Will The Next Generation of Spacecraft Land In the Water? 318
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."
Simple Answer (Score:2, Insightful)
Re:Thought about something like this (Score:2, Insightful)
Theyy could always ask Paul Revere ... (Score:5, Insightful)
"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?
Bad Summary? (Score:2, Insightful)
"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?
surface of earth is mostly water (Score:3, Insightful)
Re:Theyy could always ask Paul Revere ... (Score:5, Insightful)
Just put whatever you want to rendezvous with in whatever orbit is convenient, it won't go anywhere.
What is the downside? (Score:3, Insightful)
One vote in favor of landing on land (Score:3, Insightful)
Re:One vote in favor of landing on land (Score:3, Insightful)
Re:Theyy could always ask Paul Revere ... (Score:3, Insightful)
Because that would actually _increase_ the mass boosted towards the moon by a factor of a thousand of more. (It takes a lot of fuel to brake into Earth orbit, and yet more to change orbital planes to match up with the ISS.)
The next poster posited simply leaving the required module in a convenient orbit not at the ISS. This is a little better as it only requires increasing the mass boosted towards the moon by a factor of seven hundred or so.
no! (Score:3, Insightful)
Because it's water, not land, DUH!
Re:Simple Answer (Score:4, Insightful)
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.
Stupid Answer Re:Simple Answer (Score:3, Insightful)
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
Re:What I don't get (Score:3, Insightful)
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.
Re:Simple Answer (Score:3, Insightful)
I understand it's not all black and white, and that there is a big fat contract waiting for Lockheed Martin, but I can't see contracting a big rocket from the Russians as anything but more trouble. At least if we fail, we are the only ones to blame.
If a big Energiya was ready to go, reliable and we had the support systems to deal with it, you'd have a point.
Re:What I don't get (Score:2, Insightful)
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 [wikipedia.org]
Uh, because that's completely infeasible? (Score:2, Insightful)
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.
Re:Thought about something like this (Score:3, Insightful)