Many people who have followed the adventures of the solar powered Mars rover duo Spirit and Opportunity, have become quite attached to the contraptions and have enthusiastically cheered them on – but a sense of doom hangs in the air for Spirit.
While Spirit has rebounded from many setbacks, defying the hostile conditions even after sustaining quite serious "injuries", its days may now really be numbered.
Spirit has stalled twice in recent weeks and one of its rear wheels is still bogged down after the latest incident.
If Spirit remains stuck when winter strikes six months from now, the rover could freeze to "death". In previous winters, Spirit rested on slopes that faced towards the sun, allowing for enough power to be generated to keep internal mechanisms from freezing over. Its current position is less than favourable and dust is building up on its solar panels.
The solar panel arrays on Spirit and Opportunity originally generated around 140 watts of power for up to four hours per sol (a Martian day), 40 watts per hour more than what is needed to drive the vehicles. Energy storage is in the form of two rechargeable lithium ion batteries weighing just over 7kg each.
Slated to only last three months, the rovers have lasted nearly five years; an incredible achievement.
While Spirit’s possible demise is being greeted with much sadness, Opportunity battles on and is currently investigating the rock known as "Marquette Island." On Sol 2079 (Nov. 28, 2009), Opportunity’s solar panel energy production was 360 watt-hours for the day. At that point, the rover had travelled nearly 19 kilometres during its long mission.
On the same date, Spirit’s solar array energy production was 316 watt-hours and had travelled a total of 7.7 kilometres.
NASA hasn’t given up hope on Spirit and you can follow their efforts in NASA’s Free Spirit special coverage.
