QUESTION:
Has any consideration been given to the concept of carrying several
Surveyor-style packages within a single rocket, and then distributing them
simultaneously to different locations on Mars' surface, once the rocket has
reached the vicinity of Mars (much like a MIRV rocket, but with a much more
peaceful and useful payload)?

Seems to me that this could be a much more effective use of resources, and
would speed up research activities considerably.

The ANSWER comes from Mark Adler on July 15, 1997:
Pathfinder and the Surveyor '98 lander are too large and too expensive to
MIRV.  First, we can only afford on the order of two missions per
opportunity, and usually one of those does orbital global mapping as well as
communications support for the lander.  And the cost is not just the extra
lander copy (somewhat cheaper than the first lander), but also the larger
launch vehicle to put it on.

Second, and perhaps more importantly, sometimes launch vehicles blow up. 
For example, Mars Global Surveyor and Pathfinder launched successfully on
consecutive Delta 7925 rockets.  The very next Delta 7925 launch blew up. 
Fortunately it was only carrying a few of a series of GPS satellites, so the
loss was far less than it would have been for a unique Mars mission.  So
putting a lot of expensive landers on one launch vehicle is the proverbial
lots of eggs in one basket.  We'd like to spread our assets over multiple
launch vehicles to cut our losses when, inevitably, one blows up.

However, we will be trying out a new, much smaller and cheaper kind of Mars
lander called a penetrator.  The DS-2 (Deep Space 2) Mars Microprobe Mission
will send two penetrators to Mars attached to the 1998 Mars Surveyor Lander. 
They are small, about 4 kg each, single-stage entry systems (i.e. no
parachutes, rockets, or airbags) and will carry simple scientific
instrumentation to the surface and will return data on the ground
composition after landing.  The tricky part is that the instrumentation has
to survive a 400 mph impact with the ground, but that is possible.  We could
MIRV these kinds of landers since they are small and cheap, and in fact
there have been proposals for many seismic and/or meteorological stations
delivered this way to be dispersed on the surface of Mars.

Mark Adler