Why does it take so long to get data back from Mars?
The reason is that Mars is far away from the Earth. Depending on
the time of year, Mars can be anywhere between 78 million and 377
million kilometers from the Earth. Radio signals that carry the
data travel at the speed of light which is about 300,000
kilometers per second. At this speed, the signals can reach Earth
in as little as 4 minutes (78 million km), or can take as long as
21 minutes (377 million km). Engineers refer to this length of
time as the "one-way light time."
Will Surveyor ever return to Earth?
No, Surveyor does not carry enough propellant to return to Earth.
The spacecraft will continue to orbit Mars long after its
electronics fail or its maneuvering propellant supply is
depleted. The orbit that will be used for mapping operations was
designed to ensure that Surveyor will not fall out of orbit and
crash into the surface for at least 50 years after the conclusion
of the mission.