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Old June 17 2012, 09:02 AM   #147
Crazy Eddie
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Re: SpaceX is a go for April 30th: 1st commercial launch to space stat

publiusr wrote: View Post
That tinkertoy approach actually costs you more in the long run. Most missions we have now don't need assembly. It is just better to have all liquid handling done here on the ground. ISS modules are rather cramped--especially the Soviet versions. Remember, the American ISS parts werelaunched by shuttle so they are just cans--all propulsion was handled by orbiters which no longer fly.
All of the Salyut space stations as well as the Mir were assembled in orbit without the aid of an orbiter. China's space station concept is similar to the Mir and calls for assembly the same way. And if you consider that Skylab required some major repairs in orbit before it could be made operational, this means that ISS is the only space station ever constructed that "required" the space shuttle orbiter for construction; all of the others employed old fashioned autonomous rendezvous using either disposable space tugs or a minimum amount of self-propulsion.

As for the "rather cramped" ISS modules... nothing is more cramped than a non-existent module, which is exactly what NASA will have if it has to depend on HLVs just to service the station, let alone send up a crew. China and Russia both understand this, which is why China has no long-term plans to develop HLV capability and Russia wisely gave up after the N1 fiasco and has been using the Soyuz ever since.

So, yes, the capability of the rocket DOES come before the mission design and the payload determination.
As far as NASA is concerned, this is true. Not because it's SUPPOSED to be this way, but because the U.S. Senate has gotten used to using space exploration has a pork barrel public works project: the rocket is designed to maximize participation by selected aerospace contractors, not with any particular mission or capability in mind.

Really, it's like handing a car designer a set of specifications that say "It must use a GM transmission, a Ford engine and alternator, computers and electronics installed by either HP or Intel, a Sirius Satellite Radio, Eddie Bauer seats, an aluminum frame, and it must be really really big."

The other is the size of the SLS. If down the road we wanted to launch a telescope that could, for instance, study the entire energy balance of Earth with pixel sizes smaller than clouds, it would take a big telescope.
We already have telescopes that can do that. The NRO has been using them for decades (in fact they have so many of them that they're giving them away) None of them require HLVs to put them into orbit.

With a big rocket, you can think start to think about launching big optical systems.
The Hubble telescope doesn't qualify as a "big optical system" to you? Because it does to most people, and the entire system only weighs about 12 tons, about what you could launch on an Ariane 5 or a Proton.

The really funny thing is, if you docked those optical systems together in an array -- say, a huge fan of smaller mirror/receptors in steerable grids -- then you wouldn't have to launch the whole thing on a single rocket, you could send them a few at a time and then dock them together into an increasingly large telescope platform; the array could literally be as large as you want it to be. 12 tons or 120 tons, perfectly scalable, in addition to being much easier to repair and service. Most importantly, not requiring a $20 billion HLV to put it into orbit means it doesn't have to work perfectly the first time you put it up there, nor do you only have to settle for ONE of them.
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