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Will The Next Generation of Spacecraft Land In the Water?
Reservoir Hill writes "Work is progressing on the design of the new Orion Crew Exploration Vehicle (CEV), the next generation of NASA spacecraft that will take humans to the International Space Station, back to the Moon, and hopefully on to Mars. One major question about the spacecraft has yet to be answered. On returning to Earth, should the CEV land in water or on terra firma? After initial studies, the first assessment by NASA and the contractor for the CEV, Lockheed Martin, was that landing on land was preferred in terms of total life cycle costs for the vehicles. Getting the CEV light enough for the Ares rockets to be able to launch it, and therefore eliminating the 1500 lb airbags for landing has its appeal. A splashdown in water seems to be favored."
Something i used to think of as a kid was: How about using the propulsion you get from the water for initial thrust of the spacecraft? Sort of like the effect you get from releasing a bottle of air under water, couldn't that be utilized in a cheap way of getting that initial upwards thrust, or would it be too cumbersome to make a vessel that is light enhough for it to actually float?
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As someone who worked partially on the CEV, it has been decided. it is in the requirements that Lockheed Martin furnish a vehicle that is capable of both. One of the design limitations now is that it must actually be stable in swells of up to 14 feet, which are not uncommon in the cold North Atlantic - emergency abort scenarios land all launches there during early lift-off stages. There are huge problems with ill-effects of ocean landings for crews and they really are looking to avoid it, but even with parachute and pillow systems, they are looking at potential damage,
"One if by land, two if by sea ..."
Seriously, why not just do the moon mission, then pick up the landing bags as the ISS on the way home. Better yet, why not have a specialized vehicle just for orbit-to-moon-and-back, and transfer to a special-use re-entry vehicle at the ISS?
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So... I don't really understand the whole disposable crew idea. It would make sense to reuse the crew rather than feeding them to sharks after re-entry, or did I miss something.
I got a catholic block.
Lockheed, the Orion prime contractor, has expressed significant reservations about carrying the heavy airbags to the moon and back -- those 1500 lbs can better be used in other ways. On the other hand, there shouldn't be a problem with the weight on the more common missions to the space station and low-earth orbit, and the ability to reuse the capsule will be far greater if they put it down on land.
The speculation in this week's Aviation Week was that they would have bolt-on airbags for the earth-orbit flights, and would recover those missions on the land, and would recover at sea for the moon-return missions.
The reentry profile for the moon missions is really quite amazing. Recently Aviation Week had an article about it, describing how to get all the capsules to recover to the same spot on Earth. Do you recall way back in the Apollo days, they always described the narrow re-entry corridor? Too steep and you'd burn up, to shallow and you'd skip back into space forever? Well...
For Orion, they plan to use a skip back into space to bleed off some of the speed coming back from the moon, and to align the craft to re-enter at the correct place to land where they want, off the coast of California. It's an incredibly audacious plan, with tolerances that have to be measured in tenths of a degree of entry angle. Very cool.
Thad
I love Mondays. On a Monday, anything is possible.
What I don't get is the continued use of rockets. Is going straight up (the brute force & ignorance method) really the most efficient method of getting up there ? Isn't an approach like SpaceShipOne uses more efficient in terms of amount of energy needed per kilo of launched mass and thus costs ?
No, the first manned missions landed on land. The Soviet Union (now Russia) landed and continues to land all of their manned missions on land. If they can do it surely we can too.
The planned Ares V has a mass to LEO of 130,000 kg, the energia has 'only' 88,000 kg, so the solution isn't that simple. Besides, any weight savings on any system is obviously an advantage when the cost per kg is so high.
For the folks saying "use the ISS!': Won't work. When coming back from the moon, the approach speed is far too high to enter the orbit that the ISS or any other reasonable future space station is in. The braking is done through friction as the spacecraft enters the earth's atmosphere, and provides MUCH more delta-v than would be feasible by using rockets.
To use the ISS, the spacecraft would need to perform a complex aerobraking maneuver (basically, a partial re-entry), then have the fuel needed to circularize its new orbit so that it can rendesvous with the ISS. By the time this is done, the design for the capsule is far heavier than the 1,500lb penalty that airbags impose.
My idea, make the water landing a known 'capsule loss' scenario, the same way it is with the Shuttle. If things go _so wrong_ that a water landing is unavoidable (say, launch failure) then design the capsule for quick-egress after a water landing. Airplanes ditch in water and people have time to get out before they sink. My Piper Cherokee will float long enough for me to climb out onto the wing, and for a real shock look at the survival training that helicopter passengers go through in the military, that's some pretty intense worst case scenario stuff.
With Rogallo steerable parachutes, landfall should be available at all times except the first few minutes of launch. Skip the airbags, make the capsule so it stays afloat just long enough for egress, and train the astronauts on how to get out fast.
Spaceship one was good for getting to the 'edge of space' and back. Being in orbit is a different thing. As a general rule, it takes 30 times as much energy to get into orbit as it does to just get up there. ( the number varies with altitude, of course, but 30 is a good back-of-the-envelope approximation ). The energy that has to be bled off when coming down is roughly 30-fold. So spaceshipOne is not even close to being able to do it. It requires new materials and/or a new design. Or stick with the high maintainence and unpleasant failure rate of the shuttle.
Or you can stick to the simple way of doing it with rockets and parachutes.
There are some very good reasons for building an all-American rocket beyond mere politics. It has everything to do with developing domestic expertise in the field, and encouraging R&D in the country for these technologies, which can only serve as a foundation for developing even more.
Beyond what the other posters have mentioned, brute forcing the problem is also rarely a good solution. Instead of spending tens of million each launch to lift a huge, heavy spacecraft into orbit, its weight should be optimized, both for the sake of proper engineering and for the sake of cost cutting. I won't presume to know the specific technical difficulties of a project as complicated as the CEV, but there's a balance between more lift power and reducing spacecraft weight.
"Houston, we are ready for approach"
"Roger that. Approach the bean bag landing zone from 1 8 niner."
"Copy that Houston."
"You should see the Lava Lamps lighting your approach."
"Thank you Houston, Please prepare the after flight debriefing bong."
"grgrgrle"
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