Dr J R Stockton wrote:
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.

The requisite phone cameras were still in early development when the lander
was designed and constructed. It's an obvious idea 15-20 years later. And
some serious processing power (using up some mass budget) would be needed to
do the job. But the descent was initially fairly level, relative to local
terrain. The real problem was failure of the anchors to fire and the
subsequent bounces. Even that would not have been a problem if the lander
had not had the bad luck to come down close to a vertical surface that
blocked light to the solar panels.

--
Mike Dworetsky

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