QUESTION:
How much time can be spent transmitting to and from Mars each day?

ANSWER from David Mittman on July 12, 1997:
Actually, the rise and set time of the Earth have nothing to do with how
much transmit time we have from Pathfinder. The general rule of thumb is
that if Earth is visible over the horizon at our landing site, then we can
send or receive a signal.

However, transmitting data to Earth takes power, and we have limited battery
capacity. Generally we can transmit between two and three hours a day. Any
more transmission than that, and we won't be giving enough of our solar
power back to the battery after running it down overnight.