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."

Thought about something like this

[pkadd]

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?

Probably both, it turns out

[Thagg]

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

What I don't get

[BorgDrone]

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 ?

Re:Thought about something like this

[sholden]

Yes you wouldn't get enough velocity to make a it worthwhile, but spending more energy on the ground (well under the water...) doesn't matter. If you could come up with a way to use ten times as much fuel (for a given total weight) to launch a rocket than the standard approach, but have that fuel be used on the ground and not be lifted by the rocket it would be used in a flash (it's what a rail gun launch would be after all) - assuming you manage to not turn the people inside to smears on the wall...

Re:Thought about something like this

[IdeaMan]

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.

A stupid simple answer

[Criton]

A brain dead simple answer would be to use direct launcher http://www.directlauncher.com/ [directlauncher.com] as the crew launch vehicle. Direct launcher makes use of existing four segment srbs and existing RS68s plus it lifts 50tons in it's most basic form vs 25 for Ares I mass problem solved and 2 billion saved on Constellation. The only answer I can think of right now is the fire Griffin it's the only way to save the project. That or kill Orion outright and give all the budget to COTS type programs. I see no hardware for Orion yet but spacex is now building and testing falcon 9 and Dragon.

Constellation, Orion, Ares, and the VSE are Dying

[Anonymous Coward]

While Netcraft may or may not confirm it, the real truth is that this program is in a death spiral and is well on its way to cancellation, just like every major NASA program to replace the shuttle over the past two decades (SEI, NASP, X-30, X-33, X-38, OSP). For the gory insider details, read the recent GAO report, or the forums at nasaspaceflight, or the postings at spacepolitics or the rocketsandsuch blog. To sum it up, Ares I doesn't have enough performance to lift the Orion, so systems are being discarded off Orion to try and get its weight down - including safety and backup systems, and systems critical to containing operational costs such as the airbags for touchdown on land. NASA thinks they have a 65% chance of getting this system operational by late 2015 if they get enough funding, but the congressional GAO is recommending that NASA postpone the program indefinitely until its problems are resolved.

Sadly, NASA already have existing medium lift (Delta IV, Atlas V) and heavy lift systems (STS via DIRECT SDLV) that could be modified for launching crews at a cost that would be a fraction of the Constellation plan. But heckuva job Mikey G at NASA won't budge from his over-budget, behind-schedule, and under-performing vision. In the process, he's going to end NASA's manned space flight program for at least the next decade while we recover from this debacle, and he's throwing away our once in a generation chance for a new launch system that will enable manned exploration of the Moon and Mars.

Check out the directlauncher.com site to see what NASA should be doing, and once you've realized how maddening this situation is, write your congresscritter about it.

Re:Thought about something like this

[jackpot777]

Isaac Asimov used that idea in The Martian Way (short story, Martian colonists solve their water shortage problem by going to Saturn and bringing icy ring chunks back). He had a 'micropile' heat some of the ice to steam, then have it shoot out at extreme pressure. As acceleration = force / mass, and the force was great, the acceleration was equally as great, and the constant acceleration got the colonists back to Mars in a matter of weeks.

To use that to escape Earth gravity, though ...think of the power of a chemical rocket, and now try to duplicate that with steam!

Breaking the water

[AlpineR]

There was a MythBusters episode about this. They were testing the myth that a construction worker falling off a bridge into water could soften the impact by throwing a hammer to break the surface tension. Their conclusion was that the change in force of impact was neglible.

I don't think it's the surface tension that gets you, it's the inertia. Still, the mobility of water means that you're decellerating from 200 MPH to zero in 0.2 seconds instead of 0.1, so it's a big reduction of force.

Re:Thought about something like this

[pkadd]

Both. although, I wouldn't say diminutive. I have severe OCD while i love seeing huge things go horribly wrong (for example, i work in a moving-company, and the amount of awesomeness of a fridge accidently dropping from a 6th floor window is simply stunning)

Re:Thought about something like this

[IdeaMan]

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.

Re:Thought about something like this

[mapsjanhere]

there is a serious flaw in this set-up: To do this you need a tight seal between pug (aka spacecraft) and tube. This works fine at low speeds, but once you get into the area of the speed of a high speed bullet, lets say 3000 ft/s your friction will kill any further acceleration. And you also have to account the ability to feed water into your tube, at 10 ft diameter and 3000 ft/s you need to get 6,700 m^3 of water into that tube - every second. That's two and a half Olympic size swimming pools. Oh, and after "lift-off" you better get your engines going fast - otherwise that aircraft carrier weight of water moving at 3000 ft/s behind you might catch up and shoot you straight out of the air.

dunno about that

[Quadraginta]

First, of all, imagining that one guy at the top is bringing the whole enterprise to its knees is just classic populist wishful thinking. It never works that way. Herbert Hoover didn't cause the Depression, Joe Stalin didn't by himself cause the Cold War, Alan Greenspan didn't cause the dot-com bust or the mortgage meltdown, and your Mikey G isn't by himself blocking all future progress in manned spaceflight.

Figuring out exactly how and why a program craps out is a matter for endless debate among historians, but as a general rule, it's probably reasonable to say that any government enterprise that doesn't enjoy phenomenally (and historically aberrent) high levels of public interest and support always craps out sooner or later.

So the first real problem is not who's heading NASA, but the cold ugly fact that most Americans don't give much of a hoot what NASA is doing, would rather watch American Idol than a manned Moon (or Mars) landing, and aren't much interesting in sending their tax dollars to Huntsville for umpty years so that their grandchildren can watch Right Stuffers frolic on the Red Planet. A plain fact, which most folks in the spaceflight industry strenuously try to avoid dealing with by all different types of denial. (Including, incidentally, the paranoid delusion that one single factor -- or man -- stands in the way of the type of broad and deep public support that the space program enjoyed in the brief and historically unique period between 1945 and 1965.)

But the second real problem is that a government program is almost certainly a dead-end nonroute to the kind of massive social and technological change that spaceflight enthusiasts hope spaceflight will produce. There is, actually, no recorded instance whatsoever in history of a government program doing anything more than starting off (at best) something like the colonization of other planets. The voyages of exploration during the 16th and 17th century, and the colonization of the New World in the 18th century, were weakly and inconsistently supported by national goverments: they were, in general, private enterprises, undertaken by individuals for individual dreams of wealth and glory.

That is what is missing in space exploration. There is no individual -- or small entrepreneurial organization -- path to space, and not much private, materialistic, "greedy" and "selfish" motivation for people to risk their fortunes, lives and honor getting into space. If such a thing were to emerge, then humans would naturally get off the planet, not only without any need for massive government programs, but probably in spite of government efforts to stop them. (It would be like MP3 file sharing. Notice no government program was required to get that going? Because it's intrinsically easy? Or because people really want to do it? I'm guessing the latter.)

But until that kind of broad interest emerges, I don't think any amount of government exploration is going to be anything more than expensive entertainment. (Mind you, I don't object to the entertainment, but that's because I personally would, weirdly, rather watch a manned Moon or Mars landing than every first-class gee-whiz movie that will be made from now to the end of time.)

It's worth asking whether government can prime the pump, so to speak, and make it easier for private enterprise and individual ambitions to get into space, so that people can start to get turned on to the whole business, and a broad and deep urge to go can emerge. Maybe it can. Unfortunately, probably step #1 is to back off the goofy noble selfless we came in peace for all mankind aura that clings to the endeavour nowadays, which merely serves to cut it off from the range of activities normal, non-selfless, non-noble people do everyday and think about doing tomorrow.

great lakes

[ragtoplvr]

if the accuracy can be improved they could land in the great lakes. That at least stops the salt water corrosion. The capsule can be designed for crew survival on land, and capsule survival in fresh water, if you miss you just lose the capsule and some of the internal systems, if you hit the lake all of it gets used. If problem is detected early, just aim for the ocean. in every case crew should survive.

Rod