Mars Surface

Small quantities of methane and formaldehyde recently detected by Mars orbiters are both claimed to be hints for life, as these chemical compounds would quickly break down in the Martian atmosphere. It is remotely possible that these compounds may instead be replenished by volcanic or geological means such as serpentinization.
Exploration
Dozens of spacecraft, including orbiters, landers, and rovers, have been sent to Mars by the Soviet Union, the United States, Europe, and Japan to study the planet's surface, climate, and geology. As of 2008, the price of transporting material from the surface of Earth to the surface of Mars is approximately US$309,000 per kilogram.