Photo Of The Day

cheers luci, up till late 2009 is was still happily pootling about the place, then it got stuck, here's the account of its last movements etc

**2009
*Stuck in dusty soil with poor cohesion
***On May 1, 2009, the Rover became stuck in soft soil, the machine resting upon a cache of iron(III) sulfate (jarosite) hidden under a veneer of normal-looking soil. Iron sulfate has very little cohesion, making it difficult for the rover's wheels to gain traction. JPL team members simulated the situation by means of a rover mock-up and computer models in an attempt to get the rover back on track. Indeed, it is particularly difficult to experimentally reproduce the same soil mechanical conditions on Earth as those prevailing on Mars under low gravity and under very weak atmospheric pressure. Tests with a lighter version of a mock-up of Spirit were conducted at JPL in a special sandbox to attempt to simulate the cohesion behavior of poorly consolidated soils under low gravity. Preliminary extrication drives began on November 17, 2009.
On December 17, 2009, the right-front wheel suddenly began to operate normally for the first three out of four rotations attempts. It was unknown what effect it would have on freeing the rover if the wheel became fully operational again. The right rear wheel had also stalled on November 28 and remained inoperable for the remainder of the mission. This left the rover with only four fully operational wheels. If the team could not gain movement and adjust the tilt of the solar panels, or gain a beneficial wind to clean the panels, the rover would only be able to sustain operations until May 2010.

2010
*Stationary research platform*
On January 26, 2010, after several months attempting to free the rover, NASA decided to redefine the mobile robot mission by calling it a stationary research platform. Efforts were directed in preparing a more suitable orientation of the platform in relation to the Sun in an attempt to allow a more efficient recharge of the platform's batteries. This was needed to keep some systems operational during the Martian winter. On March 30, 2010, Spirit skipped a planned communication session and as anticipated from recent power-supply projections, had probably entered a low-power hibernation mode.

Last communication
The last communication with the rover was on sol 2210 (March 22, 2010) and there is a strong possibility the rover’s batteries lost so much power at some point that the mission clock stopped. In previous winters the rover was able to park on a Sun-facing slope and keep its internal temperature above -40 Celsius, but since the rover was stuck on flat ground it is estimated that its internal temperature dropped to −55 Celsius. If Spirit had survived these conditions and there had been a cleaning event, there was a possibility that with the southern summer solstice in March 2011, solar energy would increase to a level that would wake up the rover.

2011
*Mission end*
JPL continued attempts to regain contact with the Spirit rover until May 25, 2011, when NASA announced the end of contact efforts and the completion of the mission. According to NASA, the rover likely experienced excessively cold "internal temperatures" due to "inadequate energy to run its survival heaters" which, in turn, was a result of "a stressful Martian winter without much sunlight." Many critical components and connections would have been "susceptible to damage from the cold." Assets that had been needed to support Spirit were transitioned to support Spirit's "still-active twin", Opportunity, as well as the next-generation Mars rover Curiosity. Two NASA Mars orbiters and the Deep Space Network of antennas were prepared for the Curiosity launch which took place on November 26, 2011.

Here are some panorama's it took (click for full size)