Mars DRA 5.0: “7-Launch” NTR Mission Overview

The 7-Launch NTR Mars mission strategy (Ref. 9) for a 2033 human landing mission is illustrated in Figure 5. It assumes a long surface stay, split cargo/piloted mission approach. Two cargo flights predeploy a cargo lander to the surface and a habitat lander into Mars orbit where it remains until the arrival of the crew on the next mission opportunity (~26 months later). The cargo flights utilize “1-way” minimum energy, long transit time trajectories. Four HLV flights carried out over 90 days (~30 days between launches), deliver the required components for the two cargo vehicles. The first two launches deliver the NTR propulsion stages each with three 25 klbf NTR engines. The next two launches deliver the cargo and habitat lander payload elements which are enclosed within a large triconic-shaped aeroshell that functions as a payload shroud during launch, then as an aerobrake and thermal protection system during Mars aerocapture (AC) and subsequent entry, descent and landing (EDL) on Mars. Vehicle assembly involves Earth orbit rendezvous and docking (R&D) between the propulsion stages and payload elements with the NTR stages functioning as the active element in the R&D maneuver.

[Figure: Figure 5.—DRA 5.0 long-stay Mars 2033 mission overview: “7-launch” NTR strategy.]

Once the operational functions of the orbiting habitat and surface cargo landers are verified, and the Mars Ascent Vehicle (MAV) is supplied with ISRU-produced ascent propellant, the crewed MTV is readied and departs on the next mission opportunity. The baseline Copernicus design is capable of 1-way transit times ranging from ~150 to 220 days depending on the particular opportunity. For the 2033 mission, 150-day transit times are possible. Like the cargo MTVs, Copernicus is assembled in LEO using Earth orbit R&D. It uses the same “common” NTPS but includes additional external radiation shielding on each engine for crew protection during engine operation. Three HLV launches over 60 days are used to deliver the vehicle’s key elements which include: (1) the NTPS; (2) the integrated “saddle truss” and LH2 drop tank assembly; and (3) the crewed payload. The payload element includes the TransHab module with its six crew, the Orion MPCV for vehicle-to-vehicle transfer and “end of mission” re-entry, a secondary T-shaped DM, a contingency consumables container and connecting structure. Four 12.5 kWe/ 125 m2 rectangular PVAs provide ~50 kWe of electrical power at Mars for crew life-support (~30 kWe), a ZBO Brayton cryocooler system (~10 kWe), and high data- rate communications (~10 kWe) with Earth.
When assembly is completed, the Mars crew is delivered to LEO on either the SLS or a commercial launch vehicle and docks with Copernicus on its underside using the secondary DM that connects the TransHab crew module and contingency consumables container (shown in Figs. 6 and 7). Following the TMI maneuver, the drained LH2 drop tank, attached to the saddle truss, is jettisoned and the crewed MTV coasts to Mars under 0-gE conditions with its four PVAs tracking the Sun. Attitude control and mid-course correction maneuvers are provided by Copernicus’ split RCS that uses 200 lbf storable bipropellant Advanced Material Bipropellant Rocket (AMBR) thrusters located on the rear NTPS and the short saddle truss forward adaptor ring just behind the TransHab module. After the MOC burn, Copernicus rendezvous with the orbiting Hab lander using engine cool-down thrust and the vehicle’s RCS. The crew then transfers over to the lander using the MPCV. After crew transfer, the MPCV returns and docks to the TransHab autonomously. The crew then initiates EDL near the cargo lander and begins the surface exploration phase of the mission. After ~592 days on the surface, the crew lifts off using the MAV and returns to Copernicus using its secondary DM (shown in Fig.

[Figure: Figure 6.—Copernicus’ secondary DM provides access to the MPCV and MAV during the mission.]