Reconstruction of the Mars Science Laboratory Parachute Performance

The Mars Science Laboratory used a single mortar-deployed, disk-gap-band parachute of 21.35 m nominal diameter to assist in the landing of the Curiosity rover on the surface of Mars. The parachute system's performance on Mars was reconstructed using data from the onboard inertial measurement unit, atmospheric models and terrestrial measurements of the parachute system. In addition, the parachute performance results were compared against the end-to-end entry, descent, and landing simulation created to design and operate the entry, descent, and landing system. Mortar performance was nominal. The reconstructed aerodynamic portion of the first peak inflation force was 153.8 kN; the median value for this parameter from an 8000 trial Monte Carlo simulation yielded a value of 175.4 kN: 14% higher than the reconstructed value. Aeroshell dynamics during the parachute phase of entry, descent, and landing were evaluated by examining the aeroshell total rotation rate and total rotational acceleration. The peak values of these parameters were 69.4 deg /s and 625 deg /s(2), respectively, which were well within the acceptable range. The entry, descent, and landing simulation was successful in predicting the aeroshell dynamics within reasonable bounds. The average parachute total force coefficient for Mach numbers below 0.6 was 0.636, which is close to the preflight model nominal drag coefficient of 0.615.