Author Topic: A Minimal Architecture for Human Journeys to Mars (JPL)  (Read 52521 times)

Offline Russel

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #40 on: 07/05/2015 02:46 PM »
I would love to see a solid costing of the cost of a SEP spacecraft. Leaving aside the launch costs, just the spacecraft. If it comes down to a few tens of millions and it can automatically deployed I might have a use for one.

But if its hundreds of millions or more.. then..

What did the JPL people think the actual spacecraft would cost? And how were they proposing to have it automatically deploy?

Offline A_M_Swallow

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #41 on: 07/05/2015 07:00 PM »
I would love to see a solid costing of the cost of a SEP spacecraft. Leaving aside the launch costs, just the spacecraft. If it comes down to a few tens of millions and it can automatically deployed I might have a use for one.

But if its hundreds of millions or more.. then..

What did the JPL people think the actual spacecraft would cost? And how were they proposing to have it automatically deploy?

The cost of the solar panels will vary with time and it is likely that the cost of the thrusters will as well.

p.s. Since the SEP has more than one array and uses more than one thruster it may be possible to approximate the cost of the second SEP.
« Last Edit: 07/05/2015 07:06 PM by A_M_Swallow »

Offline gbaikie

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #42 on: 07/05/2015 09:01 PM »
I would love to see a solid costing of the cost of a SEP spacecraft. Leaving aside the launch costs, just the spacecraft. If it comes down to a few tens of millions and it can automatically deployed I might have a use for one.

But if its hundreds of millions or more.. then..

What did the JPL people think the actual spacecraft would cost? And how were they proposing to have it automatically deploy?

Ion thrusters are used in commercial  satellites. They have to compete other types of station keeping thrusters. So if you can find prices for them in this use, then you get a better understanding of their costs.

It seems to me if we had operational depots in space, this also allow a actual reflection of costs of ion.
And basically more competition, and more units made per year, allows a clearer picture of what basic cost to make Ion engines are.

Or the cost of electrical cars are related to cost of chemical cars. If got rid of chemical cars market, then the cost of electrical cars would change. Not necessarily a lower cost of electrical cars- it seems to me more likely the cost of electrical cars would increase. Or generally any time you remove competition one causes an increase in cost. And other than competition,  there would a need for electrical cars to have more capability- so electrical cars today had advantage of specialize within a larger market, and one adds complexity if electrical cars have serve broader demand-  complexity adds to costs. But mostly in competition and free market which has larger effects.
Other than operational depot, with more use of ion use in satellite, and perhaps large constellation of satellites being develop which could use ion, this will helpful in revealing actual costs.
« Last Edit: 07/05/2015 09:05 PM by gbaikie »

Offline Russel

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #43 on: 07/06/2015 12:50 AM »
Yes but I'm  still grasping for a couple of things. A fair and reasonable costing for a SEP  vehicle and a practical limit to how big a SEP you can package on the ground that doesn't need human assisted in orbit assembly.

I would imagine the cost of cells and thrusters would be the least of your worries and that the real cost is integration, testing etc.

My hope is that a 100KW class vehicle could be built (provided you can package it)  for a few hundred million. In theory it could be much cheaper if you make a number of them.

This takes me back to the observation about economics. As launch costs fall and it gets cheaper the launch chemical upper stages, SEP can only be defended if you can reuse it often enough. Missions that send SEP all the way to Mars seem to defeat this goal. And thats especially true with this minimalist mission that treats SEP as expendable.

I would also like to see people come up with a 'minimal space junk' mission. And yes Im only half joking.

Offline guckyfan

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #44 on: 07/06/2015 05:53 AM »
I would also like to see people come up with a 'minimal space junk' mission. And yes Im only half joking.

MCT. ;D

Offline Oli

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #45 on: 07/06/2015 05:23 PM »
But if its hundreds of millions or more.. then..

In the context of a Mars mission not a lot of money. Just take a look at their projected budget.

Offline spacenut

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #46 on: 07/06/2015 07:11 PM »
My idea of SEP tugs is to get a 50 ton SEP tug (empty of propellant) to LEO.  Then launch about 50 tons of propellant to fuel it.  Then launch a 50 ton cargo lander for Mars for it to carry to Mars then come back to earth for refueling and another 50 ton load.  Also, I think the SEP tug should use argon for propellant as earth's atmosphere as well as Mars' atmosphere has argon that you might be able to refuel at Mars for the return to earth.  Several of these SEP tugs could carry cargo and supplies to Mars robotically.  They can also be used to carry large satellites from LEO to GSO, or install a satellite communication grid around Mars or for searching Mars from orbit to find good landing spots for human colonists.   Maybe several of these tugs can hook together like railroad locomotives and pull 100 or more tons of cargo/equipment to Mars. 

50 ton unit tugs, propellant, and cargo landers would use Falcon Heavies to get the infrastructure in place.  Maybe Vulcan heavies if they come on line or Vulcan's with solids. 
« Last Edit: 07/06/2015 07:15 PM by spacenut »

Offline Russel

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #47 on: 07/06/2015 10:27 PM »
But the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?

Offline john smith 19

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #48 on: 07/06/2015 11:02 PM »
But as soon as your using SEP and your returning vehicle is not being destroyed but rather capturing to high Earth orbit the logic of sending a FRESH retrieval capsule up from Earth is inescapable.
But using (and keeping an Orion is a minimal risk design.

No 2nd capsule needed. No rendezvous in HEO. No (probable) new capsule design.
Quote
Overall I find the mixing of SEP and Chem in this architecture to be very poor, the SEP is underpowered as it reflects zero improvement on ARM which is ridiculously conservative.  The Chem stages don't make use of oberth effects and are big and bulky.  This proposal is almost Zubrin like in it's rejection of tech development, even the technologies already under development by NASA right now like HIAD.  Did their sand charts assume NASA's tech development budget gets zeroed out and all the money dumped into their program?

Quote
Lastly the presenters make the absurd claim that "by being specific with out plan our international partners can see themselves IN the plan and will come on board", which would makes sense if your specifics weren't composed of ALL AMERICAN VEHICLES.  After taking out the sole launch vehicle SLS, Orion, and ARM derived SEP theirs not much left for anyone else to do.  The habitat module is the only part I could see ESA or Roscosmos doing, the chemical kick-stages are grunt-work that no ones would be interested in.  Lastly the landers, everyone knows JPL would produce that, they have ALL the Mars EDL experience and this is unequivocally the most dangerous part of the mission.  None of our partners would want the PR risk that would entail.  Lastly the crew size of 4 is too small to include enough international astronauts to make the mission attractive, no nation will contribute if their nationals don't get a ticket, on the FIRST flight.
Well if you look at some of these elements as placeholders then things change a bit.

For example ESA's work on 4 grid staged ion thrusters indicates a 250Kw thruster as small as 20cm in diameter could be possible with bother efficiency and lower beam divergence than current designs.

http://www.esa.int/gsp/ACT/pro/projects/ds4g_overview.html

Likewise ESA is already supply the Orion service module.

A 4 person crew should be enough to make at least member a European.

However to do so the authors are correct that you have to be specific about what the US would be looking for from its partners. IE the shape, size and mass of the "hole" in the architecture that needs filling. That way the partner does not get stuck with effectively an unlimited commitment to make their systems fit a moving target.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Oli

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #49 on: 07/06/2015 11:40 PM »
Well if you look at some of these elements as placeholders then things change a bit.

For example ESA's work on 4 grid staged ion thrusters indicates a 250Kw thruster as small as 20cm in diameter could be possible with bother efficiency and lower beam divergence than current designs.

http://www.esa.int/gsp/ACT/pro/projects/ds4g_overview.html

The only new information I can find regarding this tech is from 2012. On a DS3G (dual stage 3 grids).

http://www.academia.edu/8480649/Recent_Developments_in_High_Power_Electric_Propulsion_Outcomes_of_HiPER_Project_Activities

Great performance compared to a reference GIE thruster, but still falls short of Hall thrusters when it comes to thrust per kw of power.





« Last Edit: 07/06/2015 11:40 PM by Oli »

Offline Impaler

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #50 on: 07/06/2015 11:46 PM »
But the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?

WAAA???  First off chemical booster stages are not FREE they have a cost to manufacture as well even if the propellent in them is cheap, second what is this awesome $1000 per kg launch vehicle, it sure ain't SLS.


But using (and keeping an Orion is a minimal risk design.

No 2nd capsule needed. No rendezvous in HEO. No (probable) new capsule design.

Taking Orion with you all the way to Mars is not low risk, it exposes the ONLY means of return to Earth to multiple YEARS of wear and tear, any failure even if detected before returning to Earth is a death sentence.

A fresh vehicle sent to High Earth orbit to retrive crew from a functional habitat is far safer, if the Orion is found to be damaged we can just launch another and another until we are confident.

I have no idea how you got the idea that I wanted to develop another vehicle, I said explicitly Orion is a perfectly adequate cis-lunar craft, that's the ONLY thing it was designed to be.  Though an upgraded Dragon capsule could probably do the job too.

Well if you look at some of these elements as placeholders then things change a bit.

For example ESA's work on 4 grid staged ion thrusters indicates a 250Kw thruster as small as 20cm in diameter could be possible with bother efficiency and lower beam divergence than current designs.

http://www.esa.int/gsp/ACT/pro/projects/ds4g_overview.html

Likewise ESA is already supply the Orion service module.

A 4 person crew should be enough to make at least member a European.

However to do so the authors are correct that you have to be specific about what the US would be looking for from its partners. IE the shape, size and mass of the "hole" in the architecture that needs filling. That way the partner does not get stuck with effectively an unlimited commitment to make their systems fit a moving target.

4 Grid stages ion thrusters are extremely high ISP and have too low a thrust density to be used for Mars, even for cargo delivery, their role is in deep outer-solar-system probes.

Orion service modules (a specific number of them) are already part of ISS barter between NASA and ESA, they don't give ESA any rights to hitch a ride on a NASA Mars mission.

The mission author only 'gaps' are complete non-starters for any other allied space-programs.  They use existing or in development NASA vehicles (that are generic assets usable in a variety of mission) and capsules at every opportunity but don't use ANY existing equipment from any other space agency.  Are partnering space agencies expected to to do ALL the new vehicle development and for components which have ZERO use outside of this mission?  That why I'm saying the gaps that have been left are either for things no one else can do, could do or would do and the masses don't even attempt to fit into anyone else's launch vehicles. 

When the Russians actually made join Mars mission proposals back in the 70's they had clearly defined roles for both sides which made sense, Russian transit vehicles (effectively space stations equipped with electric propulsion) and American Landers, this used each nations expertise and let everyone share in the glory.  This plan is nothing like that, it is in my opinion designed to cement a go-it-alone strategy for Mars while maintaining a false pretense of openness to international cooperation for public consumption.

A crew of 4 gets used up real fast when you try to include Japan and Canada.
« Last Edit: 07/07/2015 05:13 AM by Impaler »

Offline Oli

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #51 on: 07/07/2015 11:02 AM »
The mission author only 'gaps' are complete non-starters for any other allied space-programs.

A crew of 4 gets used up real fast when you try to include Japan and Canada.

- The gaps need to be small enough in order to fit into the budget of other space agencies. The lander and the transfer habitat are almost certainly too costly. But there are other parts: Surface equipment (science, rovers), the ascent vehicle, parts of the surface hab. The chemical stages are probably the part nobody wants to do.

- Assuming multiple missions, there should be enough for partners to contribute for one seat per mission. I'm certain there will be no Canadian on the first mission though ;).


Offline Russel

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #52 on: 07/07/2015 02:10 PM »
But the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?

WAAA???  First off chemical booster stages are not FREE they have a cost to manufacture as well even if the propellent in them is cheap, second what is this awesome $1000 per kg launch vehicle, it sure ain't SLS.



What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.

The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.

Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.

Choose.

Offline Oli

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #53 on: 07/07/2015 02:21 PM »
But the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?

WAAA???  First off chemical booster stages are not FREE they have a cost to manufacture as well even if the propellent in them is cheap, second what is this awesome $1000 per kg launch vehicle, it sure ain't SLS.



What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.

The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.

Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.

Choose.

If you use fantasy numbers for chemical stages you can also use fantasy numbers for SEP. Its not an argument for one or the other.

Offline ClaytonBirchenough

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #54 on: 07/07/2015 07:44 PM »
1) What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.

2) The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.

3) Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.

Choose.

1) What the heck kind of upper stage are you talking about?

2) Where SpaceX is heading. IMO this $1000/kg is a long way off. SpaceX is currently at ~$4700/kg with Falcon 9. They expect to be at $2200/kg with Falcon Heavy with an annual flight rate of four Falcon Heavy launches a year. Nearly halving that to $1000/kg is going to take a lot of effort, luck, money, time, and probably all of those combined.

Quote
The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.

"Where SpaceX is trying to head"

3) Given that's going to become a reality? Is there something you know that I don't?

BTW, I totally agree with you that chemical stages should be used instead of SEP. I just think your reasoning for supporting chemical stages over SEP is flawed.
Clayton Birchenough
Astro. Engineer and Computational Mathematics @ ERAU

Offline spacenut

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #55 on: 07/07/2015 08:03 PM »
IF, big IF, SpaceX can get reusability of their first stages, price for a second use, after refurbishment and adding a new second stage, would probably be 75% of the new use.  Then the second time it should drop to 50% of the new use, and so on.  5 times and it might pay for itself.  Thus getting total overall costs down to less than $1,000/kg.  If that happens with Falcon Heavy, then using it plus SEP tugs for non-perishable cargo, that might get you in the ballpark.  First they have to resolve the issue with the second stage, then they have to routinely land the first stages. 

Offline guckyfan

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #56 on: 07/07/2015 08:13 PM »
Elon Musks stated his goals today again. The next generation rocket presently being designed is supposed to get cost down by 2 orders of magnitude. If you take 5000$/kg as baseline, that would be 50$/kg.

Of course that would require a high launch rate to become reality. And of course like always most people will call him totally insane.

Offline ClaytonBirchenough

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #57 on: 07/07/2015 08:24 PM »
Damn. I managed to SpaceX this one accidentally I think.

Continued SpaceX discussion should probably be carried over to here: http://forum.nasaspaceflight.com/index.php?topic=36815.0
Clayton Birchenough
Astro. Engineer and Computational Mathematics @ ERAU

Offline Impaler

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #58 on: 07/07/2015 10:19 PM »
OK lets try to get some actual numbers for chemical kick-stages, this is tricky because the closes equivalent upper-stages are both somewhat different (Hydro-Lox vs Hypergolics), and are not sold A la carte but always bundled into a launch vehicle.  Still we know that 2nd stages cost something like a 1/4th to 1/3rd of a launch vehicles cost.

Centaur upper stage has a wet mass of 22 mT, an F9 2nd stage is estimated to masses nearly 100 mT wet.  The proposed upper stage for ULA's Vulcan is to varry from 41 to 73 mT.  Ariane 5 upper stage is 11 mT.  The only stage I could find a cost for was a Russian stage called Blok D at 17 mT and $4 million, note this is a Kero-Lox stage.

Even at the rock bottom Russian price (and keep in mind this stage was developed for the N-1) your still looking at around 120 million for this 500 mT of stages before launching.  And even at the optimistic $1000/kg launch cost it would cost 500 million to launch thus totaling 620 million.  I would estimate that SEP stage would be 1/4th the mass to do the same job so 125 mT and this would mean a launch cost of 125 million leaving 495 million, if SEP stage cost less then that then it is better then chemical.  If you use present launch costs that are x10 higher then your crossover cost would be 3.8 BILLION!!! 

You really need to get to some kind of crazy low cost like $100 kg which would make chemical cost 170 million total and require the SEP to cost less then 157.5 million to be competitive.




Offline Russel

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Re: A Minimal Architecture for Human Journeys to Mars (JPL)
« Reply #59 on: 07/09/2015 04:49 PM »
1) What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.

2) The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.

3) Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.

Choose.

1) What the heck kind of upper stage are you talking about?

2) Where SpaceX is heading. IMO this $1000/kg is a long way off. SpaceX is currently at ~$4700/kg with Falcon 9. They expect to be at $2200/kg with Falcon Heavy with an annual flight rate of four Falcon Heavy launches a year. Nearly halving that to $1000/kg is going to take a lot of effort, luck, money, time, and probably all of those combined.

Quote
The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.

"Where SpaceX is trying to head"

3) Given that's going to become a reality? Is there something you know that I don't?

BTW, I totally agree with you that chemical stages should be used instead of SEP. I just think your reasoning for supporting chemical stages over SEP is flawed.

1) a regular hydrolox upper stage

2) The difference between a throw away falcon heavy and a fully reusable one is the cost halving you seek

3) See 2)

Do you dispute my reasoning, or numbers?

The reasoning is sound. You pay more for an SEP vehicle. To make that worth it you have to reuse it. That's possible in Earth space where like a boomerang it comes back to you in 6 months or so. Then you get multiple reuses. When you send it to Mars, even if you can get it back, it will take so long that you only get a small number of reuses before its old.

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