Transterrestrial Musings

Comments

Zubrin has always been a poor public speaker and I'm surprised that he has gotten as far as he has. He has numerous speaking habits that really undercut his message. For instance, he rarely looks right at his audience, always glancing down at the ground. He moves around too much, and he says things like "'kay" at the end of every sentence. The latter is a psychological thing that implies that he thinks that there is no room for disagreeing with him. I haven't met him personally, but he comes across as a guy who would be really difficult to have a mature discussion with, because he's not tolerant of anyone who does not share his zeal for Mars.

Posted by William Berger at October 24, 2005 08:48 AM

Well, despite his verbal ticks, Bob can be quite articulate (though often articulately wrong), and many find him charismatic (and I'm speaking as someone who was engaged in a smaller meeting with him yesterday).

Posted by Rand Simberg at October 24, 2005 09:14 AM

Maybe some should send NASA a stern wake up call by sending a Bigelow hab to EML-1 along with a re-useable EML-1 to Luna landing module.

Then access EML-1 via t/Space (or Soyuz).

Posted by Bill White at October 24, 2005 10:57 AM

Maybe "charismatic" is a good word--I seem to remember that it has a religious connotation as well (i.e. it can be used to describe a particular type of zealot).

But what I wonder is if Zubrin can appeal to anybody who is not already inclined to believe his ideas in the first place. In other words, can he actually expand his base? Or is he simply preaching to the converted?

Many years ago I read an account of him at one of his first Mars conferences where some woman had been insulted (somebody essentially called her a prostitute) and Zubrin made a concerted effort to apologise to her. So he is obviously not completely oblivious. But I've always thought that he is not very eloquent or inspiring in his talks. He sort of belts everything out like a televangelist.

Posted by William Berger at October 24, 2005 11:57 AM

Lindsey wrote:

"The ISS construction went so badly because it depended on a single vehicle. If there had been two or three different types of vehicles available to deliver the modules, construction would have been finished long ago."

ISS actually uses shuttle, Proton and Progress for construction (Soyuz too if you include the fact that some consumables are delivered by Soyuz).

I assume that what he really means is that "not enough" different vehicles were used in construction and they should have added more--presumably Ariane 5 (not exactly reliable) and Titan IV when ISS construction started (expensive and not exactly reliable) and later EELV.

But although that may add theoretical robustness, it also adds complexity. It requires things like zero-gee refueling that has not been demonstrated yet and has to be proven as a first step, preferably before you start building lots of hardware that depends upon it.

And does this approach _really_ add robustness to the lunar architecture? There is a lot of sense to the argument that if you blow up an HLLV it takes out a big chunk of hardware at massive cost and cripples your plans. But there seems to be a good argument that this is true for a multi-launch option as well. Blow up a lunar lander on an EELV and you've just lost a key piece of hardware. Blow up a fuel tanker on an EELV and you have just lost a less important piece of hardware. But unless you have a lot of spares, and unless you are willing to launch them before conducting a full accident investigation, then you may have a lot of hardware in orbit, decaying, awaiting the conclusion of the accident investigation and the next launch. (And if you don't have spares, then all that hardware decays in orbit while you build a spare. How long does that take?)

Posted by William Berger at October 24, 2005 12:27 PM

William is right on pointing out what those people fixated on EELVs refuse to face. If we split up a lunar ship between three, five, nine or whatever number of EELVs (I keep seeing differnt numbers), then the loss of any one of them will likely scrub the lunar mission just as surely as the lost of a heavy lifter.

Posted by Mark R. Whittington at October 24, 2005 12:52 PM

It requires things like zero-gee refueling that has not been demonstrated yet

Actually, it has, though not for cryos. The Soviets demonstrated it for storables in the eighties.

...unless you have a lot of spares, and unless you are willing to launch them before conducting a full accident investigation...

It would be quite foolish not to have spares (which doesn't imply, of course that NASA might not do that), and part of the idea of multiple launches is that you'll have multiple vehicle types as well, and enough activity that we can have a good idea of vehicle reliability, and avoid the need for complete standdowns in the event of failures.

Posted by Rand Simberg at October 24, 2005 01:16 PM

...the loss of any one of them will likely scrub the lunar mission just as surely as the lost of a heavy lifter.

Nope. It would merely delay it, and the hardware lost would only be the hardware for that flight, rather than the entire stack. In addition, the most likely failure would be for a propellant flight, which is, in relative terms, a cost-free payload, for which spares are available in abundance.

Posted by Rand Simberg at October 24, 2005 01:18 PM

So, Rand, are you saying that given the time it usually takes to conduct an accident investigation, not to mention fix whatever caused the accident, that a lunar mission, using EELVs, with the loss of a critical component on an EELV, could still proceed? Count me as a bit dubious.

Posted by Mark R. Whittington at October 24, 2005 01:32 PM

...are you saying that given the time it usually takes to conduct an accident investigation, not to mention fix whatever caused the accident, that a lunar mission, using EELVs, with the loss of a critical component on an EELV, could still proceed?

Yes, I am saying exactly that. It's a feature of a resilient (as opposed to a brittle, which is what NASA is proposing) launch architecture. If we lose a lunar lander due to an Atlas launch failure, or if we lose a load of propellant on a Falcon launch, then we can put a spare on up on a Delta, while we wait for the Atlas or Falcon launch investigation to be completed (assuming that it isn't obvious what went wrong, and that we can't fix the problem quickly). With a resilient and diverse architecture, launch investigations aren't on the critical path to mission success.

Posted by Rand Simberg at October 24, 2005 02:12 PM

Mark,

I tend to slightly leant to the HLV side of the equation but if I might be so bold as to speak for Rand, I think what he is arguing is that if you have a flight failure with a brand x EELV class launcher, you would switch over to a brand Y EELV until the accidend review board resolves the issue.

If the payloads conform to a modular interface type of archetecture, then switching payloads over to a different launcher of the same class would be relatively easy.

Much in the same way the Pentagon uses the ability to switch national security payloads from one EELV to another as justification for retaining both the Atlas and the Delta EELV programs.

Posted by Mike Puckett at October 24, 2005 02:15 PM

D'oh! Rand beat me to it!

Posted by Mike Puckett at October 24, 2005 02:16 PM

> This heavy-lift issue is one that needs a vigorous, informed (and civil)
> public debate, since it's not at all clear that it ever received one in
> the workings of the exploration team at NASA.

In fact, it clearly wasn't -- one of the ground rules for the study was that a lunar mission must require no more than two launches.

Posted by Edward Wright at October 24, 2005 02:16 PM

> So, Rand, are you saying that given the time it usually takes to conduct
> an accident investigation, not to mention fix whatever caused the accident,
> that a lunar mission, using EELVs, with the loss of a critical component
> on an EELV, could still proceed? Count me as a bit dubious.

So, how does JSC manage to survive? It depends on thousands of commercial airline flights -- isn't that a terrible risk? Can JSC survive if even one of those airliners fails, causing the loss of a critical component? If one airliner crashed, wouldn't every airliner in the world be grounded for years?

Wouldn't it be better to replace commercial airliners with a National Heavy Lift Air Transportation System that can carry 10,000 JSC employees and thousands of tons of cargo, so that JSC only needs to "risk" one or two flights a year?

Posted by Edward Wright at October 24, 2005 02:48 PM

"Yes, I am saying exactly that. It's a feature of a resilient (as opposed to a brittle, which is what NASA is proposing) launch architecture. If we lose a lunar lander due to an Atlas launch failure, or if we lose a load of propellant on a Falcon launch, then we can put a spare on up on a Delta, while we wait for the Atlas or Falcon launch investigation to be completed (assuming that it isn't obvious what went wrong, and that we can't fix the problem quickly). With a resilient and diverse architecture, launch investigations aren't on the critical path to mission success."

It is worth noting that this is _not_ the way it works for commercial satellite launches, at least not as quickly as it would have to happen according to this theory. Blow up a commercial comsat and replacements are never available on the ground in a short turnaround time, even though the capitalist clock is ticking. Replacements usually only fly years later.

And suppose that all that you blow up is a propellant flight, and you have a spare. Do you also have a spare rocket ready to go in a very short time? If so, then it starts to look like an awfully expensive infrastructure, with spare components and spare rockets sitting all over the place to cover the eventuality. And the government is going to have to _pay_ for that spare to be available, because the launch provider is not going to build one just because it might get used (that's not the way that they do things now).

And really what you are going to need is _several_ spare rockets available of several types. Let's assume that using foreign rockets to launch American payloads is a non-option. Let's assume that your stable of rockets includes Atlas, Delta, and Falcon. Presumably, you're going to have multiple launches going on very short notice, so a bunch of rockets will be in the queue for a quick launch.

Now suppose that you need nine launches in short succession, and suppose that you have split these evenly among the three available boosters. What happens if your first Delta blows up? You cannot use the remaining two Deltas because they are grounded during the accident investigation. So you need two _additional_ rockets as spares. And because you cannot predict which rocket could suddenly become a problem, you need to cover all your bets. So conservatively speaking, for each nine-spacecraft mission, you need 12 rockets available, all in processing (four Deltas, four Atlases and four Falcons).

And it is probably more complicated than that. Nobody has quite gotten to perfect plug-and-play operations for even very common payloads, such as commercial comsats--it requires a little bit of work to pull one off of an Ariane and stick it on a Delta. (Probably a lot less work than in the past, but still some effort.) We can assume that the propellant vehicles will all be identical and could be qualified for all three rockets. Can we assume that for specialty hardware? Does the lunar lander need to be rated to fly on three different rockets with different acceleration loads and accoustic environments, etc? Or do you optimise some of the most complicated hardware for only one rocket type? And if so, what if that type gets grounded?

Spare lunar landers? Those things tend to be expensive. And before someone says "Ah, but they don't _have_ to be expensive," we will point out that they were the most sophisticated part of Apollo and required the most work and effort. Unless someone can demonstrate how to build a Dumb Lunar Lander on the cheap, the default position will be that lunar landers are probably the most expensive single piece of equipment that will have to be built.

Another thought: to date, rendezvous and docking ops have been relatively slow-paced events, with them happening rarely and over a period of days (for instance, shuttle arriving at ISS and attaching a large module). This multi-launch approach completely changes that, requiring multiple rendezvous over a relatively short period of time. I don't know if that is extremely difficult, but it has not been done yet.

Plus, as somebody pointed out (I forgets who), attaching 8 pieces of equipment together instead of 2 pieces means bringing 8 sets of docking collars and other related equipment along instead of just 2. So there is some weight penalty.

I have never seen anybody put together a list of the pros and cons of these two radically different approaches. It seems like the whole debate is polarized, with each side calling the other stupid or unreasonable, without acknowledging the different strengths and weaknesses of the different approaches. The HLLV crowd seems to say that multiple launches are nearly impossible, whereas the multiple launch crowd seems to say that they're easy. Objectivity seems to be a position that nobody is interested in taking.

Posted by William Berger at October 24, 2005 03:08 PM

Berger wrote:
"ISS actually uses shuttle, Proton and Progress for construction (Soyuz too if you include the fact that some consumables are delivered by Soyuz)."

Most of the modules have to be launched on the Shuttle. Griffin would stop the Shuttle program now if there were an alternative for launching the remaining ISS modules. Modifying the modules to fly on an Ariane 5 or a Russian vehicle is apparently too expensive technically and/or too complicated politically.

The availability of the Soyuz (and soon the Ariane 5 for the ATV) for delivering crew/cargo illustrates the advantages of having multiple types of launchers. The ISS would be in the ocean now if it had depended only on the Shuttle.

Posted by Clark at October 24, 2005 03:43 PM

Lousy analogy. Each comsat has its own customer who generally has only one satellite and they can't afford to self insure (which would double their satellite costs) so they carry launch and payload insurance. All of the VSE launches would be owned by a single customer who self insured. There would be multiple missions planned, so it would make sense to have adequate spares on hand (they'd simply be producing one or two items ahead of planned schedule).

As for compatability between launch vehicles, if the customer wants it, they'll have it. No one has previously demanded it, for the reasons stated above.

This multi-launch approach completely changes that, requiring multiple rendezvous over a relatively short period of time.

Not really. Buildup for an individual mission could occur over a period of months, and it wouldn't occur until all the pieces needed (including adequate propellant) were in orbit. Contrary to what Bob Zubrin was shouting on Friday, propellants can be stored indefinitely on orbit, given good insulation and refrigeration in a depot.

I have never seen anybody put together a list of the pros and cons of these two radically different approaches.

Actually, this trade has been described, and performed, many times over the years in various studies. However, that was then, and this is now, and it does indeed need to be reperformed again. It in fact was by the CE&R contractors over the last year, but NASA chose to completely ignore the results of those studies, since Griffin seems to have decided a priori that everything Steidle did was worthless.

It seems like the whole debate is polarized, with each side calling the other stupid or unreasonable, without acknowledging the different strengths and weaknesses of the different approaches. The HLLV crowd seems to say that multiple launches are nearly impossible, whereas the multiple launch crowd seems to say that they're easy.

The multiple-launch crowd claims that they're doable, and desirable. In addition to the resiliency issues, learning how to do things modularly, and refuel on orbit are essential skills to becoming a spacefaring nation. The sooner that we learn how to do this, the sooner we will achieve that status. If we believe that we must always have a vehicle large enough to deploy the entire mission, then when we decide to do a Mars mission, NASA will have to go back to Congress and ask for money for a larger heavy lifter. Why not just learn how to make do with what we have now, so we'll have adequate flexibility into the indefinite future?

Posted by Rand Simberg at October 24, 2005 03:52 PM

> Spare lunar landers? Those things tend to be expensive. And before someone says "Ah, but they don't _have_
> to be expensive," we will point out that they were the most sophisticated part of Apollo and required the
> most work and effort. Unless someone can demonstrate how to build a Dumb Lunar Lander on the cheap,
> the default position will be that lunar landers are probably the most expensive single piece of equipment
> that will have to be built.

Your "default position" is otherwise known as reasoning from a single data point. Adhering to your "default position" makes sense only if your goal is to keep costs at the Apollo level forever. If you keep doing what you've always done, the same way you've always done it, you'll keep getting the same results.

If your "default position" is correct, then it will never be possible for humans to visit the Moon except for brief times as exepsnvie political stunts. If that's the case, why bother at all?

On the other hand, if you try a different approach, you just might find costs going down over time, as they have for all other forms of transportation.

The delta-vee for a suborbital vehicle is approximately the same as the delta-vee for a lunar lander. Subotbital vehicles like SpaceShip One show that propulsion systems with the required delta-vee can be built for a fraction of the cost of the Apollo LM hardware, as can life-support, etc. SpaceShip One did not demonstrate vertical landing, but DC-X did that -- again, for a fraction of the cost of Apollo LM hardware.

> Plus, as somebody pointed out (I forgets who), attaching 8 pieces of equipment together instead
> of 2 pieces means bringing 8 sets of docking collars and other related equipment along instead of
> just 2. So there is some weight penalty.

So? Why does "weight penalty" matter if the total cost of launch is less? If your goal is to minimize weight, rather than cost, why launch anything at all? Why not cancel the space program now and avoid the weight penalty completely?

> I have never seen anybody put together a list of the pros and cons of these two radically different
> approaches. It seems like the whole debate is polarized, with each side calling the other stupid or
> unreasonable, without acknowledging the different strengths and weaknesses of the different approaches. The HLLV crowd seems to say that multiple launches
> are nearly impossible, whereas the multiple launch crowd seems to say that they're easy. Objectivity
> seems to be a position that nobody is interested in taking.

Objectivity requires looking at the evidence. A single nuclear submarine can launch two dozen rockets in a matter of minutes, while submerged. Clearly launching a few dozen rockets over a period of many months is not physically impossible or "nearly" impossible. What man has done (or had the capability of doing) man can do.

Posted by Edward Wright at October 25, 2005 02:37 AM

Actually, most of the big satellite operators do have spare satellites--on orbit. If a DirecTV satellite suffers a failure, DirecTV will switch programming over to its spare satellite and restore service within minutes.

"Spare" satellites are also launched in much the same way spare Constellation propellent stages could be launched if NASA were sane--by cascading a regular series of launches. If, say, the recent Galaxy 15 launch had failed, PanAmSat would likely at least temporarily replace it with Galaxy 16, replace 16 with 17, etc. until Galaxy 15R could be built and launched. There are sometimes some technical issues with doing that, but in general it's one of the reasons why comsat operators have consolidated into a few large constellations.

Considering that Boeing's Decatur facility can turn out 50 Common Booster Cores *a year* (Lockheed's factory is probably similarly underutilized), they would have no problem maintaining a build rate capable of handling the proposed Constellation launch rate with enough slack for an occasional extra launch.

If the pro-EELV crowd sounds a little testy, it's because, though we may not be "spacefaring" in the true sense of the word, even today's Big Aerospace can easily handle this challenge. That our second-biggest customer is so far behind us in market thinking is disheartening, especially since we also pay taxes.

Posted by Michael Kent at October 25, 2005 10:09 AM

Post a comment