QUESTION: 
How is information relayed back to earth from the Mars Rover?

ANSWER from David Mittman on January 30, 1997:
Sojourner (the rover on the Mars Pathfinder mission) radios its
information to the lander where it is stored in memory. If the Earth is
"up" on Mars, the information is then radioed to Earth using the
lander's more powerful transmitter. If the Earth has already set, the
rover's data is stored overnight until Earth rises the next day.
At the Lander's landing site on Mars, the Earth rises early in the
morning (at about 2:30 AM) and sets at mid-afternoon (about 3:00 PM).