Mercury Landers Options

[gndonald]

While the likelyhood of a Mercury Lander mission is very low, I was wondering if any planning/studies have been done on such a project?

[Guest_BruceMoomaw_*]

(1) That Mercury smash-and-grab mission is a real idea -- in fact (although I know virtually nothing about it), there was apprently at one point a Discovery proposal to do just that for one of Mercury's polar regions (to also try and obtain information on the polar deposit composition).

(2) Actually, it is thought likely that Mercury's regolith differs somehat in closeup appearance from the Moon's simply because meteoroids have been smashing into it at much higher speed. At a mnimum, there should be a lot more melted impact glass mixed into it. It's questionable, however, whether any such differences would be interesting enough to be worth a camera. But:

(3) A Mercury lander WOULD have a lot more uses. We very badly need to know more about the planet's strange internal structure -- for which seismometers, magnetometers, and (if possible) heat flow probes would be invaluable. In fact, just plain old measurements of the planet's libration rate by tracking a lander would be very informative about its interior -- Stanton Peale once suggested a Mercury lander that would do nothing else whatsoever!

And while we might be able to get good data on the element makeup of Mercury's crust from a smash-and-grab mission, there are also some important mineralogy measurements (Raman, Mossbauer, X-ray diffractometry) that could probably be done neitehr by such a mission nor by an orbiter. Finally, a surface lander might tell us more about the planet's super-rarified atmosphere than we could discover from an orbiter.

[DDAVIS]

[quote=BruceMoomaw,Aug 16 2005, 07:53 PM]

(2) Actually, it is thought likely that Mercury's regolith differs somehat in closeup appearance from the Moon's simply because meteoroids have been smashing into it at much higher speed. At a mnimum, there should be a lot more melted impact glass mixed into it. It's questionable, however, whether any such differences would be interesting enough to be worth a camera.

I cannot imagine sending a lander to a planetary body without a camera! It would be interesting to see if the character of the surface varies from the Moon, and if there is a lot more impact glass than the lunar surface one would expect a more pronounced heliogenshein effect than what one sees on the Moon. The higher gravity might cause slightly different crater details on the small scale.

Don Davis

[JRehling]

[quote=DDAVIS,Aug 16 2005, 03:30 PM]
[quote=BruceMoomaw,Aug 16 2005, 07:53 PM]

(2) Actually, it is thought likely that Mercury's regolith differs somehat in closeup appearance from the Moon's simply because meteoroids have been smashing into it at much higher speed. At a mnimum, there should be a lot more melted impact glass mixed into it. It's questionable, however, whether any such differences would be interesting enough to be worth a camera.

I cannot imagine sending a lander to a planetary body without a camera! It would be interesting to see if the character of the surface varies from the Moon, and if there is a lot more impact glass than the lunar surface one would expect a more pronounced heliogenshein effect than what one sees on the Moon. The higher gravity might cause slightly different crater details on the small scale.

Don Davis

[/quote]

Not to be a party-pooper, but the degree of specularity of Mercury's surface should be something that Messenger can characterize pretty well from orbit (even Earth-based observations have weighed in on this: Moon-Mercury light-curve comparisons are the subject of many papers -- but better resolution will say more). And I'm not sure if different surface g will alter *small* crater shape in unpredictable ways, or any at all -- the speed at which things move away from an explosion should be way, way faster than any planet's gravity would interfere with (very little outbursting material would fall back into a 10 meter crater, no?).

I could imagine there being some very subtle Moon-Mercury differences, but I bet a bit of adjustment (for hue, specularity) to a lunar landscape would be something we (I first wrote "you", but Don might be uniquely able!) couldn't tell from Mercury landscapes in a blind taste test -- of course, we'll have to get loads of Mercury landscapes to know! And there's always the off-chance that something we aren't even dreaming of will make a tangible difference. I don't think we'll see a Mercury lander without a camera anytime soon -- but then, we aren't going to see *any* Mercury lander anytime soon! If the flyby craft on a smash-and-grab mission had a rear-facing camera, however, with the next decades' technology providing quick "shutter speed", we could get something a heck of a lot like a surface panorama -- in fact, a large number of them.