Posted on 12/06/2004 8:36:03 AM PST by Paradox
I have read that this very point was one of two that brought Von Braun around to the LOR concept for Apollo, having been previously an apostle of EOR. The other being the massive size of the landing vehicle that would be wrought by going the EOR route. All very valid points. The challenges of assembly in zero gravity vacuum are quite daunting compared with tinkering things together in a terrestrial environment. That's not to say it can't be done, because we and others have done it. It's just lot more bother.
The Moon has lots of aluminum oxide. Why not use solar power to separate it into oxygen and aluminum. Then build a rocket that uses powdered aluminum fuel with liquid oxygen oxidizer? That way you wouldn't need to use hydrogen.
You could strap another 4 core boosters to the Delta IV Heavy and get around 30 mT to LEO
Nah, t'weren't cost effective. It's how the libs managed to kill the moon program in the first place. "Save those billions money for the CHILDREN!" ><
If we're going to get stuff to the moon in large quantities, we have to find something better than chemical rockets.
We didn't "cut our own throats." The unpleasant truth is that there was no market for such a heavy-lift booster once Congress shut down the moon program. Nor is there even a significant market for the Delta IV -- and that includes no commercial market for that much throw weight.
Yep!
Not to LEO -- to GTO. (The satellite's upper stage takes it the rest of the way to GEO.)
But the aerospace companies love expendables because they get to sell a whole new rocket for every mission. For that reason alone, letting them develop anything reusable is the fox guarding the henhouse.
Now, I'm nothing but a regular guy, but from what I have read, the "reusable" space shuttle costs about $500,000,000 a mission, to put up 15 metric tons of cargo. Accoring to this article, a demo mission for a Delta runs from 140 - 170 million. Even if we assume a significantly higher cost of $200,000,000 for a real flight, it looks like it is a heck of a lot cheaper per ton to launch 13 MT into orbit for 200 than 15 MT into space for 500.
I'm very willing to be educated here, but it looks to me like the disposables are the lower cost way to go, and the existing shuttle program the real boondoggle.
So, 25% of the capability of a Saturn V for LEO? Again, it still seems like we're dealing with midgets here. I really don't understand why this country goes through all the trouble to develop some really good things and then just drops the ball. Seems a shame to waste all that effort when we could have been doing some really exciting things in the meantime if we had used the treasures we worked to put into our own hands.
It'd be far cheaper to build from scratch. NONE of the Saturn V support infrastructure exists anymore, and NONE of the electronics on the boosters themselves has been manufactured for decades.
Sounds like three of these could put up a nice battlestation in geosync orbit.
Actually, no -- the Shuttle system regularly launches 250,000 lb into LEO. Problem is that 200,000 lb of that weight flies back for a landing.
The mass fraction for any reusable system is going to be similar, which is why reusables are probably never going to be cost-effective for placing large masses into orbit.
Another cost-increaser for reusables is that the intrinsic reliability numbers have to be much higher than for a single-shot expendable.
We need the SEA DRAGON.
I just looked it up, I think its him. Sea Dragon.
I stand corrected -- the Boeing reference card lists the Delta IV capacity as approximately 22 mT to LEO reference orbit. Thus, it would take six Delta-IVs to equal one Saturn V.
One other thing to add is that reusables become progressively more difficult to maintain as they age simply because of technology changes. Maintenance of the space shuttle requires engineers to constantly try to scavenge for parts like 8088s and 80286s - stuff that was very available at the time of construction but rather hard to find now.
Disposables, on the other hand, could be more or less continuosly upgraded with newer parts, with new hardware replacing old as newer technology becomes available. It's not like it's going to have to be maintained, right? So, in affect, a long term order of disposables could result in reduced cost per ton over existing launches, not only because of improved capacity utilization of manufacturing facilities, but also because of the judicious use of improving lower cost technology.
Actually, not quite. Shuttle guys are scavenging 8088s and 80286s for maintenance of the ground support equipment. Your alternative raises the challenge of trying to keep all of the instrumentation up to date and consistent with the older H/W on the boosters. It's far cheaper to find and replace old Intel chips than it is to continuously rebuild, re-test, and re-qualify new ground support equipment.
So, in affect, a long term order of disposables could result in reduced cost per ton over existing launches, not only because of improved capacity utilization of manufacturing facilities, but also because of the judicious use of improving lower cost technology.
Probably correct. The Russians demonstrated that economies of scale are real when they launched something like 1500 Soyuz boosters over the span of about 30 years -- that's something like 6 launches per month!
But that also points out the problem: there's simply no market right now for anything close to that sort of launch rate. These days the Atlas and Delta guys are lucky if they get 6 launches per year. You just can't get economies of scale when your launch rate is so low.
The existing shuttle is a perfect example how not to do a reusable. The initial idea was fine, but nearly every decision made in its development was a bad one.
When developing a reusable, you have to keep an eye on the operational maintenance you are going to need. Shuttle management did a very poor job of this when it was being developed.
While the initial idea was to lower recurring launch costs, very little attention was paid to doing that during actual development.
In addition, the shuttle is hideously inflexible as far as the flight rate, which pretty soundly negates its reason for existence in the first place.
If you are going to assume a very low flight rate and an infinite maintenance budget, there is absolutely no reason to develop a reusable, expendables will work fine.
The problem is that our aspirations and goals simply can not be met by expendables (or stupidly developed reusables.) We are planning on doing a lot in space, to do that with current hardware and architectures, NASA would have to have a budget comparable to the Department of Defense.
How much mass makes it to orbit is essentially a fuel cost if you are talking about any reasonably designed reusable. In any likely reusable scenario in the near future, fuel cost is lost in the noise.
Ideally, reusables would be used for launching personnel, since you want the reliability anyway for that and the large masses would be mined and manufactured off-planet.
I'm talking about structure mass, not fuel cost. The fuel mass (and related tankage) is governed by whatever mass has to be placed into orbit.
The only real question remaining is: how much of the mass placed on-orbit is going to have to come back home? For reusables, it means a lot of structure (and volume), which obviously takes away from the amount of actual payload you can carry to orbit.
The Shuttle-C concept was attractive for the simple reason that the design used an expendable fairing and main engines. I don't remember the exact numbers, but it seems to me that you gained about 100,000 lb to LEO.
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