This image shows the Multi-Mission Radioisotope Thermoelectric Generator for NASA'S Mars 2020 Perseverance rover during a fit check with the rover in the payload processing facility at NASA's Kennedy Space Center in Florida on April 16-17, 2020.
The Multi-Mission Radioisotope Thermoelectric Generator is designed and built by the U.S. Department of Energy, and provided to NASA as part of the space agency's Radioisotope Power Systems Program. It arrived at NASA KSC in April 2020 following its final assembly and transport from the Department of Energy's Idaho National Laboratory. The fit check is the first time that the fueled flight generator is connected to the rover. After the successful fit check, the Multi-Mission Radioisotope Thermoelectric Generator was disconnected; it will be connected to the rover for the final time on the launch pad atop the mission's Atlas V launch vehicle in July, before the planned launch of the Mars 2020 mission.
The Multi-Mission Radioisotope Thermoelectric Generator is a space nuclear power system that produces about 110 watts of electrical power to run the rover's systems and science instruments, and extra heat to keep them warm during the frigid Martian nights and winter seasons. It converts the heat from the natural radioactive decay of plutonium dioxide into electricity using thermocouples with no moving parts. The choice of a Multi-Mission Radioisotope Thermoelectric Generator as the rover’s power system gave mission planners significantly more flexibility in selecting the rover's landing site and in planning its surface operations.