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Old July 14 2012, 11:03 PM   #160
Crazy Eddie
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Re: SpaceX is a go for April 30th: 1st commercial launch to space stat

publiusr wrote: View Post
I would have no problems with hydrazine depots myself. That's what von Braun wanted, but folks are really risk averse today.
Considering your constant objections to in-space assembly, you would appear to be one of them.

newtype_alpha wrote: View Post
Actually, I'm pretty sure ULA is going to wind up being the Junior Partner to Sierra Nevada;
I wish I could believe that--but Boeing already has their own capsule that they would like to sell:
They're welcome to try, but the CST-100 -- much like the Liberty -- is really just Boeing making a play for a CCDev grant. Their spokespeople can't say two words about the CST-100 without adding "Of course, we can't do it on our own, not without some funding from NASA *ahem ahem*." Which makes it all the more mysterious when they go ahead and develop the thing anyway even though NASA hasn't actually given them any money. I'm almost beginning to believe that the spacecraft itself is just a scam and that they'll find a way to cancel/stall development as soon as NASA starts paying for it.

This is also to be launched by Atlas, so Dream Chaser will wind up having to deal with a conflict of interest.
It wouldn't be a conflict since ULA isn't the one controlling the contract. NASA's still holding the purse strings, so it's really just a question of which design NASA wants to put money behind. In the end, Boeing and ULA will have to go along with it or risk being sidelined in the entire project (especially since the Falcon-9 could easily be adapted as a second choice for the Dreamchaser).

Unlike Space X, which has moved as much component fabrication as possible in-house, Sierra Nevada usually goes outside for equipment it does not already manufacture."
Actually, SpaceX is about the only company that manufactures all their parts in-house. That's one of the reasons people think of it as the poster child for the NewSpace movement: unlike, say, Boeing or Orbital Sciences, they're not just building on existing architecture to expand the industry, they're a wholly independent party with almost no ties to the existing political-industrial complex.

What that means is that they will be even more fierce to go after the manned capsule movement. In the UK, they wanted their own planes, like TSR-2. They got force fed the F-111 because it was to be cheaper--and wasn't. But the damage was done. I fear that ULA might try to give the old Avro Arrow treatment to Dream Chaser.
Like I said, that's what they're trying to do with the CST-100. It hasn't been working very well because NASA doesn't have that much money to give and their objective isn't so much to steer cash towards defense contactors so much as fund the development of a working spacecraft in the shortest time possible. Boeing is on the short bus because -- evidently -- nobody at NASA believes that Boeing needs the CCDev money to build a working spacecraft.

newtype_alpha wrote: View Post
Interestingly, the Soviets tried the same thing with the Energia rocket
That was at the end of the USSR, after the farce that was a war in Afghanistan depleted their budgets--along with the Baikal Amur Mainline.
The budget crunch doesn't do much for the fact that their orbiting space platform tumbled out of orbit and broke up in the Earth's atmosphere hours after launch. It is the second of two datapoints demonstrating that throwing an entire space station into orbit in a single giant heave is usually a bad idea; building one piecemeal is a lot safer, a lot easier, and in the long run, a lot cheaper. This is likely to be true of manned spacecraft as well, such as the Nautilus-X concept NASA's been throwing around.

newtype_alpha wrote: View Post
LOL not by a longshot. It's a result of the fact that what they're essentially trying to do is a propulsive landing on mars with a robotic vehicle the size of a jeep
They are going to need huge aeroshells for anything larger
They're going to need a hell of a lot more than an aeroshell if they're planning to top Curiosity. Again, the only reason for the sky crane concept was because putting the landing platform UNDER the rover would put the thing at risk for damage due to dust and debris being blown around by the thrusters. Anything larger will have to sit inside of a fully protected space capsule with full propulsive and maneuvering capabilities, very probably with the ability to transfer to an alternate landing site if something is wrong with the primary. At that point you're basically doing a manned mission without the men; curiosity is almost that already.

So let me get this straight. He has already dismissed future HLLVs out of hand, but then in the same breath talks about a space elevator tens of thousands of miles tall, dwarfing any HLLV. That anti-heavy-lift mindset is what is hobbling us.
That's not anti-heavy lift, that's pro-space elevator. Those are two completely different things; space elevator proponents dismiss rocketry IN GENERAL, even to the point of pretending it won't be needed for spacecraft already in orbit.

Interestingly, the solution is implied in the problem: a spacecraft large enough to get to mars would need an enormous heatshield and would therefore be too large to put on an HLV. The obvious solution is to build a modular spacecraft so you can leave most of your mission mass in orbit and drop to the surface in a much smaller craft. HLVs would not be necessary for any part of this mission, and actually neither would space elevators.

An HLLV is just a water tower. The best thing is to just build an SLS replacement launcher in about 30-50 years time that is itself 30 meters across and just launch the aeroshell in one piece.
Meanwhile, someone with more vision and less HLV fanboyism can use six or seven Falcon-9s to boost a drive section, two habitat modules, two landers, and a big tank of xenon and fly the entire mission with a VASIMR. Since that craft doesn't have to burn up in the Earth's atmosphere every time it returns (assuming you planned your flight profile correctly) then it can make five trips to Mars and back before your SLS replacement even leaves the drawing board.

And what, prey tell, are you planning to land on Mars with a 30 meter heat shield? That's like moving to a new town by loading your house onto an airplane and flying it there.

My point in all this is for folks to understand that rocket size has been stagnant.
That's because rocketry, like everything else, is an industry. And industry is driven by market forces of supply and demand.

Rocket size has been stagnant because there is no demand for HLVs in the 70 ton class. There is a world of difference between market demand and something someone somewhere thinks would be cool to have; to wit, the reason there's no demand for HLVs is because 99% of what we're sending into orbit doesn't need to be that heavy. Even space stations can be assembled in orbit, so that's one less thing we need HLVs for. More damningly, it turns out that most of the things we THINK we need HLVs for could be accomplished just as easily with MLVs that already exist.

The only reason the SLS even exists is because Congress ordered NASA to build it. NASA has no specific reason to build the SLS other than that Congressional fiat; what they need RIGHT NOW is an MLV and a working space transportation system, and in a world that hadn't completely lost its mind, they would have parlayed those needs into new capabilities that slowly but surely build into NEW capabilities, resulting in a robust and reliable spaceflight architecture.

This is like Christopher Columbus refusing to sail to India unless Isabella could give him a 700 ton Carrack. "I can't sail around the world with three small boats, I need one really BIG boat to make the journey!"

In short, planetary scientists should stop trying to interfere with rocket growth and should embrace it.
Rocket GROWTH isn't an advantage here. The gamechanger is REUSABILITY: if you can recover at least the first stage of a booster, you can cut your launch costs in half, which allows you to send more payloads more often and for a lower price. That opens the market to broader participation, which means more payloads, which means more money AND more development, which in turn means better rockets and still lower prices.

An HLV is ENTIRELY counterproductive in that goal; it flies a tenth as often for twice the price and any reusability would actually make it MORE expensive, not less. We simply don't need bigger rockets to do useful things in space, we need a lot more of them, and for a lower price.

In the current political climate, getting SLS killed doesn't automatically mean you free its budget up for other things.
That's pretty much exactly what it means, since at the moment CCDev is the ONLY alternative to the SLS program. If SLS doesn't deliver a viable transportation architecture -- and it probably won't -- then NASA's left with a very small number of high-concept missions it can't do and a very large number of near-term missions it was planning to outsource to industry anyway.

It's also not really true to say that Congress supports the SLS. Kay Bailey Hutchinson and Ben Nelson, along with a very small number of others, support the SLS because it provides pork funds to their political sponsors. All it takes is one bad election or one lobbyist pulling out of a real-estate deal for the question to show up on the Senate floor "Why are we spending twenty billion dollars on a new rocket when we don't have a spaceship to launch on it?"
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Last edited by Crazy Eddie; July 14 2012 at 11:14 PM.
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