QUESTION:
How far will the rover travel? What is the maximum distance Sojourner can
stray from the lander and still relay data effectively? (Does flat terrain
allow Sojourner to travel much greater distances?)

ANSWER from Andrew Mishkin on February 17, 1997:
During the rover's primary mission, it will stay within about 10 meters of
the lander.  This will allow us to use the images from the lander's cameras
to decide which scientifically interesting sites to send the rover to next.
The rover will probably drive about five meters or so a day during this
part of its mission, for a total of about 50 meters.

After we've explored near the lander, we may be willing to take more risk
and drive further away, beyond where the lander can see clearly.  It really
depends on how rough the terrain is, and whether we see any particularly
interesting features to study.  The rover could travel another few hundred
meters during this extended mission.

ANSWER from David Dubov:
Sojourner can range 500m from the lander before communication (as determined
by bit error rate) degrades. This distance was confirmed in tests conducted
with engineering models of the modem for both the rover and lander. The
actual performance on Mars may be affected by factors such as temperature
and terrain. We expect to conduct simple experiments during the mission to
help measure the performance of the communication system.

ANSWER from David Dubov:
The lander and rover carry 9600baud radio modems. With allowance for the
data transfer protocols, the effective data rate between these systems is
2400bps. The communication range of the rover has been measured in tests
with engineering models of the modem at 500m. At that range, the link
degrades (as determined by bit error rate) for reliable communication. After
10m, the rover is effectively beyond the imaging range of the lander. These
images from the lander are used by ground-based operators to plan rover
operations. Beyond 10m, rover images will be used to plan traverses.