QUESTION:
Are there any geysers on Mars, or geo-thermal energy?

ANSWER from Mike Mellon on February 11, 1997:
Although there is an abundance of volcanic features on Mars (volcanos, 
cooled lava flows, etc), so far we have not observed any volcanic 
activity on Mars today. This does not mean that Mars is volcanically 
inactive. On Earth many volcanos remain dormant for years and erupt in 
short bursts. Mars may have some active volcanism, but we need to keep
looking.

There are several ways to look for such activity; we can look for 
changes in geologic landforms over time; we can look for areas that
much hotter than would be expected from solar heating alone; and we
can look for areas where the atmosphere is much more humid than normal,
indicating geysers or steam coming from underground. So far none
of these things have been found on Mars by past spacecraft. However
Mars is a big place and we may have overlooked signs of geothermal 
activity on a small scale relative to the abilities of the spacecraft
instruments. Future spacecraft such as Mars Global Surveyor will have 
the ability to look for these signs and with higher resolution. 

                         - Mike Mellon