The rover got stuck in a "sand trap" in late 2009 at an angle that hampered recharging of its batteries; its last communication with Earth was on March 22, 2010.

Aided by cleaning events that resulted in more energy from its solar panels, Spirit went on to function effectively over twenty times longer than NASA planners expected.

[7] On May 1, 2009 (5 years, 3 months, 27 Earth days after landing; 21 times the planned mission duration), Spirit became stuck in soft sand.

[8] This was not the first of the mission's "embedding events" and for the following eight months NASA carefully analyzed the situation, running Earth-based theoretical and practical simulations, and finally programming the rover to make extrication drives in an attempt to free itself.

[10] The rover continued in a stationary science platform role until communication with Spirit stopped on March 22, 2010 (sol 2208).

[11][12] JPL continued to attempt to regain contact until May 24, 2011, when NASA announced that efforts to communicate with the unresponsive rover had ended, calling the mission complete.

Opportunity lasted 55 times longer than its 90 sol planned lifetime, operating for 5498 days from landing to mission end.

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

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.

[23][24] 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.

[25] 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.

[29] It is likely that Spirit experienced a low-power fault and had turned off all sub-systems, including communication, and gone into a deep sleep, trying to recharge its batteries.

If that had happened, the rover would have lost track of time and tried to remain asleep until enough sunlight struck the solar arrays to wake it.

[13][15][30] 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."

On March 22, 2010, Spirit sent its last communication, thus falling just over a month short of surpassing Viking 1's operational record.

Both Spirit and Opportunity have pieces of the fallen World Trade Center's metal on them that were "turned into shields to protect cables on the drilling mechanisms".

[34][35] Solar arrays generated about 140 watts for up to fourteen hours per sol, while rechargeable lithium ion batteries stored energy for use at night.

[43] At the start of the mission the solar panels could provide up to around 900 watt-hours (Wh) per day to recharge the battery and power system in one Sol, but this could vary due to a variety of factors.

[46] Global dust storms in 2007 reduced power levels for Opportunity and Spirit so much they could only run for a few minutes each day.

In late 2005, Spirit took advantage of a favorable energy situation to make multiple nighttime observations of both of Mars' moons Phobos and Deimos.

[57] These observations included a "lunar" (or rather phobian) eclipse as Spirit watched Phobos disappear into Mars' shadow.

Although this resulted in changes to driving techniques, the dragging effect became a useful tool, partially clearing away soil on the surface as the rover traveled, thus allowing areas to be imaged that would normally be inaccessible.

Scientific instruments also experienced degradation as a result of exposure to the harsh Martian environment and use over a far longer period than had been anticipated by the mission planners.

Over time, the diamond in the resin grinding surface of the Rock Abrasion Tool wore down, after that the device could only be used to brush targets.

[62] Documentary film, Good Night Oppy, about the Opportunity, Spirit, and their long missions, was directed by Ryan White, and included support from JPL and Industrial Light & Magic.