Parachutes and inflatable structures: Parametric comparison of EDL systems for the proposed vanguard Mars Mission

Vanguard is a proposed post-Beagle2 mission to Mars focussed on astrobiology, but also on technology demonstration [1]. The 120 kg probe is assumed to use a Mars-Express- type bus to land a triad of robotics comprising a lander, a rover and 3 penetrating moles. The landed mass is around 65 kg. The mission is baselined to be low-cost with limited power and mass requirements to be accommodated as a secondary payload on a future mission to Mars [2]. Here the Entry, Descent and Landing system (EDLS) is investigated comparing conventional methods (hard heatshield/Parachute) to current new developments in inflatable entry structures as demonstrated by missions such as IRDT and IRDT2. Two systems are designed to provide an understanding of EDLS requirements in term of masses and volumes to land a small probe safely on Mars. Preliminary results [3] show that, despite the heritage, a conventional approach is heavier than inflatable technologies. Indeed, in this particular case, a margin of about 15 % is derived in favour of the inflatable system. For a constant-mass probe, this means that the mass is saved from the EDLS to the benefit of the payload. Moreover, despite having a larger range, and longer descent, in this case the inflatable option has in this case a wind gust sensitivity comparable to the parachute option