The Spirit was lost in 2010, six years after landing, after getting stuck on flat ground in the middle of the Martian winter, leaving the Opportunity the sole survivor of the family.
In June 2018, a planet-wide dust storm the size of which NASA had a hard time to remember ever seeing buried Opportunity’s changes of having access to sunlight to recharge its batteries. The storm and its effects lasted long enough to make the rover enter minimal operations mode and cease all communications with Earth.
For several months now, NASA has been trying to get through to the rover by all means necessary. Engineers are sending commands and listening to possible responses several times a day, but with no success.
In a plan announced late last year, NASA said it will abandon efforts to save the rover if it does not respond by the end of January 2019.
“We are doing everything in our power to communicate with Opportunity, but as time goes on, the probability of a successful contact with the rover continues to diminish," said in a statement John Callas, project manager for Opportunity.
The two Mars rovers are six-wheeler, solar-powered vehicles. They weigh 180 kg and use a rocker-bogie suspension system that allows each of the wheels to remain attached to the ground, regardless of the type of terrain.
Top speed of the vehicles is 50 mm/second (0.18 km/h), making them the slowes self-propelled vehicles ever made by man. In the 15 years it has spent on Mars, Opportunity traveled 45 kilometers (28 miles, or 3.2 km per year.