Technologically and financially the concept remains conservative, with both peak yearly and total funding to be less than the ISS up to the first mission. The plan would use standardized systems to launch a crew of 4 every four years, but accomplish the same major goals as DRA 5.0, which included a crew of six. Scaled down from DRA 5.0 and its requirements, it claims to be still acceptable from a science and exploration standpoint. Simplifications and cost cutting are obtained mainly by avoiding high risk or high cost technology development and maximizing development and production commonality:
Using a blunt-body entry vehicle having no deployable decelerators
Aerobraking rather than aerocapture for placing the crewed element into low Mars orbit
Mars Transit Habitat, takes the crew to Mars orbit and stays there until a crew returns, shielded against radiation, supports a crew of four for up to three years
Mars descent/ascent vehicle, takes the crew from the orbit down to Mars surface and vice versa
Contingency Consumables Module, can be jettisoned if depleted
Mars surface habitat, where the crew lives on the planet, transferred once in advance
Surface Power and Logistics Module, transferred once in advance to provide basic surface machinery
Procedures
A standardized liquid oxygen/liquid hydrogen propulsive stage, like Ares V or its follower SLS Block 2, would send the Descent/Ascent Vehicle, Mars Surface Habitat and Cargo elements to Mars orbit uncrewed. The DAV would aerocapture into Mars orbit, preparing it for rendezvous with the manned Transit Habitat to arrive later. The Surface Habitat and Cargo would likely do direct entry. One advantage of the combined Descent/Ascent Vehicle as the spacecraft used for the manned landing, is that it could perform an abort to orbit. A number of technologies for the descent stages were looked at, especially supersonic retro-propulsion for Mars atmospheric entry, but were otherwise very traditional with a large heat shield and retro rockets for final landing. Some concepts for the Surface Habitat include an inflatable structure and using the descent propellant tanks for waste storage. Estimated Mass of the Surface Habitat in the study was 52 metric tons. The Power/Logistics lander had the same predicted Mass. The Power/Logistic module would contain 2 Pressurized Rovers, with space for 2-Crew each. The pressurized rovers would be powered by a 5 kilowatt Stirling radioisotope generator on each rover. The P/L module would also include 2 mobile generators for surface power, as well as additional consumables and science equipment. The surface habitat would have two 5 kilowatt radioisotope Stirling generators and an ISRU oxygen generator. Unlike DRA 5.0 or Mars Direct however, In-situ resource utilization would not be used to produce propellent for the ascent into Mars orbit. After remote controlled deployment of this equipment on Mars, the Transit Habitat would carry the crew to the planet where it docks with the pre-sent MAV. The MAV lands on the surface where the crew lives in the habitat supported by the power and logistics module. After finishing their research they use the ascent vehicle to return to the Mars Transit Habitat, see alsoMars Orbit Rendezvous. It brings them back to earth orbit, from where they return to the surface with the Orion spacecraft.
