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NASA's Shuttle Plans
Gerhardius noted a NYT article (you know the obnoxious deal) about new "shuttle" designs coming out of NASA. The payloads are riding up top to avoid debris.
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NASA claims that the tile gap filler that has come loose was a result of vibrations on liftoff, NOT the result of falling debris...
So moving the return capsule up to the nose of the craft will prevent repeats of 1986 and 2003, but won't fix every problem. They should instead be trying to build a shuttle that won't rattle apart on takeoff.
Single-Stage to orbit isnt feasible (yet). We need either a breakthrough in materials technology or propulsion performance. The rocket equation is
... as a single stage ... but your not coming home. Reinforcing the ET takes such a mass penalty your payload is effectively reduced to zero.
Delta-V = g * Isp * ln( MR )
where:
Delta-V: velocity required to achieve LEO (7.6 km/s best case scenario: but you need to add gravity and drag losses, add at least 1 km/s)
g: gravity (9.8 m/s)
Isp: Specific impulse of your propellant. This is an efficiency factor: 1 kg of propellant generates Isp kg of thrust. Hydrogen and Oxygen properly mixed generates an Isp of about 450 [seconds] in a vacuum. That is the upper level of chemical propulsion.
MR: Mass ratio. Mass that sits on the launchpad divided by the mass that achieves orbit.
Play around with that equation and you will see STS0 just doesn't work out yet. Our feasible Isp is way too low and our current material properties won't let us build a ship with a MR of over 10 that can return to earth safely.
Interesting factoid though, if you attached the space shuttle main engines to the external tank and just made that a launch vehicle, as a single stage it could put damn near 100 tons into LEO
-everphilski- -- Rocket Scientist
The only reason the foam is there is to keep ice from forming on the side of the tank. Since the fuel is cryogenic, it is obviously quite cold and causes large chunks of ice to form on the side of the tank. On launch this ice would simply destroy the Shuttle's tile system, it would be much much worse than the foam. If there is nothing for the ice to damage, then you don't really need the foam anyway. Many rockets have no such foam at all. Ice just builds up on the rocket and sheds during launch. You can see this in a lot of launch footage from the gemeni/apollo days. The ice would fall to the pad as the launch clears the tower. The absence of foam is not likely a significant safety risk, but it is probably still usefull enough to keep. I'm sure it has several side benefits, such as allowing the tank to stay fueled and on the pad for longer periods of time.
It's OK, NASA figured out how to rendezvous in space with two nearly simultaneously launched vehicles in a little program called Gemini.
I think they were successful, might have to check Wikipedia though
Four weeks, Twenty papers, that's two dollars
I think that because of Star Trek, we are all beholden to the idea of anti-matter propulsion. That may come to pass in some distant future, but right now, it is a fairly unrealistic blue-sky idea.
I would put my chips on nuclear fusion as the long-term future, whenever we develop a replacement for chemical rockets. May years ago, Space.com cited some NASA experiments in the field:
NASA engineers are developing a radically new type or rocket engine that harnesses the power of stars to cut travel time to Mars, for example, from the current nine months down to three months. Called the gas-dynamic mirror engine, it traps and heats gas to temperatures as sizzling hot as those found at the core of the sun. That's hot enough to allow for nuclear fusion by combining lighter atomic nuclei into heavier nuclei.
Within a few months, a six-foot long model of the engine will be fired-up by injecting a superheated gas confined between powerful magnets at either end of the engine. Within a couple of years, the engineers hope to achieve a sustained nuclear fusion reaction in the hot plasma.
The article also mentions a fusion/anti-matter hybrid, but the former sounds like it holds more promise in the 30-50 year time frame...and who knows what future developments may hold?
In the near-term, solid rocket boosters put a lot of energy into the nozzle, so to speak. The current Shuttle gets roughly 80% of it's ascent propulsion from the solid rockets that are strapped aside the fuel tanks. That's a pretty powerful combination. The problems with solids are legendary, most notably the lack of any capability of trimming, reducing power or turning them off. The Shuttle is the only launch system that's man-rated that uses solids in a significant way, but this technology is tried and true, considering it is a veteran of many a shuttle launch. While the Challenger failure was a result of the SSRB's, it was a materials issue and not a flaw in the basic package.
You're absolutely correct; NASA is more of a jobs program. My brother recently completed his second internship at Cape Canaveral. He said it's impossible to fire anybody. Even after Columbia, people are more interested in keeping their little fiefdoms of control rather than focusing on real science.
The new manned/unmanned launch vehicle designs make a lot of sense. The US government needs to retain the capability to send people into orbit, but I would definitely be in favor of manned space flight being primarily an activity of private enterprise. However, to get the industry off the ground (pardon the pun) government subsidies and tax-incentives will be needed. NASA should continue to exist, but primarily for the sake of pure, unmanned, science.
Here you go:
Delta Clipper Experiment
Wikipedia
If you want to see what happened here's the video
IMHO, I don't think the strut failure was due to malice. I think it was simply a mistake/stupidity.
I got to watch several DC-X flights. I got to see it hover, move laterally, land, and the infamous 'dip & swoop' manuever.
I'm still dumbfounded that DC-X lost NASA's Reusable Launch Vehicle competition to the VentureStar design. Lockheed had an obviously bogus blue-sky design. McD had a working 1/3 scale proof-of-principle prototype.
A lot more design and testing would have been required to get to the full Delta Clipper orbital vehicle, but it still remains one of the better SSTO design ideas out there.
At least I got to see a rocket dance once. It was simply Incredible.
-I.V.
"These laws they're passing won't even compile anymore, let alone execute." - anon
Well the Delta Clipper had been transfered from the SDIO(DoD Star Wars office) to NASA, and upgraded when the crash occurred. It is propably safe to say that a NASA employee is the one who botched the hydraulic line though who can know if it was malevolence or incompetence that made him do it.
It should probably also be pointed out that when it was under SDIO control a hard landing cracked the shell requiring the rebuild when it was transfered to NASA so are you going to blame that accident on NASA malevolence too? Having a hard landing with this tiny prototype was bad, you can imagine what a hard landing might be like when you have to land the HUGE full size vehicle on those legs.
It should be pointed out to all the Jerry Pournelle worshipers that always sing praises of the Delta Clipper that NASA upgraded DC-XA's record altitude was 3140 meters. It was a really long way from being proved feasible.
If its was such a great idea rumour has it that many of the people that worked on it ended up Jeff Bezos' rocket company Blue Origin and they may be trying to revive it with NASA no where in sight. If it was a NASA conspiracy killing it will rise from the ashes like a Phoenix and prove they were wrong. Wouldn't bet on it though.
Personally I could maybe see using it for a cargo transport but the reentry scheme is pretty dangerous in its own right. It comes in nose first and then retro rockets HAVE to fire to turn it around and these heavily reused main engines have to fire to slow the decent and keep it upright otherwise it would be a disaster too. The test program wasn't even close to attempting that complex reentry profile.
The other issues are building a single vehicle big enough to hold all that fuel needed to get to orbit and still have enough to get back down again, and carry a cargo big enough to be worth it. You also need some REALLY big, extremely reliable and very long lived engines. I think they ended up being way beyond Space Shuttle Main Engine class to actually get to orbit and back. SSME's only have to fire once per flight. In the Clipper they have to fire twice. To satisfy the Clipper hype they then have to turn around and do it all over again without any refurbishing. Easy to do flying to 9,000 feet, harder to do to LEO and back multiple times on one set of engines with no maintenance.
The parent is right NASA's manned space program is obviously a jobs program and any launcher that might result in the laying off the small armies in Florida and Texas will likely result in the congressional delegations from Florida and Texas killing it, or mandating the staffing levels stay the same even if they have nothing to do, which is already happening to CEV. The ONLY reason NASA's manned space program has any political support left at all is due to the fact it IS a jobs program, so the congressmen who districts all those jobs are in fight like wildcats to keep it alive even if its a total waste which it is at the moment.
@de_machina