Author Topic: DIRECT v3.0 - Thread 1  (Read 1310358 times)

Offline fotoguzzi

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Re: DIRECT v3.0 - Thread 1
« Reply #3280 on: 07/26/2009 05:44 am »
Ares III for LEO, Ares IV for the Moon. None of this DIRECT nonsense, you see...
Let's hope they don't try to abbreviate Shuttle Inline Transport-1 and Shuttle Inline Transport-2

Modify: or transit
« Last Edit: 07/26/2009 05:45 am by fotoguzzi »
My other rocket is a DIRECT Project 2

Offline Lab Lemming

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Re: DIRECT v3.0 - Thread 1
« Reply #3281 on: 07/26/2009 06:14 am »
Maybe they would get more congressional support if they called it "Pretty Obvious Rocket Kludge"

Ares III for LEO, Ares IV for the Moon. None of this DIRECT nonsense, you see...
Let's hope they don't try to abbreviate Shuttle Inline Transport-1 and Shuttle Inline Transport-2

Modify: or transit

Offline simon-th

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Re: DIRECT v3.0 - Thread 1
« Reply #3282 on: 07/26/2009 06:20 am »
These are all good points.  But it is worth pointing out that a number of other proposed missions get stranded at the study phase because they do not fit on an existing launch vehicle.  Mars and Venus sample return are good examples of this.  Mercury landers also fall into this category.  And that is just planetary.  We haven't even started talking big telescopes yet...

Mars sample return isn't reality because of funding issues as well as technical constraints on any Mars surface payload upper mass, not because there aren't any launch vehicles to fly that mission. Ariane 5 does just fine for a simple, small Mars sample return mission.

ESA for instance assumes 5 different spacecraft for the mission anyway - an orbiter around Mars; a transfer stage; the descent module with a rover; an ascent module and an Earth reentry module which rendezvous with the ascent module in Mars orbit.

Right at that moment the costs are preventing the mission to go anywhere.

Offline Analyst

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Re: DIRECT v3.0 - Thread 1
« Reply #3283 on: 07/26/2009 07:26 am »
...   These are all really high energy, high weight, because the basic task is to throw a giant mass of hydrazine out there, with some instrumentation going along for the ride. The lunar orbiters are barely possible with Atlas V 551 or Ariane V ECA or even (at Flagship cost level) DIVH/AVH. But the landers may not be, and the Europa submarine is probably the single greatest mission we can hope for in our lifetime (apart from optical interferometer space telescopes, for pretty much the same reason!)

And this is the problem. These missions, on their own, independent of the launcher, are only possible at the flagship level. Or above, way above (Europa submarine, MSR ...). We know how often flagships happen.

And no, the missions won't get cheaper because they can have more mass. The costs come from the complexity, not the limited mass budget.

HLV may give new opportunities for science, in theory, but so did Saturn V and Shuttle. Only we don't have the money to use them. SMD surely does not have the budget. The only one who thinks he needs HLV is the beyond LEO HSF advocat.

Analyst
« Last Edit: 07/26/2009 07:27 am by Analyst »

Offline rklaehn

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Re: DIRECT v3.0 - Thread 1
« Reply #3284 on: 07/26/2009 09:13 am »
And no, the missions won't get cheaper because they can have more mass. The costs come from the complexity, not the limited mass budget.

One could argue that a significant part of this complexity comes from the limited mass budget.

But avoiding technology development by using a simple, more massive system is so contrary to the current aerospace culture that it probably wouldn't happen even if a HLV was available.

Due to the politics involved in publicly funded missions, a dollar spent on developing for example an elaborate scheme for landing on mars is much preferable to spending a dollar on a larger launch vehicle to avoid having to use the elaborate landing scheme in the first place.

So a HLV could significantly reduce the cost of flagship missions. But due to the aerospace culture and politics of publicly funded projects, it probably won't happen.

Offline simon-th

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Re: DIRECT v3.0 - Thread 1
« Reply #3285 on: 07/26/2009 09:55 am »

So a HLV could significantly reduce the cost of flagship missions.

Costs for the launcher are just a fraction of a flagship mission. Even building the mission hardware is just a fraction. Most costs are incurred for development, management and planning and operations. An HLV instead of an Delta-IV H or an Atlas 551 won't decrease those costs. It's not going to be cheaper to design and build a 50mt spacecraft compared to a 7mt spacecraft, no matter what you do and which approach you take.

Offline Lab Lemming

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Re: DIRECT v3.0 - Thread 1
« Reply #3286 on: 07/26/2009 10:43 am »
No, but if you overspend a billion dollars folding a 6.5 meter mirror into a 5 mirror fairing, an 8.4m fairing is an easy way to simplify the mission.

An ideal solution would be to budget an extra decadal flagship into SMD with the money they save by scrapping Ares.  Afterall, they are probably the most popular thing NASA does these days (with possible exception of the rovers).  Just look how much more interest there was in the shuttle when it went to a telescope instead of the space station earlier this year.


So a HLV could significantly reduce the cost of flagship missions.

Costs for the launcher are just a fraction of a flagship mission. Even building the mission hardware is just a fraction. Most costs are incurred for development, management and planning and operations. An HLV instead of an Delta-IV H or an Atlas 551 won't decrease those costs. It's not going to be cheaper to design and build a 50mt spacecraft compared to a 7mt spacecraft, no matter what you do and which approach you take.

Offline rklaehn

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Re: DIRECT v3.0 - Thread 1
« Reply #3287 on: 07/26/2009 10:56 am »

So a HLV could significantly reduce the cost of flagship missions.

Costs for the launcher are just a fraction of a flagship mission.

And that is exactly why spending more on a launcher to reduce all the other costs might make sense.

Quote
Most costs are incurred for development, management and planning and operations. An HLV instead of an Delta-IV H or an Atlas 551 won't decrease those costs.

Operations can be simplified and shortened by using direct trajectories instead of complex trajectories with gravity assists. Avoiding a gravity assist means two years less you have to keep the team together. Surely that is worth a lot of money.

Quote
It's not going to be cheaper to design and build a 50mt spacecraft compared to a 7mt spacecraft, no matter what you do and which approach you take.

Nobody says that you have to use the full payload capacity. There are various scenarios where building a 10mt spacecraft will be cheaper than building a 7mt spacecraft. Especially if 7mt is the upper limit for your launcher, and due to some unforeseen weight growth the spacecraft ends up with a weight of 7.5mt.

Offline Analyst

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Re: DIRECT v3.0 - Thread 1
« Reply #3288 on: 07/26/2009 01:27 pm »
Quote
1) So a HLV could significantly reduce the cost of flagship missions.
2) But due to the aerospace culture and politics of publicly funded projects, it probably won't happen.

1) You are wrong.
2) Has nothing to do with culture and politics. The complexity does not come from the limited mass budget, but from the tasks the spacecraft has to perform.

If it were otherwise, Pegasus, Taurus, Delta II ... all would be out of business and only the biggest launch vehicle would be used, even for a SMEX explorer. Heck, for a small satellite Delta IVH is heavy lift, yet they don't use it.

Quote
No, but if you overspend a billion dollars folding a 6.5 meter mirror into a 5 mirror fairing, an 8.4m fairing is an easy way to simplify the mission.

I doubt you have anything substantial supporting the claim JWST problems are the result of the folded mirror. More likely they have to do with state of the art science instruments with very narrow tolerances, very tight requirements for spacecraft pointing ...

I would support an extra flagship, instead of Ares I. Sure. but I would be even more happy if the only currently planned flagship (to Jupiter and Europa) stays on its 2020 schedule, which is very doubtful these days. One way or another, a HLV won't help here.

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And that is exactly why spending more on a launcher to reduce all the other costs might make sense.

It does not work this way. Again, the tasks a spacecraft has to perform define its complexity, which defines its costs. More mass does seldom help here, and never helps enough to justify the higher cost for the launcher. Again, why is not everyone using the biggest vehicle available? Why are Pegasus et al. flying? Why?

Quote
1) Operations can be simplified and shortened by using direct trajectories instead of complex trajectories with gravity assists. Avoiding a gravity assist means two years less you have to keep the team together.
2) Surely that is worth a lot of money.

1) You have to decide: Heavier spacecraft or faster trajectories. The first won't save you cost, the latter increases arrival speed (and therefore delta v, and therefore mass, larger tanks, longer burning engines ... or more complicated EDL.)
2) Much less than you think. Spacecraft can sleep.

SMD won't use HLV. They can't afford it. They can barely afford a new mission here and there. They are looking for a Delta II replacement.

You are looking for a problem for your solution.

Analyst
« Last Edit: 07/26/2009 01:31 pm by Analyst »

Offline tamarack

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Re: DIRECT v3.0 - Thread 1
« Reply #3289 on: 07/26/2009 02:04 pm »
OK-

1) A couple of pages back, there was a graphic of a ET with 4 SRBs strapped to it. The follow-up mentioned that while scary-capable, that beast was also HEAVY- as in crack-the floor, break-the-back-of-the=crawler and dig-ruts-in-the-crawler-way HEAVY. Well- what about using 3 SRBs, or adding two (or more) of the midget-solids that Delta uses? Any benefit there without pushing things beyond their Young's Modulus?

I'm with you on making the most capable ARES V possible(3SRB), but there are many that think a half-size (DIRECT, ARES IV) will do just fine.
For almost all science missions, ISS resupply and LEO crew transfer - there is a slew of capable rockets that ARES I is supposed to join. If we intend on putting a lot of mass into space for sustained presence and exploration - larger rockets are cheaper/lb and do jobs half-sizes can't.
The arguments for half-size are: two rockets, though more expensive, can still put up enough mass for missions and might also carry science missions that are 4x too heavy for other launch systems. IMO half-sizes are a waste of time with no foreseeable need and the Constellation program seemed to agree when they approving the ARES V heavy/ARES I standard, but canceled the half-size ARES IV.
« Last Edit: 07/26/2009 02:06 pm by tamarack »

Offline clongton

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Re: DIRECT v3.0 - Thread 1
« Reply #3290 on: 07/26/2009 02:04 pm »
All of these posts are exactly why the DIRECT position is not an either-or stance on heavy/medium/light lift launchers. Light and/or medium lift launchers are more than sufficient for a lot of our space lift needs. But that's because the spacecraft they are lifting actually "fit" very well into the capabilities of the launcher. The most expensive part of any space mission, manned or unmanned, is the spacecraft. If a spacecraft is physically too large for any existing launcher, then the only way to lift it is to make it vastly more complex by turning it into some kind of transformer where it folds in on itself in Frankenstein-like fashion to enable it to fit the fairing. That can easily double or triple the cost of the spacecraft itself, calling into question whether or not the budget can even afford the mission. The solution is to use a launcher that is large enough to let the spacecraft fit in the fairing.

But now we have the question of how big is enough? Here is where we believe the Jupiter fits the bill nicely. We do not advocate building a huge launch vehicle, like the Ares-V, because it would have very little use. The expense cannot be justified by the flight rate. And yet there are times when that kind of lift capacity can prove to be very useful. The answer is to create a medium lift launcher with a high enough useful launch rate to justify its existence, and that can fulfill the heavy lift needs on demand by adding capability to that launcher thru use of an upper stage. In other words, build one launch vehicle that can fill both roles.

Anything that does not require the lift capability of a Jupiter can, and should, be flown on an EELV-class launcher, not a Jupiter. But when high-medium/heavy lift is needed, there just is no substitute for the right launch vehicle. The Jupiter-24X is that launch vehicle.
« Last Edit: 07/26/2009 02:06 pm by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline spacenut

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Re: DIRECT v3.0 - Thread 1
« Reply #3291 on: 07/26/2009 02:28 pm »
If you really wanted to lift 200 tons or more in one vehicle while still using existing facilities, you would have to go kerolox.  One could fit a 12 meter kerolox booster inside the VAB and it stll be light enough to transverse the crawlerway.  No solids since they are very heavy.  The Saturn V could have been upgraded by improving the existing F-1 engines to 2.2 million lbs of thrust, and the J-2 upper stages from 200k lbs each to the J-2X for about 275k lbs each.  This would have gotten you into the 150-175 ton range.  Modern construction methods, CC boosters, etc, and you can get 200 tons.  It would require today a clean-sheet design.  Do we have the time or money or will to do this?

Offline robertross

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Re: DIRECT v3.0 - Thread 1
« Reply #3292 on: 07/26/2009 03:31 pm »
If you really wanted to lift 200 tons or more in one vehicle while still using existing facilities, you would have to go kerolox.  One could fit a 12 meter kerolox booster inside the VAB and it stll be light enough to transverse the crawlerway.  No solids since they are very heavy.  The Saturn V could have been upgraded by improving the existing F-1 engines to 2.2 million lbs of thrust, and the J-2 upper stages from 200k lbs each to the J-2X for about 275k lbs each.  This would have gotten you into the 150-175 ton range.  Modern construction methods, CC boosters, etc, and you can get 200 tons.  It would require today a clean-sheet design.  Do we have the time or money or will to do this?

The problems with that are many. Some are:

1) No F1 engines exist is production, so that's money and years away.

2) Since this is so big, and you would have (hopefully at least) something using existing facilities for regular launches, so what you need for his one would all have to be built from scratch. Again, more time and money.

3) Most of what you would need for HLV is non-crewed, so investing in EELV-upgrade of vehicles is best. So just pay ULA to build their biggest and baddest. In 15-20 years, you can have your 200T HLV. Leave it to the pros.

Offline gospacex

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Re: DIRECT v3.0 - Thread 1
« Reply #3293 on: 07/26/2009 05:22 pm »
   * Jovian *lunar* orbiters: Europa, Ganymede.
   * Saturnian *lunar* orbiter: Titan
   * Neptune orbiter
   * Europa lander. Europa *submarine*!
   * Titan lander

   These are all really high energy, high weight, because the basic task is to throw a giant mass of hydrazine out there, with some instrumentation going along for the ride. The lunar orbiters are barely possible with Atlas V 551 or Ariane V ECA or even (at Flagship cost level) DIVH/AVH. But the landers may not be, and the Europa submarine is probably the single greatest mission we can hope for in our lifetime (apart from optical interferometer space telescopes, for pretty much the same reason!)

   Jupiter 130 could really change that.

I vote for a Sedna orbiter, with HIRISE sized telescope. Seeing the first known Oort cloud object up close?!! YES!!!

Offline gospacex

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Re: DIRECT v3.0 - Thread 1
« Reply #3294 on: 07/26/2009 05:27 pm »
Quote
1) Operations can be simplified and shortened by using direct trajectories instead of complex trajectories with gravity assists. Avoiding a gravity assist means two years less you have to keep the team together.
2) Surely that is worth a lot of money.

1) You have to decide: Heavier spacecraft or faster trajectories. The first won't save you cost, the latter increases arrival speed (and therefore delta v, and therefore mass, larger tanks, longer burning engines ... or more complicated EDL.)

Larger tanks and longer burns do not cost anything if they fit comfortably under LV's payload limit.

Offline Analyst

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Re: DIRECT v3.0 - Thread 1
« Reply #3295 on: 07/26/2009 05:58 pm »
And this is wrong too. Larger tanks means heavier spacecraft means different attitude control, thermal, structure ...

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Offline Eerie

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Re: DIRECT v3.0 - Thread 1
« Reply #3296 on: 07/26/2009 06:05 pm »
I vote for a Sedna orbiter, with HIRISE sized telescope. Seeing the first known Oort cloud object up close?!! YES!!!

You did the numbers?

Offline Ben the Space Brit

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Re: DIRECT v3.0 - Thread 1
« Reply #3297 on: 07/26/2009 06:45 pm »
And this is wrong too. Larger tanks means heavier spacecraft means different attitude control, thermal, structure ...

I think you are guilty of 'glass half empty' thinking.  Yes, different weights, ratios of propellent to payload and so on would lead to its own issues.  However (and this is purely from an amateur standpoint), I'm sure that there is a way to balance all of this to improve performance.  The point is that a LV with a higher payload limit would give you the room to play around with various things to acheive that end. 

That is the case of the spaceborne nuclear reactor I mentioned earlier too.

After that, it becomes a funding issue.  Is America willing to pay $n million to answer all those nagging questions about the Oort Cloud, Europa, the Kuiper Belt Objects or whatever? We have the technology if you have the cash.
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Offline rklaehn

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Re: DIRECT v3.0 - Thread 1
« Reply #3298 on: 07/26/2009 07:01 pm »
Quote
1) So a HLV could significantly reduce the cost of flagship missions.
2) But due to the aerospace culture and politics of publicly funded projects, it probably won't happen.

1) You are wrong.
2) Has nothing to do with culture and politics. The complexity does not come from the limited mass budget, but from the tasks the spacecraft has to perform.

If it were otherwise, Pegasus, Taurus, Delta II ... all would be out of business and only the biggest launch vehicle would be used, even for a SMEX explorer. Heck, for a small satellite Delta IVH is heavy lift, yet they don't use it.

This is a strawman argument. I never made the claim that you should use the biggest available launcher for all missions. Obviously there is some kind of economical optimum for mission mass above which mass increases are no longer beneficial.

All I am saying is that there is frequently too much emphasis on squeezing a mission on the smallest possible launcher and that for some large missions (mars sample return, outer planet missions, large telescopes) the incremental cost of a heavy lifter launch could be lower than the cost caused by trying to launch with an EELV.

Quote
Quote
1) Operations can be simplified and shortened by using direct trajectories instead of complex trajectories with gravity assists. Avoiding a gravity assist means two years less you have to keep the team together.
2) Surely that is worth a lot of money.

1) You have to decide: Heavier spacecraft or faster trajectories.

Wrong. If you have sufficient excess capacity (as you would probably have when e.g. launching an outer planet mission on a jupiter instead of on an EELV heavy) you could accept some weight growth and still use a faster trajectory.

Quote
The first won't save you cost,

Super lightweight components are always more expensive than standard components. So why should having a larger weight budget available not save costs? You might argue that the cost saving does not justify moving to a bigger launcher, but that there is no cost saving whatsoever is just ridiculous.

Quote
the latter increases arrival speed (and therefore delta v, and therefore mass, larger tanks, longer burning engines ... or more complicated EDL.)

Wrong again. A direct trajectory to jupiter can have exactly the same arrival velocity as a trajectory using multiple gravity assists, but still arrive years earlier.

Quote
2) Much less than you think. Spacecraft can sleep.

Obviously the spacecraft does not have to be babysitted by the entire team while it is in transit. But the entire team has to be available at arrival. It costs money to guarantee that.

Quote
SMD won't use HLV. They can't afford it. They can barely afford a new mission here and there. They are looking for a Delta II replacement.

But they can afford designing a very complex landing mechanism for MSL.

By the way: I think this is getting off-topic for the DIRECT thread.
« Last Edit: 07/26/2009 07:06 pm by rklaehn »

Offline Eric Hedman

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Re: DIRECT v3.0 - Thread 1
« Reply #3299 on: 07/26/2009 07:10 pm »
I vote for a Sedna orbiter, with HIRISE sized telescope. Seeing the first known Oort cloud object up close?!! YES!!!

Would there be enough light out at Sedna where an orbiter could get good images without a long duration exposure (might be difficult with a rotating object)?  How about a lander that has a flash for illumination plus some instruments to sample and analyze the surface?  The mission could also have a few surface penetrators.  If we go through the effort to get out that far, wouldn't it make sense to get a better idea just what this object is made of?  I for one would be interested in the results.

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