In sci.astro message , Fri, 14
Nov 2014 08:46:54, Mike Dworetsky
posted:


The main requirement would seem to be an ability to slow the descent
speed to near zero just before surface contact. This requires radar
and a rocket engine that can be throttled. Both add mass to the
lander, so one or more scientific experiments would probably need to be
removed to accommodate it.

Radar may not be needed.

A few phone-cameras around or near the equator of the lander, used
during descent to put the mean horizon in the right place, and
subsequently for pretty pictures.

A phone-camera on each foot, facing downwards, and an algorithm which
makes, using thrusters, the mean rate of ground movement in each camera
the same and radially outwards at a constant suitable rate; when focus
or brightness is lost, landing has occurred.

A centre-line recoilless gentle shotgun, used first, to spray suitable
ammo at the ground to ensure that it is not featureless.


And, on general grounds, phone cameras looking in the 20 icosahedral-
face (= dodecahedral-vertex) directions, in case the scenery is not
where it was intended to be.

--
(c) John Stockton, near London. Mail
Web http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, and links.