INVESTIGATION OF THE FEASIBILITY OF USING A FLEXIBLE AEROBRAKE FOR MARS ENTRY

The feasibility of using a flexible aerobrake is investigated numerica lly for two baseline Mars missions, Mars Rover and Sample Return (MRSR ) and Mars Environmental Survey (MESUR). Flexible aerobrakes construct ed of an insulating fabric are used to aerodynamically decelerate a pa yload from orbit onto the surface of Mars, which saves a considerable mass fraction over the use of chemical propulsion. The MRSR mission us es an aerobrake to transfer a lander from low Mars orbit to the surfac e of the planet. Viking data, experimental results, and inviscid flowf ield computations were used to estimate the performance of the aerobra ke. For MRSR, aeroheating was not found to be an issue, so emphasis wa s placed on validating aerodynamic performance. The MRSR mission requi rements dictated a much lower entry speed and therefore a more benign environment than for the MESUR mission and can easily be accomplished with present day materials. The MESUR mission uses the aerobrake to de celerate a lander from an inbound hyperbolic trajectory directly down to the surface with no intervening parking orbit. The MESUR mission is more aerothermodynamically stressing than the MRSR mission, prompting an investigation into the viscous real gas aeroheating. Viscous equil ibrium chemistry flowfield computations performed for the MESUR aerobr ake design show high heating rates and considerable flow separation. T his is a complex design problem and may not be feasible with today's m aterials.