Ditching Space Capsules

I don’t like the idea of our astronauts returning to earth in capsules. It seems like a big step backwards. What if we used something like SpaceShipOne to get them to the ISS, where the Earth Departure Stage was already waiting for them, having been launched on a conventional rocket?

Upon return from the moon, instead of plunging a capsule into the atmosphere, the return craft (something I’ve never seen being proposed) would have the capability to enter earth orbit, dock with the ISS, and allow the crew to return to their original SpaceShipOne-esque vehicle for descent to land. If the Earth Departure Stage and the as-yet-unseen return-to-ISS vehicle were the same vehicle, it could potentially even be refueled for a future mission.

Are the hurdles of getting a SpaceShipOne-type vehicle that can reach orbit, and an Earth Departure Stage that can make the trip back to earth orbit insurmountable with current technology (and budgets)?

Capsules work very well and have a decent amount of testing backing them up.

You’re mixing up a whole lot of stuff here too by the way. Why would you want to do in-orbit assembly/transfer to get to the moon when you can simply launch and land? Why impose an ISS requirement when it isn’t needed? And then you go on to insist that the return vehicle slow enough to mate with the ISS, transfer people across to an other platform and then get out of orbit.

SpaceShip One was pretty impressive but it only popped up into space and fell back down. SpaceShip Two hasn’t even been seen yet, (though the Eve Mothership was at the EAA this year) so it isn’t a candidate either.

SpaceShip One can’t get into orbit. It was able to get up to a height considered “space”, no mean feat, but to get into orbit you have to not only get high enough, you also have to be going fast enough while up there. Burt Rutan and others are working on better ways to accomplish that, but they haven’t succeeded yet.

And get down again.

We have a spacecraft that is designed for getting up to orbit and then returning from orbit. It’s called the Space Shuttle.

The design challenges are more severe than you seem to credit.

Whatever vehicle goes to space must have enough thrust to get to orbit. SpaceShipOne did not have that capability, and the follow-on will not have that ability. And assuming it could get to orbit, it then faces the same problem that the Shuttle and capsules had to solve - how to slow back down and not burn up coming through the atmosphere. SpaceShipOne hasn’t addressed that problem because it doesn’t get anywhere near the speed that orbital vehicles do.
SpaceShipOne doesn’t have the tile or heat shielding, and to give it that kind of heat shielding would require a major redesign.

Quite apart from that is the challenge of a Moon/Earth shuttle that docks to an orbital space station. The big challenge there is getting to the right timing and flight profile. Essentially, the space vehicle traveling back from the Moon will be going very fast, and need to slow down to achieve orbit. That slowing down will require either aerobrakes and the atmosphere, or thrusters and fuel. Thrusters and fuel mean size and weight, which complicates the whole journey. Aerobrakes mean you’re already interacting with the atmosphere, why then stop in orbit instead of continuing to the surface?

Capsule design does seem a step backwards from the Shuttle idea of reusability, but heat shield design is safer than the issues faced by shuttle tile.

First of all, owing to an orbital inclination that was intended to make the ISS accessible via the Soyuz transport system launched from Baikonur Cosmodrome. This orbital inclination is far from ideal as a staging point for Lunar missions, and in fact there are only a handful of direct insertion windows per year where this would even make sense, whereas acceptable windows for a subtropical launch zone occur several times a month.

Second, I’ve seen repeatedly both here and elsewhere an objection to using a capsule-type vehicle as being “a step backward”, but no one seems to be able to clearly elucidate why this is so other than vague claims that this configuration is “going back to Apollo”, et cetera. In fact, the STS Shuttle was recognized as being a highly compromised design even early in the concept phase. The idea of using a reusable shuttle as a space truck for heavy lift cargo was never considered fiscally viable compared to expendable launch vehicles. The two driving assumptions/requirements behind the STS system is that it would provide the ability to perform on-orbit recapture and return of satellites for repair/refurbishment, and that the amount of cross range permitted by the large wing surface would allow for single circuit polar orbit launches from the SLC-6 facility at Vandenberg AFB, allowing quick deployment of surveillance satellites. Neither of those capabilities turned out to be fiscally viable and were of questionable technical meit. One of the most significant operational problems with the STS has been the thermal protection system, which is both delicate and difficult to maintain. In contrast, the “ablative” heat shields on the blunt-arsed Gemini and Apollo capsules were so robust that their operational margin is simply assessed as “very large” (i.e. >5), and one of the Gemini spacecraft was reflown (unmanned) atop a Titan-IIIM with a mockup of the Manned Orbiting Laboratory as a proof of concept for the Blue Gemini program with no adverse effects on the spacecraft. Capsule forms are robust and an efficient use of space and payload mass, unlike winged reentry vehicles. The Chrysler SERV proposal for the STS, which used what was essentially a massively scaled up Apollo outer mold line, was one of the more interesting proposals for the STS, but was so far afield from the spaceplane concept defined by Von Braun that it was never given serious consideration.

Third, the operation you describe–transferring from an ascent vehicle to a Lunar transit vehicle–might be suitable for an established infrastructure (a la that portrayed in Kurbrick’s 2001: A Space Odyssey) but it adds considerable complexity for a handful of single missions. Every time you have to rendezvous and hook up with another craft, there is the potential for things to get pranged up, which is why the original Apollo approach went with one vehicle and a Lunar Orbit Rendezvous (LOR) with all modules launched on one vehicle rather than the Earth Orbit Rendezvous (EOR) approach that you recommend (and which has been done mostly successfully with Gemini, Apollo/Skylab, and of course the ISS). The EOR is the currently planned mission mode for Constellation Lunar missions. However, this seems predicated on the alleged benefit of merely man-rating only the Ares I launch vehicle (which itself is pretty problematic). There is a lot of criticism of this mode as being more expensive and contributing greater risk than man-rating a Saturn V class heavy launch vehicle for unitary launch and LOR mission mode.

I’ll also point out that SpaceShipOne was not an orbital vehicle and can’t simply be scaled up a bit to make orbit and return. Its thermal protection systems are rudimentary, and the “stop-cock” method of controlling reentry speed is fine for a ballistic sub-orbital trajectory to the limit of the atmosphere, but just isn’t capable of dissipating the kind of mechanical energy at orbital speeds and rarefied upper atmosphere. SS1 and SS2, and similar configurations, would come apart like a sprouting dandelion floret.

The ISS is not designed to support on-orbit refueling operations, and lacks the facilities to do so, aside from not being in a useful orbit for Lunar insertion operations. You’d still have the cost of lifting fuel to orbit using another launch vehicle. A dedicated “orbital gas station” could be constructed for this purpose, but the only real advantage is in permitting larger vehicles than could be launched from a single ascent vehicle, not in reducing operational cost or complexity.

Stranger

Not really. There is no reason that a capsule can’t be designed for refurbishment and reuse (as the Orion spacecraft is), and while the reuse of the Shuttle Main Engines has gotten better, they still require a partial teardown and complete inspection between missions, so leaving a Service Module and Earth Departure State in orbit or to burn up in the atmosphere is not as costly as it may seem, especially if making it expendable means that you can accept lower life cycle margins. Making a vehicle that is reusable and will survive N number of ascents adds considerable cost and complexity versus an expendable vehicle.

Stranger

Looking at it another way, any rocket that can reach orbit is mostly fuel, anyway, and there’s no way you’re going to be able to reuse the fuel.

While the OP is a bit garbled, there is one related aspect already touched upon by Stranger.

As I once read in a book somewhere, all you really need to bring down safely is the people and maybe some data on CDs and perhaps some small physical samples from low/zero g experiments.

At one extreme you have the shuttle, where tons of shit are reused/refurbished/rebuilt. At the other end of the spectrum you have something like Soyuz or the Apollo capsules.

Whether one end is cheaper and or safer is not blatantly obvious, though IMO experience has shown the Shuttle to not be that great overall cost wise.

You can still push one extreme though. When the Soyuz or Apollo capsules reenter, they are still carrying much stuff you don’t need once everything OTHER than actual reentry into the atmosphere has been done. You dont need all those electronics to survive reentry. Or the cameras, or the life support systems, or the guidance systems, or the rockets/thruster parts, or the long life support systems (and probably some other stuff ).

All that needs to survive is a person, in space suit, with life support for an hour or so, and a parachute (and the heat sheild for all this).

In theory, engineering wise, it might be possible to have a seperate really minimal rentry system that seperates from all that fancy getting into orbit and surviving/manuevering/communicating parts of the capsule and still come out ahead costs wise.

Not saying its a given, just saying it doesnt seem outside the realm of possibility.

The problem with the space shuttle was that it hung off the side of the booster tank. Anytime you fill a tank with liquid hydrogen or liquid oxygen, you either get ice falling off or the insulation falling off. Or both…

The shuttle needed those tiles as insulation to get back from orbit. Space ship one does not have to be so insualted.

The ideal would be to use a small shuttle-like craft as the people and small cargo transfer vehicle. However, if it’s small enough to fit on top of the booster, it likely won’t do much except maneuver a bit to get to rendezvous (ISS or transfer vehicles). If so, who cares how it returns? Doe it need wings? The real key is to make it cheap and if possible, reuseable.

If it’s big enough to be a real spaceship, then it incorporates a lot more (like being 50% plus of tank space) and it gets more complicated, and we’re back to the shuttle. Too heavy and the stages below to support it need to be built bigger stronger and heavier, etc.

once you get to items the size of the Hubble or ISS components, perhaps a returnable wrapper is a waste of booster capacity. Soyuz has it right. Make cheap simple boxes that are basically a lightweight air bubble for people, with a small maneuvering motor and a heat shield for re-entry.

I didn’t know that. Which one? I’m guessing it was one of the capsules used for unmanned tests prior to the manned Gemini missions.

And I’ll add one item to the thread at hand: I believe the Orion capsule that is under development will be able to come down on either land or sea. The Russians have always brought their spacecraft down on land because they have a lot of land to use for the purpose. We always did water landings, which was massively expensive because they had to call out half the surface fleet of the Navy for recovery operations in prime and back up landing areas.

Also, the capsule mode has a long history, is well understood, and bypasses some of the complexities of the shuttle. In terms of engineering, it seems like a good way to go.

MOOSE. Of course, this is really a last ditch device for re-entry, with no avionics for guidance or any kind of life support or flotation devices once you land wherever your final impulse and Isaac Newton send you. It sounds like a hell of a ride, but personally I think I’ll stick with a capsule that at least provides the illusion of protection.

Nope, it was the refurbished Gemini 2 capsule, used for Gemini-B [PDF]. Basically, a hole was cut through the head shield and a hatch installed, some internal modifications to allow for astronauts to through the transit tube, and removal of some of the extended life support equipment that wasn’t needed for its short operational lifetime. It was even intended to land on the ground in the Mojave with provisions for pop-out skids and a horizontal parasail. (Wing wipers didn’t want to rely on squids to pull them out of the drink, I guess.)

Stranger

Thats what I was thinking of when I wrote that, but couldnt recall the name. I like your word choice of illusion btw.

Like you said though, once the final impulse is over, you dont need the rest of the capsule crap.

Hell, in another few years, all they need to do is have a good manueverable parachute, some landing training, a decent cell phone/gps in their pocket, aim for the central USA, and it would probably still be safer than all this fancy shuttle / big military armadda types of landings that have been the mainstay of manned space flight.

Yeah, no thanks. I think at a minimum I’d rather opt for something like this. I don’t want to be in the middle of a de-orbit maneuver when Verizon decides to arbitrarily cut off my account, nor do I want to land in the middle of South Dakota and spend the next three days walking to something resembling civilization.

Stranger

Oh, now come on. You’ve already doubled the mass of the previous idea !

If you don’t have a " pretty mouth" or look like Ned Beaty you should be perfectly safe :slight_smile:

A very back of the envelope calc.

The Apollo heat shield alone was a bit over 600 pounds per astronaut.

The MOOSE system total is a bit under 500.

Yeah, thats an apples to oranges comparision, but as a very crude measure, its shows that perhaps a Mountain Dew Commercial EXTREME ! type of reentry might possibly be more mass effective than a professional rocket man Apollo type of reentry.