Human Exploration Missions to Phobos Prior to Crewed Mars Surface Missions

Phobos is a scientifically interesting destination which offers engineering, operational and public outreach activities that could enhance subsequent Mars surface missions. A Phobos mission would serve to facilitate the development of the human-based Mars transportation infrastructure, unmanned cargo delivery systems, as well as habitation and exploration assets that would be directly relevant to subsequent Mars surface missions. It would also potentially provide for low latency teleoperations (LLT) of Mars surface robots performing a range of tasks from landing site validation to infrastructure development to support future crewed Mars surface Missions. A human mission to Phobos would be preceded by a cargo predeploy of a Phobos surface habitat and a pressurized excursion vehicle (PEV) to Mars orbit. Once in Mars orbit, the habitat and PEV would spiral to Phobos using solar electric propulsion (SEP)-based systems. When a crewed mission is launched to Phobos, it would include the remaining systems to support the crew during the Earth-to-Mars orbit transit and to reach Phobos after insertion into a high Mars orbit (HMO). The crew would taxi from HMO to Phobos in a spacecraft that is based on a MAV to rendezvous with the predeployed systems. A predominantly static Phobos surface habitat was chosen as a baseline architecture. The habitat would have limited capability to relocate on the surface to shorten excursion distances required by the PEV during exploration and to provide rescue capability should the PEV become disabled. PEVs would contain closed-loop guidance and provide life support and consumables for two crewmembers for two weeks plus reserves. The PEV has a cabin that uses the exploration atmosphere of 8.2psi with 34% oxygen. This atmosphere enables EVA to occur with minimal oxygen prebreathe before crewmembers enter their EVA suits through suit ports, and provides dust control to occur by keeping the suits outside the pressurized volume. When equipped with outriggers, the PEV enables EVA tasks without the need to anchor. Tasks with higher force requirements can be performed with PEV propulsion providing the necessary thrust to counteract forces. This paper overviews the mission operational concepts, and timelines, along with analysis of the power, lighting, habitat stability, and EVA forces. Exploration of Phobos builds heavily on the development of the cis-lunar proving ground and significantly reduces Mars surface risk by facilitating the design, development and testing of habitats, MAVs, and pressurized rover cabins that are all investments in Mars surface assets.