Results from the Mars Science Laboratory parachute decelerator system supersonic qualification program

In 2010 the Mars Science Laboratory (MSL) Mission will deliver the most massive and scientifically capable rover to the surface of Mars. To deliver this payload, an aerodynamic decelerator is required to decelerate the entry vehicle from supersonic to subsonic speeds, in advance of propulsive descent and touchdown on Mars. The aerodynamic deceleration will be accomplished by a mortar-deployed 21.5-m Viking-type disk-gap-band parachute (DGB), and will be the largest extra-terrestrial decelerator in the history of space exploration [1]. The parachute will deploy at up to Mach 2.2 and 750 Pa, resulting in the highest load and speed experienced by a parachute on Mars. The MSL parachute extends the envelope of the existing heritage deployment space in terms of load, size and Mach number. This has created the challenge of leveraging the existing heritage supersonic-high-altitude database, implementing a ground-based qualification program, and quantifying known aerodynamic instabilities associated with supersonic operation in the Mach regime of the MSL deployment. To address these challenges MSL has embarked upon a physics-based modeling and validation program to explore the fundamental physics associated with DGB-parachute operation in supersonic flow. The functional dependence of parachute performance and stability on Mach number, Reynolds number, parachute size, entry-vehicle size and parachute to entry vehicle proximity, is under investigation. The quantitative understanding garnered from this analytical effort will be used to leverage the existing heritage database of the Viking Lander, Viking Balloon Launched Decelerator Test (BLDT), Mars Pathfinder (MPF) and Mars Exploration Rover (MER) programs for the larger scale, deployment conditions, and modern construction techniques of the MSL parachute system. The physics-based modeling and validation effort includes the development of a coupled fluid and structural solver, i.e. fluid-structure-interaction code, and supersonic wind-tunnel experiments with subscale representations of the flight configuration.