[X] My Assistant

[Phil Stooke]

I need a list of Discovery missions from each of the competitions since the Discover Program commenced. Not including Lunar Prospector, for which I have plenty of information already. Can anybody help me out?

At a minimum I just need a list, I guess, but other information or sources would be very useful as well, as eventually I have to go there as well.

Phil

[Guest_BruceMoomaw_*]

Yes, I have an Alphonsus traverse map, though without sample stations etc.  Alphonsus was always popular as a second choice, but never made it to the top of the list.  One problem was that the later Apollo sites had to have multiple objectives - at Taurus-Littrow you had the valley floor basalts, the Serenitatis basin massifs, the supposed volcanic vent at Shorty (incorrect interpretation) and a young landslide.  Alphonsus had the dark halo craters, but the pre-Imbrian walls (such old material was a major objective of the last 2 missions) were likely covered with a thick layer of Imbrium ejecta.

Phil

Yeah, I know about that problem. My main reasons for suspecting that it would still likely have been chosen are that:

(1) Apollo 14 would have revealed Littrow to be a failure as a source of young volcanics (restoring interest in Alphonsus for that purpose); and

(2) There don't seem to have really been any other possible sites that were more promising as a source of highlands material uncontaminated by Imbrium ejecta (although that WAS the single most important science goal for Apollo 17). Taurus-Littrow, would, I imagine, have been ruled out as too close to the Apollo 14 site (as well as having no young volcanics), and other sites in the highlands between Mares Serenitatis and Crisium (according to the Apollo 17 postflight report) were ruled out on the grounds that there was a good chance the Soviets would sample them (which, in fact, they later did). By contrast, there was considered to be at least a fair chance that Alphonsus would have some non-Imbrium highlands material (which Gassendi, Copernicus, Davy Rill and the Marius Hills would definitely not have had), as well as those young volcanics.

Still, there's obviously a huge amount of guesswork in this conclusion of mine. After Apollo 14 had revealed Littrow not to have young volcanics as expected, it's hard to really predict where the last three missions would have been sent (except that Descartes strikes me as a certainty for one of them).

[dvandorn]

Still, there's obviously a huge amount of guesswork in this conclusion of mine.  After Apollo 14 had revealed Littrow not to have young volcanics as expected, it's hard to really predict where the last three missions would have been sent (except that Descartes strikes me as a certainty for one of them).

If 13 had landed at Fra Mauro and 14 at Littrow, I don't think that would have affected the selection of either Hadley or Descartes. Assuming the same eventual cancelation of the Apollo 15 H-mission and of Apollo 19, you would be looking at selecting sites for the J missions using the same requirements as were actually used -- multiple sampling opportunities, Imbrium and pre-Imbrium impact materials, lava features -- all of which drove the selection of Hadley-Appenine. And Descartes was going to get a J mission somewhere.

I will point out that Descartes was originally a prime site consideration for the *first* J mission, but was bumped to the second because of lack of good photography. When 13 aborted and was unable to get good Descartes pictures, it was left for Apollo 14 to get good coverage of Descartes so that it could be validated as a safe landing site. But since the good site photography wasn't available until after Apollo 14 (and after the site for 15 had to be selected), Descartes fell out of the running for 15. If 13 had gotten that good Descartes coverage, I think Apollo 15 *would* have flown to Descartes.

*Then* you can ask whether Hadley would have been the 16 or the 17 site. Without something like Taurus-Littrow beckoning (and I agree, if 14 had landed at the original Littrow site, Taurus-Littrow would never have been selected for a J mission), then I think it likely that 16 would have landed at Marius Hills and that 17 would have landed at Hadley.

-the other Doug