🚀 go-pugleaf

By today's standards, the Viking landers are large craft.  The
question of using small robots versus large ones is almost a religious
question.  The greatest failing of those proposing small robots is the
naive assumption that using multiple, small robots increases overall
system reliability.  This is not true because one can not assume a
priori that the failure modes are independent.  That is, if the robots
are identical, and one of them fails in a particulr manner, this
implies that the others will also be prone to that particular failure
mode.

From a technical viewpoint, the major drawback to small robots in
telemetry.  To transmit a signal from Mars, you need a moderately
large antenna and a bunch of power, if you want reasonable data rates.
I do not have my references in front of me for doing link
calculations, but from the moon (which is right next door), you need a
.5 m dish on the moon, putting out 20 W of power to a 10 m dish on the
earth to get data rates of between 10k-100k bits per second.  The
problem from mars is much more difficult.  In addition, mars has winds
which will make antenna pointing difficult, thus degrading data
transmission.  To overcome these problems, a larger vehicle is needed.
By larger, I am thinking of a vehicle with a mass of 100-200 kg, as
opposed to a number of micro rover concepts that have a mass of < 10
kg.  These micro rovers would be incapable of meaningful scientific
exploration. 

--
Gerry Roston (gerry@cmu.edu)    | It would be almost unbelievable, if history
Field Robotics Center,          | did not record the tragic fact, that men have
Carnegie Mellon University      | gone to war and cut each other's throats
Pittsburgh, PA, 15213           | because they could not agree as to what was to
(412) 268-3856                  | become of them after their throats were cut...
                                | For some reason, too deep to fathom, men
The opinions expressed are mine | contend more furiously over the road to
and do not reflect the official | heaven, which they cannot see, than over their
position of CMU, FRC, RedZone,  | visible walks on earth.  Walter Stacey
or any other organization.      |