From: Henry Spencer <firstname.lastname@example.org>
Subject: Re: Apollo Program
Organization: SP Systems, Toronto
Date: Fri, 29 Dec 1995 00:10:40 GMT
In article <email@example.com> firstname.lastname@example.org (Jim Scotti) writes:
>...Sites mentioned for the later
>missions included Kepler, the Orientale Basin and a farside site, amongst
>others, but since the landings were cancelled relatively early, we can only
Actually, the sites mentioned sound like a vague recollection of Harrison
Schmitt's attempt to sell NASA on a program of four dramatic landing sites
-- Tycho, Mare Orientale, the North Pole, and a farside site -- which he
hoped would reinvigorate public support. As far as I know, none of these
sites except Tycho was ever on NASA's short list. For example, NASA never
did any serious work on the communications-relay satellite that would have
been needed for a farside landing.
Even Tycho was on the official lists only on a "wouldn't it be nice"
basis, pencilled in for Apollo 20 in hopes that the technical problems
could be solved by then. It was dropped fairly early when it was clear
that they couldn't be.
>An excellent book on the subject of lunar landing site selection and on the
>geology behind site selection and the landings is called "To a Rocky Moon",
>written by Don E. Wilhelm, published in 1993 by the UA Press. I highly
>recommend this book...
Wilhelms, not Wilhelm. I concur with the high recommendation. I'd add
the NASA History book on the Apollo missions, "Where No Man Has Gone
Before", NASA SP-4214, which has quite a bit of background on crew
selection and site selection.
Look, look, see Windows 95. Buy, lemmings, buy! | Henry Spencer
Pay no attention to that cliff ahead... | email@example.com
Date: 7 Dec 92 08:02:26 GMT
From: Henry Spencer <firstname.lastname@example.org>
Subject: cancelled Apollos
>> Do you mean that the Apollo 18 mission was targeted for Hadley, not 15? ...
>I don't remember the targeting assignments, but the crucial fact here is
>that there were two flavors of Apollo missions involved...
More Apollo archeology...
Site selection had settled down by early 1970, with minor ongoing
revision. The cancellation of Apollo 20 had more or less coincided
with a decision that a landing in Tycho crater was too difficult, and
that had been the primary target for Apollo 20, so that one was easy
(although regrettable because Tycho was of great geological interest).
There was also some reshuffling of missions then, because the Marius
Hills mission required instrument development that might not be done in
time for its Apollo 16 slot, and also the site was reachable within the
mission rules only in summer. So the list then was
13 Fra Mauro
18 Marius Hills
Apollo 13 was meant to visit Fra Mauro, because the Fra Mauro Formation
was thought to consist of material excavated by the impact that formed
Mare Imbrium -- a major event in lunar history, dating of which was
important, and also one that probably excavated material from deep down.
The Apollo site-selection board decided, in the wake of the Apollo 13
failure, that Fra Mauro was still first priority, so Apollo 14 went
there instead of Littrow. They also recommended moving 15 to a site
near Davy crater, assuming Apollo 14 could get adequate photos.
Not only did the 14 photos not come through in time, but by then, it
was clear that more missions were going to die. After lengthy discussion
and review of a number of sites, Littrow, Descartes, Hadley, and the
Marius Hills were deemed to be both feasible (both Copernicus and
Censorinus were now off the list due to excessively rough terrain)
and scientifically significant.
For Apollo 15, it was thought desirable to have a high probability of
major advances in lunar science, adequate photography without waiting
for Apollo 14 results, mission feasibility without deep analysis, and
a site suitable for either an H or J mission so that it could be flown
regardless of which type 15 was (at the time it was still an H, but
if missions were to be cancelled, cancelling the last H mission was
an obvious possibility). This last was particularly significant
because it meant picking a site that didn't need the J's lunar rover
but would benefit if it were available. Hadley got high marks for
providing access to several different geological features even without
a rover, being on various disciplines' high-priority lists, and putting
an ALSEP package at a high-latitude site (highly desirable to give
three-dimensional coverage for the seismometers and retroreflectors,
since most other sites were near the equator).
When two more Apollos, including the last H mission, were canned,
Hadley and Marius Hills fought it out for Apollo 15. Hadley won by
a nose: the two sites were very evenly matched until David Scott,
picked to command the mission, said he preferred landing at Hadley.
The board picked Hadley for 15, pencilled in Descartes for 16, and
left 17 open with several possibilities being debated.
Site selection for 16 ended up debating Descartes vs. Alphonsus.
Both looked like good places for highlands material and volcanic
material. Descartes got the nod mostly because it was thought
preferable to have the 14 and 15 results fully in hand before
committing to a landing at Alphonsus; Alphonsus was left as a
candidate for 17. In the end, it turned out that the Descartes site
was not volcanic at all, which caused a lot of re-evaluation of the
site-selection photogeology, because it had sure looked like it.
Confusion about the Moon's geological history was getting worse,
not better, with more Apollo results.
Site selection for 17 looked like it might produce a full-scale war,
so it got started early, well before 16 flew. However, in the end
it wasn't that bad, because the fact that it was the last chance for
many years produced strong consensus on objectives: pre-Imbrium
highlands as far from Mare Imbrium as possible, "young" volcanic
rocks, coverage from orbit of areas not previously seen up close,
and best coverage for some new geophysics instruments. Three sites
made the short list: Taurus-Littrow, Gassendi, and (a distant third)
Alphonsus. T-L got top marks on most everything with the bonus of
a reasonable walking mission if the rover failed. T-L had one
problem: in worst-case conditions, Apollo's nominal-landing-area
ellipse would not fit the suitable terrain. Gassendi also had
operational problems, though, since a slightly off-target landing
might make major objectives entirely unreachable. The trajectory
people were encouraged to reconsider the T-L calculations based on
15's precision landing; the results cleared T-L and it was picked.
Most of the above is from NASA SP-4214, "Where No Man Has Gone Before",
which is the NASA History volume covering Apollo lunar exploration
proper (as opposed to hardware development).
>I don't remember exactly which CSMs got used for Skylab.
116 (the fifth J CSM) flew the first crew, 117 the second, and 118
the third. 111 (the last H) was Apollo-Soyuz. 119 (the last[?] J)
was allocated as Skylab rescue if necessary, then shifted to Apollo-
Soyuz backup. Where 115 went I'm not sure.
MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology
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