The transit habitat was located centrally in the aerobrake with an external airlock and an MCRV attached to the top (an Apollo-style ECCV was used to represent the MCRV). The airlock allowed access to the MEV crew cab and surface habitat during all phases of the transfer mission until the MEV separation 50 days prior to Mars arrival.
The MCRV was used for mission scenarios featuring direct-entry crew return; these scenarios expended the entire MTV upon return to Earth. In a reusable mode, the entire MTV would be aerocaptured back at Earth for refurbishment and re-use; a second airlock would be located in place of the MCRV. The aerobrake was of identical geometry and construction as the MEV aerobrake, but was stronger and heavier due to its larger payload mass, and did not require any engine doors. The propulsion system (TEI) was divided symmetrically into two tank-stacks swaddling the transit habitat), like the MAV tank set configuration.
The propulsion system was oriented at an angle relative to the aerobrake axis, with the two engines aimed out the rear of the aerobrake, to avoid TPS penetrations while still permitting mass-balanced operation during the burn.
Mass breakdown was as follows:
Crew Size: 4.
Gross mass: 163,700 kg (360,800 lb).
Span: 30.00 m (98.00 ft).