Reconstruction of the Mars Science Laboratory Parachute Performance and Comparison to the Descent Simulation

Abstract

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 has been reconstructed using data from the on-board 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 (EDL) simulation created to design, develop, and operate the EDL system. Mortar performance was nominal. The time from mortar fire to suspension lines stretch (deployment) was 1.135 s, and the time from suspension lines stretch to first peak force (inflation) was 0.635 s. These times were slightly shorter than those used in the simulation. The reconstructed aerodynamic portion of the first peak force was 153.8 kN; the median value for this parameter from an 8,000-trial Monte Carlo simulation yielded a value of 175.4 kN -14% higher than the reconstructed value. Aeroshell dynamics during the parachute phase of EDL were evaluated by examining the aeroshell rotation rate and 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 EDL simulation was successful in predicting the aeroshell dynamics within reasonable bounds. The average total parachute force coefficient for Mach numbers below 0.6 was 0.624, which is close to the pre-flight model nominal drag coefficient of 0.615.

Parachute Models Used in the Mars Science Laboratory Entry, Descent, and Landing Simulation

“…This paper has described the models to the extent necessary to understand how they work and some of their limitations. In a companion paper, 4 results from a parachute performance reconstruction using Mars flight data for MSL are presented, and compared to some of the parachute models and simulation discussed here. This comparison indicates that the parachute models and simulation provided a reasonable prediction of the parachute system flight behavior on Mars.…”

“…Reconstruction of the MSL flight data 4 indicates that the model over-predicted the deployment time. It is possible to create a model that explicitly took into account the mortar system performance, aeroshell deceleration at mortar fire, and other relevant variables to create a physics-based model that could predict the deployment time more accurately.…”

“…Based on the experience of creating the models described above, implementing them in the simulation, and/or comparing the model predictions to the reconstructed values from the MSL flight data, 4 several improvements to the parachute system models can be suggested. These improvements are described below.…”

Fast computation of the wall distance in unsteady Eulerian fluid‐structure computations

“…The material properties of these two components and the cross‐sectional area of the braided cords are summarized in Table (see also the work of Lin et al). The geometry and finite element (FE) model of this parachute system are based on those of the decelerator system used in NASA's Mars Science Laboratory landing . The canopy has a diameter equal to 15.447 m. It is supported by 80 suspension lines that are 36.578 m long each.…”

“…The geometry and finite element (FE) model of this parachute system are based on those of the decelerator system used in NASA's Mars Science Laboratory landing. 53 The canopy has a diameter equal to 15.447 m. It is supported by 80 suspension lines that are 36.578 m long each. These are assumed here to be fixed at their anchoring point.…”