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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."
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?
Kevin Smith on Prince
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.
Well, when people say something like "hard to control" i thing this: 1% chance of it actually working as intended 99% chance of it failing horribly 100% chance of it still looking incredibly awesome :D
Pure awesomenes
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.
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.
Actually the submersion idea is brilliant. The piece missing is the launch tube.
Build a 30 foot diameter tube 2 miles deep, with a piston on the bottom. Put brakes on the piston that will limit the acceleration down to about 5G. Empty the piston of water, lower spacecraft onto piston, when you launch just let the piston rise. The thousands of PSI of water pressure should give the spacecraft a significant amount of speed by the time it reaches the surface, light off rocket at a higher altitude than normal so the nozzle can be optimized for a higher altitude burn. I'll work on the math for this.
They ARE out to get you simply because They are in it for themselves and they don't care about you.
"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"
The Kruger Dunning explains most post on
The setup:
30 mile long tube buried at a shallow angle, say 5-20 degrees. This lowers the pressure requirements at the bottom end of the tube.
Pressure (every 33 feet per 14.7 psi) Depth = sin(20)*length in feet = 24,100 psi
Acceleration = 5G, d = 1/2*a*t^2, therefore T = 44.5 seconds.
V = Acceleration * time, therefore V = 7110 ft/s
1 m/s = 3.28 ft/s
Delta-v to low orbit is 8600 M/s, or 28000 ft/s
So this method will give us 1/4 of the delta-v needed to get to low orbit.
If an ocean contour could be found that somewhat matched the angle involved, the tube buoyancy and alignment problem could be solved by anchoring it to the sea floor.
12G at 50 miles, 20G@30 miles give 14kft/s (1/2 low orbit delta-v)
50G @ 50 miles gives 29kFt/s, more than enough for LEO if you ignore drag.
This class of launch tubes would be suitable for refueling geo-synch shuttles.
62 mile tube @ 10 degrees (similar idea as the 100km launcher proposed for Antarctica) gives 25kPSI, 9k deltav @ 4 g.
I'm not sure if it would be easier to build a straight tube in Antarctica or in the Ocean.
One other problem is that once you surpass the speed of sound in a medium you no longer receive thrust from it. Speed of sound in water is 1482 m/s, or 4862 feet/s, so you would need to start pumping a hot gas, either rocket exhaust or hot hydrogen into the tube once you passed 4.8kft/sec.
They ARE out to get you simply because They are in it for themselves and they don't care about you.