Space Shuttle replacement

In My Humble Opinion
1

There are a few threads about the lates STS mission, and the Shuttle programme in general. Stranger on a Train, in particular, has been critical of the Shuttle.

Right. The Space Shuttle has not lived up to its promise of cheaper flights. As Stanger has pointed out, the Russians have been doing very well with their old-tech boosters and Soyuz spacecraft. Given that the Shuttle will be grounded for an indefinite period after STS-114 lands, and that they are to be grounded permanently in five years, what will we do to replace it?

First, we need to have a craft capable of putting large payloads into space. The ISS needs Shuttles to loft its components. It seems to me that we can dust of the Saturn 1B blueprints and build a very nice, very reliable ship – upgraded with modern components, of course – that can take large payloads into orbit. These can be unmanned launches.

Next, we need a way to get crews into space. Soyuz has proven very reliable, in spite (or perhaps because) of some deaths in the '60s. But they’re small. I think we should have a ship that can carry more than a pilot, co-pilot, and one passenger. I think the ship should be reusable. I don’t have a very good reason to think this; only I hate to throw perfectly good things away. Perhaps a large ‘capsule’ could be used, and the service module could be re-used as a component to a space station while the capsule can be used for re-entry and discarded. But I prefer a dignified glide back to a runway, instead of a splashdown followed by bobbing round waiting to be picked up. Personal preference.

But let’s say we have a reusable craft. We’re right back to the Orbiter, in that we’ll have a ship that has ceramic tiles that are prone to damage. What do we do? How about this: Since payloads will be delivered by unmanned boosters, the New Orbiter can be made smaller. No need for a big cargo area. A smaller ship would have fewer tiles to be damaged. In addition, it might be able to enclose it in a cover that is jettisoned after it reaches LEO. I’m thinking of the ‘clamshell’ arrangement used to house the LM on the Apollo flights. From what I remember reading in 2001: A Space Odyssey, the ‘Pan Am Clipper Orion’ was launched on a Saturn V booster. The New Orbiter would be smaller and lighter than the fictional craft, so it would not need a Saturn – but it could be launched on a version of the new, Saturn 1B-inspired booster I mentioned before. Or, given a protective enclosure, it could be used on the existing STS booster system.

In a nutshell:
[ul][li]New heavy-lift unmanned booster for putting payloads into orbit[/li][li]New, smaller Orbiter for getting crews to and from orbit[/li][li]Jettisonable enclosure for New Orbiter to protect its fragile tiles during launch[/ul][/li]
Here’s something else to think about: Time. Apollo ended in 1972 (with the exception of the Apollo-Soyuz mission). The Space Shuttle had to be designed and built, which took time. Four years, I think; which seems a very short period. Approach and Landing Tests took nearly a year, in 1977. Challenger flew in 1981.

Now, five years from the end of Apollo through the ALT seems like a very short time. With Congressional wrangling and a war that’s diverting our attention to many important things, plus more public scrutiny vis a vis safety (by a Public that seems to not understand basic aerodynamics, let alone flight test), and not having (as far as I know) a concept of what the Shuttle follow-on will be, I have a feeling it will be a decade after the Shuttle stops flying until we see its replacement. Unless NASA et al get on the stick and crank up the R&D machine now.

Those are my thoughts. I’d like to hear what others think, especially Stranger, who seems to be very well-versed on the issue.

2

I think that the Soviet copy of the shuttle had some very smart improvements. The external fuel tank was reuseable, like the boosters, and it was a proper rocket in it’s own right. It appeared to be covered in heat-resistant tiles like the orbiter was, so I don’t think you’d have the same problems with foam falling off.

I think that NASA should build a few of those.

3

They were even up to testing a Single stage to orbit vehicle (simular to the linked concept) just a few years ago that proved promising, why was it abandoned?

4

I’ve got a plan. In both shuttle accidents a bit element was the horizontal stack design. I prose reassembling the shuttle for a vertical stack. Chop the main engines off and replace them with a flange to mount to a boost vehicle. Perhaps that can’t take the entire launch load so we build a truss frame to distribute the load from the old engine position to the fuel tank attachment points on the belly of the shuttle, the guys from OCC could bang that out in in a couple of days if they can get a big enough tube bender. We’ll need a new booster design but this is more a matter of building tank/body for engines and systems we already have.

We’ll need a new launch pad and platform but that kind of construction is far less expensive than an entirely new shuttle. I suggest putting the boster below grade level so the shuttle can be mounted without raising it higher than it is now on the pad. Perhaps a modification to the existing crawlers could lower the booster down through the middle on an arrangement like old fashioned aircraft carrier elevators. Unfueled it should be light enough to do that way. We assemble the shuttle on the pad the way the Russians do and we’ve removed a large part of the risk while retaining the investment in the existing shuttle.

Sheer folly I know but IAMARS so I know this will be picked apart. I want to know why it couldn’t work.

5

Sorry, found the test photo I was looking for here.
From the same Delta Clipper DC-X website:

That’s what I find really amazing, how much cargo can the shuttle carry?

6

From Space.com:

That’s a maximum payload of 32.5 tons, depending on the orbit.

I think what NASA needs is an unmanned vehicle that can lift a large component up to Space Station Alpha, a light (not necessarily reusable) vehicle that can lift 4 or 5 people plus supplies to Alpha (3 station crew, 1 or 2 flight crew), and a reusable crewed vehicle based on the Shuttle.

I’m using the space station as my standard of measure because that’s where a lot of the space flight action will be for the next several years.

7

The Saturn tooling was destroyed, and at least some of the documentation has been reportedly lost. Huntsville alledgely has all of the plans on microfilm, but I question that they have actual component parts rather than ICDs and upper level assembly drawings. In any case, no doubt many of the component manufacturers have disappeared from the face of the Earth (as they tend to do) and those components would have to be reverse engineered; not an undoable feat, but more complex than just sending down some drawings an ordering up a new shipment of thingabobs from Bob’s Machine Shop.

Still, the Saturn family was an engineering marvel of its time and was well on its way to design maturity and economy of scale. However, there are more modern, and more importantly, already in development or production boosters, such as the Kistler K1, the various configurations of Energia and Zenit boosters, and indeed, the Shuttle’s boost systems, which have provent to be quite reliable despite problems with the Orbiter itself. Even the flawed design of the Shuttles SRBs hasn’t prevented them from being the most reliable large solid rocket booster in existance; as far as unmanned heavy-boost capability goes, they’re certainly an acceptible choice. But economy–dollars per pound to orbit–and reliability should be the deciding factor. On that basis, reviving the Saturn at this point probably doensn’t make sense.

The CEV will most likely be at least semi-reusable, even if it is a capsule. Gemini was actually designed to glide down to a landing on a parawing–in several of its re-entries it came down within spare miles of its retreaval ship–and the abortive Blue Gemini program (Air Force) was actually intending to put skids on the bottom of the Gemini capsule and land it in the desert (because they didn’t want to ask the Navy for retrieval assistance.)

Still, reusability should be a consideration of cost, not a fundamental requirement. One of the advantages that Gemini and Apollo had over the Shuttle was that when problems were encountered the capsules and service modules could be modified in the design and preproduction stage without massive rework. Making significant modifications to the Shuttle, though, requires considerably more effort, and a lot of things are left in a suboptimal condition because it is just too much work and risk to change them. The original flight computers are an example; Challenger was flying with Apollo-era (and, in fact, a variation on Apollo hardware) computers.

Well, we have to figure out some way of maintaining the ISS in the interval; the best solution is probably to revive and develop the propulsion module for the ISS so that it doesn’t depend upon the Shuttle for regular boosts to higher orbit. I sure hope we don’t go another decade without a Shuttle replacement–I don’t think the aerospace contractors will allow themselves to be strung along that long, unless they can milk the taxpayers for one design study after another–but I fear that the replacement may end up being no improvement, and that the direction from the current administration (which I don’t agree with, but at least its a vision) will vaporize into the political wind, just as the last space initiative did.

The remaining “second flight” Shuttles (Discovery, Atlantis, and Endeavor) are rated to carry a payload of 28,800lbs to LEO; probably somewhat less from the Kennedy SC launch site to the ISS, given the position and inclination of its orbit (which is preferred for launches from Baikonur, allowing the Soyuz to reach the ISS).

The 10 ton cargo limit for the SSTO is just a conceptual number; in all likelyhood, it would have carried significantly less. A good SSTO design that is able to be relaunched without significant refurbishment would be a great boon as a personnel transport, but it probably wouldn’t be an effective cargo hauler per studies done in the late '70s. Even SSTO proponents like Jerry Pournelle admitted that it had limited payload capability.

Stranger

8

I think if they were to do a vertical stack, like Padeye suggests, there wouldn’t be a source of debris to damage the tiles in the first place, so no need to enclose it in a shell.

But there’s just no way the shuttle could be modified to a vertical stack. I’m thinking a good replacement would be something like the European Space Agency’s Hermes design, with room for more people, less cargo and shorter endurance (since it’s only going to and from the ISS).

9

I’m thinking that we should go all the way to the drawing board and use laser-boost.

Laser boost is a neat trick which involves firing a laser into a shaped compartment in the back of the shuttle/rocket/whatever. The compartment is built to automatically correct the vessel’s direction, so it remains perfectly straight. You need one whopping power plant on earth, but thats surely better than trying to carry 50 bazillion pouns of rocket fuel.

10

Or maybe we should just re-consider Project Orion.

We’d use up all that nuclear bomb material the tree-huggers and hippies hate so much. :smiley:

11

On the positive side, the money from the TV contract would help offset the cost. :smiley:
I am sitting here laughing my ass of at the thought of the guys from OCC buiding a space ship. Hey maybe we could have a build off between OCC and Jesse James.

12

This concept is not just highly speculative but probably physically infeasable. Not only would you have to build a laser with massive throughput, many orders of magnitude beyond what we can currently achieve, but you’d need to use some wavelength that is virtually transparent to atmosphere (x-rays?), lest you expend all of your energy in heating air, and the resulting thermal blooming issues. It’s not even a remote consideration.

Orion is actually a very interesting idea, and at least in concept, quite feasable. (The original Orion project got to the point of buiding a scale model powered by conventional explosive charges that was successfully flown.) The two-stage pusher and ablative oil covering reduce what would seem to be an absurd idea (riding a nuclear bomb into orbit) into a managable engineering problem.

The problems with Orion, other than the atmospheric test ban issues, are two-fold; one, it suffers from a problem of scale; unlike chemical rockets, which are limited by the specific impulse potential of their fuel and can only get so large before extra fuel is just expended in lifting its own mass, Orion-style boosters actually become more efficient with increasing size, and unworkable when scaled down to something approximating a Saturn V. This is due to a number of reasons but predominately because small nuclear devices are fairly inefficient in their energy release. Physicist Ted Taylor, who worked on Orion’s “fuel” system, actually designed some of the smallest fission devices then devised, making use of very thin shells of uranium and using what were then very new techniques in enhancing (boosting) the efficiency of the device. Although these techniques were developed early in the US nuclear development program, they were largely abandoned with the advent of the thermonuclear fusion bomb (“The hydrogen bomb, Dmitri!”) and required what were then very sophisticated computer simulations. Anyway, the thing is, to make an ground-launched Orion safe and efficient you have to make it enormous; down to somewhere around 200 tons on the very low end, and at least 600-800 tons to get to optimal usage. (The Air Force initially looked at Orion as a superbooster–kind of an early, massive MIRV–but decided that it would be too big for their purposes.)

The other problem is reliability; you have to deliver one or two devices per second, from some kind of magazine or hopper, through the pusher plate and into the detonation chamber. With the larger Orion a single hangfire wouldn’t endanger it, but multiple misfires could, and there’s no conceivable way that you could hope to lower something that big back to ground on parachutes. Orion goes up; she doesn’t come down and she can’t abort half-way.

Still, it’s a very interesting concept, and even more with a smaller pure fusion device (small deuterium-tritium or deuterium-He[sup]3[/sup] pellets compressed and ignited by a particle beam) which would have negligable fallout and allow you to use smaller detonations, but this, too, is pretty speculative; certainly not in the timeframe of an immediate replacement for the Shuttle.

Stranger

13

I was fortunate enough to hear Capt James Lovell (apollo 13 commander) speak last week. Absolutely spellbinding and highly recommended.

FWIW, One thing he said was that it was a shame the Saturn 5 rocket was discontinued. That the Saturn 5 mas much more cost effective than the shuttle.

14

The advantages of reusability are not as apparent as you’d think. The Shuttle, for instance, has to haul wings and landing gear into orbit - items that have no benefit whatsoever other than in vehicle recovery. Had the shuttle been just a cargo canister, the amount of cargo it could haul into orbit would be much, much greater. Plus, you could leave the shell itself in orbit for use.

So why not build a heavy lifter that uses a shuttle launch stack (external tank plus SRBs), but which doesn’t carry an orbiter? Make it unmanned, and you don’t have to worry about man-rating everything and you don’t have to waste cargo capacity for crew space, consumables, and support gear. Then build a smaller manned vehicle to take the crew into space, maybe using an SRB with a crew pod on top.

This is exactly what NASA is planning.

As for how long this will take, current estimates are for a gap of no more than four years (shuttle retiring in 2010, CEV flying 2014 at the latest), but now NASA is trying to move the timetable up so that CEV is flying when the Shuttle retires. Congress may even earmark more funds to make this happen.

To give you an idea how much payload the orbiter costs, the Shuttle-C, which is virtually identical to the shuttle system except replacing the orbiter with a non-reusable cargo pod, could haul a maximum of 78,000 kg into a 400 mile LEO, compared to about 30,000 kg for an equivalent shuttle payload.

15

I’ve noticed that sometimes what I type is not necessarily what I was thinking. Re: the Saturn 1B. I typed ‘It seems to me that we can dust of the Saturn 1B blueprints and build a very nice, very reliable ship – upgraded with modern components, of course – that can take large payloads into orbit.’ What I meant was that the Saturn 1B was a reliable launch vehicle, and that it would be nice to have something very similar in concept; not that we should actually build an upgraded 1B. I should have taken more time when I wrote that. Sorry.

This is the second time I’ve read one of your posts that says ‘some of the documentation has been lost’. I’ve heard the Urban Legend (though I can’t find it right now) that the documentation for Saturn was destroyed. The ‘de-bunking’ I read was that it was not destroyed; that it is on microfilm. According to the article I remember, the big problem with building an actual Saturn is tracking down 40-year-old transistors. But what I’m curious about, is what documentation has been lost?

In any case, Sam Stone’s spaceref link shows that plans for getting stuff in space are already in the works. I hadn’t really looked into it before.

I have an unbuilt model of a Gemini capsule, and it has optional-position landing skids.

16

'Kay, I might have to eat crow on this one; for a long time, NASA quietly acknowledged that some documentation had been “lost”; i.e. it wasn’t in their possession and Boeing couldn’t provide the plans. This may have just been a dodging tactic to avoid even considering going back to the Saturn V after the destruction of Challenger. This is also consistant with what I’ve seen in the aerospace industry; trying to get design information about the North American Aviation-built Apollo capsule from Rockwell (who bought them) or from Boeing (who bought most of Rockwell’s aerospace and defense divisions) is like performing surgery with a spork. A lot of the information has either been lost, or it has been filed in some archive by a guy who retired years ago and subsequently died of a heart attack. Whenever I see a drawing now that comes from Goodyear Aerospace, I know not to even look. (I think the only reason we still have decent drawings on Minuteman and Peacekeeper is because we’re still upgrading and modifying those birds.)

The tooling for the Saturn V was certainly destoryed; that alone would be a massive reinvestment. And a lot of the undocumented “legacy data” with how the thing operated is irretrivably lost; we’d end up making the same mistakes over again. I’m sure, with sufficient investment, the Saturn family of boosters could be revived and even improved, but in terms of economy we’re better off using or improving upon a current system.

Stranger

17

Currently, the specs NASA’s talking about for the shuttle replacement (called the CEV) call for it not only being capable of going to Earth orbit, but Lunar orbit as well. So, we’re not simply talking about something that can go up to the ISS and back, but it’s got to go to the Moon, and be capable of docking with some kind of landing craft.

Of course, if we’re going to do this thing, it needs to be done right. First and foremost there’s the matter of cost. In order to get the costs down, the CEV has to be capable of being launched frequently and rapidly, without needing a thorough examination like the shuttle does. It also needs to be easy to service, unlike the shuttle. That is, if you’re planning on a reusable craft. Disposables, like what was used prior to the shuttle, don’t need to be easily serviced, but they do need to be capable of being produced in largish numbers fairly quickly, if you’re wanting to keep the costs down. A hybrid set up, like what the shuttle uses, with the orbiter and SRBs being reused, while the main tank is scrapped, is also possible.

If we use the Shuttle-C concept, where the current stack is used to send cargo modules up, we then have the question of how do we get the CEV and the LEM into orbit? Do we use the current stack or do we use some other system? If we’re going to use the Shuttle-C concept, then I propose we do one or two things with the ET. Either it’s redesigned to be reusable, or its “stored” for future use. By “stored” I mean, it’s parked in orbit, and used for space station modules (Hilton’s been wanting to put a hotel in space for decades now) or we fling it at the Moon, so that future settlements have easy access to the materials the tank’s made out of. As for the design of the CEV, if it’s a lifting body, then there’s no issues (or at least smaller issues) with the wings (and let’s just ditch the whole ceramic tile business and use a spray on heat shield, it worked great for Rutan), but we have the issue of weight. If we build a really large CEV, that requires the same kind of fuel load that the shuttle currently requires, then we’ve got to use a seperate launcher of some kind to get the LEM into orbit. If we make it smaller, so that on Lunar missions, the LEM can be strapped to the stack along with the CEV, then we have the issue of launching non-Lunar missions with an ET that’s oversized for the job.

Ideally, I think that we should go for a modular system, one in which the launch vehicle for the CEV can be configured so that it can hurl the CEV into LEO, or send it and the LEM towards the Moon with the addition of a couple of stages, or cargo modules, where ever. This would require redesigning the launch platform (and if we put the CEV at the top of the stack, we don’t have to worry about it getting whacked by foam), but part of the costs of this can be absorbed via the unmanned program. NASA needs to develop a standardized “pallet” for delivering probes. Have one for landers, one for “deep space,” and one for atmospheric. That way, you slash the costs of development, since the same pallet for studying the Martian atmosphere can be used for other planets in the system, for example. With the configurable nature of the CEV booster, and the standardization of probe design, you could launch entire floatillas of probes at once. So, for the price of one launch, you could send several landers, atmospheric, and orbital probes to Mars all at once (Ooooh! Data overload!), or you could send a bunch of landers to Mars, a bunch of atmospheric probes to Jupiter, and orbital probes to Neptune (for example).

18

My first recommendation would be to start using off-the-shelf parts whenever possible. For instance, if you’re going to put a window on this thing, use a currently existing design instead of designing something fresh that will need a whole bunch of trial and error at the manufacturing stage. Whenever possible use parts that are the same size instead of using a 2mm hex screw here and a 2.5 mm philips head screw there. When in doubt, use a pencil or a crayon instead of developing a space pen.

Second, let’s up and abandon the ISS. Nobody’s doing anything up there except sitting around talking. Even if it had a full crew there’s no reason to be sitting in a low earth orbit to do namby pamby science experiments. Is the damn thing even in a stable orbit or does it still need the occasional boost to a safe distance?

Third, what are we going to space for? If it’s just to diddle around and maintain an aerospace industry on the public dollar, well, that’s stupid. If it’s to explore and set up humanity in the rest of the solar system, let’s do that. If it’s to mine asteroids, let’s start solar-powered smelters.

19

To obtain orbit, the shuttle must travel considerably faster than SpaceShipOne.

20

Yes, but the capsules used by Apollo/Gemini/Mercury didn’t use ceramic tiles, they used an epoxy resin for their heatshield which burned away as the capsule reentered the atmosphere, so while the formulation that Rutan used probably wouldn’t work for the CEV, the idea of a heatshield which can be rapidly applied, and didn’t necessitate lots of painstaking inspection and repair post-mission is a sound one.