QUESTION: 
How much does the Mars rover weigh on Mars?

ANSWER from Jack Farmer on November 20, 1996:
There are all size classes of rovers being designed and tested at NASA's
Jet Propulsion Laboratory and elsewhere within NASA. There are microrovers
like Sojourner that will go to Mars next month on Mars Pathfinder. It is a
small rover that on Earth weighs about 10 kg. On Mars things weigh about
one-third less. 

But there are also much larger rovers like the Russian-built 
Marsokhod rover which we have been testing the past few years.
It is a macrorover that weighs much more. Then we also are designing 
nanorovers that only weigh a few kilograms. All of these will be
options at different points in Mars exploration, and will be used for
different types of missions having different mobility and payload 
requirements.