Author Topic: DIRECT v3.0 - Thread 1  (Read 1312291 times)

Offline cro-magnon gramps

  • Full Member
  • ****
  • Posts: 1548
  • Very Ancient Martian National
  • Ontario, Canada
  • Liked: 843
  • Likes Given: 11008
Re: DIRECT v3.0 - Thread 1
« Reply #3240 on: 07/24/2009 11:07 pm »
I think there's a bit of confusion above, so let me try to clarify:

Prior to the committee, NASA came up with NASA's own numbers -- nobody else was ever involved.   This is true for CxP and also for NSC as well.
Ross.

Then I was mistaken and I owe Gramps an apology. I thought they were involved with processing NASA's Ares numbers before the commission was announced.



{peace, love, and tranquility} it's all good as the kids say... living with 7 kats gives one a distinct perspective on inter Kat relationships, and various personalities ;)
Gramps "Earthling by Birth, Martian by the grace of The Elon." ~ "Hate, it has caused a lot of problems in the world, but it has not solved one yet." Maya Angelou ~ Tony Benn: "Hope is the fuel of progress and fear is the prison in which you put yourself."

Offline fotoguzzi

  • Full Member
  • ***
  • Posts: 335
  • Phobos first!
  • PDX, Oregon, USA
  • Liked: 0
  • Likes Given: 0
Re: DIRECT v3.0 - Thread 1
« Reply #3241 on: 07/24/2009 11:27 pm »
Thanks Ross, that makes me feel a lot more confident about the commission.
If we had ever tried to get them to analyse DIRECT for us, our little band of rebels could never have afforded their fee! :)
Quote
No oversight at all.
Where is the guy looking over their shoulder?   
NASA administrator.
President.
GAO.
My other rocket is a DIRECT Project 2

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10565
  • Liked: 815
  • Likes Given: 40
Re: DIRECT v3.0 - Thread 1
« Reply #3242 on: 07/24/2009 11:31 pm »
Where is the guy looking over their shoulder?   
NASA administrator.
President.
GAO.

Griffin proposed it, so wasn't interested in questioning it.
President wasn't a rocket scientist so didn't know How to question it.
GAO Did question it, multiple times, but was ignored each time.

Oversight Score:   F Minus.

Ross.
« Last Edit: 07/24/2009 11:31 pm by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Nathan

  • Member
  • Full Member
  • ****
  • Posts: 710
  • Sydney
  • Liked: 16
  • Likes Given: 3
Re: DIRECT v3.0 - Thread 1
« Reply #3243 on: 07/24/2009 11:34 pm »

But folded that would give you a 30 meter heat shield...


There are lots of different folding techniques. You can get a 30m heatshield into a 7.5m diameter payload fairing. You basically have a core heat shield of 7.5m and segments from the outer heat shield folded upright around it all in the 10m length.
 
And no, you don't need an EVA to assemble a segmented heathshield. Actually folding techniques have been used in space forever and they work. Automatic bolting works as well.

I've always wondered why people dislike the segmented, folded heatshield for Mars payloads approach so much. As far as I see it, as long as we stay with conventional Mars descent techniques (that is a heatshield and later on parashutes and some powered descend for the last part) going with segmented heatshields makes the most sense. Rather than having to design your modules around constraints of a 10m, 12m or 15m heathshield (depending on the diameter of your payload fairing) you can just design your modules and design the appropriately sized heatshield for it.

Yeah - I've always wondered why this concept is continually overlooked. It is a good solution.
Robert Zubrin's Mars Direct used this approach. His ARES Rocket was a shinning example of a Shuttle Derived Vehicle(payload remaining on top). If the engines were simply bolted on like in New Shuttle C rather than flying back to be reused  then it would be viable. Indeed it may be a good compromise between Direct & CxP & New Shuttle C.
I've never truly understood why NASA (or even the DIRECT team) simply didn't adopt the basic Mars Direct architecture. There would be no issues now. It has a heavy lifter. It has technology that can be used/tested on the moon. It gets a Mars program happening quickly and relatively cheaply.
The only extra element needed is Delta IV or Falcon9H launch of Orion for LEO missions.
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline mars.is.wet

  • Full Member
  • ****
  • Posts: 804
  • Liked: 0
  • Likes Given: 0
Re: DIRECT v3.0 - Thread 1
« Reply #3244 on: 07/24/2009 11:41 pm »
Where is the guy looking over their shoulder?   
NASA administrator.
President.
GAO.

Griffin proposed it, so wasn't interested in questioning it.
President wasn't a rocket scientist so didn't know How to question it.
GAO Did question it, multiple times, but was ignored each time.

Oversight Score:   F Minus.

Ross.

That's what the Air Force uses FFRDC's (like Aerospace, MIT, Sandia, etc) for.

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10565
  • Liked: 815
  • Likes Given: 40
Re: DIRECT v3.0 - Thread 1
« Reply #3245 on: 07/24/2009 11:45 pm »
Without wanting to sound too optimistic, it seems Ares 1 / V is dead.

If a "Direct" type of launcher is chosen, will NASA,
a. Start from scratch
b. Take the Direct concept, validate it, embrace it and deploy it

Option b would save about 1 - 2 years, and a corresponding amount of money, because early concept design, prior to PDR, takes time.

Option a risks heading off to a Not Invented Here hatchet job. Engineers who have been working on Part Number 3714 for Ares 1 really feel it ought to fit into the new "Direct" architecture.

So how do you brainwash smart Ares engineers to love Direct?


Speaking very bluntly, there are a LOT of engineers and managers within NASA who already think its a better plan.   We have a lot of grass-roots support at all of the major NASA centers, amongst both civil service and contractor employees.   Since we started this project, I have personally received well over 2,000 messages of support from people working within the program -- and I'm fairly sure that is just a small fraction of them.   While we have 69 employees on the Team itself, the support base is much, much larger than that.

There are some who still implicitly believe whatever their management tell them to believe.   All they really need is for their management to provide a different line and they'll follow that easily.

Then there's a whole bunch who simply don't care one way or the other.   To them its just a job and they will just work their days on whatever they're told to work on.

And finally, there is an ever diminishing group of hardcore Ares supporters.   They won't give it up, probably not even after it has already died and been swept away.   You're never going to convince them otherwise and its a complete waste of time to try.   While this group used to be very large, the realities of the budget, schedule and especially the workforce reductions, have turned most of the workforce away from this group now.   Today, this group is largely (not entirely, just mostly) made up of senior CxP managers who have chosen to tie their careers to Ares.   I'm expecting a "clean house" pretty soon though, so I don't think they will be a long-term problem.

All IMHO, of course.

Ross.
« Last Edit: 07/24/2009 11:47 pm by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline mars.is.wet

  • Full Member
  • ****
  • Posts: 804
  • Liked: 0
  • Likes Given: 0
Re: DIRECT v3.0 - Thread 1
« Reply #3246 on: 07/24/2009 11:48 pm »
EELV didn't do too badly on its government cost estimates.  Nobody knows how much the contractors spent ... but the schedule was largely held, so it couldn't have been too bad.

I'm sure somebody like Aerospace was involved in that estimate.

Offline JMSC

  • Full Member
  • *
  • Posts: 112
  • Liked: 42
  • Likes Given: 3
Re: DIRECT v3.0 - Thread 1
« Reply #3247 on: 07/25/2009 12:11 am »
It bears repeating. I said: "Ours and theirs cost profiles do not match line for line, but overall we are in the ballpark"

Some have taken that to mean that the "validation" arrived at approximately the same number as us. Not true. I apologize if that's the impression given. What was "validated" was that our numbers were not "unreasonable". That's why I used the term "ballpark". Our numbers were "reasonable" enough to not be dismissed. That's an important distinction.

To put this in perspective, "nobody's" cost figures worked out exactly as stated. To end up "in the ballpark" after scrutiny is like teeing off and the golf ball landing on the green. That doesn't get you a score yet, just puts you within range of the score. It validates your efforts to score and makes you a credible player. It recognizes you as a genuine contender. That's where we are.


Ross/Chuck,

Maybe you guys can take a guess at this, but for me the trouble with estimating the Ares program costs has always been which version of the Ares V rocket do you cost out.  The old five engine RS-68 5.5 segment 10m core which is what the $35 billion figure is based on?  Or the current 6 RS-68 engine 5.5 segment rocket, or the Godzilla-7 with RS-68 regenerative engines, 6 segment boosters, and an 11m-core monster that may be needed to close the performance gap?

DIRECT seems pretty reasonable to cost out since at worst it seems like you might need to go to 5 segment boosters or a J-2X upper stage if your upper stage mass fractions turned out to be as bad as NASA claims they would. But the Ares V could need something like 50 percent margins just to account for all the uncertainty with the design.  I doubt Aerospace Corp would share with you much in the way of how they are dealing with this, but I was curious if anybody had any thoughts on this aspect of the Augustine Commission.

John

Offline NUAETIUS

  • Full Member
  • ****
  • Posts: 427
  • Liked: 1
  • Likes Given: 0
Re: DIRECT v3.0 - Thread 1
« Reply #3248 on: 07/25/2009 12:29 am »
I've never truly understood why NASA (or even the DIRECT team) simply didn't adopt the basic Mars Direct architecture. There would be no issues now. It has a heavy lifter. It has technology that can be used/tested on the moon. It gets a Mars program happening quickly and relatively cheaply.
The only extra element needed is Delta IV or Falcon9H launch of Orion for LEO missions.

Because Zubin is a great advocate, but he has always been a cult of personality.  That's the beautiful thing about the Direct, it's an great idea without a personality.  IF NASA adopted any of Zubrin's ideas, they would then have to deal with his ego, and with having a public advocate who would come out and undercut the changes they would have to make.

On the other hand, NASA can take the idea's from Direct that they like and use them without have someone as known as a Zubin or Peter Diamandis running around screaming they corrupted my idea.  Bad enough that Griffin would call the Jupiter 130 a "gimped" Ares V.

The other reason that NASA might adopt Direct, but didn't look at Zubrin is the Direct team went to GREAT lengths to take the giggle factor out of their work.  Through Direct 1, 2, and then 3, they did the hard work of PROVING their numbers, making the sausage of politics, and honestly working themselves to death.

It's real easy to have an idea in a forum, it's hard to write a book, but it's near deadly to write a proposal for a human space system, and then fix the holes.  Zubin has never went back and tried to fix his holes, or have his data evaluated by a 3rd party professionally, Direct has multiple times.
“It has long been recognized that the formation of a committee is a powerful technique for avoiding responsibility, deferring difficult decisions and averting blame….while at the same time maintaining a semblance of action.” Augustine's Law - Norm Augustine

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10565
  • Liked: 815
  • Likes Given: 40
Re: DIRECT v3.0 - Thread 1
« Reply #3249 on: 07/25/2009 01:49 am »
Ross/Chuck,

Maybe you guys can take a guess at this, but for me the trouble with estimating the Ares program costs has always been which version of the Ares V rocket do you cost out.  The old five engine RS-68 5.5 segment 10m core which is what the $35 billion figure is based on?  Or the current 6 RS-68 engine 5.5 segment rocket, or the Godzilla-7 with RS-68 regenerative engines, 6 segment boosters, and an 11m-core monster that may be needed to close the performance gap?

That $35m figure is for development of the current baseline launch vehicles, which is:-

Ares-I - 5-seg, J-2X, 5.5m Upper Stage
Ares-V - 5.5seg, 6x RS-68B (ablative), 10m Core Stage, J-2X, 10m Upper Stage

This does include both manufacturing and launch facility modification costs as well.

Regen RS-68 will be extra to develop.   Estimated vary between $500m and $1bn for a human rated Regen variant.

Godzilla-7 would be more expensive still.   Most of the difference would be for extra infrastructure costs to support that vast Core Stage structure.   But every flight would also require an extra RS-68 Regen too, which doesn't help their costs any.


Quote
DIRECT seems pretty reasonable to cost out since at worst it seems like you might need to go to 5 segment boosters or a J-2X upper stage if your upper stage mass fractions turned out to be as bad as NASA claims they would. But the Ares V could need something like 50 percent margins just to account for all the uncertainty with the design.  I doubt Aerospace Corp would share with you much in the way of how they are dealing with this, but I was curious if anybody had any thoughts on this aspect of the Augustine Commission.

John

Actually, we took care of that already :)

The EDS version which we actually submitted for review to the Augustine Committee included 2,500kg of additional "Managers Reserve" on the Upper Stage mass allocation, and was powered by a J-2X.

This resulted in an Upper Stage dry mass of 14,656kg and a burnout mass of 16,431kg.   The additional Manager's Reserve accounts for approximately 17% of the total mass allocation.

The pmf (NASA calc method: Usable Propellant/GLOW, not Regular pmf calc method: Gross Propellant/GLOW) was thus a much more reasonable 0.9164!

We did this to be extra-conservative, specifically for this review process to head-off the concerns about pmf and to ensure that any FUD spread by the competition could easily be discounted.

We actually calculated that the mission would still be able to close CxP's 71.1mT thru TLI performance targets even if that Managers Reserve was increased to 5,000kg!   And we informed Aerospace Corp of that finding too.

We deliberately refrained from publicizing these details because we didn't want to tip-off the competition before Aerospace Corp was finished with its analysis.

I sure don't mind if the competition expended all their energies fighting this pmf issue behind closed doors.   They can bi*ch and complain about our pmf as much as they like -- because it was pretty irrelevant for the variant which was actually being studied!



Ain't I a stinker!!!

Muwahahahahahah!  ;D ;D ;D

Ross.
« Last Edit: 07/25/2009 01:53 am by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline robertross

  • Canadian Member
  • Senior Member
  • *****
  • Posts: 17943
  • Westphal, Nova Scotia
  • Liked: 662
  • Likes Given: 7929
Re: DIRECT v3.0 - Thread 1
« Reply #3250 on: 07/25/2009 01:56 am »

We actually calculated that the mission would still be able to close CxP's 71.1mT thru TLI performance targets even if that Managers Reserve was increased to 5,000kg!   And we informed Aerospace Corp of that finding too.

We deliberately refrained from publicizing these details because we didn't want to tip-off the competition before Aerospace Corp was finished with its analysis.

Ain't I a stinker!!!

Muwahahahahahah!  ;D ;D ;D

Ross.

I'll start calling you Ross 'Von Braun' Tierney soon!  LOL
See, NASA needs to get back to designing like this. Then there would be fewer problems!!!

Offline JMSC

  • Full Member
  • *
  • Posts: 112
  • Liked: 42
  • Likes Given: 3
Re: DIRECT v3.0 - Thread 1
« Reply #3251 on: 07/25/2009 02:27 am »
Ross/Chuck,

Maybe you guys can take a guess at this, but for me the trouble with estimating the Ares program costs has always been which version of the Ares V rocket do you cost out.  The old five engine RS-68 5.5 segment 10m core which is what the $35 billion figure is based on?  Or the current 6 RS-68 engine 5.5 segment rocket, or the Godzilla-7 with RS-68 regenerative engines, 6 segment boosters, and an 11m-core monster that may be needed to close the performance gap?

That $35m figure is for development of the current baseline launch vehicles, which is:-

Ares-I - 5-seg, J-2X, 5.5m Upper Stage
Ares-V - 5.5seg, 6x RS-68B (ablative), 10m Core Stage, J-2X, 10m Upper Stage

This does include both manufacturing and launch facility modification costs as well.

Regen RS-68 will be extra to develop.   Estimated vary between $500m and $1bn for a human rated Regen variant.

Godzilla-7 would be more expensive still.   Most of the difference would be for extra infrastructure costs to support that vast Core Stage structure.   But every flight would also require an extra RS-68 Regen too, which doesn't help their costs any.


Quote
DIRECT seems pretty reasonable to cost out since at worst it seems like you might need to go to 5 segment boosters or a J-2X upper stage if your upper stage mass fractions turned out to be as bad as NASA claims they would. But the Ares V could need something like 50 percent margins just to account for all the uncertainty with the design.  I doubt Aerospace Corp would share with you much in the way of how they are dealing with this, but I was curious if anybody had any thoughts on this aspect of the Augustine Commission.

John

Actually, we took care of that already :)

The EDS version which we actually submitted for review to the Augustine Committee included 2,500kg of additional "Managers Reserve" on the Upper Stage mass allocation, and was powered by a J-2X.

This resulted in an Upper Stage dry mass of 14,656kg and a burnout mass of 16,431kg.   The additional Manager's Reserve accounts for approximately 17% of the total mass allocation.

The pmf (NASA calc method: Usable Propellant/GLOW, not Regular pmf calc method: Gross Propellant/GLOW) was thus a much more reasonable 0.9164!

We did this to be extra-conservative, specifically for this review process to head-off the concerns about pmf and to ensure that any FUD spread by the competition could easily be discounted.

We actually calculated that the mission would still be able to close CxP's 71.1mT thru TLI performance targets even if that Managers Reserve was increased to 5,000kg!   And we informed Aerospace Corp of that finding too.

We deliberately refrained from publicizing these details because we didn't want to tip-off the competition before Aerospace Corp was finished with its analysis.

I sure don't mind if the competition expended all their energies fighting this pmf issue behind closed doors.   They can bi*ch and complain about our pmf as much as they like -- because it was pretty irrelevant for the variant which was actually being studied!



Ain't I a stinker!!!

Muwahahahahahah!  ;D ;D ;D

Ross.

Ross,

Thank you for your answer, it usually seems to be the unknowns that cause government program cost to spiral out of control.  E.g. the government doesn’t adequately define what they want a program to accomplish in the first place, “We really wanted an airplane that can fly twice as far as we asked for”.  Or the uncertainties in developing the new technology or equipment required to accomplish the mission as they have defined it.  5,000 kg of mass is quite a huge margin to add, around 30% if I’m thinking about things correctly, it should be hard for even MSFC to to come up with an upper stage to use up all of that margin and even if they could design such an underperforming stage, would it really be that hard to squeeze a little more performance out of the RL-10s! 

It looks like you guys really took the upper stage FUD seriously when developing DIRECT 3.0.  Maybe that explains why they want to attack your extra EOR docking vs. going after their favorite DIRECT 2.0 target which seemed to me to be the upper stage.

The thing I like best about DIRECT is that more than the competing designs it seems to remove the uncertainties associated with accomplishing CxPs return to the moon as NASA has defined it.  Even the NSC has more unknowns in terms of crew abort issues and fundamentally changing the flight dynamics of the shuttle stack by adding around twice the weight of the orbiter to the side.  It looks like the biggest uncertainties remaining are the avionics, which shouldn’t be too great of an issue since all designs will face this issue, even the NSC will need to update the shuttle avionics to some degree, and the extra docking in low earth orbit.  But heck if the Russians can reliably do it with 1950/60s era Soviet Technology we shouldn’t have too much trouble with it.

Good luck with the remaining month or so until the Augustine Commission releases its report.  Hopefully Obama can recognize a real bargain for the Nation’s Space program when it is offered to him.

John

« Last Edit: 07/25/2009 03:23 am by JMSC »

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10565
  • Liked: 815
  • Likes Given: 40
Re: DIRECT v3.0 - Thread 1
« Reply #3252 on: 07/25/2009 02:35 am »
The main reason why Zubrin's In-Line launcher, also called "Ares", was not considered is because it has a few technical concerns.

Firstly, it uses the more powerful 4-segment ASRM Boosters -- which were canceled for Shuttle after their costs went out of control.   They were replaced by the SLWT, which produced a similar performance improvement.

Second, the Upper Stage has an engine in the SSME thrust class, but which also needs to produce 465s vac Isp -- which is approximately 13s better than SSME, yet needs to be air-startable and then re-startable too.

Both of these elements are pretty costly items which most people don't realize were included.   You're talking about a similar cost ($1.8bn+) to the 5-segs in order to get the ASRM's and you're talking about a really serious development program ($2bn anyone?) to get that combined-higher-efficiency-SSME-air-start/re-start engine qualified for human use.

But if you swap those for existing systems (or J-2X in the case of the US engine), the performance for the vehicle drops significantly.   But if it drops, it can no longer support the size of mission Zubrin was hoping for -- and that short-circuits the plan :(


Also, since that study was conducted its concepts have been refined a lot by Zubrin and the Mars Society.   The "Mars Society Mission" seems to be the most recent iteration from that quarter and the mission size for MSM has grown since "Mars Direct" was first proposed.   It wouldn't fit on two of Zubrin's Ares vehicles now anyway.

Ross.
« Last Edit: 07/25/2009 02:42 am by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Eric Hedman

  • Senior Member
  • *****
  • Posts: 2508
  • The birthplace of the solid body electric guitar
  • Liked: 2208
  • Likes Given: 1313
Re: DIRECT v3.0 - Thread 1
« Reply #3253 on: 07/25/2009 03:19 am »
Ross or anyone else in the know:

If the Augustine commission picks Direct and General Bolden Obama, and Congress agree,  who should run the Direct development so it gets done right?  Does NASA have anyone that should be moved into the position that won't screw it up?

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10565
  • Liked: 815
  • Likes Given: 40
Re: DIRECT v3.0 - Thread 1
« Reply #3254 on: 07/25/2009 03:32 am »
Brilliant question Eric.

Honest answer:   I'm not sure.

Wayne Hale seems to have some time on his hands since he did something to tick Griffin off and earned himself a Latteral Transfer to Obscurity (y've all noticed that, right?).   He shone very brightly after Columbia was lost and managed the Shuttle Program through one of its darkest times.   That tells me he's certainly got the skills to manage something this tough.   I'm just not sure how well versed he is as a "development" manager as opposed to an "operations" manager though -- they are subtly different jobs.

John Shannon also looks like a fine person for such a job, and with Shuttle closing in just 14 months time it looks like he would be available too.


While we need a new Associate Administrator for Exploration and we also need a new head of Constellation Program, I don't think we need a new head of Launch Vehicle Development at all.   The development work should really be done by the contractors now and NASA's role should be primarily about Oversight and Analysis.   NASA should clearly define the Standards which must be met, define the Requirements which the program needs to achieve and then let the contractors handle all of the details.   Mind you, NASA people should also be looking over their shoulders at every step of the way to ensure nobody is cutting any corners too!


For the more senior positions, I don't really know all of the NASA people at that level, certainly not well enough to be able to separate the good from the bad.   Someone else (Bolden/Garver presumably) is going to have to work that out and sift those who have been promoted to their highest level of incompetence from those who can actually do the job.

A particular concept which has worked in some other organizations facing such similar difficult reorganizations, has been to return EVERYONE back to the lowest ranks, put everyone back in the trenches again.   And then make everyone compete again for the management positions.   The best of all the available talent gets promoted, the others don't.   But that takes time to accomplish and time is something we don't really have much of right now.

One things for sure:   Bolden and Garver are going to have their work cut out for them identifying all of Griffin's cronies and exorcising the agency of their incompetence while leaving the quality personnel in place.   I hope the rot isn't so ingrained that they just have to amputate the entire limb of upper management entirely, even cutting away some good parts just to be sure.   I sure don't envy them the job, but I think a Marine Major General should certainly be up to the task.

Ross.
« Last Edit: 07/25/2009 03:44 am by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Lancer525

  • Full Member
  • **
  • Posts: 244
  • Liked: 2
  • Likes Given: 0
Re: DIRECT v3.0 - Thread 1
« Reply #3255 on: 07/25/2009 03:34 am »
Ross or anyone else in the know:

If the Augustine commission picks Direct and General Bolden Obama, and Congress agree,  who should run the Direct development so it gets done right?  Does NASA have anyone that should be moved into the position that won't screw it up?

That's the $64,000.00 question.
"For some inexplicable reason, everyone seems to want to avoid simple schemes."   -John Houbolt

Offline rsp1202

  • Elite Veteran
  • Full Member
  • ****
  • Posts: 1083
  • 3, 2, 1 . . . Make rocket go now
  • Liked: 0
  • Likes Given: 0
Re: DIRECT v3.0 - Thread 1
« Reply #3256 on: 07/25/2009 03:47 am »
The main reason why Zubrin's In-Line launcher, also called "Ares", was not considered is because it has a few technical concerns.

Firstly, it uses the more powerful 4-segment ASRM Boosters -- which were canceled for Shuttle after their costs went out of control.   They were replaced by the SLWT, which produced a similar performance improvement.

Second, the Upper Stage has an engine in the SSME thrust class, but which also needs to produce 465s vac Isp -- which is approximately 13s better than SSME, yet needs to be air-startable and then re-startable too.

Both of these elements are pretty costly items which most people don't realize were included.   You're talking about a similar cost ($1.8bn+) to the 5-segs in order to get the ASRM's and you're talking about a really serious development program ($2bn anyone?) to get that combined-higher-efficiency-SSME-air-start/re-start engine qualified for human use.

But if you swap those for existing systems (or J-2X in the case of the US engine), the performance for the vehicle drops significantly.   But if it drops, it can no longer support the size of mission Zubrin was hoping for -- and that short-circuits the plan :(


Also, since that study was conducted its concepts have been refined a lot by Zubrin and the Mars Society.   The "Mars Society Mission" seems to be the most recent iteration from that quarter and the mission size for MSM has grown since "Mars Direct" was first proposed.   It wouldn't fit on two of Zubrin's Ares vehicles now anyway.

Ross.

Do you recognize this concept? I've had it saved for a while and forgot about it.

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10565
  • Liked: 815
  • Likes Given: 40
Re: DIRECT v3.0 - Thread 1
« Reply #3257 on: 07/25/2009 04:28 am »
Do you recognize this concept? I've had it saved for a while and forgot about it.

I haven't seen that particular sheet before, but I have seen the performance and some cost results for all three of those configurations.   We calculated those configurations for ourselves back around the time of the original "Ares-IV" rumors -- whenever those were! :)

The first option has 4 SRB's.   The added weight of those definitely requires a new Crawlerway & Crawler Transporters, probably also requires new Concrete Hardstands at both Pads and may even require the VAB's floor to be reinforced.   Costs the Earth.   Never gonna happen.

The second option is plausible.

The third option is a pig.   You need to deep throttle all the engines in flight and then you also have to shut down two of the engines all in order not to breach the 4g limits.   And when you do that while carrying a 150ton Core Stage to LEO, the performance is barely enough to lift an Orion (about 30mT Gross).   Highly inefficient way to do what a Delta-IV Heavy can already do.

Personally, I think this approach misses the sweet spot by quite a distance.

YMMV of course.

Ross.
« Last Edit: 07/25/2009 04:33 am by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Eric Hedman

  • Senior Member
  • *****
  • Posts: 2508
  • The birthplace of the solid body electric guitar
  • Liked: 2208
  • Likes Given: 1313
Re: DIRECT v3.0 - Thread 1
« Reply #3258 on: 07/25/2009 05:10 am »
Ross:

Thanks for the answer.  By the way, like me, you are up too late staring at your computer.

Offline kkattula

  • Member
  • Senior Member
  • *****
  • Posts: 3008
  • Melbourne, Australia
  • Liked: 656
  • Likes Given: 117
Re: DIRECT v3.0 - Thread 1
« Reply #3259 on: 07/25/2009 05:26 am »
re: ... mini-shipyard...

.... apparently if you name it Spacedock a spatial distortion automatically relocates it to a random L point and quadruples its facilities ;)...

... a bit much for what's supposed to be an inexpensive and Direct-style beginning effort at a much-needed and long overdue bit of space infrastructure that will complement Direct...

... not because of NASA EDS FUD, but because it would greatly expand the use of space-assembled probes and modules that don't need to carry expensive automated docking gear...

... now... once the original has been proved out in LEO I can see another version being assembled by the original mini-shipyard and boosted out to wherever next gen space operations are staged...  a starting seed package sort of deal...
 

Exactly!  Eventually we ought to have a combined shipyard/depot/communication hub/crew haven in LEO, L1/L2, Mars orbit etc.

Build the first one in LEO, apply the lessons learned to improve the next one and the next.  Just don't change the design so much it becomes a new development each time.

Tags:
 

Advertisement NovaTech
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0