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What are the reasons...

Posted by: Ekkehard Augustin - Tue Sep 20, 2005 11:14 am
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Post What are the reasons...   Posted on: Tue Sep 20, 2005 11:14 am
Obviously NASA is planning to base their future missions to Moon and Mars on expendable service modules, an expendable lander and - supposedly - expendable second stages.

On the other hand SpaceX is working on fully reusable Falcon V and Falcon IX.

Additionally Ball is working on ballutes.

As far as I understand it and remember news both SpaceX and Ball have scheduled the completion of their works so that thex are ready a significant time before NASA's missions to the Moon and Mars.

What are the technological and engineering reasons for NASA not look at and work with those too regarding their missions - this would get them the chance to achieve their goals cheaper and - perhaps - faster.

Has it to do with methods or principles of technology and engineering, with the CEV being manned or are there other engineering reasons?



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Post    Posted on: Tue Sep 20, 2005 12:12 pm
I think that if NASA was beginning from scratch they might have gone for a more reusable design but their plans are more to do with politics and public perception than engineering.

Using the existing shuttle facilities to create their next generation launch vehicles allows money to be channeled to US states that have always supported the space program because of jobs and revenue derived from NASA (I think the Americans call it pork barrel politics- dont ask me why). It also stops some of the protests from people who see the shuttle as a never ending source of revenue who would extend its life time with arguments for modification rather than replacement.

Also the choice of a more conventional capsule fits in with their conservative approach with regard to safety, another space disater would probably mean the end of manned space flights in the US. By being less cutting edge NASA will ensure that it actually gets vehicles rather than another paper study.

I guess the Russian Kliper might turn out to be more advanced, although I read a while back that they were considering using the avionics designed for the Hermes space plane if ESA decides to partner with them so that wont be all that modern either.

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Post    Posted on: Tue Sep 20, 2005 12:29 pm
Alright - but couldn't they also keep that all if they would use SpaceX's technology?

The service module and the lander could be reusable then. The people they have to satisfy for political and economical reasons could go to SpaceX who may become more and more interesting in the future even without NASA once they have had a successful Falcon I launch - so the incentive to go there will be already there.

And the cheaper solution developed by SpaceX would enable to order more reusable stages from SpaceX - they could keep the employment.

So - back to the topic technology - may there be any problems regarding integration of Falcon's stages and NASA-hardware? SpaceX's service could also enable NASA to restart cancelled projects perhaps.

Would the Falcon-stages have to be modified or changed?



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Post    Posted on: Tue Sep 20, 2005 5:21 pm
Ekkehard Augustin wrote:
may there be any problems regarding integration of Falcon's stages and NASA-hardware? SpaceX's service could also enable NASA to restart cancelled projects perhaps.

Would the Falcon-stages have to be modified or changed?


The main problem is that Falcon IX is not big enough, at its biggest it will only place 24,750kg in LEO. It could launch the CEV at a push which is quoted at 25 ton but it would not be able to put the Earth Departure stage and Lunar lander in orbit. Even if it could we come back to the argument about multiple launches and the risks associated with time delays and rendezvous. If NASA wanted to do it in multiple launches they could use EELVs (shudder and cringe at the thought).

Add to this that NASA has already got flight hardware knocking about from the shuttle and that they need a vehicle capable of launching ISS components so that they can retire the shuttle, even if the ISS isn't finished and Falcon IX doesn't look like such a good bet. Particularly considering its only just been announced and probably wasn't an option available when NASA's plan was being drawn up. NASA would not put its future in the hands of a small company who has never launched a rocket, Falcon I is still awaiting its maiden launch and the last I heard there had been a problem with the engine. No matter how much confidence you have in SpaceX that is still a big gamble.

If Falcon I is successful and SpaceX go on to build Falcon V and IX they will no doubt compete for ISS contracts and may even dominate the market but at this point in time they are just to small and have to prove themselves.

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Post    Posted on: Wed Sep 21, 2005 10:01 am
Oh, sorry - I wasn't talking precisely sufficiently. I simply thought of the way SpaceX enables complete reusability. According to the Synopsis Technology thread this hasn't to do with the capacity and volume of the stages and Falcons reported but with the technology of reusability only.

I suppose that the reusability-technology has to do with materials used, circumstances of reentry and the like.

So the central thought of mine was that NASA could order stages of the capacity they need from SpaceX which would mean that the stages would include SpaceX'S reusability-technology. Falcon V and Falcon IX I mentioned only because of their complete reusability - they both together seem to mean that currently the reusability can be applied to each scale of volume and weight.

Then SpaceX can be assumed to be able to construct an Earth departure stage that is fully reusable, a lander that is fully reusable and a service module that is fully reusable. Would these things still mean a requirement to adjust, to modify or to change or alter NASA's hardware? Regarding technical or technological safety perhaps?



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Post    Posted on: Wed Sep 21, 2005 7:29 pm
But, Ekke, the program announced by Griffin is Shuttle-derived technology, in other words it is based on re-usable technology. The SRBs which form the first stage of the CEV launcher and the strap-ons for the cargo launcher are the same as the Shuttle SRBs which are refurbished and re-used after each flight. The LOX/LH main engines of the cargo booster and the upper stage of the CEV launcher are SSMEs, which are purposely designed to be re-usable. It would be prohibitively expensive to use SSMEs on a fully-expendable rocket, so there must be a plan to re-use them as well. The CEV crew capsule is also specifically described as being re-usable.

And all of that technology has flown before. Hundreds of times, some of it. Falcon has not. NASA is playing the hand they were dealt; and it actually makes sense for the first time in 30 years.


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Post    Posted on: Wed Sep 21, 2005 10:19 pm
SawSS1Jun21 wrote:
It would be prohibitively expensive to use SSMEs on a fully-expendable rocket, so there must be a plan to re-use them as well.
You are just assuming that they will re-use the SSMEs, they haven't actually said they will, AFAIK. You know what happens when you assume, right?


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Post    Posted on: Thu Sep 22, 2005 7:33 am
Hello, SawSS1June21,

All or at least some of what you say may be the reason why the don't use SpaceX's technologies.

Regarding the CEV - is it impossible to use SpaceX's reusability-technology for all stages used to launch the CEV?

My focus was on the Earth departure stage merely - I understood it all as if that stage will be expendable. And the stages to carry the Earth departure stage into orbit sounded to me as if they will be expendable too.

The external tank of the Shuttles were not reusable but expendable- will that be changed?

I am wondering about the second stages, the service modules and the lander mainly - plus the Earth departure stage - but not about the CEV (although I would be interested why it can be used 10 times only...). Do the four others all use SSMEs too? The lander for example? As far as I remember the recent articles the lander will use oxygen plus methane as propellants and the illustrations don't indicate any SSME. Am I wrong?

It has been said that the service module will go into the ocean which is the reason why the CEV is going to land elsewhere - but there wasn't a single word that the service module will be recovered from the ocean. This sounds like expendability to me - what are (or would be) the technological reasons of it? Why not use SpaceX's resuability-technology?



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Post    Posted on: Thu Sep 22, 2005 4:00 pm
I think that we should wait until SpaceX actually reuse their rocket stages before making judgements about how successful their technology is. NASA has tried to avoid unproven technology wherever it can so I am not surprised that they didn't use SpaceX's.

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Post    Posted on: Thu Sep 22, 2005 5:26 pm
From point of view it would be sufficient if they would have built in the possibility to switch over to SpaceX. But they didn't as far as I understnd what has been reported about their plans.

Their schedule is more than 5 years long and SpaceX has scheduled the first flights of their fully resuable vehicles in 2007 or 2008. At my own job such possibilities to switch over are usual and important to be able to keep budgets and terms.

The questions weren't menat to criticies NASA - I am really interested to know if there are technological obstacles to use SpaceX's reusability-technology.



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Post    Posted on: Thu Sep 22, 2005 6:23 pm
How can they build a possibility of switching to SpaceX technology, if the technology does not exist? Even if the technology works perfectly on Falcon I it is not clear whether it would be scalable for the size of launchers NASA will want.

At present no one knows whether there are obsticle because of the questions about the SpaceX technology and details on how the NASA rockets will be built. You are talking about 2 things that have not made it off the drawing board yet and as such may be subject to many changes that may make it harder or easier to integrate them.

No one can do an analysis of whether the two can be used together without knowing whether either will work on their own.

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Post    Posted on: Fri Sep 23, 2005 7:36 am
There may be a misunderstanding again - I wasn't speaking about a technical switch but about a decision-switch to be done by the project management.

To be able to do such a switch would have the advantage to be able to use an advantage that becomes accessable during a time of several years.
As far as I remember NASA's schedule is more than 5 years long while SpaceX has a schedule for full reusability aiming at 2007 - two years long only.

So it would be reasonable if NASA would be able to switch over to SpaceX's technology in early 2008. That would be the date they should check SpaceX's technology - together with the company - for usability for their own purposes and goals. This should be included into their schedule.

I am missing issues about this and so I fear they didn't even think about it - but they are faced to a 104 billion dollar-project currently and to think abou it could open up the chance to save several billions.

As long as the technologies aren't off the drawing boards there is the chance to make them compatible - once they are off most of such chances are gone. ... ... ...



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Post    Posted on: Fri Sep 23, 2005 3:43 pm
I have reflected upon this for some time now and I am beginning to suspect that the "re-usable" specification of the upper stages of Falcons V and IX (the upper stage of I is NOT re-usable) is probably lip service to Bigelow.

To be sure, Merlin is designed to a re-usable spec, but getting the engines back in an overhaul-friendly condition is WAY easier than de-orbiting a giant beer can (as described in an article on the SpaceX website) in one piece.

Aluminum melts at 660 C, vaporizes at 2467 C, and is combustible in air at temperatures less than it's boiling point. Falcon is just an aluminum tube (hence the self-effacing 'beer can' reference) in all of her stages. But ASP rules say that the vehicle must be fully re-usable.

If I'm Musk and I'm doing my homework on ASP and I realize that shucks, V will do the lift job but there's just no way that I can also loft thermal protection for the upper stage as well because the bird ain't big enough, well then what?

Hmm... I'll roll out IX early! It has variable fairing sizes, so I can extend the shroud diameter to cover the entire upper stage, put some ablative coating on a thin niconel outer skin, insulate the remaining gap, and presto! ASP here I come! Sure, it actually COSTS MORE to do it this way, but the press coverage and the Bigelow contract make it worth the silliness.

When Griffin calls me to send a crew to ISS, I use the REAL Falcon IX upper stage, which is gonna cost less anyway, and you bet I'm gonna make my docking mechanisms fit CEV and the lunar hardware.

Will Griffin keep the technology streams separate? Hell yes. If Musk has to survive by being clever and competitive, his price will stay down. And if CEV explodes or Falcon augers, there is still a way to put American crews in orbit because THERE IS NO COMMON HARDWARE TO SUSPECT!

NASA's lunar vehicle is expendable because of the beer can thing, too, BTW. The landing stage is left in place as a resource for later missions (so it is re-usable), the ascent stage is the beer can. It's a metal balloon which simply contains a habitat. The Apollo LEM was so thin that you could actually visibly detect the bulging of the egress hatch at a mere 0.2 atmospheres. There is no practical way to bring something like that back to the surface of the earth and no reason to expend more energy to send anything more robust.


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Post    Posted on: Fri Sep 23, 2005 3:47 pm
Perhaps NASA will look in a few years to see whether SpaceX technology can be used on their new launchers, but they are not going to think about it now as there isn't anything to use. You cant expect NASA to wait for SpaceX to come up with something before building their own rockets, there have already been to many delays.

If the technology is usable in the future then NASA will probably adapt it but at the moment they will use what is available which means that the boosters will be largely expendable.

While this approach is not ideal at least something will get built, if they wait for inovations then the development time will be to long and there is a possibility that the US government might cancel.

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Post    Posted on: Fri Sep 23, 2005 5:12 pm
Hello, Andy Hill, and hello, SawSS1June21,

this seems to mean that there no real technological obstacles to switch the decision over to SpaceX's technology if it is available in 2007 or 2008 in a flight-tested status. They simply wouldn't have talked about it.

I didn't have in ind that they should wait for SpaceX but simply keep the chance to switch their decison while currently working on the non-SpaceX-approach.

Regarding the lande - it could be recovered the same way as the suspected ASP-stage in principle if it would fit into the Falcon IX. It might be possible to build an even larger which the lander fits in.



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