Capsules can carry modest amounts of return cargo, but anything bigThat depends a lot. If you are running the cargo variant of the capsule, then it should be able
wouldn't fit (unless you build a very large capsule!).
to bring down anything its capable of taking up. Now, taking down a satellite that is bigger
than that would definitely be a problem, but that's life. The odds of any satellite anywhere
getting brought down to shuttle is now very close to zero anyway.
In fact, most satellite owners would really prefer to do final assembly
and checkout in orbit, after the bouncy, noisy part is over... but it
was difficult to pursue that much with the shuttle.
Yeah, if the capability were reasonably priced, it would greatly reduce both the insurance and the design costs. And those are usually a lot more expensive than the launch cost portion of a satellite mission. I know that Dennis Wingo has done a lot of research into this area, and I've put in a fair deal of time into coming up with ideas for the same.
Sander Pool wrote:
Sure. But their argument was 'more experience' not "it's easier" :-)
We may have more experience with operations, but we have a ton more experience with design of capsules. We also have operations data for a much larger range of systems for capsules than winged-lifting reentry.
I'm hoping that eventually we'll get more reusability but for now expendable is what we have, yes.Of course, it *is* possible to make a capsule that could fit on the Falcon (especially now
that the payload capacity is now estimated at 1500lbs), and more especially the Falcon
Heavy (which would have enough mass to carry two people, or 2000lbs, or some mix to
the ISS, or some other space station). They are both mostly reusable--they have an
expendable upper stage, but you may be able with a capsule to move the two biggest
cost items (the Flight Termination System controls, and the Avionics system) into the
reusable part, thus only having to toss an engine and some tankage. So, steps are being
taken in the right direction, and if SpaceX succeeds, it may well attract more suppliers
(and hopefully customers) to the market.
Henry wrote:
On Fri, 19 Sep 2003, Sander Pool wrote:While this would be optimal, just having the ability to do on-orbit checkout would be a benefit
You wouldn't launch the crew until automated processes have confirmed that the components survived the launch.You don't really have the option of automated checkout here -- the whole
point of doing orbital assembly is that the hardware does not have to be
built to 100%-reliably survive launch without a single connection coming
loose. The components are launched in shipping boxes (okay, special
ultra-lightweight shipping boxes), powered down and disconnected.
even if they didn't take it all the way to its logical conclusion. It would reduce insurance by a
large margin, because you'd have the ability to intact abort the payload at all points, and to check
it out in orbit before it is launched. If it has a problem, it's tons cheaper to deorbit it, fix it, and
relaunch it, then to replace the whole thing like they usually do. And if you could have that
benefit of inspection, you could already design the system cheaper. So you could reduce your
two biggests costs *immediately* without even having to completely change the way you do
satellites (that is nice, as it allows a smooth transition from the status quo to a much lower cost
method). But I agree, that the optimum would be to assemble the whole thing in orbit then
inspect it before sending it off. Just doing that alone would reduce the cost of satellites, and
increase the odds of them succeeding, both of which will help increase the market and make
them more competitive with ground systems for many applications.
Besides, that order is backwards. The crew goes up first, because thereThis is a good idea where possible. Once you get a vehicle that can put about 4000-4500lbs
is some chance -- however slight -- that if they're on hand first, they
might be able to deal with a problem that would otherwise strand the
components. Which are, to put it bluntly, more expensive than they are. In fact, it would make sense to have a crew on the component launch.
This is why you have crews on even cargo airliners: the small chance that they will save an expensive vehicle and an expensive cargo is ample reason to have them there on every flight.
in orbit, you could probably send up both a person and about 1000lbs worth of cargo.
Not necessarily. Particularly if the hardware is reusable, flying a small vehicle several times can be cheaper than flying a big one once.Yeah, and if both of them are on reusable and recoverable capsules, it greatly reduces your
odds of losing the satellite.....but I've already beaten that dead horse enough.
Yeah, there is a lot to be said for a spacious drydock system. If designed right though, that partI suppose (day dreaming here) we could build a small space station in an appropriate orbit that is specifically designed to support satellite/probe deployment. You'd need to launch a lot of satellites for that to make sense of course.Highly desirable, though, because you really want a pressurized hangar
for assembly and checkout.
could be an inflatable structure (and I have a very lightweight idea for the interior structure that
would allow a lot wider diameter of usable space than the standard Transhab type design). The
big problem is getting a drydock with a sufficiently large diameter door to allow satellites out and
supply ships in. I guess you could get away (as someone mentioned elsewhere) with some sort
of metal frame for the seal, and a Kevlar-esque material for the main door section, but it still needs
some thought.......
Justin S. McFarland wrote:
Last time I checked, the United States has a lot more experience flying the X-15 and the Shuttle into space than capsules. But, the failure rate is higher, we lost 3 winged vehicles to 1 capsule. Of course, the Russians are a completely different story as it is all relative.The thing is that experience with the X-15 while helpful isn't 100% relevent to designing an
orbital RLV. X-15 never did much more than most of the X-prize vehicles will do, and
never had to experience anywhere near as extreme of a reentry environment as the shuttle
or capsules. So, if you want to compare orbital systems to orbital systems, you can see
that we have more experience flying shuttles, but we have a lot more experience designing
capsules. And so far, the only fatal US capsule incident was a ground fire incident that
would've been just as likely to happen with a winged, shuttle-like vehicle as a capsule had
the accident not occured with Apollo 1.
As by you all probally know by now, the capsule design has a higher geeWhile that may be true, the Apollo capsules showed themselves rather capable of landing very
loading because it doesn't have as much lift on re-entry. You also know that the your cross range landing accuracy is a helluva lot better with winged vehicles as well - since runways are generally a lot harder to land on for a capsule (instead of 100 miles away).
close to target (though their crossrange wasn't very high as you point out). There are tradeoffs,
and the gee loadings have been well within what is tolerable.
Personally, I see no reason why not to develop the best of EACH- winged and capsule. You have two completely independent vehicle designs. If one should be discovered to have a flaw and the entire fleet grounded, you still have an alternative. If both designs are compairable in cost - build 4 each and make everyone happy. As is the goal of the project that development costs would be minimal - and since each vehicle produced would probally be unique - it appears to be at least a feasible means of increasing reliable access to space.The only problem is cost. Since for OSP, NASA is going to insist in sticking its fingers in as
much as possible, it'll likely cost several billion dollars just for one approach. Funding two is
completely out of the picture for NASA, especially with it's paltry demand.
Now, if multiple private orbital vehicles could be developed, and the markets for them also
developed, more power to them. Competition and several different approaches are good
things.
~Jon
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