I stumbled across a witty poem today at Crooked Timber that more or less reflects my mood about the ESAS report:
If something can get worse it will
Is a phrase I’ve often sardonically used
But here’s some grist for Mr Murphy’s mill
I used to be disgusted
Now I’m just amused
I’ve been thinking about what to say and how to say it about this report for the past two days. I was putting it off hoping to come up with something very clever and insightful (and also waiting for more time to do such a writeup), but I’ve got some time on my hands now as I wait for my computer to spit out pretty FEA pictures telling me how screwed up my tank sump design is, so I may as well make the most of it.
Before I am too tempted to point out all the glaring fallacies that Mark’s been churning out over at Curmudgeon’s Corner, I want to start by commenting on an analysis that I mostly agree with. Henry Vanderbuilt over at the Space Access Society is one of my favorite space commentators. The fact that his views often are fairly similar to mine, and that he’s seen as being a rather smart person in the alt.space crowd thus making me look smart too has absolutely nothing to do with it. Anyhow, in previous Space Access Updates, Henry had been taking a cautiously optimistic tone toward the whole VSE. There was originally hope for it to actually be done in a non-stupid way, and there was even hope for it helping catalyze the development of a true and thriving cis-lunar economy. It was a long-shot, but sometimes long-shots are worth it. As part of this gamble, the SAS had joined a coalition supporting funding increases for NASA for carrying out the VSE. However, as NASA’s plan has been rolled out over the past several months, Henry has changed his mind. As he put it:
To be blunt, we have big problems with this plan. It’s the same basic approach as Apollo, disposable (mostly) spacecraft, on big NASA-proprietary boosters, flown a few times a year, by a standing army of NASA and contractor employees. This is Apollo 2.0, with somewhat more delivered exploration, at moderately higher cost, on a significantly slower schedule.
We have to ask, after forty years of stunning technological progress, shouldn’t we be able to improve on Apollo’s cost-to-exploration ratio a bit more than this? US taxpayers will get little more Buck Rogers for their inflation-adjusted buck than they did in the 1960’s
Henry then goes on to hit on many of the same points I’ve been hitting on over the past few months. One of his good points is the danger in putting too much faith in commercial ISS resupply contracts and the other “Innovative Programs” that Griffin has been touting in order to gain the support of the alt.space crowd (emphasis mine):
[T[here are potentially useful bits in ESAS, not least of them the plan’s flirtation with Station resupply being put out to commercial bid. Mind, with all due respect to various of our colleagues who pin large hopes on this, we have to say we see a strong liklihood that it, along with all sorts of other useful NASA non-manned-space functions (what does that first “A” stand for again?) will end up defunded to pay for ESAS’s big upfront vehicle developments.
We also see considerable danger that commercial Station resupply will turn into (despite the best will in the world by those at HQ conceiving it) a tarbaby (a glue-trap for you kids never taught the old folk tales) as the people actually administering Station set impossible standards for would-be vendors, until they go broke and go away. (Last we heard, not even Shuttle and Soyuz meet the official “prox ops” Station docking rules; both had to be grandfathered in.) Our hypothetical turf-jealous Station managers could then go to Congress saying “see, those damned
amateurs couldn’t hack it, now fund us pros to do the job!”
The only part of ESAS that is even worth funding is the Innovative Programs office, but precisely because it is seen as being “off the critical path”, it is the most vulnerable to cost overruns and budget cuts. As it is, it’s looking as though Congress is trying to zero-out Centennial Challenges and the ISS commercial contracts already. Without the Innovative Programs work, there really isn’t anything in the ESAS architecture worth supporting, as the rest of it is pretty much welfare for space nerds.
Henry’s suggestions were more or less what I’ve been saying here, so I agree with them 100%. Quoting Henry (emphasis again mine):
– NASA should let go of controlling their own space transportation from start to finish. They should make an exploration plan based on a variety of existing commercially available boosters, then put the entire ground-to-orbit leg of their new deep space missions out to bid.
– NASA should lay off and/or BRAC large parts of their Shuttle/Station establishment as Shuttle is shut down and Station completed, rather than again compulsively trying to “keep the team together”. It’s been a long time since this team had a winning season, the payroll is crippling, and the game has changed. Rebuild from the ground up.
– NASA should let go of numerous arbitrary and/or dated “this is best” prejudices the organization has accumulated over the years. Old NASA (as someone once said of a notoriously inbred european royal house) forgets nothing, and it learns nothing.
Henry then went a little into what he saw as being the ramifications of a commercially launched Earth Orbit Rendezvous-type system. Here’s where I have to pick on quick nit. Henry mentions that due to the fact that hydrogen is “hard to store for long”, if you insist on using only the fastest transfer orbits, the launch windows are short, and that can be a big problem. This is a more intelligent (but still slightly flawed, IMO) variant on a commonly heard complaint that if you go with on-orbit assembly or refueling, that if a single launch fails, you lose your entire mission. If you look at the real numbers, the problem just isn’t as big as most people assume. Borrowing from Bruce Dunn’s analysis, a properly insulated tank in the size range we’re looking at will probably have less than 1lb/hr of LH2 boiloff, and about 3/4 that of LOX boiloff. That’s not a lot. Over a full month we’re talking about less than 4% of the LH2 boiling off, and less than 0.5% of the LOX. That ends up coming out to only about 1% of the total propellants after a full month of delay. Even if you assume the worst case numbers they were showing (that required less insulation), you’re still only talking about something like 4% of the total propellant boiling off. And if you use a heat exchanger like Bruce suggested to use some of the LH2 boiloff to cool the LOX tanks, you can get those numbers back down to 2% or so of the total propellant volume over a full month worth of delays. Extra tankage isn’t free, but most propellant tanks weigh about 1lb for every 10-100lbs of propellant (depending on the density of the propellant).
What that all means is that even if you insist on using LH2 (which isn’t neccessarily as stupid of an idea as Henry makes it seem to be–I’ll probably write a future blog entry about the pros and cons of LH2 for cislunar flight), the boiloff issue just isn’t that rough. It isn’t a real argument for not doing on-orbit refueling. A trivial design expense up-front can more than handle making sure the tanks have sufficient margin. Doing slower multi-burn trajectories to open up more launch windows, or going with a more space storable fuel like propane or methane make the problem even smaller, but even if you insist on the fast flights, and the LH2….you get the point.
Anyhow, that’s enough for now. Henry’s article is a good take on the whole situation. What a bloody waste.
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