White House Decides to Outsource NASA Work

[CaptainBeowulf]

I'd say that when carbon nanotube composites can be manufactured on a large scale, we could probably just dust off the X-33 Venturestar plans and make the oddly shaped tanks out of those. The early 90s NASP plans would likely also work. But we can't be sure how quickly carbon nanotubes will mature.

The optimist in me likes to think they will mature by 2020, and Ares V, EELVs and Falcon 9 will be replaced by much more capable boosters made up of carbon tanks, with spaceplanes for crew transport following on soon after. The realist in me says that we don't know when the technology will mature. I think it's adequately funded by a number of different institutions, unlike fusion, which has been underfunded, with most available funding going to ITER, an eggs-in-one-basket approach. I think fusion could be done soon if all the possible avenues were explored, while nanotubes are taking care of themselves and will happen when they happen.

I'd also like to see some work on aerospike engines resume. IIRC the aerospike concept dates back to the 70s or late 60s. They seem likely to provide better thrust because the exhaust plume changes shape according to atmospheric pressure, rather than being shaped by a bell nozzle. The aerospike was unnecessarily morphed into the linear aerospike on the X-33, which collapsed under its own weight because NASA tried to do too much all in one go. A Delta IV, Atlas V or Falcon 9 with carbon composite tanks and a big aerospike engine could be quite interesting... maybe make those HLV a little less attractive.

[KitemanSA]

Think rope. The specific velocity of Sprecta 2000 and various beta SiC fibers are about 2.5km/sec. This approaches the specific velocity of most rocket fuels. Thus, tether assist like HASTOL and KITE launch could combine into a remarkably cheap, reusable launch system. Launching 5Mg at a time at <$100/kg is a good alternative to megasize ELVs. Remember, most of the mass needed is STILL the consumables. A medium ELV can send up a very large, but empty, deep space rocket.

[93143]

A medium ELV can send up a reasonably large, but empty, inflatable crew habitat.

Fixed that for you.

Seriously, most things you'd want on a deep space mission - large propulsion modules, nuclear reactors - simply will not fit on an EELV-class vehicle, either volume-wise or mass-wise, or both. Even when empty.

Also remember that spacecraft tend to be even more expensive than launch vehicles. You've got to weigh the extra cost of orbital ops against the launch cost, and it isn't a foregone conclusion that chasing a couple hundred five-ton packages all over the sky is going to be cheaper and easier than just launching a half a dozen big ####ing rockets.

This is all moot for the time being, since tether systems are not close to being fielded...


...


I may be a rocket scientist, but I'm not a very experienced one, and it's possible that I could have the wrong impression on a lot of this stuff. Maybe I should try to sound a little less arrogant?

...nah. It's more fun this way.

[djolds1]

Wrong model. Access to space via current methods is more like Zheng He's Fleet. If you don't do it in scale and maintain the huge infrastructure, you don't do it to any worthwhile degree.

Excellent model... for my argument!. Zheng He's fleet is NASA. It explored a few places in huge, expensive ships, then went kaput! It was the the other side of the world that made it, with little tiny groups of little tiny cast off ships. Hardly ships at all.

What we truly need is a viable way for the discontent to move out to LEO and beyond. MegaRockets (tm) ain't the way! VolksRockets are. Tiny, cheap, single family type; send 'em up by the thousands ways into LEO, the moon and beyond. JMHO!

I don't see current technologies (EELV/LCLV) allowing a Conestoga/Caravel analogue. Certainly not with cargo capacities of <= 25 metric tonnes.

...except that even with heavy lift, or even Nova-class super heavy lift (which might allow a one-launch Mars mission, which is the closest we're going to get to the "covered wagon" analogy), the cost of chemical rocketry is still too high. If we want to move people out into space, we need new technology. Exploration is as much as we can do right now. So the question now is, do we want to explore? Or do we want to build exploration vehicles in LEO?

Exploration is all we can do if we insist on the return leg. Mars is much easier to colonize if our people are not coming back. 2+ times as much mass usable at the destination.

Once a commercial company can plausibly offer a heavy lifter (and SpaceX for one is evidently working on it), NASA - and hopefully other interested parties - can buy those services. Until then, a bird in the hand is worth two in the bush.

Even the SpaceX Falcon 9 Heavy is a relatively light lifter next to the DIRECT Jupiter 240 or Ares V.

[KitemanSA]

A medium ELV can send up a reasonably large, but empty, deep space rocket.

Fixed that for you.

Thanks but no thanks. Wasn't broken.

Seriously, most things you'd want on a deep space mission - large propulsion modules, nuclear reactors - simply will not fit on an EELV-class vehicle, either volume-wise or mass-wise, or both. Even when empty.

You presume I want a large propulsion module when in fact I suspect I want multiple redundant small modules. By the by, how heavy would one coil of an SC Polywell be? We may actually have to start planning for a 15-25Mg tether launch system.

[MSimon]

Maybe I should try to sound a little less arrogant?

...nah. It's more fun this way.

A man after my own heart.

ROTFLMAO

[Betruger]

F9H isn't the big SpaceX rocket. Musk mentionned a heavier design to match a Saturn V a couple of years back. Apparently it's still in their plans.

[Josh Cryer]

Private companies unlike NASA will be looking for customers.

NASA makes a good first customer. No gimmies. Once they sign they go all the way. I was always an advocate for Dragon for the Orion ship.

http://www.spacex.com/dragon.php

If you know any engineers in space (I believe you said you worked in that sector before), you'd know that many insiders in NASA did *not* want to go with Ares I. This was very often reported on NasaSpaceFlight and NasaWatch. Now it looks like Obama is getting rid of Ares I, and getting companies to bid for an Orion replacement.

The stick, while an engineering marvel, was never going to be cheaply engineerable. Griffen got it completely wrong. He thought he could take the facilities for the SRBs and use them to make the stick, but it turns out the stick needed a lot of additional stuff for it to actually work. And even then it is not survivable in the 30-90 second window of abort (hot debris from the SRB explosion would melt the chutes, it is not able to be engineered around).

Ares I was a boondoggle of bureaucracy. Let someone in the private sector build the ship, and since we tax payers would be their first come first serve customer, we're going to pay up, and we'll help them get their business off the ground (for tourism and the like).

[Skipjack]

One of the ways to make access to space cheaper is flight frequency. The more flights, the lower the price per flight and the safer the whole thing gets too.
So having to fly more often might actually be benficial to having very few HLV flights.
What I like about the approach by SpaceX is that every vehicle uses the same engines, just more or less of them. It is great, because even the heavy and super heavy variations of their vehicles will benefit from at least a bit from the high flight frequency "issue".
I am also pretty sure that if we had RLVs that are even cheaper, higher flight frequency would be even more desirable and would in the end probably be cheaper than fewer heavy lift flights. If you factor in the cost savings for non HLV- missions, it should be much cheaper in any case.

On the "we need to get out of LEO" argument: If we went to Mars, or the moon again, or an asteroid, with the current cost of even getting to LEO, it would once again be unsustainable. It would once again only be a one shot like Apollo (with potentially another 40 year gap until we go somewhere). In return, if we have a functioning and sustainable space infrastructure in LEO, going anywhere else should be much more affordable.

[djolds1]

F9H isn't the big SpaceX rocket. Musk mentionned a heavier design to match a Saturn V a couple of years back. Apparently it's still in their plans.

Cite/link?

[alexjrgreen]

F9H isn't the big SpaceX rocket. Musk mentionned a heavier design to match a Saturn V a couple of years back. Apparently it's still in their plans.

Cite/link?

Perhaps it was this: SpaceX looks at Saturn V class

[djolds1]

F9H isn't the big SpaceX rocket. Musk mentioned a heavier design to match a Saturn V a couple of years back. Apparently it's still in their plans.

Cite/link?

Perhaps it was this: SpaceX looks at Saturn V class

Looks like Musk is considering single engine performance in the F-1/Beal BA-2 range.

[Betruger]

F9H isn't the big SpaceX rocket. Musk mentionned a heavier design to match a Saturn V a couple of years back. Apparently it's still in their plans.

Cite/link?

Don't have one, sorry. Saw it mentionned years ago (too long to recall specifics) and I haven't seen anything to contradict it since. E.G. his standing bet to put men on Mars by 2025 or so. Or that Merlin 2 was never explicitely denied. You'll probably have as much ease in finding evidence from looking through google (e.g. "merlin 2", "spacex, BFR", etc) as me trying to find it for you.

Or even simpler, you could find evidence that his BFR plans are indefinitely on hold or cancelled altogether.

[93143]

Okay, you said:

A medium ELV can send up a very large, but empty, deep space rocket.

This implies, at the least, a complete (if unfueled) monolithic mission stage, with enough capacity to support a large manned interplanetary expedition.

I doubt an EELV could get much more than about 150 mT of LH2/LOX capacity into orbit in one launch. Any more than that and the huge, fluffy hammerhead configuration becomes aerodynamically unworkable.

That's not really very big for a Mars mission. And it's just the EDS - there's room for maybe 10 mT of compact spacecraft systems, but that won't even get you to the Moon and back, let alone anywhere else. The spacecraft is a separate launch. Probably more than one, actually.

By the by, how heavy would one coil of an SC Polywell be? We may actually have to start planning for a 15-25Mg tether launch system.

Assembling a Polywell on orbit strikes me as a really difficult and complicated endeavour. Also, Polywell is not a given. Suppose you need a fission reactor?

You know, this argument has drifted. Originally I simply intended to challenge the widespread assumption that assembling a mission in space from little bits, launched with rockets we already have, is obviously better than launching it in a few big chunks using a larger rocket. It's not.

Clearly the availability of cheaper, easier orbital access methods with stringent mass and volume limitations would change the dynamic somewhat. I'm dubious of tethers; the Mach 12 aircraft, the required rendezvous precision, a dozen other unsolved problems all make it unlikely to be as cheap and easy as you claim. Skylon is a better bet IMO. But there will still be a need to put stuff in orbit that weighs more than 15 mT or whatever the system can haul up in one trip, and there will definitely be a need to put stuff in orbit that's a lot larger than the system can handle and can't be made inflatable. For that, you need something big.


I'll say it again: spacecraft are typically more expensive than launch vehicles. Overcomplicating the spacecraft to save on launch costs is a waste of time and could easily end up costing more overall.

[KitemanSA]

[/quote]

Okay, you said:

A medium ELV can send up a very large, but empty, deep space rocket.

This implies, at the least, a complete (if unfueled) monolithic mission stage, with enough capacity to support a large manned interplanetary expedition. I doubt an EELV could get much more than about 150 mT of LH2/LOX capacity into orbit in one launch. Any more than that and the huge, fluffy hammerhead configuration becomes aerodynamically unworkable.

I was actually figuring on the equivalents of the S-IVB size, each of which weighs about 13Mg and carry ~100Mg of fuel. Certainly one of the vehicles you seem to be calling a medium lift ELV (Delta IV H?) could take that up.

That's not really very big for a Mars mission. And it's just the EDS - there's room for maybe 10 mT of compact spacecraft systems, but that won't even get you to the Moon and back, let alone anywhere else. The spacecraft is a separate launch. Probably more than one, actually.

Well, I would think a dozen or so medium ELV and a large number of KITE/HASTOL launches. Of course, your "inflatable" may reduce the number of ELVs significantly.

By the by, how heavy would one coil of an SC Polywell be? We may actually have to start planning for a 15-25Mg tether launch system.

Assembling a Polywell on orbit strikes me as a really difficult and complicated endeavour. Also, Polywell is not a given. Suppose you need a fission reactor?

Really? Seems simple to me. Take up six or maybe 20 coils, bolt them together. Plug in the power leads and cooling lines. I mean it is not as if you have to provide a vacuum chamber or anything. Well, maybe a real thin one for operations in near planet orbit.

You know, this argument has drifted. Originally I simply intended to challenge the widespread assumption that assembling a mission in space from little bits, launched with rockets we already have, is obviously better than launching it in a few big chunks using a larger rocket. It's not.

I would certainly accept MAY not be. But assembing such a mission on orbit is the way to go if the infrastructure is there. And I see this whole "Mars or Bust" shinanigan from Prexy Shrub as being a fast way to the "Bust" part of that equation. I am tired of NASA stifling space enterprise.

Clearly the availability of cheaper, easier orbital access methods with stringent mass and volume limitations would change the dynamic somewhat. ......

I'll say it again: spacecraft are typically more expensive than launch vehicles. Overcomplicating the spacecraft to save on launch costs is a waste of time and could easily end up costing more overall.

However, space-craft are so expensive partially because launch costs are literally astronomical. Who in their right mind would try to save $50M on a space-craft when launch costs approach $150M for that craft? Demanding that 99.999xx% reliability is what costs. If the launch costs were $1.3M rather than $150M I suspect you would see the price of the space-craft plummet!