QUESTION:
Would it not be wise to send two probes at the same time and have them land
at opposite sides of Mars to conduct radar experiments through the interior
of the planet?

ANSWER from Steve Wall on July 15, 1997:
It is a great concept.  We really need to understand the interior of the
planet, although it might be better to use siesomological techniques than
radar.  That is because radar signals would need huge amounts of power to go
through the planet.  But you can use siesmographs (like the ones used on
Earth to detect eqrthquakes) to listen for Marsquakes, and if you had two or
more stations listening at the same time you could discover information
about the inside of Mars.  We tried to do this with the two Viking landers,
but no Marsquakes were heard.  Good idea - maybe we'll try it again!