 or 20 EELV Heavy launches per year does seem to be in the general vicinity of the breakpoint where SLS is cheaper, though Falcon should still beat it, at least to LEO.  It's the spacecraft costs, complexity, technical risk, and extra mass overhead that may (depending on exactly what it is you're doing) make SLS the best choice.

Faster?  Yes.  I will give you that.

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To go to mars or space mining you need SLS from what people say may be not the moon but mars or space mining you need SLS.

Asteroid mining is not really near-term, even in the way Mars is.  And the word "need" may be a bit strong.  But it can help.  Perhaps a lot, if the program is bold and robustly funded (always the catch).
« Last Edit: 09/20/2011 05:07 am by 93143 »

Offline nec207

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You're stating it too simply.  15 or 20 EELV Heavy launches per year is close to the breakpoint where SLS is cheaper,

With out SLS or HLV you will have to go up many times 15 or 20 times to put all those little tons to make one big ton that is where it may be more costly and take longer to get to where you are going.

Quote
though Falcon should still beat it, at least to LEO.  It's the spacecraft costs, complexity, and extra mass overhead that may (depending on exactly what it is you're doing) make SLS the best choice.
SLS can put 130 tons in space in one shot I do not think Falcon can come any where close.

What does spacecraft costs, complexity, and extra mass overhead have to do with Launch vehicle.

Quote
Space mining is not really near-term, even in the way Mars is.  And the word "need" may be a bit strong.  But it can help.  Perhaps a lot, if the program is bold and robustly funded (always the catch).

Well Obama proposed going to mars and doing space mining some where around 2025 or 2030.
« Last Edit: 09/20/2011 05:14 am by nec207 »

Offline 93143

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You're stating it too simply.  15 or 20 EELV Heavy launches per year is close to the breakpoint where SLS is cheaper,

With out SLS or HLV you will have to go up many times 15 or 20 times to put all those little tons to make one big ton that is where it may be more costly and take longer to get to where you are going.

...isn't that what I just said?

Quote
Quote
though Falcon should still beat it, at least to LEO.  It's the spacecraft costs, complexity, and extra mass overhead that may (depending on exactly what it is you're doing) make SLS the best choice.
SLS can put 130 tons in space in one shot I do not think Falcon can come any where close.

No, it can't.  As far as I'm aware, there isn't a Falcon in serious development that could hit that number, although concepts have been tossed around.

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What does spacecraft costs, complexity, and extra mass overhead have to do with Launch vehicle.

They're things you can end up with more of if your launch vehicle is too small for the mission you're trying to do.

Quote
Quote
Space mining is not really near-term, even in the way Mars is.  And the word "need" may be a bit strong.  But it can help.  Perhaps a lot, if the program is bold and robustly funded (always the catch).

Well Obama proposed going to mars and doing space mining some where around 2025 or 2030.

First, you misinterpreted him.  He said "touch" an asteroid, not "mine" an asteroid.  The latter is considerably more difficult, and wouldn't make money without massive cost reductions in launch vehicles and spacecraft.

Second, who cares what Obama said?  He'll be long gone by then, and he's no JFK.  Bush said we're going back to the moon and on to Mars.  Maybe we are.  Certainly the ice in the moon's polar craters is interesting as a resource to use for further exploration, and we've always been going to Mars (eventually).  But judging by the way people have been talking for the last year and a half, what Bush said is no longer relevant.  I don't expect what Obama said to be held relevant six years from now, never mind fifteen or twenty.
« Last Edit: 09/20/2011 05:35 am by 93143 »

Offline notsorandom

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
Propellant transfer doesn't solve the problem of Mars EDL. To land humans on the surface of mars the lander needs an entry mass of 100-150mt....
That's just plain false.

If you land an empty ascent vehicle beforehand that becomes filled with ISRU-derived propellants, nothing even near 100mT is needed as an entry mass (probably could make do with just 10mT or less landed dry mass at a time...). And besides, 100mT entry mass still requires ballutes or other more difficult EDL technology.

Heck, the Apollo lunar module, which could probably fit 3 in a pinch (after all, Apollo 17 had over 100kg of samples, plus the two astronauts), and had enough delta-v for a Mars ascent vehicle (if not thrust) weighed only about 4 or 5 tons dry and could have considerable weight shaved off if it used modern electronics and batteries and aluminum-lithium alloys

It also depends if you want a crew of 8 (like some of the Mars architectures had) or a smaller crew of 6, 4, or even 2 (say, for the short-stay missions... some crew could stay on orbit, ala Apollo).
I spent the evening looking over a few proposed Mars missions. Haha I didn't have anything better to do. Your claim that 10mt or less could would work doesn't seem doable. DRM 5 thinks 40mt is the smallest individual piece. Mars Direct uses ISRU and it requires the ability to land 28,500 kg on the Martian surface. The habitat, power, and life support is over 10mt for a crew of four. Its something that can't really be split up into smaller pieces.That doesn't include any consumables, lab equipment, space suits, rovers, backup spares, or astronauts. A crew of four is going to require 10.4mt of consumables alone. The ISRU parts don't fit under 10mt either.

For safety reasons the crew is going to need to land with plenty of consumables, a long range rover, and a habitat in case they land too far the other mission elements such as their ride home. A lot has to land with the astronauts in order to reduce the risk of an off target landing. Once again going by the Mars Direct figures that is going to be more then 10mt. The lowest mass landed element I can realistically and safely cobble together is at least 16mt from the elements in Mars Direct. I bet there was good reason to not even go that small by the study's authors.

I'm not saying that the full 130mt SLS is needed for a Mars mission. However, it looks like the Falcon Heavy is too small for the job even with advanced EDL technology, ISRU, and propellant depots. Its been proposed that the core version of SLS with a 70-100mt payload and propellant depots could be the best way to go. There would need to be more study of this concept but personally I am leaning in that direction.

Its interesting that in many proposed Mars mission I read over while compiling this post a lander mass around 130mt kept showing up. Anyone want to bet where the 130mt SLS payload requirement came from?
« Last Edit: 09/20/2011 07:08 am by notsorandom »

Offline MikeAtkinson

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
Propellant transfer doesn't solve the problem of Mars EDL. To land humans on the surface of mars the lander needs an entry mass of 100-150mt. The percentage of a Mars lander that is fuel is not above 50 percent meaning that a Falcon Heavy could not lift one dry. In other words the unfueled mass of the lander is still too much for LVs smaller then SLS to launch into LEO. That does not mean that we need the whole 130mt of SLS with propellant transfer, the version without the upper stage may be enough.

Another issue current launcher will have with getting a Mars lander into LEO will be the diameter of the heat shield. The extra fairing diameter of up to 10 or 12 meters will really simplify things compared with the 5m of currently available launchers.

Mars EDL is a huge challenge. With our current technology most of Mars' surface is inaccessible and we can not put more then 1mt on the ground. I'm attaching a presentation on crewed Mars EDL if people are interested.

DRM 5.0 used an EDL stage of about 60 tonnes, over 10 tonnes of which was fuel. Mass wise FH seems adequate. FH could almost certainly not lift a 12 m biconic aeroshell like DRM 5.0 used, however there are many approaches to Mars EDL and it is not obvious (to me at least) that some of these would not be possible using FH.

All other elements of DRM 5.0 (those that opperate separately for some of the mission) are under 50 tonnes unfuelled.

The same could be said of Lunar missions the largest element that opperates separately is under 50 tonnes.

There seem to be few integration advantages of launching elements that have to opperate separately on the same flight. There probably are significant opperational advantages due to less mission complexity, but in my opinion they are not large enough to necessitate lanchers with payloads to LEO much greater than 50 tonnes.

It would have been much more sensible in my opinion to have a single core launcher of 40-50 tonnes to LEO with the option of a 3 core heavy version of 120-180 tonnes (depending on cross-feed) which could be implemented if needed.

Offline notsorandom

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
Propellant transfer doesn't solve the problem of Mars EDL. To land humans on the surface of mars the lander needs an entry mass of 100-150mt. The percentage of a Mars lander that is fuel is not above 50 percent meaning that a Falcon Heavy could not lift one dry. In other words the unfueled mass of the lander is still too much for LVs smaller then SLS to launch into LEO. That does not mean that we need the whole 130mt of SLS with propellant transfer, the version without the upper stage may be enough.

Another issue current launcher will have with getting a Mars lander into LEO will be the diameter of the heat shield. The extra fairing diameter of up to 10 or 12 meters will really simplify things compared with the 5m of currently available launchers.

Mars EDL is a huge challenge. With our current technology most of Mars' surface is inaccessible and we can not put more then 1mt on the ground. I'm attaching a presentation on crewed Mars EDL if people are interested.

DRM 5.0 used an EDL stage of about 60 tonnes, over 10 tonnes of which was fuel. Mass wise FH seems adequate. FH could almost certainly not lift a 12 m biconic aeroshell like DRM 5.0 used, however there are many approaches to Mars EDL and it is not obvious (to me at least) that some of these would not be possible using FH.
I noticed that too. That is the lander mass with out the aeroshell or payload. Integrating those three things in orbit would be a a very complex operation. I don't know what it would take to load the payload in the lander while in LEO but its hard enough to integrate a payload in a LV on Earth. All this would have to be done in zero G with only a few astronauts rather then on Earth with the benefit of plenty of equipment and people. Even if it is doable it may not be worth the draw backs compared to going ahead with SLS. Having the whole thing assembled on the ground should allow for more through testing and a simpler, safer, and likely cheaper design.

Offline MikeAtkinson

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Its interesting that in many proposed Mars mission I read over while compiling this post a lander mass around 130mt kept showing up. Anyone want to bet where the 130mt SLS payload requirement came from?

Some of it seems to be circular reasoning, given a 130 tonne Ares V launcher what Mars mission can we design ( DRM 5.0 ) - its not surprising it came up with requiring a 130 tonne HLV.

Some of it seems to be optimising for least IMLEO (as a proxy for launch cost), this ends up with DRM 5.0 using NTR even though the development (and probably operational cost) will be more than chemical.

In my opinion although there have been many schemes for Mars missions, there is still lots of inovation required before we reach one that is close to optimum in terms of cost (or performance/cost). Whether it turns out that a 50 tonne launcher is adequate, or 130 tonne or 200 tonne is needed is an open question at present. As are such things as ISRU use of matian water, the health effects of martian gravity, whether artificial gravity is needed for the transhab, the mitigation strategies for cosmic rays.

Offline MikeAtkinson

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DRM 5.0 used an EDL stage of about 60 tonnes, over 10 tonnes of which was fuel. Mass wise FH seems adequate. FH could almost certainly not lift a 12 m biconic aeroshell like DRM 5.0 used, however there are many approaches to Mars EDL and it is not obvious (to me at least) that some of these would not be possible using FH.
I noticed that too. That is the lander mass with out the aeroshell or payload. Integrating those three things in orbit would be a a very complex operation. I don't know what it would take to load the payload in the lander while in LEO but its hard enough to integrate a payload in a LV on Earth. All this would have to be done in zero G with only a few astronauts rather then on Earth with the benefit of plenty of equipment and people. Even if it is doable it may not be worth the draw backs compared to going ahead with SLS. Having the whole thing assembled on the ground should allow for more through testing and a simpler, safer, and likely cheaper design.

I agree that it is unlikely to be easy, certainly not with the EDL scheme used by DRM 5.0. There seems to have been little work done on this however, and it is quite possible that some clever engineer will come up with a way.

The scheme used by DRM 5.0 does not optimise for dry IMLEO, given that propellant depots are going to be required for Mars missions with a 50 tonne launcher that opens up other options. A powered landing with ballute might for instance require 70 tonnes (dry) in LEO, and then fuel up with an extra 50 tonnes of propellant.

It would be embarassing, to say the least, if after 25 years and more than $50 billion spent on SLS it turned out that due to weight growth of the largest payload to be landed on Mars or optimism about future EDL techologies, the EDL + Payload mass turned out to be 150 tonnes.

Offline Ben the Space Brit

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Really, propulsion is everything.  With extant EDS-capable upper stages, there is currently no way of launching an EOR-assembly lunar mission where the crew ride out with the lander.  It is possible to send the cargo ahead using EOR and ion drive tugs and then send the crew out using two launches (one for Orion and one for the propulsion stage), although the time factor for crew launch would be very tight.

Realistically, crewed lunar missions must wait on the production of powerful enough upper stages that the time constraints on crew launch are relaxed.  That means waiting for SpaceX's Raptor and ULA's Common Centaur.  Both could launch an appropriately-equipped crew vehicle direct to LLO for a LOR mission.  Both could be available by ~2016

If you want to do EOR on your mission stack, you need to improve upper stage longevity.  That means ULA's ACES family or NASA's CPS.

Either that or go with propellent transfer instead.  Using prop transfer, you can launch the cargo 'dry', launch the Earth departure propellent with the crew, tank up the EDS after rendezvous and carry out TLI on Flight Day 2 or 3.  However, that's a hefty R&D program in its own right and would stretch out the timeline a lot.

If you want to land, you need to develop a lander.  There isn't any in serious development at the moment except the small Morpheus, which I believe was originally part of a plan to land Robonaut 2 on the Moon.  Scaling that up to serve as a two-way crew lander capable of supporting a significant service mission will be both expensive and take a while, even if the maximum number of lessons are learnt from Grumman's work on the LEM.

I'd say that, if you went by developing current medium ELVs, you could reach lunar orbit by 2018 for the Apollo 8 hemicenteniary and you just might get to the lunar surface by 2022 for the Apollo 17 hemicentiary.  Go with SLS and, whilst almost any realistic mass constraint is removed, the time-line shifts rightwards by as much as half a decade, mostly because of reduced mission development funds being available.
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Offline JohnFornaro

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I don't know how fast you all are going, but this sounded pretty fast to me:

From "Celestial Mechanics and Astrodynamics",1964, Victor Szebehely, editior, p. 56, there is a 36 hour trajectory to the Moon suggested.  It's seems like a lead and shoot trajectory.  Lead the Moon by a certain amount, fire off the rocket, and hit (not land, necessarily), 36 hours later.

It prompted me to ask about the delta-vee penalty for flying to the Moon, basically as fast as possible.
« Last Edit: 09/20/2011 02:44 pm by JohnFornaro »
Sometimes I just flat out don't get it.

Offline Robotbeat

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One of SLS's advantages, especially for Mars, is that it can launch very large pieces (both mass-wise and size-wise) in one shot, which helps with architecture design.

No, it doesn't, not if you allow for propellant transfer, as you should. As for crowds of anti-SLS posters: this whole site is pro-SLS by 2:1...
Propellant transfer doesn't solve the problem of Mars EDL. To land humans on the surface of mars the lander needs an entry mass of 100-150mt....
That's just plain false.

If you land an empty ascent vehicle beforehand that becomes filled with ISRU-derived propellants, nothing even near 100mT is needed as an entry mass (probably could make do with just 10mT or less landed dry mass at a time...). And besides, 100mT entry mass still requires ballutes or other more difficult EDL technology.

Heck, the Apollo lunar module, which could probably fit 3 in a pinch (after all, Apollo 17 had over 100kg of samples, plus the two astronauts), and had enough delta-v for a Mars ascent vehicle (if not thrust) weighed only about 4 or 5 tons dry and could have considerable weight shaved off if it used modern electronics and batteries and aluminum-lithium alloys

It also depends if you want a crew of 8 (like some of the Mars architectures had) or a smaller crew of 6, 4, or even 2 (say, for the short-stay missions... some crew could stay on orbit, ala Apollo).
I spent the evening looking over a few proposed Mars missions. Haha I didn't have anything better to do. Your claim that 10mt or less could would work doesn't seem doable. DRM 5 thinks 40mt is the smallest individual piece. Mars Direct uses ISRU and it requires the ability to land 28,500 kg on the Martian surface. The habitat, power, and life support is over 10mt for a crew of four. Its something that can't really be split up into smaller pieces.That doesn't include any consumables, lab equipment, space suits, rovers, backup spares, or astronauts. A crew of four is going to require 10.4mt of consumables alone. The ISRU parts don't fit under 10mt either.

For safety reasons the crew is going to need to land with plenty of consumables, a long range rover, and a habitat in case they land too far the other mission elements such as their ride home. A lot has to land with the astronauts in order to reduce the risk of an off target landing. Once again going by the Mars Direct figures that is going to be more then 10mt. The lowest mass landed element I can realistically and safely cobble together is at least 16mt from the elements in Mars Direct. I bet there was good reason to not even go that small by the study's authors.

I'm not saying that the full 130mt SLS is needed for a Mars mission. However, it looks like the Falcon Heavy is too small for the job even with advanced EDL technology, ISRU, and propellant depots. Its been proposed that the core version of SLS with a 70-100mt payload and propellant depots could be the best way to go. There would need to be more study of this concept but personally I am leaning in that direction.

Its interesting that in many proposed Mars mission I read over while compiling this post a lander mass around 130mt kept showing up. Anyone want to bet where the 130mt SLS payload requirement came from?
Mars DRMs are not the minimum required for landing humans. I'm talking about the minimum size, not even necessarily the optimum size.

So, you made lots of assumptions:
1) minimum surface crew size 4 (again, no reason why 4 is the minimum required for a short-duration mission)
2) precision landing can't be relied on (the lunar-roving-vehicle had a mass of only 210kg, and had a range with 2 astronauts of almost 100km... modern batteries could do better, maybe twice as long)
3) the size of power, consumables (for less than 30 days), etc, can't be reduced
4) Mars Direct is the best possible option for lowest mass elements (it already assumes an HLV, so if the conclusion after looking at Mars DIRECT is that you should use an HLV, you are begging the question).

All the astronauts REALLY need to land with in case of an off-nominal landing is a small unpressurized rover, a couple of space suits with enough consumables to last a day or so while they drive to their landing spot. OR, you make an off-nominal landing so unlikely that those things aren't required, or that even an off-nominal landing would be within walking distance or a remote-controlled rover with enough range can be pre-landed, etc.

Halving the crew could have the effect of nearly halving the minimum entry mass.  We have a 6-person manned outpost right now that has crew that gets there and back with only a 3-person spacecraft. So, even if you lower the minimum crew to 2 or 3 doesn't mean your outpost can't support higher numbers. Far more important than having large numbers is getting there at all, in my opinion.
« Last Edit: 09/20/2011 03:29 pm by Robotbeat »
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Offline Lobo

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Well, those are two very different questions.

If the question is, "What is the cheapest/fastest way to get to the Moon", then the answer is probably a 2-launch SpaceX FH with a new hydrolox upper stage.  SpaceX could develop one of their own, or ULA could develop ACES, which would be preferable for other reasons.  Plus they already have hydrolox upper stages and have been designing ACES for some time.  THey could probably get there faster and more reliable than SpaceX, which would be starting from scratch with a brand new engine and tech.
So NASA can buy FH from SpaceX, and ACES from ULA.  Stack them at the VAB themselves on the modified Ares 1 ML.  Like NASA did with the stages of Saturn.
I would imagine if that was the PoR, you could get there in about 4 years.  (Please correct me if I'm wrong).
But you need a lander.  I think ULA's ACES-lunar proposal is a good one, and probably the fastest and best for non wide body LV's.  It's all based around 5m diameter stages and horizontal landers.  So you don't have to put anything too wide on the 3.6m FH cores.
If that became the PoR right now, I don't know how many years it would take to get the lander developed and built.  I think we have to assume 6-7 years.  Orion  CSM should be ready by then. 
So, maybe by 2018? 

If the question is going to Mars.  then either you need a whole new system that can be used for the Moon, but is big enought o go to Mars, like SLS, FX, FXX, or AVP3a.  FH and ACES would probably be too small in scale for MArs. Maybe, maybe not.  BUt if MArs is the ultimate goal, then you probably want something of larger scale, with wider payloads for the Mars heat shield, which will need to be probably wider than you could put on an FH.  Unless you used an aeroshell or hypercone or something.

Just my $0.02.  :-)

Offline 93143

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Unless you used an aeroshell or hypercone or something.

DRM 5.0 already uses biconic aeroshells.  They're 10 m across and weigh 43 t.

Its interesting that in many proposed Mars mission I read over while compiling this post a lander mass around 130mt kept showing up. Anyone want to bet where the 130mt SLS payload requirement came from?

Some of it seems to be circular reasoning, given a 130 tonne Ares V launcher what Mars mission can we design ( DRM 5.0 ) - its not surprising it came up with requiring a 130 tonne HLV.

Looks like you may have missed something...  [emphasis added]

Offline A_M_Swallow

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{snip}

All the astronauts REALLY need to land with in case of an off-nominal landing is a small unpressurized rover, a couple of space suits with enough consumables to last a day or so while they drive to their landing spot. OR, you make an off-nominal landing so unlikely that those things aren't required, or that even an off-nominal landing would be within walking distance or a remote-controlled rover with enough range can be pre-landed, etc.

Alternatively the astronauts land in the pressurised rover.  At 4 tons the rover is a bit heavy for a lander cabin but not impossible.  The lander control panel will need including.  The ECLSS will have to be designed to work on both the planet and in microgravity.

Offline notsorandom

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I spent the evening looking over a few proposed Mars missions. Haha I didn't have anything better to do. Your claim that 10mt or less could would work doesn't seem doable. DRM 5 thinks 40mt is the smallest individual piece. Mars Direct uses ISRU and it requires the ability to land 28,500 kg on the Martian surface. The habitat, power, and life support is over 10mt for a crew of four. Its something that can't really be split up into smaller pieces.That doesn't include any consumables, lab equipment, space suits, rovers, backup spares, or astronauts. A crew of four is going to require 10.4mt of consumables alone. The ISRU parts don't fit under 10mt either.

For safety reasons the crew is going to need to land with plenty of consumables, a long range rover, and a habitat in case they land too far the other mission elements such as their ride home. A lot has to land with the astronauts in order to reduce the risk of an off target landing. Once again going by the Mars Direct figures that is going to be more then 10mt. The lowest mass landed element I can realistically and safely cobble together is at least 16mt from the elements in Mars Direct. I bet there was good reason to not even go that small by the study's authors.

I'm not saying that the full 130mt SLS is needed for a Mars mission. However, it looks like the Falcon Heavy is too small for the job even with advanced EDL technology, ISRU, and propellant depots. Its been proposed that the core version of SLS with a 70-100mt payload and propellant depots could be the best way to go. There would need to be more study of this concept but personally I am leaning in that direction.

Its interesting that in many proposed Mars mission I read over while compiling this post a lander mass around 130mt kept showing up. Anyone want to bet where the 130mt SLS payload requirement came from?
Mars DRMs are not the minimum required for landing humans. I'm talking about the minimum size, not even necessarily the optimum size.

So, you made lots of assumptions:
1) minimum surface crew size 4 (again, no reason why 4 is the minimum required for a short-duration mission)
2) precision landing can't be relied on (the lunar-roving-vehicle had a mass of only 210kg, and had a range with 2 astronauts of almost 100km... modern batteries could do better, maybe twice as long)
3) the size of power, consumables (for less than 30 days), etc, can't be reduced
4) Mars Direct is the best possible option for lowest mass elements (it already assumes an HLV, so if the conclusion after looking at Mars DIRECT is that you should use an HLV, you are begging the question).

All the astronauts REALLY need to land with in case of an off-nominal landing is a small unpressurized rover, a couple of space suits with enough consumables to last a day or so while they drive to their landing spot. OR, you make an off-nominal landing so unlikely that those things aren't required, or that even an off-nominal landing would be within walking distance or a remote-controlled rover with enough range can be pre-landed, etc.

Halving the crew could have the effect of nearly halving the minimum entry mass.  We have a 6-person manned outpost right now that has crew that gets there and back with only a 3-person spacecraft. So, even if you lower the minimum crew to 2 or 3 doesn't mean your outpost can't support higher numbers. Far more important than having large numbers is getting there at all, in my opinion.
It was not me who made those assumptions, it was the designers of many different studies. There is a lot of agreement across many different studies in what is needed on the surface of Mars to make the mission work. There is just no way to reduce the minimum size of some of those mission critical elements below 10mt.

1: A crew of 4 is necessary due to safety. If a crew member becomes incapacitated the rest of the crew can compensate. The work load to make it back to Earth safely is just to much for one or two people to handle on their own. Besides reducing the crew doesn't make the biggest single mission elements any smaller.
2: How far away can we land and still make it to the other elements of the mission? The longer that distance the safer the mission. An Apollo type rover isn't going to work. Astronauts can't spend more then a day in their suits. Its not like they can get out of them to eat and do other body functions. Even if precision EDL is 100% reliable it doesn't change the fact that there are other mission elements aside from the landing party bigger then 10mt.
3: 30 days of consumables is 624 kg. Any less air, water, and food and the astronauts are not going to make it 30 days. A closed loop system is going to add more mass then it saves for a period that short. If they could have been made any smaller in the studies they would have. The authors did not pad these figures just so that they would need an HLV.
4: I focused on Mars Direct because you stated that ISRU would make the largest single landed item less then 10mt. Mars Direct is the most complete and detailed study utilizing ISRU propellant production. I was only looking at the landed portions of Mars Direct, with the question what had to be on the surface? I did not look at their conclusions for any other part of the mission from an inch off the Martian surface all the way back to the Cape.

I am not looking at this from a bias claiming that SLS is absolutely needed or not. My perspective is what do we need on the surface of Mars. Trying to make mission elements smaller rapidly increases complexity and risk and there is a point at which they can't be made any smaller. Some of that we are just going to have to live with since we are not going to be building a rocket big enough to launch an entire Mars Mission in one go. The question is what is the optimum size of a LV? My take on all of this is that an HLV of 70mt is likely necessary and retires a significant amount of risk, cost, and complexity. That is the broad consensus of the professional community. Right now the only contender is SLS. If it were Atlas Phase II, Falcon XX, AJAX, Jupiter, or any other HLV in that range I would support that too because that is what it will take to do a Mars mission.

Offline Robotbeat

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Apollo had 2 surface crew. How did they do it?

I buy the argument that maybe more crew are needed for the long trips in case someone gets sick, etc, but that's for the trips to and from. The surface mission can be short enough that you can get by with a few crew at a time.

Early Mars mission proposals had 70 crew. Yup, 70.

It's necessary for us to think creatively, beyond just what the various Mars DRMs proposed, in order to do a Mars mission within our lifetimes. If that means only 2 or 3 crew per descent or ascent vehicle because of EDL constraints, then that shouldn't be a show-stopper since that's what we do with Soyuz right now anyways. Just use twice as many descent and ascent vehicles.

EDIT: Shuttle tells us that NASA thought you need to (or at least should) do crew rotations all at once. Yet, three-seated spacecraft seems to work just fine with 6 crew (though it needs backup, obviously). So, that a NASA-origin Mars DRM shows 6 or 8 crew per ascent/descent vehicle is no reason why you can't do just fine with a smaller ascent/descent vehicle (and just use two or three of them if you want a larger surface crew...)

Mars EDL techniques scale up poorly, so having small vehicles works out better from a physics and engineering perspective.
« Last Edit: 09/21/2011 02:54 am by Robotbeat »
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Offline MikeAtkinson

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Its interesting that in many proposed Mars mission I read over while compiling this post a lander mass around 130mt kept showing up. Anyone want to bet where the 130mt SLS payload requirement came from?

Some of it seems to be circular reasoning, given a 130 tonne Ares V launcher what Mars mission can we design ( DRM 5.0 ) - its not surprising it came up with requiring a 130 tonne HLV.

Looks like you may have missed something...  [emphasis added]

Most of the others assumed a HLV as well. The size of this HLV seems to have varied between 100 - 150 tonnes to LEO.

Proponents of HLV have almost always provided Mars missions (at least in outline) for their chosen launcher design.

Offline Patchouli

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The cheapest fastest way to Mars I think would be to use a spilt/sprint class architecture like the 1987 Ride report but leverage things like SEP and LEO assembly and if possible an L1 depot.
The crew will take sprint class trajectories keeping the total mission time under 450 days.
The cargo would take a more conservative Holman transfer and make use of solar sails or solar electric propulsion.
I'd use Falcon Heavy and the 48 mT Delta IV heavy upgrade as the primary launch vehicles.

As for the MTV I'd base it one or two or more BA330s and it would be assembled in LEO.
Crew size would be six with future options to 12.
The MTV would then spiral out to L1 under solar power then top off.
Since ion is being used to lift the bulk of the mass from LEO to L1 it might be preferable to use methane in place of hydrogen propellants and just deal with the lower ISP as it would make boil off a lot less of a problem.

Next the crew will meet with the MTV at L1 using Orion or Dragon and it's ACES derived departure stage would fire.
NTR would be nice to have here.

The lander and hab would have been sent ahead of time.
The first mission will only be a 20 day surface stay as to allow catching back to Earth before it gets too far away.
The lander and MAV would be based off either lunar lander systems or VTOL sub orbital.

No ISRU MAV would use NOFBX propellant while the ISRU MAV/Lander methane lox.

Entry system heat sheild would be based off inflatable technology or a biconic DCY shape.
http://www.nasa.gov/topics/aeronautics/features/irve.html

Return same MTV is used and 12 hours before reentry crew enters Orion or Dragon and does direct return.
MTV captures in high ellipse and uses ion propulsion or electrodynamic tether to slowly return to LEO.
The MTV also could simply be disposed of by reentry or being left in solar orbit or crashed into the moon.


« Last Edit: 09/21/2011 07:54 am by Patchouli »

Offline Warren Platts

IMO, the cheapest and fastest way to Mars would be a simple (as in pretty much fully propulsive), reusable (cheaper since it can be used over and over again), all chemical (faster than SEP), architecture that was evolved from previous spacecraft a la the ULA Lunar plan.

Zegler et al. say their DTAL lander could easily be evolved for use on Mars. My own BOTE calculations suggest that a stretched tank DTAL lander (i.e, an ACES-71) equipped with a heat resistant titanium hull (so it could withstand the full 1 W/cm2) could land fully propulsively--no ballutes, parachutes, or heat shields required.

Then the ULA MTV has a crew capacity of 16 and a nominal delta v of 11 km/sec. If there was refueling capability in Mars orbit, the ULA MTV could cut the 1-way transit times by over half compared to the Hohman transfer; if refueling was deemed impractical (probably the case for the initial missions), it would have enough delta v to do a round trip taking Hohman transfers. Again, this would all be fully propulsive--no heat shields required.

The 7 hundred tonnes of propellant would only cost about $350 million, if refueled at L2 (with Lunar derived LH2/LO2).

See, so the whole thing would be faster and cheaper, since it would be a simple evolution from the ULA Lunar architecture, which is itself a simple evolution from the Centaur 3rd-stage architecture.

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Offline DLR

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I don't think we will use fully propulsive Mars landers. Ever tried firing a rocket into a hypersonic jet stream coming at you?

A Mars lander derived from ULA's DTAL would probably be equipped with a conical aeroshell and maybe a ballute, with propulsion being used for final deceleration and descent only. That way you save a lot of propellant as well.

Mars' atmosphere is a resource. Use it.

Online mmeijeri

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It is unlikely heavy payloads can be landed without using propulsion for substantially more than final descent and landing. Of course that doesn't mean you don't want to use aerodynamic deceleration to the maximum degree possible.
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Offline Warren Platts

I don't think we will use fully propulsive Mars landers. Ever tried firing a rocket into a hypersonic jet stream coming at you?

That's not the way it would work: the main burn happens in orbit above the atmosphere, and the lander essentially falls straight down, subsonically, until it achieves a terminal velocity, and then there's another burn right at landing.

Quote from: martijn
Topic Summary
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It is unlikely heavy payloads can be landed without using propulsion for substantially more than final descent and landing. Of course that doesn't mean you don't want to use aerodynamic deceleration to the maximum degree possible.

I agree that other things being equal, you can save a lot of propellant by using aerobraking, but for heavy payloads, that's not trivial. There are faring issues as well. Meanwhile, a fully propulsive Mars lander could be had more or less off the shelf if it were a beefed up Lunar lander.
 
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Online mmeijeri

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I agree that other things being equal, you can save a lot of propellant by using aerobraking, but for heavy payloads, that's not trivial. There are faring issues as well. Meanwhile, a fully propulsive Mars lander could be had more or less off the shelf if it were a beefed up Lunar lander.

Hey, I'm all for that, in fact I've advocated just that. But eventually I think both propulsive braking and aerodynamic deceleration will play substantial roles. Large single-use heatshields that require huge fairings - not so much.
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Offline Warren Platts

I agree that other things being equal, you can save a lot of propellant by using aerobraking, but for heavy payloads, that's not trivial. There are faring issues as well. Meanwhile, a fully propulsive Mars lander could be had more or less off the shelf if it were a beefed up Lunar lander.

Hey, I'm all for that, in fact I've advocated just that. But eventually I think both propulsive braking and aerodynamic deceleration will play substantial roles. Large single-use heatshields that require huge fairings - not so much.

Roger that my friend! :)
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Jim has shown that a 10m heat shield can be folded in half to fit a 5m EELV.  There is also the possibility of an inflatable heat shield.  Mars' gravity and atmosphere is not as great as earth, like 35-40% I think. 

Offline Ben the Space Brit

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Mars' gravity and atmosphere is not as great as earth, like 35-40% I think. 

IIRC, Mars gravity is 0.28g and its atmosphere is 1mb, 1/1000 of Earth.

It is the latter that makes aerobraking a marginal (but not impossible) prospect and all-propulsive landing possible.
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Offline douglas100

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Surface gravity 38% Earth, average surface pressure around 7mb.
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So air braking might be just as costly as propulsive braking or landing? 

Offline 93143

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Jim has shown that a 10m heat shield can be folded in half to fit a 5m EELV.

Only if it's a disk.  The DRM 5.0 aeroshells were biconics and 10 m across.

Offline Robotbeat

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Jim has shown that a 10m heat shield can be folded in half to fit a 5m EELV.

Only if it's a disk.  The DRM 5.0 aeroshells were biconics and 10 m across.
And those aeroshells have never been tested on Mars. As long as we're doing that, why not a ballute?
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So air braking might be just as costly as propulsive braking or landing? 

To answer that question you have to be very careful about which costs you include: development costs, fixed costs, variable costs? Another question is how this affects commercial launch prices. Once we have RLVs (or ISRU) propulsive solutions will become much more interesting. Conversely, starting with propulsive solutions can jump start development of RLVs through demand-pull or as Musk calls it, by providing a forcing function.
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Offline Kaputnik

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IMO, the cheapest and fastest way to Mars would be a simple (as in pretty much fully propulsive), reusable (cheaper since it can be used over and over again), all chemical (faster than SEP), architecture that was evolved from previous spacecraft a la the ULA Lunar plan.

Zegler et al. say their DTAL lander could easily be evolved for use on Mars. My own BOTE calculations suggest that a stretched tank DTAL lander (i.e, an ACES-71) equipped with a heat resistant titanium hull (so it could withstand the full 1 W/cm2) could land fully propulsively--no ballutes, parachutes, or heat shields required.

Then the ULA MTV has a crew capacity of 16 and a nominal delta v of 11 km/sec. If there was refueling capability in Mars orbit, the ULA MTV could cut the 1-way transit times by over half compared to the Hohman transfer; if refueling was deemed impractical (probably the case for the initial missions), it would have enough delta v to do a round trip taking Hohman transfers. Again, this would all be fully propulsive--no heat shields required.

The 7 hundred tonnes of propellant would only cost about $350 million, if refueled at L2 (with Lunar derived LH2/LO2).

See, so the whole thing would be faster and cheaper, since it would be a simple evolution from the ULA Lunar architecture, which is itself a simple evolution from the Centaur 3rd-stage architecture.



Any links to the ULA Mars architecture?
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Offline Warren Platts

http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

http://www.ulalaunch.com/site/docs/publications/DepotBasedTransportationArchitecture2010.pdf (this one has a cool picture of their proposed MTV)

http://www.ulalaunch.com/site/docs/publications/DualThrustAxisLander(DTAL)2009.pdf

These mostly describe ideas about how to do a Lunar program, but they say the Lunar architecture would be relatively easily evolved for use on Mars missions. It would be distinguishable from more conventional proposals in that the architecture would mostly  be reusable, and would probably take advantage of Lunar ISRU propellant (although they don't say this, Lunar propellant would be the only way to affordably fill up that MTV they propose).
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Offline constantius

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Personally, I feel like the cheapest and most efficient way to go to mars has to make maximum use of ISRU capabilities. I am also skeptical of the idea that a mars mission needs to bring much scientific hardware. I am not as enthusiastic about martian life as I am about, say, finding mineral ores or other industrial materials that humans can use. We must make as our goal the settlement of mars. That is also why I favor a 1-way mission (which would also free up a lot of mass).

Offline Warren Platts

Personally, I feel like the cheapest and most efficient way to go to mars has to make maximum use of ISRU capabilities.

Are you talking about the Moon or Mars or both?

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I am also skeptical of the idea that a mars mission needs to bring much scientific hardware. I am not as enthusiastic about martian life as I am about, say, finding mineral ores or other industrial materials that humans can use.

Find life or evidence of former life might be as easy as walking out and picking up the right rock. I would recommend trying to find an active geyser or fumarole. Or it might take some drilling to try and find a deposit of liquid water. Life on Earth exists miles down underground. If it's Mars, that's probably where it is. But drilling more than a few feet is going to be relatively mass intensive. Another reason for using Lunar ISRU; that way you're not mass starved.

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We must make as our goal the settlement of mars. That is also why I favor a 1-way mission (which would also free up a lot of mass).

Mass is the nut to crack. Getting it there cheaply will entail reusable vessels as much as possible. If you've got reusable MTV's, there's no reason astronauts can't be rotated out IMO.
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Offline neutrino78x

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Personally, I feel like the cheapest and most efficient way to go to mars has to make maximum use of ISRU capabilities.

Are you talking about the Moon or Mars or both?

Personally I think ISRU should be a big part of both!! Also, to the greatest extent possible, I would want hardware that can be used on both Mars and the Moon. :)

Offline colbourne

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The cheapest and probably the first  way to go to Mars is a one way mission, and will probably be carried out by Musk as he has the will and potentially the means to achieve such  a feat.

For a long term large base requiring a high mass to be transferred  from Earth the ideal candidate would be the rotorvator. This would provide the cheapest cost per unit of mass but would be expensive to construct. A second rotorvator at Mars could be useful for landing and returning from Mars.

Offline Andrew_W

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Without going through the thread, can I just point out that the Apollo spacecraft could have gone to Mars, so any future Lunar hardware can probably be modified to being Mars capable hardware. So who's in in the best position to get men back to the Moon? Probably SpaceX.
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Offline Kaputnik

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Without going through the thread, can I just point out that the Apollo spacecraft could have gone to Mars, so any future Lunar hardware can probably be modified to being Mars capable hardware. So who's in in the best position to get men back to the Moon? Probably SpaceX.
I don't quite get what you are saying. Apollo lacked the delta-v, mission duration capability, and would have been far outside its thermal/environmental design range. In no practical sense could it have 'gone to Mars'. The CM could perhaps have made a re-entry at Mars-return speeds but that's not the same as saying you could go to Mars and back.

Secondly, there is, of necessity, a fundamental difference in design between a Mars lander and a moon lander (and, for that matter, an Earth lander). On the moon, with no atmosphere, you have only way of landing, using propulsion all the way; fortunately the relatively low gravity makes this feasible without a ridiculously large spacecraft. On Earth, the thick atmosphere makes it feasible to use aerodynamic landing instead. Mars occupies an awkward middle ground with the disadvantages of both environments- just enough atmosphere to complicate an all-propulsive landing, enough gravity to really push up the delta-v requirement, but not enough atmosphere to really accomplish as much braking as you would like.
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Offline MATTBLAK

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The Apollo Command Module would have been docked to a Skylab-type Habitation Module, along with a Mars Excursion Module and a cluster of propulsion stages and propellant tanks. The CSM probably would have been a "Block IV" without fuel cells, modified to remain dormant for very long periods of time, if need be. Improved hypergolic propulsion systems would have allowed the CSM's RCS and SPS engines to withstand radiation and long, deep thermal cycles and variances. Without fuel cells, the CSM would have had to rely on an array of batteries capable of being charged from the Mars Mothership's solar arrays.

It certainly wouldn't have had to fly to Mars and back on its own. Any future involvement by Orion or Dragon in such a mission would be similar. I recommend anyone reading this to seek out Stephen Baxter's excellent alternate-history novel "Voyage" that portrays just such a mission.

http://en.wikipedia.org/wiki/Voyage_%28Stephen_Baxter_novel%29
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Offline 93143

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Secondly, there is, of necessity, a fundamental difference in design between a Mars lander and a moon lander...

You may be overstating things.  IIRC, a reusable lunar lander capable of making a two-way trip between a lunar pole and L2 would require around 5.5 km/s of delta-V, and this sort of lander has been proposed before.  According to my calculations, it should be possible to do a fully-propulsive landing on Mars for well under 5 km/s, even with the trajectory shaped to get the lander slow before it gets low.

Early missions will probably use heat shields.  But if we get a base going, with established ISRU infrastructure, a reusable architecture might be more attractive, just as with the moon.  The required landing delta-V is not too much higher than the launch delta-V; if you refuel the lander on the surface you can use it for that, instead of bringing a dedicated ascender.  Then, if you refuel it on orbit, you can use it to land again.  So instead of throwing away a heat shield and lander, as well as a one-shot ascender and its ISRU equipment, that got there via another heat shield and lander, which in DRM 5.0 adds up to 173.6 tonnes of mostly dry hardware (not counting the surface hab), you're throwing away maybe 200 tonnes of hydrolox propellant, or <300 tonnes of methalox, a significant fraction of which can be locally sourced at the base.  And that's assuming the same ~40 tonne landed payload; if there's already a base, you might be fine with less...

You know, the difference in gravity between the moon and Mars is roughly equivalent to the difference in thrust between the RL-10 and the RL-60...

...

On the other hand, if you could devise a reusable launch vehicle for Mars that had an integrated heat shield and could go up and down on one propellant load, it could be used to fill Mars orbital propellant depots instead of being a drain on them.  It would probably be bigger, though, and/or have less payload, and you'd lose commonality with the lunar lander...

A full-capability reusable lunar lander like that would have enough delta-V for literally any body we might ever want to land on other than Earth and Venus, though surface ISRU would be required on a couple of the bigger ones.  Modifications would probably be required for certain targets...
« Last Edit: 02/21/2012 10:31 am by 93143 »

Offline Warren Platts

If you want to do ISRU on Mars, you might as well go for highest Isp LH2/LO2. In which case, you'll probably want to demonstrate the technology on Lunar ice first. In which case you'll have Lunar ISRU at your disposal. Which in turn means you can take Martian ISRU off the critical path.

I've looked at the ULA Lunar lander that they say can be scaled up to work on Mars. E.g., using an ACES-71 and a titanium or Inconel skin would have enough delta v to land fully propulsively and deposit a 20 to 25 mT dry cargo. A beefed up ascender could be reused, but it would have to be filled up on the surface.

Since you'll be going for Martian ISRU anyways, and to make a big difference, you'll want to make 1,000+ tonnes, then you're going to need a big tank farm to manage the feedstocks and products, so reusability, at least for the first decade or two isn't really advisable, because you'll need to build up the tank farm anyway. The ascender could dock with an ACES-71 lander sent fresh from Earth, and the fully loaded ascender/descender could land with the ascender ready to take off again.
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Offline Robotbeat

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If you want to do ISRU on Mars, you might as well go for highest Isp LH2/LO2. ...
Why? CO/O2 is really easy.
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Offline Warren Platts

If you want to do ISRU on Mars, you might as well go for highest Isp LH2/LO2. ...
Why? CO/O2 is really easy.

A. LH2/LO2 is not hard as long as you have water

B. You can drink it and breathe it and wash with it and grow crops with it

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one

D. LH2/LO2 has a much better Isp than CO/O2

E. You can run RL-10's and RL-60's on LH2/LO2

F. You can run fuel cells on LH2/LO2

G. You'll have a single, common fuel to run your entire cis-Martian architecture on

H. You can take Martian ISRU off the critical path, thus reducing development and time costs

I. LH2/LO2 can be exported for beyond Mars uses--like returning to Earth

J. Hydrogen extracted from water is useful in many ISRU beneficiation processes where a reducing agent is needed

K. Save development costs of CO/O2 ISRU infrastructure (because its unnecessary) and development costs of CO/O2 rocket engines which don't exist now, and wouldn't have proven reliability by the time they're needed in a critical path role on Mars surface
« Last Edit: 02/21/2012 04:38 pm by Warren Platts »
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Offline Robotbeat

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1) It doesn't need to be mined and is always available on every point on the planet in unlimited quantities and requires no hard cryogenic storage. This vastly simplifies the whole project.
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Offline Warren Platts

1) It doesn't need to be mined and is always available on every point on the planet in unlimited quantities and requires no hard cryogenic storage. This vastly simplifies the whole project.

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one. Therefore, you are merely adding an extra, unnecessary layer of duplicated effort that vastly complexifies the whole project.
« Last Edit: 02/21/2012 05:02 pm by Warren Platts »
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Offline Warren Platts

Since the thread is about the cheapest way to get to Mars, if the Mars project came after a vibrant, Lunar propellant station was up and running, if you think about it, the big ticket development costs for a Mars landing would essentially be zero. Even the MTV would simply be an evolved version of the L2 Gateway station (probably be a Bigelow module surrounded by discarded ACES-121/JUS upperstages or their equivalent). Practically everything needed would already be developed; it would just be a matter of saddling up and going.
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Offline Robotbeat

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1) It doesn't need to be mined and is always available on every point on the planet in unlimited quantities and requires no hard cryogenic storage. This vastly simplifies the whole project.

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one. Therefore, you are merely adding an extra, unnecessary layer of duplicated effort that vastly complexifies the whole project.
We need water anyway, so why do we bother breathing air?

If you bold a point, it doesn't make it more important. I read it the first time.

Besides, your main point is Moon development, you barely care about going to Mars.
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Offline Warren Platts

!
« Reply #120 on: 02/21/2012 07:16 pm »
1) It doesn't need to be mined and is always available on every point on the planet in unlimited quantities and requires no hard cryogenic storage. This vastly simplifies the whole project.

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one. Therefore, you are merely adding an extra, unnecessary layer of duplicated effort that vastly complexifies the whole project.
We need water anyway, so why do we bother breathing air?

What?!?

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If you bold a point, it doesn't make it more important. I read it the first time.

And if you ignore a point, that doesn't make it any less true. Sniffing CO2 out of the air isn't going to relieve you of the necessity of mining water. Deal with it...

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one.

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Besides, your main point is Moon development, you barely care about going to Mars.

Absolutely FALSE!! I care about Mars development more than you do! That should be obvious, as evidenced by the fact that I take the time to think about what a sustainable Mars program would be like, that would have a ghost of a chance of forming the nucleus of an eventual Mars settlement! (Hint: water is not a nice-to-have.)

EDIT: This whole Moon vs. Mars thing you insist on fomenting is based on a totally bogus, false dichotomy. It's not a zero-sum game. The Moon and Mars are complementary. Each is a stepping stone to destinations further out. 


« Last Edit: 02/21/2012 09:52 pm by Warren Platts »
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Offline A_M_Swallow

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We need water anyway, so why do we bother breathing air?

Extracting the hydrogen from water requires a lot of energy.  ISRU equipment can use nuclear power and solar power.  Plants can use sun light as a power source but animals, including humans, main source of energy is oxidising hydrocarbons.  The oxygen is obtained by breathing.

Offline Warren Platts

We need water anyway, so why do we bother breathing air?

Extracting the hydrogen from water requires a lot of energy.  ISRU equipment can use nuclear power and solar power.  Plants can use sun light as a power source but animals, including humans, main source of energy is oxidising hydrocarbons.  The oxygen is obtained by breathing.

Yeah, you would think. That's the good thing about H2O:

B. You can drink it and breathe it and wash with it and grow crops with it.

If we're going to go to the trouble and expense of sending people to Mars in the first place, I'd like to see it done in a sustainable manner--as in one that won't get cancelled after the first set of flags 'n' footprints. That means a permanently manned research station on Mars.

And if we're going to the trouble of setting up a permanently manned facility on Mars, we're going to have to do some ISRU mining or drilling for water. Importing hydrogen from Earth like in most Mars Direct scenarios is just lame...
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Offline Kaputnik

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C. You need water anyway, so going with CO/O2 isn't going to get you out of that one.

You need to be careful that when you make these assertions you realise that your context (long term sustainable settlement of large numbers of people, using reusable and possibly cis-lunar infrastructure) may differ from other people's.

FWIW, a great deal has been written about how to do Mars missions without having to dig for water. And, as Robotbeat has pointed out, there are huge advantages to tapping into a globally available atmospheric resource instead.

(One more point- water is available in the atmosphere, but only in very small quantities- but perhaps enough to make up for small leaks/losses in a Mars-Direct style mission.
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Offline Warren Platts

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one.

You need to be careful that when you make these assertions you realise that your context (long term sustainable settlement of large numbers of people, using reusable and possibly cis-lunar infrastructure) may differ from other people's.

No, I am not talking about "long term sustainable settlement of large numbers of people". I am talking about a modest, permanently manned research station along the lines described by Chris McKay in his address to the Mars Society. And yes, I am fully aware that this vision is quite different from the Zubrinista, fly-by-night, Mars-Direct-on-a-shoestring-style context.

Quote
FWIW, a great deal has been written about how to do Mars missions without having to dig for water. And, as Robotbeat has pointed out, there are huge advantages to tapping into a globally available atmospheric resource instead.

And what are the common elements of these missions? 100's of tonnes go up, one tiny capsule goes back. Nothing to show for the billions and billions but a box of rocks. Apollo redux on Mars, basically. A wasteful and unsustainable allocation of resources, in other words.

You would think we would learn some lessons after 50 years about how not to go about things. But I guess not...

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(One more point- water is available in the atmosphere, but only in very small quantities- but perhaps enough to make up for small leaks/losses in a Mars-Direct style mission.

See, I just don't understand why you guys go out of your way to make life so unnecessarily hard for yourselves. The fundamental problem of Mars Direct and offspring is that they are based on the philosophy of scarcity. Everything is so starved for mass, that you willingly entertain thoughts of sifting out individual water molecules out of the thin air.

You really don't have to play it that way:

H. You can take Martian ISRU off the critical path, thus reducing development and time costs.

You could go in instead with a reusable, abundant chemical, Mars "Indirect" sort of architecture where you wouldn't have to put Martian ISRU on the critical path. You have enough margin to bring all the drinking water and propellant with you, since it's all LH2/LO2. Meanwhile, you have enough downmass that you can rapidly build up a real ISRU capability within a decade or two. And by real, I mean an ISRU capability that generates more than a self-licking ice cream cone: what you want is more propellant than you know what to do with (on the order of 1000+ tonnes/year) in order to sponsor sortie missions all over Mars surface, and to allow fast transit delta v's so things like cyclers and such might start to make sense.
« Last Edit: 02/21/2012 09:48 pm by Warren Platts »
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Offline deltaV

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B. You can drink it and breathe it and wash with it and grow crops with it

C. You need water anyway, so going with CO/O2 isn't going to get you out of that one

F. You can run fuel cells on LH2/LO2

All of the above tasks are compatible with recycling the water after use. If water recycling is done well then food imported from Earth contains enough hydrogen to make up for the inevitable losses. Food and packaging is apparently 1.83 kg/person/day (http://www.nasa.gov/audience/foreducators/stseducation/materials/Sustaining_Life.html), or 0.668 tonnes/person/year. Importing food would only become a major nuisance once we have dozens of people on Mars at a time. At that point we should start developing other water sources such as burning all the hydrogen-containing waste we can find and condensing water from the combustion products. Once we have more people on Mars at a time than have been in space so far in all of history then even with careful hydrogen recycling the imports may get annoying. At that point it may make sense to look at ISRU water for human use. But that's way too far in the future to affect engineering trades today!

Bottom line: mining Martian water makes sense if and only if it's the best choice as a propellant source. Its use as a source of water for human use is barely relevant to the trades. Avoiding importing water for human use because it's "just lame" is poor engineering.
« Last Edit: 02/21/2012 09:57 pm by deltaV »

Offline Warren Platts

Bottom line: mining Martian water makes sense if and only if it's the best choice as a propellant source. Its use as a source of water for human use is barely relevant to the trades. Avoiding importing water for human use because it's "just lame" is poor engineering.

G. You'll have a single, common fuel to run your entire cis-Martian architecture on.

LH2/LO2 is the best choice. It's the engineer's choice, because it is the best chemical propellant we know about.

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If water recycling is done well then food imported from Earth contains enough hydrogen to make up for the inevitable losses.

Do you have some numbers to back up this assertion, or is this just your intuition speaking?

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Food and packaging is apparently 1.83 kg/person/day (http://www.nasa.gov/audience/foreducators/stseducation/materials/Sustaining_Life.html), or 0.668 tonnes/person/year.

Thanks for the reference. :)

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Importing food would only become a major nuisance once we have dozens of people on Mars at a time.

You will never get there with a Mars Direct-style architecture.

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At that point we should start developing other water sources such as burning all the hydrogen-containing waste we can find and condensing water from the combustion products. Once we have more people on Mars at a time than have been in space so far in all of history then even with careful hydrogen recycling the imports may get annoying. At that point it may make sense to look at ISRU water for human use. But that's way too far in the future to affect engineering trades today!

Look at everything you want to do here: practically zero loss water recycling (takes mass), burning of trash and recovering the hydrogen (takes mass). In the context of a permanently manned base, you're running a big risk. You have no local ISRU, and you depend on tempermental recycling systems that if they break down for lack of a spare part, you're screwed.

Meanwhile, under the abundant chemical paradigm, separate storage of tonnes of water isn't necessary, and in fact, even water recycling isn't necessary, since the boiloff will provide enough water (after it's been reconstituted by the fuel cells) for the crews needs. Similarly, there will be enough residual propellant upon landing to provide enough water for the 600 days of a conjuction-class mission or more.

Sure, there will still be water recycling: you'll need dehumidifiers to extract water out of atmosphere if nothing else, but you won't have to worry about dieing of thirst if you don't extract every last gram of H20 out of all the human feces that are produced...
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Offline deltaV

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G. You'll have a single, common fuel to run your entire cis-Martian architecture on.

LH2/LO2 is the best choice. It's the engineer's choice, because it is the best chemical propellant we know about.

The spacecraft and launch vehicles that use other propellants demonstrate that many aerospace engineers disagree with you.

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If water recycling is done well then food imported from Earth contains enough hydrogen to make up for the inevitable losses.

Do you have some numbers to back up this assertion, or is this just your intuition speaking?

One good source of real-world closed environmental control is the ISS. I haven't found any good sources of the ISS environmental control mass flow rates, but here are some calculations based on less than good sources.

Installing the system that recycled urine and other liquid wastes apparently cut ISS water importation by 65% by producing 6 klb/year of water. (http://www.nasa.gov/mission_pages/station/behindscenes/waterrecycler.html) After this system was installed (35/65)*6 = 3.2 klb/year of imported water were presumably required.

The new Sabatier system produces up to 1000 liters per year, i.e. 2.2 klb/year. (http://news.discovery.com/space/water-space-station-nasa.html) The Sabatier reaction recovers half of its input hydrogen as water and vents the other half as methane. If the hydrogen were instead combined with oxygen extracted from the Martian atmosphere it would produce twice as much water, i.e. 4.4 klb/year. This would yield 4.4-3.2=1.2 klb/year of excess water.

I'm giving this rather sketchy calculation credence only because it agrees with what one would expect from counting hydrogen atoms in and out.

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Sure, there will still be water recycling: you'll need dehumidifiers to extract water out of atmosphere if nothing else, but you won't have to worry about dieing of thirst if you don't extract every last gram of H20 out of all the human feces that are produced...

If you have a tonne per person of stored water you can wait a few years for spare parts to arrive if the feces burner breaks.

Edit: I'm not mentioning a feces burner because I think we should build one for the first Mars mission. I mention it only to counter your assertion that we must mine Martian water.

Edit: feces are probably better used as fertilizer than burned.
« Last Edit: 02/21/2012 11:49 pm by deltaV »

Offline Warren Platts

Thanks for the calculations and interesting links. I agree that we want to close the loops as much as we can as we go along.

As for the choice of LH2/LO2, yes propellants exist. And LH2 isn't perfect, obviously, because of the boiloff issues and it's density of cotton candy. But Zegler et al. emphasize the desirability of commonality across a total architecture:

Quote from: Zegler et al. (2009)
The guiding philosophy that we have followed in developing the proposed sustainable exploration architecture is to use the least number of distinct elements. This meant not only all-up vehicles but the least number of main engines, avionics systems, fluids systems, ECLSS systems, etc. By keeping the many elements as common as possible development is foreshortened and costs suppressed.

That's arguably one problem with Mars Direct approach: there's all kinds of different systems that will have to be invented de novo to make the plan work. It's not a recipe for efficient space travel IMO.
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Offline A_M_Swallow

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If I recall correctly the water on Mars is near the poles.  So a base built away from the poles would have to transport the water for many days.  This may not be difficult for an established base but would put significant restrictions on a single lander.

Offline Warren Platts

Neutron results seem to indicate that there are perhaps 10% water in the top meter of Martian regolith, even at equatorial latitudes.

http://spaceclimate.net/Mars.Water.7.06R.pdf
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Offline Robotbeat

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Forgetting about planetary protection requirements temporarily, if you brought in a wheelbarrow or shovel full of icy Martian regolith in to the hab through the airlock and simply let it melt and evaporate, the ECLSS recycling system would recover the water for you.
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Offline Warren Platts

Planetary protection! What about astronaut protection? You're forgetting about all those nasty perchlorates. Not that volatile enriched Lunar regolith is going to be any better, since it's loaded with mercury. We'll definitely want fractional distillation units.

Ordinary Lunar regolith shouldn't have the mercury problem, however, and would probably make a really good growing medium, analogous to fresh volcanic soils on Earth. On Mars, you'll probably have to stick with hydroponics until they figure out a way to get rid of the percholorates.
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Offline Kaputnik

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No, I am not talking about "long term sustainable settlement of large numbers of people". I am talking about a modest, permanently manned research station along the lines described by Chris McKay in his address to the Mars Society. And yes, I am fully aware that this vision is quite different from the Zubrinista, fly-by-night, Mars-Direct-on-a-shoestring-style context. (snip)
And what are the common elements of these missions? 100's of tonnes go up, one tiny capsule goes back. Nothing to show for the billions and billions but a box of rocks. Apollo redux on Mars, basically. A wasteful and unsustainable allocation of resources, in other words.

You would think we would learn some lessons after 50 years about how not to go about things. But I guess not...

I see that you would consider an "Apollo redux" Mars mission to be worse than no mission at all. Well, on that point we will just have to differ.
I don't see why you have to measure a mission by 'what comes back'. Heck, Curiosity isn't going to come back, do you think that's a mistake too?

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See, I just don't understand why you guys go out of your way to make life so unnecessarily hard for yourselves. The fundamental problem of Mars Direct and offspring is that they are based on the philosophy of scarcity. Everything is so starved for mass, that you willingly entertain thoughts of sifting out individual water molecules out of the thin air.
It's more a case of 'everything is starved for cash'. Mass costs.

Your vision seems to hinge on operating RLVs on another planet. I don't doubt that this could eventually be a better way of working, just, given that we've had fifty years to get RLVs right on Earth, it's unlikely to be an easier, or a cheaper, one.
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Offline 93143

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Besides the fact that we seem to actually be close to getting Earth RLVs working (the tech definitely wasn't there 50 years ago, but our efforts since then have not been totally in vain), it's an abysmal analogy.  An RLV on Mars (especially one that can tank up at both ends of the trip) is way easier because the delta-V requirement is 45% of what it is here.  If you know anything at all about the rocket equation, you know what that means...

I'm not sure it's necessarily the best approach for initial missions, but long-term it's silly to throw away all that hardware when it's so easy not to.

Offline Warren Platts

I see that you would consider an "Apollo redux" Mars mission to be worse than no mission at all. Well, on that point we will just have to differ.

I don't see why you have to measure a mission by 'what comes back'. Heck, Curiosity isn't going to come back, do you think that's a mistake too?

To expand a little on what 93143 said, if your MTV comes back in the exact same configuration as when you left in it, you can use it again, and thus save the cost of building another one from scratch and then launching it from Earth.

Ideally, we would like a permanently manned research station: this would minimize the $$$/man-day on Mars, while at the same time allow speedy research into what it takes to survive on Mars, as well as search for Martian life. This is going to take some interplanetary infrastructure. The whole point of Mars Direct is to do Mars without the need for any such infrastructure. It's still going to be expensive as hell though, so the question then becomes, If we're going to do it at all, why not do it right the first time?

Quote from: Kaputnik
Quote from: Warren Platts
See, I just don't understand why you guys go out of your way to make life so unnecessarily hard for yourselves. The fundamental problem of Mars Direct and offspring is that they are based on the philosophy of scarcity. Everything is so starved for mass, that you willingly entertain thoughts of sifting out individual water molecules out of the thin air.
It's more a case of 'everything is starved for cash'. Mass costs.

That's why we've got to go beyond business as usual to find ways to bring down the cost of spaceflight. Mars Direct is the epitome of business as usual: full-up, Apollo-style flags 'n' footprints. Thus it sucks out all the oxygen in the room, and little else can be done in the meantime. If budgets are flat, the only way to continually do more is to continually do more for less. That's why we've got to look at things like Lunar ISRU, so that we can use the resources of space itself to leverage our spaceflight capabilities.

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Your vision seems to hinge on operating RLVs on another planet. I don't doubt that this could eventually be a better way of working, just, given that we've had fifty years to get RLVs right on Earth, it's unlikely to be an easier, or a cheaper, one.

I agree with 93143. The much weaker gravity on Moon and Mars makes the task of a SSTO LV an order of magnitude easier than a similar craft launching from Earth. Check out the DC-X; it was basically the sort of reusable, SSTO, Lunar/Mar lander that I'm talking about. Before it crashed and burned, it demonstrated a 26 hour turn-around-time, and a delta-v of 1.4 km/sec, which is 70% of the delta-v required to get to LLO.
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Offline Kaputnik

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To expand a little on what 93143 said, if your MTV comes back in the exact same configuration as when you left in it, you can use it again, and thus save the cost of building another one from scratch and then launching it from Earth.
Yes, it's a nice idea. Just like the Orbiters were supposed to work, huh?

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Ideally, we would like a permanently manned research station: this would minimize the $$$/man-day on Mars
You have to balance cost/hour (or cost/landed mass) against total program cost. In reality, the only program that has a chance of flying is one that can be met with a reasonable up-front budget. And grandiose visions of lunar propellants and Martian RLVs do not strike me as having low up-front costs.

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That's why we've got to go beyond business as usual to find ways to bring down the cost of spaceflight. Mars Direct is the epitome of business as usual: full-up, Apollo-style flags 'n' footprints. Thus it sucks out all the oxygen in the room, and little else can be done in the meantime.
Ah come on, if you really want to sling mud at a mission plan, why not pick on DRM5.0? Mars Direct is quite nifty by comparison.

It sounds as though your vision relies heavily on some order of magnitude reduction in the costs of operating hardware in space. I'm not holding my breath for that.

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If budgets are flat, the only way to continually do more is to continually do more for less. That's why we've got to look at things like Lunar ISRU, so that we can use the resources of space itself to leverage our spaceflight capabilities.
If anything is going to 'suck the oxygen out of the room', it's a diversion to the moon. You honestly expect it would be economically possible to create a lunar ISRU facility on a flat budget? Whose budget??

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I agree with 93143. The much weaker gravity on Moon and Mars makes the task of a SSTO LV an order of magnitude easier than a similar craft launching from Earth. Check out the DC-X; it was basically the sort of reusable, SSTO, Lunar/Mar lander that I'm talking about. Before it crashed and burned, it demonstrated a 26 hour turn-around-time, and a delta-v of 1.4 km/sec, which is 70% of the delta-v required to get to LLO.
I am well aware of the DC-X. It doesn't change the fact that operating an RLV in a hostile environment, far from any workshop facilities, and expecting it to safely carry people around, is not exactly going to be easy, and therefore not cheap either.
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Offline Warren Platts

To expand a little on what 93143 said, if your MTV comes back in the exact same configuration as when you left in it, you can use it again, and thus save the cost of building another one from scratch and then launching it from Earth.
Yes, it's a nice idea. Just like the Orbiters were supposed to work, huh?

Gimmee a break! You think a mere, fully propulsive transfer between MLO and EML2 is somehow equivalent to the Shuttle orbiter having to launch from Earth and then safely shed 10 km/sec of velocity through friction? ? ? I hope that is intentional hyperbole....

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Ideally, we would like a permanently manned research station: this would minimize the $$$/man-day on Mars
You have to balance cost/hour (or cost/landed mass) against total program cost. In reality, the only program that has a chance of flying is one that can be met with a reasonable up-front budget. And grandiose visions of lunar propellants and Martian RLVs do not strike me as having low up-front costs.

What does not have low up-front costs is Mars Direct. A Lunar propellant station would be supremely expensive: 100 to 200 $B for sure. But once it was there, the up-front cost of a Mars mission would be nil.
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It sounds as though your vision relies heavily on some order of magnitude reduction in the costs of operating hardware in space. I'm not holding my breath for that.

How does it feel to be an advocate for business as usual?

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If budgets are flat, the only way to continually do more is to continually do more for less. That's why we've got to look at things like Lunar ISRU, so that we can use the resources of space itself to leverage our spaceflight capabilities.
If anything is going to 'suck the oxygen out of the room', it's a diversion to the Moon. You honestly expect it would be economically possible to create a lunar ISRU facility on a flat budget?

There are worse problems to be had than getting bogged down on the Moon for 20 or 30 years. If you would bother to actually think through what a Lunar ISRU facility would entail, you would arrive at the same conclusion I have: not only is it possible, it is mandatory.

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I agree with 93143. The much weaker gravity on Moon and Mars makes the task of a SSTO LV an order of magnitude easier than a similar craft launching from Earth. Check out the DC-X; it was basically the sort of reusable, SSTO, Lunar/Mar lander that I'm talking about. Before it crashed and burned, it demonstrated a 26 hour turn-around-time, and a delta-v of 1.4 km/sec, which is 70% of the delta-v required to get to LLO.
I am well aware of the DC-X. It doesn't change the fact that operating an RLV in a hostile environment, far from any workshop facilities, and expecting it to safely carry people around, is not exactly going to be easy, and therefore not cheap either.

Nothing in space is "cheap". But at $50M a DC-X is a relative bargain. The hardest part about DC-X was handling the cryogenic liquids--not refurbishing the RL-10's. Moreover, it's ridiculous to assume that there won't be "workshop facilities" on the Moon. That's the whole point! To set up "workshop" facilities. . .

I got news for you Mars Direct folks who think we should blow off the birth-right of the United States: hand-waving about the Moon-qua-diversion isn't going to cut it amongst the wonks in the know anymore.
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Offline Kaputnik

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Warren,
I don't really have time to deal with all of your points individually. I see that we are looking at Mars exploration from two fundamentally different perspectives, and I do not intend to try to change your mind.

On the whole I think you vastly underestimate the difficulty and expense in creating a reliable in-space infrastructure such as you envision.

Quite why you continue to pick on Mars Direct as 'the bad guy' is beyond me. Pick on NASA DRMs if you have to, perhaps pick on Zubrin's mass estimates, but his vision of how to do Mars exploration on a flat NASA budget is, I think, to be applauded.

There is one point that did make me laugh though:

A Lunar propellant station would be supremely expensive: 100 to 200 $B for sure. But once it was there, the up-front cost of a Mars mission would be nil.

I hope you can see for yourself what I consider to be the flaw in this statement. It is indicative of you viewpoint in general.
« Last Edit: 02/24/2012 09:29 am by Kaputnik »
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Offline DLR

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Warren's path to human solar system exploration seems to be much more worthwhile and sustainable than alternatives which do not tap into Lunar propellant.

His approach crucially depends on getting the cost of propellant production on the Moon down and on developing a space transportation system with a very long operational lifetime and minimal maintenance requirements. The former can only be tested on the Moon, while the latter should not be too hard to be achieved here on Earth. Current engines are not designed for durability, but for maximum performance. On reusable in-space systems, we have to focus on durability, at the cost of some performance.

10000t of LOX/LH2 propellant at L2 would enable not only the sustainable exploration of Mars but "all-chemical" missions to Jupiter's moons as well, provided autonomous propellant manufacturing stations are set up at the destination. But more on that in a thread I openend in the "Advanced Concepts" section.

Zubrin was right about the Moon as a diversion when the prospects of economically mining Lunar propellants were dim (at the time the "Case for Mars" was written, we basically didn't know how much readily accessible ice there is at the poles, so studies focused on producing oxygen only), but now the Lunar waystation has the potential to open the inner solar system to human exploration without the need to develop new forms of in-space propulsion.

Offline Solman

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 Solar thermal/electric in-space propulsion using NEO derived propellant processed in GEO by telerobots and ISRU at the Moon and Mars as they are visited and hopefully settled.

Steve

Offline JohnFornaro

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To expand a little on what 93143 said, if your MTV comes back in the exact same configuration as when you left in it, you can use it again, and thus save the cost of building another one from scratch and then launching it from Earth.
Yes, it's a nice idea. Just like the Orbiters were supposed to work, huh?

Clearly, you're not trying to be supportive of the idea of re-usability.  As it turns out, there is no law of nature which forbids mankind to build his machines so that they can be re-used.

Neither, of course, is there a law of nature which forbids mankind's politicians from lying about the possible reusability of various machines, such as the Orbiters, just to pick a machine at random.

Just tryin' to figger out what you're for.

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If anything is going to 'suck the oxygen out of the room', it's a diversion to the moon. You honestly expect it would be economically possible to create a lunar ISRU facility on a flat budget? Whose budget??

So, what is it that you're for? Because the same thing can be said about any martian mission.

[The] path to human solar system exploration seems to be much more worthwhile and sustainable than alternatives which do not tap into Lunar propellant.

[The] approach crucially depends on getting the cost of propellant production on the Moon down and on developing a space transportation system with a very long operational lifetime and minimal maintenance requirements. The former can only be tested on the Moon, while the latter should not be too hard to be achieved here on Earth. Current engines are not designed for durability, but for maximum performance. On reusable in-space systems, we have to focus on durability, at the cost of some performance.

Good comments.  I point out that "the" path and "the" approach you mention are held by many individuals and that those concepts weren't "invented" by the individual you name.

One of the memes I'm trying to foment (or promulgate) is that "mass is your friend".  Mass helps with durability.  Check out our home planet for a massive case in point.  The performance hit for a rocket engine will be because of the additional mass needed to assure durability.  Low delta-vee cost of robotically produced prop at the needed scale would go a long way towards making the mass less of a problem than it currently is.
Sometimes I just flat out don't get it.

Offline Kaputnik

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Just tryin' to figger out what you're for.
Fair enough- I probably have been a bit negative.
What I am interested in and supportive of is plans that strike me as realistic. As a species we have had fifty years of messing around in space and have figured out that it's pretty hard to get right. I used to be in the "well clearly they're doing it wrong then" camp but over the years learned to temper my expectations and have a little more respect for the people in the industry who have actually achieved great things. Yes, it is frustrating sometimes, watching NASA spend $10bn and five years failing to turn STS into a HLV, but that is the reality that we are dealing with here.

When it comes to Mars, I tend to roll my eyeballs when a plan relies too heavily on unknowns and assumptions. What we need is simplicity, the fewest possible new hardware designs on the critical path, the greatest reliance on heritage where this is sensible. Those are the kinds of plans that get me excited, not "everybody gets a pony" ones involving moon bases and making assumptions about massive increases in budgets or reductions in launch costs.

Now, more specifically...

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Clearly, you're not trying to be supportive of the idea of re-usability.  As it turns out, there is no law of nature which forbids mankind to build his machines so that they can be re-used.

Neither, of course, is there a law of nature which forbids mankind's politicians from lying about the possible reusability of various machines, such as the Orbiters, just to pick a machine at random.

I am all for reusability where this looks realistic and sensible. In the world today, it rarely is. Look at, for example, SeaLaunch: they operate a vehicle whose first stage was originally designed from the ground up to be reusable. They are a wholly commercial operation. Yet recovering their first stages is never even mentioned- it would seem that the economics do not stack up. I don't doubt that reusability is possible, it's just that nobody has to date made it work.

In-space hardware could hopefully fare better, of course. I would fully expect that Mars surface equipment would be reused many times. Reuse of a MTV is probably doable as well. However I find that most people overstate the cost/size of the MTV. It doesn't have to be big, or particularly complex, expecially if it is disposable and launched with supplies pre-loaded. For a crew of four, something like a Salyut docked to a Dragon return capsule would probably be OK. The capsule would make a direct entry, leaving a 20t craft to either discard, or to brake into Earth orbit using a huge quantity of propellant which pushes the total mission mass up greatly. Then you have to refurbish and resupply that craft, probably using something like an ATV launch. I doubt that the numbers would work in its favour.
A reusable MTV would make more sense if it was a SEP or NEP device.
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Online mmeijeri

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A reusable MTV would make more sense if it was a SEP or NEP device.

Or if it cycled between high Earth orbit and high Mars orbit instead of between low Earth orbit and low Mars orbit. That could even done by hypergolics, optionally supported by SEP just for prepositioning propellant. That would require no new technology.
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Offline Kaputnik

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A reusable MTV would make more sense if it was a SEP or NEP device.

Or if it cycled between high Earth orbit and high Mars orbit instead of between low Earth orbit and low Mars orbit. That could even done by hypergolics, optionally supported by SEP just for prepositioning propellant. That would require no new technology.

Quite likely. What sort of delta-v would we be talking about? And do you mean a high elliptical orbit, or a circular one?
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Quite likely. What sort of delta-v would we be talking about?

Delta-v chart

From Jim's favourite online aerospace authority, so consider the source. ;)

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And do you mean a high elliptical orbit, or a circular one?

Probably Lagrange points as they seem the most flexible.
« Last Edit: 03/07/2012 09:53 am by mmeijeri »
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Offline Kaputnik

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As I understand it, it is quite efficient to make a OI burn during a close pass to the planet, thus benefitting from the Oberth effect and resulting in a highly elliptical orbit; but if done at Earth you are then going to be crossing the VA belts on every orbit, which doesn't seem too clever.
Unfortunately I'm out of my depth when talking about the delta-v and the prcess required to park at a Lagrange point. Must go and read up...
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As I understand it, it is quite efficient to make a OI burn during a close pass to the planet, thus benefitting from the Oberth effect and resulting in a highly elliptical orbit;

Correct, and a second burn would be needed at apoapsis if you wanted to circularise.

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but if done at Earth you are then going to be crossing the VA belts on every orbit, which doesn't seem too clever.

Yeah, that would be a disadvantage of elliptical orbits. It's also very expensive to reorient the ellipse, Lagrange points are more flexible in that sense.

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Unfortunately I'm out of my depth when talking about the delta-v and the prcess required to park at a Lagrange point. Must go and read up...

I think the numbers in the chart already reflect use of powered flybys.
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Offline JohnFornaro

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Just tryin' to figger out what you're for.
What I am interested in and supportive of is plans that strike me as realistic.

Ain't we all.

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As a species we have had fifty years of messing around in space and have figured out that it's pretty hard to get right. I used to be in the "well clearly they're doing it wrong then" camp but over the years learned to temper my expectations and have a little more respect for the people in the industry who have actually achieved great things. Yes, it is frustrating...

Well, broadly speaking, we got to the Moon with vacuum tubes and slide rules, so the brute technology and capability has been with us, unused, for forty years.  I'm still in the "well clearly they're doing it wrong then" camp, and I think that the Constellation cancellation is the existential proof of my preference of camping sites.

The technology has not failed; it is the policymakers who have failed.  For example, it will be pointed out that VentureStar failed because of technology; the aerospike engine, the fuel tanks, the SSTO concept, etc.  But I insist that it was the policymakers who demanded that all this new technology be assembled together for the first time, accompanied by a false promise of the chances of its combined success.  They should have, and probably did know better.

The issue for me is not the respect for the worker bees at all.  They are the ones who do great things.  My disrespect is for the policymakers who have lost themselves in Machiavellian roles where politics is only about winning at all costs, and that the principles of life, liberty, and the pursuit are fairy tales only, told to children to get them to sleep at night.  But enough of my ranting on that.

The last few months have been eye openers for me, as I gain familiarity with the wide field of new commercial entrants into the space economy.  So I think there's some hope for the future.

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When it comes to Mars, I tend to roll my eyeballs when a plan relies too heavily on unknowns and assumptions. What we need is simplicity, the fewest possible new hardware designs on the critical path, the greatest reliance on heritage where this is sensible. Those are the kinds of plans that get me excited, not "everybody gets a pony" ones involving moon bases and making assumptions about massive increases in budgets or reductions in launch costs.

Hey. Don't get me going about ponies.  They are better promised than unicorns...

Unfortunately, the thread title, summarizing the OP is too broadly written to be useful.  It is hard to conceive of a faster tracectory than this:

From "Celestial Mechanics and Astrodynamics",1964, Victor Szebehely, editior, p. 56, there is a 36 hour trajectory to the Moon suggested.  It's seems like a lead and shoot trajectory.  Lead the Moon by a certain amount, fire off the rocket, and hit (not land, necessarily), 36 hours later.

And it could be pretty cheap too, if all you want to achieve is a real world demonstration of the trajectory.  Technically, in this den of technical specialists, that is a "mission".  Ipso fatso about the OP then.

But as to missions themselves, I agree with you in general.  It is incorrect, I continue to insist, on developing a human mission to Mars, particularly with today's technology.  The moon base, singular, not plural, is the appropriate next step; it doesn't require massive increases in budgets; lower launch costs; new hardware; or even ponies.  It will be said that we don't have a lander; but this machine would be new in name, not in function.  It will be argued that a Mars lander will be cheaper than a lunar lander, if only by a dollar; but this ignores the cost difficulties associated with the six month journey to and fro.

Now, more specifically...

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Clearly, you're not trying to be supportive of the idea of re-usability.  As it turns out, there is no law of nature which forbids mankind to build his machines so that they can be re-used.

Neither, of course, is there a law of nature which forbids mankind's politicians from lying about the possible reusability of various machines, such as the Orbiters, just to pick a machine at random.

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I am all for reusability where this looks realistic and sensible. In the world today, it rarely is. Look at, for example, SeaLaunch... I don't doubt that reusability is possible, it's just that nobody has to date made it work.

O ye of little faith.  SeaLaunch as one example cannot be expected to hold for all examples.  Look at Stratolaunch; it would expand on Mr. Rutan's idea, but what do they propose to launch? A disposable rocket, not a reusable human vehicle.  It's not that nobody can make it work; it's that nobody, wiht the bucks, is proposing to make it work.

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In-space hardware could hopefully fare better, of course. I would fully expect that Mars surface equipment would be reused many times. Reuse of a MTV is probably doable as well. ... The capsule would ... brake into Earth orbit using a huge quantity of propellant ...A reusable MTV would make more sense if it was a SEP or NEP device.

Or if it cycled between high Earth orbit and high Mars orbit instead of between low Earth orbit and low Mars orbit. That could even done by hypergolics, optionally supported by SEP just for prepositioning propellant. That would require no new technology.

Of course, SEP and NEP are tomorrow's scaled technology, which would be usefully demonstrated and perfected in the cislunar arena.  The only thing I'd change about Martijn's suggestion is that the MTV should cycle between hi Earth orbit, say L1, and lo Mars orbit.  It should be a spacecraft that is built for a fifty or more year lifetime, say, and used at least fifty times, say.

It will be a massive vehicle, but it should not be designed now.  There's plenty of martian surface to crawl over and explore and learn.  To save money, we should go back to the Moon to stay, and go to Mars for the first time to stay.  In due course.

And after that, but only after that, everyone gets a pony.
Sometimes I just flat out don't get it.

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Of course, SEP and NEP are tomorrow's scaled technology, which would be usefully demonstrated and perfected in the cislunar arena.

Maybe not even scaled, propellant is easily divisible. A 50kW SEP tug could probably be made mostly from stuff that has flown before, just not in that particular combination.

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The only thing I'd change about Martijn's suggestion is that the MTV should cycle between hi Earth orbit, say L1, and lo Mars orbit.  It should be a spacecraft that is built for a fifty or more year lifetime, say, and used at least fifty times, say.

Why low Mars orbit?
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Offline Kaputnik

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The only thing I'd change about Martijn's suggestion is that the MTV should cycle between hi Earth orbit, say L1, and lo Mars orbit.  It should be a spacecraft that is built for a fifty or more year lifetime, say, and used at least fifty times, say.

Why low Mars orbit?

Perhaps it is to use the NEP/SEP for the maximum practical delta-v, thereby shifting some of the burden off the MAV.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Online mmeijeri

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Perhaps it is to use the NEP/SEP for the maximum practical delta-v, thereby shifting some of the burden off the MAV.

If you use EP for the MTV that would make sense, but that would require massive upscaling of present technology. Not necessarily a problem, since all this is far in the future anyway, but I was thinking about using chemical propulsion for the MTV. In that case only cycling between high orbits and refueling there maximises the use of EP for propellant transportation.
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Offline Robotbeat

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The only thing I'd change about Martijn's suggestion is that the MTV should cycle between hi Earth orbit, say L1, and lo Mars orbit.  It should be a spacecraft that is built for a fifty or more year lifetime, say, and used at least fifty times, say.

Why low Mars orbit?

Perhaps it is to use the NEP/SEP for the maximum practical delta-v, thereby shifting some of the burden off the MAV.
It's not a straight-forward trade.
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Offline JohnFornaro

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Quote from: JF
The only thing I'd change about Martijn's suggestion is that the MTV should cycle between hi Earth orbit, say L1, and lo Mars orbit.  It should be a spacecraft that is built for a fifty or more year lifetime, say, and used at least fifty times, say.

Why low Mars orbit?

Perhaps it is to use the NEP/SEP for the maximum practical delta-v, thereby shifting some of the burden off the MAV.

Generally my thinking, but...

It's not a straight-forward trade.

...what he said.  I don't know enough to speak on that trade any more than in generalities.

But it should be a very re-usable spacecraft, built with tomorrow's technology.
Sometimes I just flat out don't get it.

Offline Kaputnik

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It's not a straight-forward trade.

Indeed. The main effect I would think of is the considerable period of time needed for a NEP/SEP craft to slowly spiral its way to the desired orbit.

It may also be tempting to consider that an ISRU-propelled MAV is using 'free' propellant and therefore there is no harm in making it bigger, and able to reach a high orbit on its own. I think that this assumption would be wrong, however, as the larger the craft the more difficult/expensive it would become.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

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