ESG7@DFVLROP1.BITNET (11/17/86)
This note concerns Henry Spencer's posting in Vol. 7, No. 45 in Space
Digest. I would like to begin by offering my thanks to Henry for his
distillations from Aviation Week. I'm located in Goettingen, West
Germany (AVA-DFVLR). The DFVLR library doesn't receive Aviation Week
until fairly late, so Henry's efforts are greatly appreciated. Also it
seems that Henry does a much better job of reading Aviation Week than I
do, since he's always finding tidbits that I missed. Henry's last
postings raised two questions in my mind. Why is it, that to
remanufacture the old F-1 engines is more expensive than using SSMEs?
It seems ludicrous to be throwing a reuseable SSME into the sea when a
cheaper and higher performance F-1 (which is designed to be
use-once-throw-away) is the obvious choice. Admittedly there is an
initial tool up expense. However it is hard to believe that this
expense couldn't be quickly offset by the lower launch cost for an F-1
based Jarvis. I've always thought that the F-1 engine was one of the
more important technologies to come out of the Apollo program, and
its premature obsolesence was a serious error. On another
subject the TAU (Thousand Astronautical Unit) spacecraft smacks of being
a boondoggle. Who in his right mind would want to fund a multimillion
dollar spacecraft that literally goes nowhere? If you want to argue
that it is a test bed for a high preformance nuclear-ion propulsion
system, then my snappy comeback is the money could be better spent
on a comet rendevous using the same technology. An even better mission
would be a Pluto orbiter. I've always thought that Pluto might well be
an example of a "rogue planet" which was created outside of the solar
system. The theory is that Pluto approached the solar system on a
hyperbolic trajectory, (which by definition means it would have escape
velocity), but was captured because it had a near miss with the moon
Triton orbiting Neptune. Both Triton and Pluto have very irregular
orbits, and Pluto does intersect with Neptune's orbit. Therefore this
theory isn't as nutty as it first sounds. When Voyager flies by Triton,
we'll have more evidence to fuel or quench speculation. On any event
this TAU mission strikes me as a misuse of limited planetary exploration
funds.
Gary Allenadamsd@crash.UUCP (Adams Douglas) (11/18/86)
In article <8611171047.AA09235@s1-b.arpa> ESG7@DFVLROP1.BITNET writes: >...On any event > >this TAU mission strikes me as a misuse of limited planetary exploration > >funds. > > Gary Allen I attended the original lecture on the TAU proposal over a year ago, and I can assure you it would be neither a waste of funds nor a boondoggle. The primary mission of TAU is to permit very precise astrometry of nearby stars orders of magnitude better than any we can achieve now. With a 1000 AU baseline, we will be able to determine accurate stellar distances for stars all the way to the galactic center ('nearby stars' being a relative term here). Add to this the fact that TAU essentially involves putting a HST grade telescope outside our solar system, thus giving us the capability for a useful perspective on our own system form a very different vantage point. One should also not ignore the fact that this ion-powered bus gliding out of our system gives us the perfect opportunity to do good hard science in near-interstellar space (5 times the distance at which we will lose contact with Voyagers 1 and 2). Many intruments besides the telescope can be hung on the platform, which--unlike Voyager--is designed to be talked to at that distance. TAU 'goes nowhere' only in the same sense that the Voyagers or the Pioneers do. It's what it'll gather on the way that makes it so valuable. Oh, yes, I don't have any personal interest in the project here at JPL. My comments are strictly from my own interest in seeing the best use made of the limited planetary exploration budget. -- ======================================================= Adams Douglas ARPA:crash!adamsd@nosc.arpa AT&T:818-354-3076 JPL/NASA UUCP:{akgua | hplabs!hp-sdd | sdcsvax | noscvax}!crash!adamsd My opinions! Do you hear? MINE! Not JPL's. "Do not be angry with me if I tell you the truth." -- Socrates
henry@utzoo.UUCP (Henry Spencer) (11/19/86)
> ... Why is it, that to > remanufacture the old F-1 engines is more expensive than using SSMEs? My guess would be that the problem is not so much cost as uncertainty. The F-1 production line shut down a long time ago, and it's not clear that the tooling and plans were preserved properly. (To say nothing of the analogous problem with subcontractors, e.g. the people who used to supply small quantities of very precisely formulated alloys -- they may not even be using the same production processes nowadays, which would make it very hard to be sure that the resulting alloys are exactly the same.) There's no doubt that production could be restarted; the hard part is restarting it accurately enough that you don't need to start engine testing all over again. Even small variations in materials could affect things enough to make it a gamble to fly new-production F-1s without a thorough test program. Hughes can't afford such a test program if it's going to make the deadline for the USAF MLV contract; as it is the Jarvis will be a bit late, although Hughes hopes that the large payload will make up for this. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,decvax,pyramid}!utzoo!henry