NASA’s Perseverance rover was successfully placed on the surface of Mars on February 18, 2021. On that date, the rover began to explore Mars. One of the crucial technologies on board the protective aeroshield that helped document the spacecraft’s entry, descent and landing (EDL) is MEDLI2. All MEDLI2 data has been stored in Perseverance for transmission to Earth after a successful landing.
MEDLI2’s job was to collect critical data on the environment during entry into the planet’s atmosphere. The system had three types of sensors, including thermocouples, heat flow sensors and pressure transducers. These sensors are designed to measure extreme heat and pressure during entry.
The system also had electronics and hardware to record thermal and pressure loads experienced during the entry and launch of the parachute. MEDLI2 used collected measurements to determine the heating and atmospheric forces that occurred in the heat shield and the back layer. Together, these components formed the aeroshell that housed and protected the Perseverance rover while traveling to Mars and EDL.
The mission controllers triggered MEDLI2 five hours before the rover started to descend to the surface of Mars, known as “7 minutes of terror”. Turning on the systems five hours before entry allowed the electronic components to stabilize the temperature and measure internal conditions before entry. The system was successfully activated and the team was able to monitor the input data over the five-hour shore phase prior to entry.
Most of the sensors and primary electronic components were mounted on the Mars 2020 heat shield. About 10 seconds after the supersonic parachute was launched, MEDLI2 was shut down for the last time with its work completed. MEDLI2 systems were switched off a few seconds before the heat protector separated to prevent potential energy problems from occurring. Three days after a successful landing, all remaining MEDLI2 data was transmitted back to Earth. The researchers are currently working on data analysis and performance reconstruction operations.