Testing of the Mars Exploration Rovers to Survive the Extreme Thermal Environments

NASA's Mars Exploration Rover (MER) project involved delivering two mobile science laboratories (rovers) on the surface of Mars to remotely conduct geologic investigations, including characterization of a diversity of rocks and soils. The rovers were launched separately in 2003 and have been in operation on the surface of Mars since January 2004. The rovers underwent a comprehensive pre-launch environmental assurance program that included assembly/subsystem and system-level testing in the areas of dynamics, thermal, and electromagnetic (EMC), as well as venting/pressure, dust, radiation, and solid-particle (meteoroid, orbital debris) analyses. Due to the Martian diurnal cycles of extreme temperature swings, the susceptible hardware that were mounted outside of the thermal controlled zones also underwent thermal cycling qualification of their packaging designs and manufacturing processes. This paper summarizes the environmental assurance program for the MER project, with emphasis on the pre-launch thermal testing program for ensuring that the rover hardware would operate and survive the Mars surface temperature extremes. These test temperatures are compared with some of the Mars surface operational temperature measurements. Selected anomalies resulting from operating the rover hardware in the Mars extreme thermal environment are also presented.