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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."
Re: "Getting the CEV light enough for the Ares rockets to be able to launch it," .. the solution is simple .. buy/license/whatever the Energiya booster from the ruskies instead, and you'll have much more weight to play with.... OH sorry, I forgot, the Energiya isnt build in the correct congressional district... my bad.
I'd imagine that would be insanely hard to control even if it was possible.
"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
"landing on land was preferred in terms of total life cycle costs for the vehicles."
Landing on land is cheaper, check.
"eliminating the 1500 lb airbags for landing has its appeal"
Landing on land lets it be lighter, check.
"A splashdown in water seems to be favored."
Huh? WTF? Am I supposed to go RTFA or something?
It's much easier to hit the water, and in theory you should be able to get a softer landing on water. However, if you land in the middle of the south pacific, it's a bit more difficult logistically to pick you up from there and get you home, vs. landing on some runway with roads connecting it to the regular highway system of your homeland.
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To be honest in principle I don't see the downside of a water landing. The craft has to have a sufficiently low density to float, which could increase air resistance, but a certain degree of air resistance will be needed for re-entry anyway, too little of it and the majority of the slowdown will occur in lower ( i.e denser ) parts of the atmosphere. You want to decelerate over as long a distance as possible tor educe the requirements on the heat-shield. I guess you must test the whole thing for water-compatibility, but if it is to deal with vacuum, intense heat, and solar wind, I would imagine it should be able to deal with some water. I suppose there may be investment costs associated with developing new technology for water based landings, but it does seem like it should be the easier and more fault-proof way to do it, so I wouldn't be surprised if it will work out cheaper in the end.
I'm 111% confident that it cannot land in water.
Because it's water, not land, DUH!
You can't take the sky from me...
Oh, good lord. What Energiya would that be? The prototypes corroding away somewhere, never having been launched? There is no such thing as an Energiya, aside from old photos with a Buran attached, and some blueprints. You'd do better to start from scratch than with Energiya plans.
And of course, you overlook the many domestic alternatives that *actually exist*. Like EELVs (Delta and Atlas). Or those that could be restarted since they just quite making them a few years ago (Titan IV - roughly equivalent to a Saturn 1B).
Brett
If you're talking about air launch, it only gives you a minor improvement, and if you're talking about a heavy launch vehicle like Ares V, you're not going to find an aircraft capable of launching it. The Orbital Sciences Pegasus rocket launches off of an L-1011 aircraft, and has a fairly small payload.
Remember that most of your energy is spent with energy in the direction of the orbit rather than going straight up, and thus why orbital flight is an order of magnitude more difficult that the suborbital flight that SpaceShipOne did.
In theory, yes you are right. A couple things to remember however:
1)SpaceShipOne was sub orbital (did not reach orbital velocities) and launching into orbit would require a couple orders of magnitude more energy/fuel.
2) Everything else being equal, a spaceplane will cost more to develop than a rocket (aluminum tubes vs a plane airframe capable of hypersonic flight). Development costs are rather significant for spacecraft as the number of units produced is very low.
3) It has been tried before, rather unsuccessfully: http://en.wikipedia.org/wiki/Rockwell_X-30
The moon and the ISS are orbiting in planes 45 apart. It would require a prohibitive amount of fuel to get from the moon to the ISS. They'd pretty much need another fuel tank and another pair of solid rocket boosters to get there.Seriously, why not just do the moon mission, then pick up the landing bags as the ISS on the way home.
Traveling in space is not like traveling on the ground. On the ground, if you want to go somewhere, you only have to move to its position. In space, getting to a given position is the easy part; it's getting to the right velocity at that position that is hard.
For instance, if you want to go from Earth to the Moon, you can do it with no fuel whatsoever if you don't care about your starting or ending velocity: a Hohmann transfer orbit lets you coast to the Moon and back without any effort at all. The hard part of the journey is that when you're in low Earth orbit, you're not going the right velocity to be on a transfer orbit; and then when your transfer orbit gets to the Moon, you're not going the right velocity to land there. You need a burn at Earth and another one at the Moon to get your velocity right.
This is not like travel on the ground. In general, you can't just accelerate your car, shut off the engine, and coast to your destination. On the ground, travel is dominated by friction and obstacles. Distance is what costs. The fuel required to get up to highway speed is tiny compared with the fuel required to travel even one mile. Because of that, we talk about miles per gallon. If you want to calculate your fuel cost for a trip, you base it on how many miles you'll travel.
In space, there are no friction or obstacles. You get up to the right velocity, coast for some time, then slow down again. The fuel required during the coasting phase is insignificant compared with the fuel required to change velocity. To plan the fuel cost for a chemical rocket trip, you base it on the total "delta V", or total change in velocity. Distance and duration don't figure into the calculation.
Changing the plane of an orbit is one of the most expensive maneuvers there is. With some exceptions (like sun synchronous orbits), there are no shortcuts: you just have to burn enough fuel to cancel your velocity in one direction and gain velocity in the desired direction.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
HEY! Put a warning on that accursed, godforsaken, nightmare-causing site in your sig, you bastard, you almost got me fired!
A-Bomb