Timeline of Spirit

These give scientists the information they need to select promising geological targets and drive to those locations to perform on-site scientific investigations.

The panoramic image below shows a slightly rolling surface, littered with small rocks, with hills on the horizon up to 3 kilometers (1.9 mi) away.

"Sleepy Hollow," a shallow depression in the Mars ground at the right side of the above picture, was targeted as an early destination when the rover drove off its lander platform.

According to the camera designer Jim Bell of Cornell University, the panoramic mosaic consists of four pancam images high by three wide.

The next day the rover radioed a 7.8 bit/s beep, confirming that it had received a transmission from Earth but indicating that the craft believed it was in a fault mode.

The fact that the problem persisted through reboot suggested that the error was not in RAM, but in either the flash memory, the EEPROM, or a hardware fault.

On January 24, 2004 (sol 19) the rover repair team announced that the problem was with Spirit's flash memory and the software that wrote to it.

Examination of the freshly exposed interior with the rover's microscopic imager and other instruments confirmed that the rock is volcanic basalt.

[8] On March 5, 2004, NASA announced that Spirit had found hints of water history on Mars in a rock dubbed "Humphrey".

In contrast to the rocks found by the twin rover Opportunity, this one was formed from magma and then acquired bright material in small crevices, which look like crystallized minerals.

If this interpretation holds true, the minerals were most likely dissolved in water, which was either carried inside the rock or interacted with it at a later stage, after it formed.

As the produced energy from the solar panels was lowering due to the setting Sun and dust the Deep Sleep Mode was introduced.

Slowly, Spirit made its way around the summit of Husband Hill, and at sol 344 was ready to climb over the newly designated "Cumberland Ridge" and into "Larry's Lookout" and "Tennessee Valley".

NASA scientists speculated a dust devil must have swept the solar panels clean, possibly significantly extending the duration of the mission.

Mission members monitoring Spirit on Mars reported on March 12, 2005 (sol 421), that a lucky encounter with a dust devil had cleaned the robot's solar panels.

[18] On sol 656 Spirit surveyed the Mars sky and the opacity of the atmosphere with its pancam to make a coordinated science campaign with the Hubble Space Telescope in Earth orbit.

This was an interesting target, but Spirit would be driven later to the McCool Hill to tilt its solar panels towards the Sun in the coming winter.

Spirit arrived at the north west corner of Home Plate, a raised and layered outcrop on sol 744 (February 2006) after an effort to maximize driving.

The rover made its first drive, a short turn to position targets of interest within reach of the robotic arm, in early November 2006, following the shortest days of winter and solar conjunction when communications with Earth were severely limited.

Named "Zhong Shan" for Sun Yat-sen and "Allan Hills" for the location in Antarctica where several Martian meteorites have been found, they stood out against the background rocks that were darker.

The storms intensified and by July 20, both Spirit and Opportunity were facing the real possibility of system failure due to lack of energy.

NASA released a statement to the press that said (in part) "We're rooting for our rovers to survive these storms, but they were never designed for conditions this intense".

To increase the amount of light hitting the solar panels, the rover was parked in the northern part of Home Plate on as steep a slope as possible.

[30] On November 10, 2008, a large dust storm further reduced the output of the solar panels to 89 watt-hours (320 kJ) per day—a critically low level.

[37] On May 1, 2009 (sol 1892), the rover became stuck in soft sand, the machine resting upon a cache of iron(III) sulfate (jarosite) hidden under a veneer of normal-looking soil.

To 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.

[44] On January 26, 2010 (sol 2155), after several months attempting to free the rover, NASA decided to redefine the mobile robot mission by calling it a stationary research platform.

[45] 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.

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.

[51][52][53] According to NASA, the rover likely experienced excessively cold "internal temperatures" due to "inadequate energy to run its survival heaters" that, in turn, was a result of "a stressful Martian winter without much sunlight."