AERODYNAMIC REQUIREMENTS OF A MANNED MARS AEROBRAKING TRANSFER VEHICLE

In this investigation, entry corridor analyses are performed to identify the aerodynamic requirements of a manned Mars aerobraking transfer vehicle. The major emphasis is on identifying the required aerobrake hypersonic lift-to-drag ratio (L/D) to insure a successful aerocapture. Aerobraking entry requirements are also imposed on a set of interplanetary mission opportunities to demonstrate their effect on mission flexibility. The entry corridor analyses are performed with the use of an adaptive atmospheric guidance algorithm that utilizes bank-angle modulation to relieve the high deceleration loads characteristic of interplanetary aerocapture and maximize the width of the flyable entry corridor. Based on the requirements of a 1-deg corridor width, deceleration into a parking orbit with an apoapsis altitude of 33,640 km, and a 5-g deceleration limit, this analysis has shown that a manned Mars aerobrake characterized by an L/D of at least 1.5 is required for entry velocities as high as 10.0 km/s. If Mars entry is limited to velocities below 8.5 km/s, a minimum L/D of 0.5 is required; over a very limited entry velocity range, an aerobrake with L/D of 0.3 is feasible. Limiting the Mars entry velocity to values below 8.5 km/s is shown to induce a minor restriction on mission flexibility while alleviating aerothermodynamic and vehicle packaging concerns; hence, Mars entry velocities in the range of 6.0-8.5 km/s are suggested, and a manned Mars aerobrake characterized by an L/D between 0.3 and 0.5 is recommended.