How long has the sojourner been on mars?

The lander and rover performed for much longer and better than expected, but eventually contact with the lander was lost on sol 83. The lander's silver-zinc battery was only capable of being recharged about 40 times, as a consequence after about 40 sols, the battery was not able to keep the lander warm at night. The exact reason for the final failure of the lander is not certain, but it was probably due to an electronics failure due to the very cold night-time temperatures that were experienced in the final weeks of the mission. After sol 92, the automatic backup procedures should have instructed the rover to return to the lander and circle it whilst attempting to re-establish communications. This behaviour would have continued until hardware failure. The lack of communication though means that the rover's final exact location and state are unknown. NASA's efforts to recontact Pathfinder ended on March 10, 1998.