High Mass Mars Entry, Descent, and Landing Architecture Assessment

Abstract

As the nation sets its sight on returning humans to the Moon and going onward to Mars, landing high mass payloads ( 2 t) on the Mars surface becomes a critical technological need. Viking heritage technologies (e.g., 70 sphere-cone aeroshell, SLA-561V thermal protection system, and supersonic disk-gap-band parachutes) that have been the mainstay of the United States’ robotic Mars exploration program do not provide sucient capability to land such large payload masses. In this investigation, a parametric study of the Mars entry, descent, and landing design space has been conducted. Entry velocity, entry vehicle conguration, entry vehicle mass, and the approach to supersonic deceleration were varied. Particular focus is given to the entry vehicle shape and the supersonic deceleration technology trades. Slender bodied vehicles with a lift-to-drag ratio (L=D) of 0.68 are examined alongside blunt bodies with L=D = 0.30. Results demonstrated that while the increased L=D of a slender entry conguration allows for more favorable terminal descent staging conditions, the greater structural eciencies of blunt body systems along with the reduced acreage required for the thermal protection system aords an inherently lighter vehicle. The supersonic deceleration technology trade focuses on inatable aerodynamic decelerators (IAD) and supersonic retropropulsion, as supersonic parachute systems are shown to be excessively large for further consideration. While entry masses (the total mass at the top of the Mars atmosphere) between 20 and 100 t are considered, a maximum payload capability of 37.3 t results. Of particular note, as entry mass increases, the gain in payload mass diminishes. It is shown that blunt body vehicles provide sucient vertical L=D to decelerate all entry masses considered through the Mars atmosphere with adequate staging conditions for the propulsive terminal descent. A payload mass fraction penalty of approximately 0.3 exists for the use of slender bodied vehicles. Another observation of this investigation is that the increased aerothermal and aerodynamic loads induced from a direct entry trajectory (velocity 6.75 km/s) reduce the payload mass fraction by approximately 15% compared to entry from orbital velocity ( 4 km/s). It should be noted that while both IADs and supersonic retropropulsion were evaluated for each of the entry masses, congurations, and velocities, the IAD proved to be more mass-ecient in all instances. The sensitivity of these results to modeling assumptions was also examined. The payload mass of slender body vehicles was observed to be approximately four times more sensitive to modeling assumptions and uncertainty than blunt bodies.