QUESTION:
Will the Mars Global Surveyor, when it arrives, be able to relay
communications between the current Sojourner mission and Earth?

ANSWER from Charles Whetsel on July 30, 1997:
Unfortunately, no.  Here's a summary of what our status and plans are for
communcations at Mars.  The Mars Pathfinder Lander has radios which are able
to communicate with both the Earth, and with the Sojourner Rover.
Unfortunately, the radio on the Sojourner Rover is only strong enough to
talk to the Pathfinder Lander, not to the Earth, or even to the Mars Global
Surveyor (MGS) spacecraft once it reaches orbit around Mars.  The MGS
spacecraft has radios which can talk both to the earth and to landers on the
surface (except Pathfinder, due to differences in the radio frequencies
used).  Originally, MGS was to have been used to communicate with a joint
Russian-French mission to Mars this year, but unfortunately, that mission
was lost shortly after launch last December (1996).  In 1998, we are
planning to launch another orbiter and another lander (but without a rover:
The '98 Lander will carry a robotic arm, mounted to the spacecraft which
will carry out other experiments).  When the '98 lander is on the surface,
it will have radios which can talk directly to the earth (although very
slowly) but it will also have a radio which can send data to either MGS or
the Mars Surveyor '98 Orbiter at very high rates. Finally, in 2001, we are
planning to send another orbiter and another lander with another rover. By
the time these spacecraft reach Mars, it is likely that the Mars '01 Lander
and Rover will have 3 satellites to choose from to "relay" their data back
to earth: Mars Global Survey ('96), Mars Surveyor '98 Orbiter and Mars
Surveyor '01 Orbiter.

Charles Whetsel
Chief Project Engineer
Mars Surveyor Operations