Aerobraking Challenges for a Combined Mars Orbiter and Lander in 2018

ESA and NASA had been working on a pair of joint missions to Mars: a 2016 orbiter and a 2018 lander. Budget pressures associated with the cost of two NASA supplied launch vehicles triggered a study into what might be achieved with a single launch in 2018. The combined conceptual mission consisted of a lander plus a relay orbiter. The lander would be dropped off a few days before a direct entry at Mars, while the periapsis of the orbiter would then be raised to 500 km before a propulsive capture into a 4 sol orbit. The orbit period would be propulsively reduced to 1 sol before starting an Aerobraking phase that would circularize the orbit into a 400 km orbit. This paper will describe the Aerobraking challenges associated with the low inclination orbit dictated by the requirement to provide a relay link to the co-manifested lander during the Mars Orbit Insertion burn coupled with the very tight propellant budget associated with the launch of two spacecraft on a single vehicle.