Mars Entry, Descent, and Landing Instrumentation 2 Trajectory, Aerodynamics, and Atmosphere Reconstruction

Abstract

On February 18th, 2021, the Mars 2020 entry system successfully delivered the Perseverance rover to the surface of Mars at Jezero Crater. The entry capsule carried a set of instrumentation installed on the heat shield and backshell, named the “Mars Entry, Descent, and Landing Instrumentation 2.” The instruments include pressure transducers, thermocouples, heat flux gauges, and radiometers to measure the aerodynamic and aerothermodynamic performance of the entry vehicle. This paper describes the trajectory and atmosphere reconstruction results based on the pressure sensor measurements. The process uses a Kalman filter approach to estimate the freestream atmospheric properties from the pressure measurements combined with a model of the pressure distribution of the heatshield and other sensor inputs, including an inertial measurement unit and other on-board navigation sensors, and several external atmospheric observations. The results indicate that the upper altitude density was up to 150% higher than nominal, which is consistent with the observed early entry guidance start time. The density below 40 km was within 12% of the preflight predictions. The reconstructed axial force coefficient was approximately 2% lower than the preflight prediction across the flight range.

Scientific Instrumentation Complex for the ExoMars-2022 Landing Platform

“…Density values for the upper atmosphere can vary many-fold from models, and it is not surprising that more than two-thirds of landings on Mars have failed. We know 11 atmospheric profiles measured during descent: Mars-6 (Avduevsky et al, 1975); VL-1, -2 (Seiff and Kirk, 1977); Mars Pathfinder (Magalhães et al, 1999); Mars Exploration Rovers (MER) Opportunity and Spirit (Withers and Smith, 2006); Phoenix (Blanchard and Desai, 2011); Mars Science Laboratory (MSL) (Holstein-Rathlou et al, 2016);ExoMars-2016Schiaparelli (Aboudan et al, 2018; InSight (Karlgaard et al, 2021) and Perseverance (Karlgaard et al, 2023). To reconstruct the descent profile, the ExoMars-2022 project included measurements of the deceleration of the descent capsule using data from the spacecraft's inertial unit, the AMELIA experiment (Ferri et al, 2019), and with MTK accelerometers.…”