What is it about?

The Mars InSight program accomplished a successful landing on the surface of Mars on November 26, 2018. This program utilized several Viking-era technical approaches in support of this achievement including its Entry, Descent, and Landing (EDL) architecture comprised of a 70-degree sphere-cone aeroshell, a supersonic Parachute Decelerator System (PDS), and landing thrusters for terminal descent. The PDS consisted of a mortar deployed, 11.8 m diameter Viking-type Disk Gap Band (DGB) parachute that utilized slightly different materials and construction techniques than that of the nearly-identical Mars Scout Phoenix (PHX) PDS. Mortar fire was initiated at an IMU-derived dynamic pressure and Mach number. This was followed by rapid inflation of the parachute that resulted in a peak inflation load well below the permissible flight maximum. Prior to the EDL, a Monte Carlo analysis was performed to predict the “nominal” and expected range in performance of various aspects of the PDS including: time from mortar fire to line stretch, parachute inflation time and inflation profile, and peak inflation load. Similar to recent Mars missions, the IMU data acquisition sampling rate was sufficiently high to enable accurate reconstructions to be made of the entire parachute descent stage. This paper explores the key aspects of the PDS and its differences with PHX system, discusses details of the PDS performance based upon the returned data, and describes current best estimates for: mortar deployment subsystem performance, parachute inflation time and inflation profile, peak parachute inflation load, and drag performance. Pre-EDL simulations are also discussed, most of which compared favorably to the returned flight performance data.

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Why is it important?

Checking how a system performs on a single-use mission, especially when the returned data is of high quality, helps future mission designers understand what they can and cannot do with this type system.

Perspectives

This particular mission was perhaps bittersweet for the author Witkowski, as it was likely his last mission as a program manager and his last in collaboration with the excellent team who produced so many successful planetary probe decelerator systems.

Al Witkowski
Katabasis Aerospace, LLC

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This page is a summary of: Mars InSight Parachute System Performance, June 2019, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/6.2019-3481.
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