posted 07-21-2009 10:18 PM               

Space-plane limits geometry and design? And a capsule shape does not limit geometry and design?

The capsule design is looking in the past for a solution that was not there. One forgets that the quest for a space-plane was in part to cut down the high cost of capsule access to low earth orbit. Also, the "horse-drawn" space-plane offers far more low earth orbit capability than will ever be realized by any capsule. To use the capability the Space Shuttle has shown one needs lots of $$$, but the capability is there to use.

Besides the obvious mission difference, look at an Apollo capsule beside the Space Shuttle... it was like going from the Wright flyer to a single wing design in one design iteration. This is huge! People seem to have expected a Wright flyer to Boeing 747 jump in one design iteration. Why? This has not happened in the past.

One obviously would not want to send a winged space-plane to the moon: a lot of useless mass. A capsule does not have the capability needed for other than rare "small scale" travels to the moon. It's more volume and geometry restricted. Therein lies what is probably the biggest problem with both the space-plane and capsule concept used by NASA: having one vehicle for all "missions" is like producing only tracker-trailers for use as transportation for manufactured goods as well as for family vehicles for everyone to use to go back and forth to work.

A space-plane (drop the delta wings to lower re-entry heating...great cross range landing gone, but more robust design...see early 60s design concepts) is the way to go for low earth orbit crew and small payload transport, Saturn class vehicle for large payloads to low earth orbit, and radically different designs are needed for travel to/from the moon and planets. (Again, see 60s design concepts...they had it right but missing technology pieces... now the technology is here to make it happen.) This all costs big $$$$. There is no way around big $$$. (For starters, the use frequency is way too low.)

I am obviously all over the place, but there are many points to address and limited reply space.

posted 07-21-2009 10:58 PM               

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Originally posted by BNorton:
Space-plane limits geometry and design? And a capsule shape does not limit geometry and design?

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posted 07-21-2009 11:34 PM               

If I spent six months getting to Mars, having to spend eighteen to twenty-four months on the Martian surface - waiting for the next Mars/Earth corridor alignment - spending another six months on the return, I probably wouldn't be keen on testing the assumption that my craft (screaming back at 50,000kph) could perform a series of 'S' turns to bring myself and my crew, to a safe landing. A capsule is the easiest, safest, and most cost effective way to ensure the safe return of crew from beyond LEO.

posted 07-22-2009 12:45 AM               

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Originally posted by Apollo Redux:
A capsule is the easiest, safest, and most cost effective way to ensure the safe return of crew from beyond LEO.

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How can we be realistic? I honestly think that LEO is the way to go for the next decade or two. Developing a vehicle that can satisfy those needs and retire the Space Shuttle is ideal. A reliable and cheap spaceplane. As mentioned, the technology is there, why not continue to perfect it?

posted 07-22-2009 02:09 PM               

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Originally posted by MrSpace86:
I would embrace it either way, as long as we don't have to beg Russia to take us to the Space Station or anywhere in space for that matter (Cernan hit that right on the head).

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A space plane in some form or another is a must. However, based on improving upon the shuttle concept, I think private enterprise is better suited to take up that banner. If they can make a buck, they'll make it happen. They already have a destination - the ISS.

As for the other exploration visions, I'm on the side of David Randolph Scott (Commander Apollo 16) - "Man must explore..." It's inherent to our very essence, and I believe governments can best ensure their survival by providing their citizens with; basic and fundamental security;guaranteed equal representation before the whole of society; and to inspire them to look beyond themselves and to dare to achieve that which seems beyond their own individual grasp.

Space exploration should have a esteemed and intrinsic place in government policy (actions not just platitudes), while space exploitation should be left to those private enterprises bold enough to pursue it.

The shuttle was worthwhile, a replacement similar to it is equally worthwhile, but if we're not going somewhere, you are never going to inspire the next generation to take up the cause of exploration or make the sacrifices that will return benefits( some of which may not even be contemplated today).

As we are on a fossil fuel ball with limited resources, our future as a species lies elsewhere. Leaving to future generations,what we can start today, is myopic and cowardly.

As a Canadian, I can attest that there is very little difference (belief systems) between us and Americans.

"Geography has made us neighbors. History has made us friends. Economics has made us partners. And necessity has made us allies. Those whom nature hath so joined together, let no man put asunder.

What unites us is far greater than what divides us..." - John F.Kennedy (Address Before the Canadian Parliament in Ottawa. May 17, 1961)

The moon can help get us to Mars and beyond.Heating up the regolith will produce hydrogen that in turn can be used to power spacecraft and other power systems, and as an extension of Earth, I feel it is a resource that we can not afford to disregard.

posted 07-22-2009 07:13 PM               

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Originally posted by Apollo Redux:
As for the other exploration visions, I'm on the side of David Randolph Scott (Commander Apollo 16) - "Man must explore..."

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posted 07-22-2009 08:05 PM               

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Originally posted by spacebrane:
Actually, Dave Scott commanded Apollo 15. John Young commanded Apollo 16.

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posted 07-25-2009 03:31 PM            

The only other possible justification might be cost. That is usually supported on the basis of the 'resusability' of a spaceplane. However re-use requires a greater robustness of componentry, and that usually means more weight, so the cost per pond of payload goes up. Given the requirements for crew safety, everything in a reused vehicle must be checked out and inspected before subsequent use, just like a throw away vehicle. Since all parts have a failure rate, the more often you fly a given vehicle, the more replacements/repairs you have to do. This increases the cost per launch in a way that single-use systems do not. Bottom line, re-usable usually will come up as more expensive to prepare for launch.

Given that design and construction cost sfor a re-usable vehicle will exceed those of a single use one, the supposed advantages of re-usable vehicles seem illusory, at least in today's world.

Add it all together and there's really no advantage to a spaceplane, reusable or not, that I can think of. I don't think that will change until we can build a self-testing vehicle with MTBFs several orders of magnitude higher than we can do today.

posted 07-25-2009 07:19 PM               

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Cernan absolutely nailed that. Relations between the two counties have historically run from openly hostile, to grudgingly tolerable - hardly a track record to pin your exploration hopes on. Let alone to trust that they won't rip you off when driving you to the home you basically paid for.

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Which is why in my opinion the ISS was a mistake as it will never be able to perform research to cover it's ridiculous cost. Between the cost to the US taxpayer, the never ending repairs and the Russians using it as a money making flying hotel, the ISS never receives any real favorable press and from that people form their opinions that the ISS was a waste of time, money and lives.

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The shuttle was worthwhile, a replacement similar to it is equally worthwhile, but if we're not going somewhere, you are never going to inspire the next generation

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The Shuttle spending 30 years going up, orbiting and returning to earth with the loss of life, the amazing amount of delays and the perception of any exploration of significance due to being stuck in low earth orbit for a generation and a half makes it a white elephant.

The shuttle started as a worthy idea but became saddled with the "safe" decision of going with the ISS. The US should have simply stuck with the shuttle and spacelab missions and in tandem developed a new moon or mars program and phase the shuttle out. The US was sucked into the "let's all work together and be friends" mindset which came at a too high of cost.