🚀 go-pugleaf

In article <Bzqq90.JLs.1@cs.cmu.edu> rcs@cs.arizona.edu (Richard Schroeppel) writes:
>I notice the proposed LEI probe doesn't include imaging.
>(1) How do they know where the probe is looking when it's taking data?

The instruments are not particularly directional, as I understand it.
The mapping from data to lunar surface is established mostly by the
location of the probe at the time.  Once the thing's primary mission
is complete, one strong possibility for an extended mission is to take
it to very low altitudes over particularly interesting areas, to improve
mapping resolution there.

Imaging is nice, but it takes a lot of downlink bandwidth and it's
awkward to do from a spin-stabilized probe (which is simpler and lighter
than a three-axis-stabilized one).  There's also not a lot of point to
it unless you can do it well, given that we already have so-so images
of most of the Moon.  Better imaging, especially multispectral imaging,
would certainly be useful, but it's a different mission.

>(2) Since "permanent solar shadow" != "permanent Earth shadow",
>    how about looking for ice glints by Earthlight?

The poles don't get much Earthlight either (possibly none at all in a
nice shadowy polar crater, although I'm not sure of the numbers).  There
is also some reason to suspect that persistent polar ice might well be
buried slightly.

The only way to settle the issue once and for all -- short of surface
exploration, that is -- would be radar imaging, I would think.  Alas,
that means a big spacecraft, for large antennas and plenty of power.
-- 
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  henry@zoo.toronto.edu  utzoo!henry