Transterrestrial Musings

Comments

Rand, what would be wrong if you completly removed the orbiter and added a cargo pod and used cheap throw-aways like RS-68's for the main engines?

Isin't the major cost and headache of the shuttle processing and maintaining the orbiters themselves?

Eliminate the orbiters and you eliminate this major expense.

Replace the dead weight of the orbiter with cargo and at a minimun, you cut the $ per pound by a factor of 2 or 3 as you are launching two to three times the useable payload. Even while ignoring the eliminated expenses for orbiter processing.

Besides, this would provide a politically acceptable path to wean NASA of the shuttle albatross.

Locheed Martin and Thiokol would not be out in the cold and Boeing could produce the expendable cargo pod as the RS-68 is their baby.

Posted by Mike Puckett at November 16, 2003 10:52 AM

That's a new launch system.

Posted by Rand Simberg at November 16, 2003 10:56 AM

I'll add that retaining the orbiters for automated use would be assinine as you would have to retain everyone who now supports the orbiters.

I stil say that the orbiter is the albatross, keep the rest.

Posted by Mike Puckett at November 16, 2003 10:57 AM

You would class it as a new launch system?

We would still use the same pads, the VAB, ET's, SRB's and RS-68's we have already developed and paid for for shuttle and EELV uses. New perhaps but 95% of its constituient parts already exist and are paid for.

The political will to retain the shuttle as it has a strong constituency in congress. We need a way to break the stranglehold.

I respectfully disagree on your argumenmts against heavy lift because some structures just cant be scaled down effectivley to smaller launchers. Why limit oursleves to working within the restrictions of a small mold?

I know this is a somewhat simplistic argument(and you will proabally rip me a new one for making it) but look at the cost per habitable sq/ft inside skylab and habitable sq/ft in ISS.

One was launched in an all-up configuration via heavy lift and the ohter was assembled tinker toy style via medium lift and remains unfinished.

Posted by Mike Puckett at November 16, 2003 11:07 AM

We would still use the same pads, the VAB, ET's, SRB's and RS-68's we have already developed and paid for for shuttle and EELV uses.

It's not components that make a launch system--it's integrating them all together into something that actually works. Yes, it's an entirely new launch system, using off-the-shelf parts, to the degree they're applicable (and it's not at all clear that it would be a good one).

And yes, if you have a heavy lifter (as we did during Apollo) it makes sense to lift a station in a single launch (though it's still very high risk, because if the launch fails, you've lost your entire space station).

Given the risk of losing an all-or-nothing payload, it certainly doesn't make any sense to develop a new heavy lifter for the purpose of launching a space station. The money would be much better spent on something that actually significantly reduces the cost of launch (which is almost certainly a small vehicle in the near term).

Posted by Rand Simberg at November 16, 2003 11:20 AM

"...while shuttle derived hardware might best solve the larger cargo needs."

"... shuttle derivatives are a very important part of that..."

"...ways to take advantage of the existing infrastructure."

"The spacecraft was known as Shuttle-C."

" 'It's a whole family of capability based on the reliable shuttle parts...' "

" '...it really means a much more generic look at the pieces that make up the shuttle...' "

It's pretty clear to me that what is referred to in much of the article is a Shuttle-derived vehicle, and not the 'autonomous orbiter' kluge which only appears at the end. Autonomous orbiter is a very bad idea (most of the headaches of the present STS, with little additional cargo capability), but Shuttle-derived has a lot of potential. Even if, as you indicate, it would effectively be a "new" vehicle, there's comparatively little new in it vs. a completely new, blank-sheet design.

I know you don't like OSP, but after the other reasons you've previously articulated, I'm surprised to see you bemoaning here its lack of new technology (your TRL6 reference). Isn't that a good thing? Would it be preferable for NASA to take the Shuttle/X-33 route, throwing in a bunch of unproven technologies that could end up dragging out the project, driving up the costs, and possibly killing it after the money is all spent with nothing to show for it? To my eye, the progressive simplification of the OSP towards a capsule configuration suggests that NASA is increasingly regarding it as a means to an end, rather than an end in itself -- a flexible piece of hardware for supporting other activities instead of The Next Great and Glorious and Heroic NASA Undertaking(tm).

While it would be better still to have such a capability provided by the private sector, if NASA is going to pursue OSP anyway it's encouraging to see them tending towards this means-to-an-end perspective.

Posted by T.L. James at November 16, 2003 11:23 AM

[i]And yes, if you have a heavy lifter (as we did during Apollo) it makes sense to lift a station in a single launch (though it's still very high risk, because if the launch fails, you've lost your entire space station). [/i]

But what is the risk of an actual vehicle loss from such an HLLV shuttle?

Currently, the shuttle has had only [b]one[/b] lauch failure in 113. It could even be designed for at least partial redundancy with an engine out capability from multiple RS-68's.

But apart from that, if you are going to build a station one module at a time, it seems the basic structure of each module should interchange so if you loose a module, you don't stop the entire project untill a replacement is made.

Posted by Mike Puckett at November 16, 2003 11:34 AM

Ok, sue me! UBB code dont work here! How do I italicize and bold things?

Posted by Mike Puckett at November 16, 2003 11:35 AM

Thomas, there's a difference between "Shuttle-derived vehicles" and the more specific case of Shuttle-C, which was really not a new vehicle. It was taking the existing stack and replacing the orbiter with something that appeared like an orbiter to the rest of the stack (in terms of loads, thrust, etc.) It's possible to come up with other (and more useful) Shuttle-derived vehicles that simply use Shuttle components, but that's a much more extensive new development. It's not at all clear from this article what they're referring to here--the whole thing is pretty incoherent.

And I'm not "bemoaning" the fact that OSP has little new technology. I'm just pointing out that Mr. Martin doesn't seem to know what he's talking about, but Mr. Banke just stenographs it without comment. Of course, I guess he doesn't want to dry up his sources...

What I bemoan is that something with "little new technology" is going to cost in excess of ten billion dollars to get us back to where we were forty years ago, with zero prospects for affordable human launch capability.

Posted by Rand Simberg at November 16, 2003 11:45 AM

Nobody knows what the risk of a launch is from a new vehicle. One of the problems with low flight rates is high cost per flight, but the other one is low reliability, because we don't fly the thing enough to get any kind of statistical understanding of it, and develop routine, smooth operations.

As for building space stations, you plan to build enough of them that you have extra components in the pipeline. As I've said many times, if we're not serious enough about space to start doing enough of it to get costs down and reliability up, then we should quit wasting the money on it.

And you use HTML tags (i.e., enclose in angle brackets, not square ones).

Posted by Rand Simberg at November 16, 2003 11:50 AM

Ok Rand, don't pull out any more hair, but I need to be a critic here...

I was somewhat surprized at Mike's comment that you are 'against heavy lift.' I thought what you were against was the cronyism that makes our space program a pork barrel rather than finding a cost effective way to utilize space (and opening it up to the average citizen.)

I'm pretty sure we disagree about the use of expendables. I'm a big dumb booster fan with recover of just the main engines... Skylab is unimpeachable evidence it costs less with this approach. While assembly and eventually manufacturing in space are certainly in our future, doing it in shirt-sleeves in the gravity well are orders of magnitude cheaper.

We do have an opportunity here to break the grip of the ol' boys network, but it has to be done with an understanding of the political realities.

The old boys are going to be part of the show, not accepting that fact just marginalizes any other viewpoint.

Right now the old boys are vulnerable for lack of vision. So what visions can the alternative crowd (that'd be us) offer?

Posted by ken anthony at November 16, 2003 12:17 PM

I'm against heavy lift in the sense that I wouldn't spend a dime of my own money on it right now, whether done privately or publicly. As I said in my interview with Phil Bowermaster, we built little airplanes, and figured out how to do useful things with them long before we built 747s. There was a reason for that.

Posted by Rand Simberg at November 16, 2003 12:28 PM

So, if for example, the President announces a return to the moon (known as RTTM forevermore) you feel that heavy variants of the delta 4 and atlas 5 would be more practical?

My support of a true HLLV variant derived from shuttle and EELV tech is two fold.

1) Large bulky payloads.

2) A politically acceptable off ramp to kill the black hole that is the shuttle orbiter while offering more capability.

It has long been my understanding that the reason the STS was so damn expensive was the large number of people employed in its operation and that well more than half of them were involved in orbiter and orbiter support functions.

If that is correct, removing the orbiter could save billions of dollars per year and give us a much more cost effective way of launching large payloads.

Posted by Mike Puckett at November 16, 2003 12:40 PM

Yes, heavy EELVs would be much more cost effective than any Shuttle-derived system. The orbiter isn't the only problem. The SRBs are a nightmare as well, and EELV tankage is less costly than the ET. And once you decide that you're not going to use the SSMEs, and go to a different engine type, then you've got a new vehicle design, so why not go with a modern one?

But in fact, it's probably even cheaper to go to the moon with existing vehicles--no need for a heavy lifter, as long as you're not trying to do it "by the end of the decade." We could have done it with Titans in the sixties--we just couldn't have beaten the Russians that way.

Posted by Rand Simberg at November 16, 2003 12:53 PM

Now I really am surprize, being against heavy lift means being against any of the capabilities it provides... including reducing cost for certain missions.

I also think your 747 analogy fails because we already have Jumbos as well as having had Saturn V's. While valuable things can be learned at any scale, how does this preclude building and learning to cheaply produce something that gives us added capability?

Believe me Rand, if I could stop the government from taking your dimes (other than for the common national defense) I'd be all for it. But your dimes, like mine, are being spent whether you like it or not.

Large structures to Earth orbit and beyond, cry out for heavy lift. Now you're going to tell me you're against large structures (then I'll know that Transterrestrial is a misnomer and I'll be devastated! ;-) )

Posted by ken anthony at November 16, 2003 02:13 PM

Now I really am surprize, being against heavy lift means being against any of the capabilities it provides... including reducing cost for certain missions.

You assume without basis that it reduces cost for some missions (at least, relative to some other way of doing it). You have to account for development cost in any such assumption.

I also think your 747 analogy fails because we already have Jumbos as well as having had Saturn V's.

We had Saturn Vs because they enabled us to beat the Soviets to the moon, not because they allowed us to do so cheaply.

While valuable things can be learned at any scale, how does this preclude building and learning to cheaply produce something that gives us added capability?

It's much cheaper and easier to develop and learn to operate little vehicles than it is big ones.

Large structures to Earth orbit and beyond, cry out for heavy lift.

That's an opinion, not a fact.

What they cry out for is affordable lift, which is something that we are not going to get from large expendable boosters at any currently-planned scales of operation.

Posted by Rand Simberg at November 16, 2003 03:14 PM

"You assume without basis" I have a basis... Skylab.

"You have to account for development cost."

Actually, I don't think I do. Any system is going to have fixed development costs, unless you're arguing for no system at all, but unless we do it like NASA does...develop then throw away... the variable operation costs are the ones to be paying attention to.

"We had Saturn Vs because..." we had to have the heavy lift capability to send Apollo regardless of beating the Russians. Each mission had a launch vehicle that was scaled up for the needs of the mission.

"not because they allowed us to do so cheaply."

Imagine no shuttle and no ISS, instead we just refine the Saturn. Now, tell me Saturn V's could not have been developed into a cheap way to put tons of material into space. What were the $/mass cost vs. the shuttle anyway?

"It's much cheaper and easier to develop and learn to operate little vehicles than it is big ones." Development costs would certainly be cheaper, I agree. However, you sacrifice capability and it cost more for certain missions... did I mention Skylab?

...cry out for heavy lift. "That's an opinion, not a fact." An opinion strongly supported by the facts.

"What they cry out for is affordable lift, which is something that we are not going to get from large expendable boosters at any currently-planned scales of operation."

Yeah, I'd like to see scaled up the operations too! ;-)

I'm probably becoming tedious here Rand, if so please forgive me.

Posted by ken anthony at November 16, 2003 05:32 PM

But Rand, he meant well. And you're criticising him. So he's right and you're wrong.

Posted by Andy Freeman at November 16, 2003 05:39 PM

Ken, while it cost a lot less than ISS, Skylab wasn't cheap, so as I said, you have no basis.

And yes, I'll cheerfully and truthfully tell you that Saturns couldn't have been refined to be low-cost. You may fantasize about it all you like, but it doesn't make it reality.

They would have been cheaper than Shuttle, and we'd have been better off had we stuck with them, but that's damning them with faint praise. Neither Saturns, or Shuttles, or Shuttle-derived vehicles, or Orbital Space Plane are going to open up space. NASA has no plans to do so, and shows no signs of interest in developing any.

Posted by Rand Simberg at November 16, 2003 05:56 PM

We could have done it with Titans in the sixties--we just couldn't have beaten the Russians that way.

It sure seemed that way at the time, but given the massive problems the N-1 had, do you really think they would've beat us?

Posted by Rick C at November 16, 2003 06:43 PM

Whether it was actually necessary or not, we thought it was, which was all that mattered at the time in terms of the decision.

Posted by Rand Simberg at November 16, 2003 07:28 PM

There's really only one justification for flying Shuttle--as a means of getting crew to and from space.

The other reason is that all the ISS modules were designed to be flown on the shuttle. So we are left with a circular justification for the Shuttle. The Shuttle is needed to carry hardware and crew to the ISS, and the ISS is needed so the Shuttle has someplace to take hardware and crew.

I say scrap both the ISS and the Shuttle and use the money to design and build

small, cheap launchers with high flight rates

as Rand proposes.

Posted by Rocket Man at November 16, 2003 10:35 PM

IOW, "a rocket a day keeps high costs away"
DoD operationally responsive small launcher program, dubbed "falcon" ( not to be confused with SpaceX Falcon ) has much higher importance o cheaper space launch than all shuttle-derived nightmares together.
If you can build a rocket in a day, its friggin inevitably cheap.

Posted by at November 17, 2003 03:47 AM

Rocket Man: "scrap both the ISS and the Shuttle"

Watch it, RM, someone might accuse ya of being a NASA man... isn't that just what they do? Spend money, then throw away the result? Which makes sense from their point of view since it's just a jobs program for their cronies?

I'm told the main shuttle engines are the most efficient (not the most powerful which may be the F1) chemical engines ever developed. If that's not just propaganda, then doesn't it make sense to use those engines in the future even without a shuttle? Looking forward to hearing the response.

Posted by ken anthony at November 17, 2003 12:22 PM

There are many other measures of effectiveness than efficiency (whatever you think that means--I suspect that you mean highest thrust to weight and specific impulse). From an operability and cost standpoint, SSMEs are a disaster.

Posted by Rand Simberg at November 17, 2003 12:26 PM

I'll just point out that there are two interesting articles in the most recent JBIS that discuss the issue of dozens of small payloads vs. one big one.

The argument is pretty simple, there's a fair amount of extra upmass associated with the hardware for mating dozens of little pieces into a space station. There's also the additional manpower and extra launches to consider. At some point you reach a crossover where it's cheaper to pay to develop the heavy lifter and put it all up at once. Obviously this wasn't taken into serious consideration when the space station project was started.

I'll add that the 'eggs-in-one-basket' risk has to be weighed against the 18 or so flights doing things piecemeal + the EVA risks associated with on-orbit assembly. Personally, I'd rather take a single 5% risk of something bad happening to cargo rather than 18 tries at the 2% chance of something bad happening to cargo AND crew.

- Eric.

Posted by Eric S. at November 17, 2003 06:44 PM

Obviously this wasn't taken into serious consideration when the space station project was started.

When the space station program was started, a Shuttle-derived launcher made a lot of sense, and would have given us much more station for much less life-cycle cost, a la Skylab.

But that was then, and this is now. If we want to get serious about space, we need to learn how to operate and build things in that environment, and we need to bring the unit cost of access to it way down. That's not going to happen with large expendable boosters.

Posted by Rand Simberg at November 17, 2003 09:21 PM

As much as I like flying around in light aircraft, a 747 is analogous to a heavy lift vehicle (even being designated as such by ATCS because of the need for special handling with regard to it's affects on surrounding traffic.) Although you can imagine larger aircraft, these already pretty much strain the limits of what you want coming off a runway. But apparently they make economic sense because airlines continue to buy them. I understand you disagree, but big dumb boosters really could bring unit costs down more than numerous lighter alternatives even though I agree that quicker turnaround would improve cost efficiency (or would in a competitive environment.) More important is that there are some things you just can't do without heavy lift.

To your other point... Of course we need to learn how to build things, but how does a Skylab (or Mir) approach prevent that? We could go the to the other extreme and just provide the equivalent of a box of legos for the astronauts to assemble, but we don't do that. I don't understand how you can argue that larger assembly's have a greater unit cost when clearly the opposite has definitively been shown historically to be true? Which is not to say that improvements are not possible.

Posted by ken anthony at November 18, 2003 07:50 AM

Ken,

The ISS is an example of a Sunk Cost (Costs that are irrevocable and should not be used to influence current decisions.) It doesn’t matter how much money has already been spent on the ISS, what matters is how useful it is to accomplishing current and future objectives. In my opinion, the ISS accomplishes next to nothing and the money spent maintaining it (and the Shuttle that services it) would be better spent on unmanned planetary probes and on building a useful replacement to the Shuttle.

As to the SSME, Rand answered that question much more succinctly than I could.

Posted by Rocket Man Blog at November 18, 2003 09:13 AM

You're absolutely right, RM, and I fully agree with your paranthetical definition. We shouldn't throw good money after bad with regard to the ISS Albatros. I think I made the point somewhere else that the people within NASA that sold us this turd were essentially lying to the public and the way to prove my assertion wrong would be to put up another Soyuz, fully staff the thing and show some results. Not much chance of that happening right?

I don't claim to know anything about shuttle engines other than your basic high school F=MA and whatever I may have read. My point is, and I think this is part of the NASA mentality problem also, is that better is often the enemy of good enough. Smarter guys than I can determine if developing new chemical engines would provide sufficient performance enhancement to justify abandoning what we've already paid for. I have no doubt that better solutions not only exist but will be developed.

I think Project Prometheus or something with the same goals (as I understand them) may open the door in the long term (although Rand got me excited about the solar sail concept.)

I believe that Zubrins Mars direct concept makes more sense than anything I heard from any other source (although the Mars Society camp-out club seems a bit misdirected to me.)

I believe government derives it's rights from the governed and while property rights (not IP, but real dirt) are being assailed from all directions, the possibility of establishing private ownership of extra-terrestrial real estate makes the most financially sound arguments for the development of space.

I like reading about what X-Cor, Armadillo and the rest are doing, but I think the guy that comes up with a practical asteroid mining tug is the company that's going to reap the benefits that we've all been dreaming about since 'Have Spacesuit will Travel' and similar youthful amusements.

Grok that?

Posted by ken anthony at November 18, 2003 12:40 PM

I would agree with you Ken that NASA often views the better as the enemy of the good and also that they mislead the public with their sales pitch for the ISS.

However, if the Shuttle and the ISS were abandoned by NASA, we would still have all the launchers we need. The Atlas V, Delta IV, Ariane V, Proton, etc. can launch any desired satellites or planetary probes, so we would wouldn't need another launch vehicle (much less a man rated one) that might use the SSME unless there was a plan to send people beyond LEO.

Zubrins Mars Direct plan and others are out there, but the best way to implement one of them will probably be with a new vehicle that does not use the SSME.

Posted by Rocket Man Blog at November 18, 2003 01:32 PM

Ok, RM, I don't want to lose your main point that we've wasted enough money on the shuttle and ISS and shouldn't waste any more. I think it's a good and important point and if they gave me the switch to turn the thing off I could flip it.

Yes, the systems you mentioned would do the jobs you mentioned. I guess I only hesitate to fully support what you say because I see other jobs to be done which these systems can not support.

I don't know what the point of going back to the Moon might be other than perhaps some farside project which may be easier to do in other ways, or some kind of resort for those willing to pay for it.

Eventually we will reach the point where living in free space makes sense but that time has not yet come.

What I see right now is a rich world full of resources that we can get to with current technology that will get our eggs out of this one basket we are all living in. We are stagnating because of lack of viable frontiers. It is almost as long from Kitty Hawk to the 'one small step for man' as it is from the Moon landing to today. It is amazing to me that the human spirit would allow this and I truly believe we need to do something to break the logjam that has that spirit bottled up today.

Call me a Mars nut (actually I'm just a plain old vanilla nut, but Mars will be my passion until we start to show some results.) We have the chance to do something today that humanity has only dreamed about until now. We can colonize a new world. Not collect samples... not plant a flag... colonize! Start a new branch of humanity.

America has been a human experiment with pretty good results from my perspective. Settling Mars could potentially be much more so.

Rands dream of cheap, fast turnaround systems could be what really fuels the next 'land rush' (we are going to have to coin a new term for that concept.) But I think the natural, two year launch window for Mars sets a pace that will result in a sustainable program. I think the three day jaunt that it takes getting to the Moon is actually a liability for any sustainable program. When something is too easy (relatively) to do, it's just as easy to abandon.

Some have argued we shouldn't go to Mars because it would be on their dime and they don't want to pay. That would be a good argument except for the fact that they are already paying, but with no result. I would rather see the small amount (relative to the entire space budget) that is required be used for a program that will finally get us permanently committed to living off this planet.

And so, RM, I take exception to the idea that we already have all the rockets we need because we don't have the HL rocket that could take a small group of people away from the Earth. Until we get it, the Earth is all we will ever have (I may be wrong, but you can't prove it with the facts of today.)

Posted by ken anthony at November 19, 2003 07:19 AM

About all I can think of that would fit in the heavy-lift STS-derived area would be a dry external tank strapped to a fuelled one, with the old aft cargo carrier design in the nadir of the dry ET. the ACC would carry the main engines, and both tanks would go to orbit. The dry ET could carry roughly 90 tons of cargo and atmosphere to orbit. Basically Skylab writ large, each ET 150 feet long and 28 feet in diameter. That's a lot of habitable volume, and only 8 such launches are necessary to build something like the space island. http://www.spaceislandgroup.com

Posted by ed minchau at November 19, 2003 11:40 AM

I strongly agree with you Ken that the next logical step is to send people to Mars. But until such time as a decision is made to actually go to Mars and a plan on how to best get there is put together, we have no need for any more launch vehicles than the ones currently available.

After a plan is in place, we will definitely need a man rated launcher eventually, but keeping the Shuttle around while we put together a manned Mars mission is a waste of money. As for the vehicle that will be used to carry the cargo into orbit for such a mission, there are arguments that can be made for a few heavy lifter launches or many small launches as Rand did in his post, or we could just use existing expendable rockets. The bottom line is that without a plan in place, the best way to proceed is not clear enough to start development of any new launch vehicle.

The last thing I want to see is another vehicle developed that in the end does not perform any useful function.

Posted by Rocket Man at November 19, 2003 04:22 PM

You da man! The Rocket Man! When you put it that way, how can I do anything but agree?

I keep thinking that Mars Direct is a plan, but having worked with some planning engineers when I was with the FAA (and seeing how slow these things move) you are probably refering to what I would call an institutional plan (the type of thing that drives entrepenuers nuts, but civil servant types seem to require.)

Of course, then those civil servants procede to modify the basic plan into something unrecognizable and more importantly, unworkable.

I wish I knew how to get there from here (to the workable plan that is) but frankly, I don't have a clue. I suspect that others do and can and will while I wait and rant and annoy as little as I possibly can while being wildly enthusiastic about what may come.

I'd even pay Rand's dimes if he'd lose a little gravity well snobbery (tweek!) ;-) I mean, it's Mars, not Jupiter... it's sort of like the Moon only it put on a few pounds over the holidays... and has lot's of gifts to share, all wrapped up and waiting for us...

Posted by ken anthony at November 19, 2003 07:00 PM

ken anthony wrote:
>Ok, RM, I don't want to lose your main point
>that we've wasted enough money on the shuttle
>and ISS and shouldn't waste any more.

Congress itself was never interested in anything beyond the Shuttle. They have consistantly NOT funded any type of replacement.
The ONE thing they did insist on, (the X-33) was a dismall failure. They mandated that NASA would act as a sub-contractor, (and provide the funding) for the project while Lockheed/Martin (because everyone knows that 'private' companies can do these things better than NASA :o)would manage and direct the project.
Once LM found they couldn't do the light-weight composite tanks that they had designed the X-33/V* around, they dithered the project (and funds) away unit NASA took over.. in time to cancel the project.

Congress is already putting NASA, (and everyone else) on notice that they are 'iffy' about OSP. Asking for further reviews and studies before NASA (actually Congress) would commit funds.

With the axeing of the 122million dollars allocated for ISS operations and expansion from next years budget, they are basically telling everyone that the ISS is now complete. With their consistant foot-dragging over a replacment vehicle for manned flight, they are also posting notice that in all likely hood we can look forward to depending on the Shuttle to get crews and equipment to the ISS. Unit the NEXT accident, at which time we can probably look at the ISS being abandoned, (if not sooner) and endless studies for 'access to orbit' vehicles. Along with various 'upgrades' to existing expendables, to keep the manufactureres in business.

There is really no motivation for the major aerospace companies to produce cheaper access to orbit. Especially for manned access.

On the converse side of course, the start up companies, (such as Kistler, XCor, Rutan, etc.) as well as the Japanese aerospace agency, are at least doing what probably SHOULD have been done from the begining. Step by step, upscalling and expanding as the demand, and market, allow.
(Considering that the Japanese are having success with THEIR composite cryogenic tanks, I have to wonder what LMs problem was. As far as I can find all the incident reports say the same thing. The MAIN cause of the failure of the tank was the wrong choice of inner material for the tanks. Simple really. Maybe we should just look to buy tanks from the Japanese :o)

As for the SSME, we don't need it for a heavy lift launcher. We currently have a production "F1" class rp-1/Lox engine that Rocketdyne put together. 1.2 million pounds of thrust per engine. They are also putting the finishing touches on the RS-38, a Lox/LH2 design engine that (they claim) will be simpler and cheaper to operate.
Couple one of these engine types, a modified ET, and the proposed Paraffin hybrid motors and though we have something that LOOKS like a Shuttle stack, but isn't. And without the orbiter. (the most costly part of the system)

ed minchau wrote:
>About all I can think of that would fit in the
>heavy-lift STS-derived area would be a dry
>external tank strapped to a fuelled one..

Think, more accuratly, a constructed cargo canister, or a large scale space industry/living habitat. (aka the Russian Shuttle launch vehicle who's name escapes me at the moment :o)

Just an aside:
>The dry ET could carry roughly 90 tons of cargo
>and atmosphere to orbit. Basically Skylab writ
>large, each ET 150 feet long and 28 feet in
>diameter. That's a lot of habitable volume, and
>only 8 such launches are necessary to build
>something like the space island.

Despite the various 'plans' to turn ETs into orbital real-estate, I've YET to see a plan that actually takes into account the massive amount of EVA work that would be neccessary to turn the space into anything approching habitable space. EVA is NOT cheap, nor easy, nor even all that safe. (Lets face it folks, current and most projected suits suck to work in for any length of time :o)
I should also mention that the ETs are pretty thin skin and would not be the safest place to spend the night.
(Can you say mobile, {not manufactured or modular} home in a hurricane? :o)

The BEST bet would be actuall modules designed from the start to be easy to inhabit and easily changed to meet changing on-orbit needs without extensive vacuum work. Transhab comes to mind.

Randy

Posted by Randy Campbell at November 21, 2003 02:45 PM

But you could pre-configure the dry ET. EVA's would be largely/completly unnecessary.

Posted by at November 21, 2003 07:04 PM

(someone :o) said:
>But you could pre-configure the dry ET.
>EVA's would be largely/completly unnecessary

Your speaking of course of the Duel-ET to orbit launcher idea?
>http://www.spaceislandgroup.com/dual-launch.html

While the 'dry' ET idea is almost as good as something like a TransHab, it's like comparing a tin-shed to a modular home.
As I understand it, the skin on the ETs is not all that thick, which leads to pressurization issues as well as sheilding and thermal issues. (The high density foam used currently does not take to long term exposure to vacuum well from what I've read)

In any case it's not the DRY ET I'm talking about, but the 'wet' ET. And though the pictures look nice and the idea has promise, your still stuck 'converting' your wet ET.
And again, the article seems to 'toss-off' the work and manufacturing needed to redesign/rebuild the "ET's lower end and elsewhere will be redesigned to handle these new loads, and wall thickness in other area may be increased to improve radiation or micro-meteor protection on orbit" which will also cut into your fuel and payload mass.

And your talking quite a bit with hatches pre-cut into the tanks and strengthening the interstage between the Lox tank and the LH2 tank. I've also noticed that in almost the pictures the tanks are still in one piece so your looking at a transfer tunnel between the tanks also.

And also a lot of man-hours re-working the wet ETs. I'm not saying it can't be done, it obviously can. The question though would be, is it worth the cost?
Would it not be simpler to keep the ETs for future uses, and simply put cargo pods, and habitat sections as payloads?

(I can see the ETs as fuel storage, boosters, and maybe other types of storage, but fitting them out as habitat space seems a bit tough for 'starting out' at something.)

While I applaud the idea of Island One, I think focusing on the idea of conversion for the ETs as neccessary, (which they do) is probably NOT the way to go. While a nice-to-do-if-you-can-afford-it-and-it-isn't-a-man-hour-sink idea, the truth is that the SpaceHab folks already designed a very useful piece of equipment for the purpose of private operations in space, and premisising the plan for Island One on extensive on-orbit conversions of ETs is probably a non-starter.

Just my opinion of course... :o)

Randy

Posted by Randy Campbell at November 24, 2003 02:00 PM

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