| Popis: |
In the frame of the Mars Sample Return mission a preliminary design has been performed in the context of ESA-Aurora program in which a circular orbit around Mars is proposed for the orbiter vehicle. The orbiter and the Mars Ascent Vehicle (MAV) will carry out autonomous rendezvous operations in this orbit to transfer the collected sample from one vehicle to the other. The choice for the circular orbit has been derived from the existing European technology for autonomous rendezvous operations that have been studied and developed since the late eighties. However, it appears worth to investigate also the elliptical orbit scenario for several advantages provided to the overall mission design. Of crucial importance is the benefit, on the mission mass budget, deriving from this choice leading to save 1000 kg mass with respect to the circular scenario. This amount results from the cascade effect that the saved ΔVs (on three of the most demanding maneuvers) have on the overall mass budget and represents 25% of the current orbiter mass defined for the circular scenario. In this paper they are presented and detailed most of system and GNC concepts defining the elliptical scenario option for Mars Sample Return (MSR) mission. Special emphasis is put on the following issues: mission analysis aspects and orbit characterization, MAV ascent trajectory optimization, approach phase definition, terminal rendezvous phase design. GNC system is also addressed for the Terminal RendezVous phase assuming autonomous operations between the chaser (Orbiter) and Target (MAV) vehicle based on optical navigation sensors such as a Lidar and a Camera. |
