Copernicus “Split Crewed Mission” Option for Achieving 100—90-day Transit
Times

Copernicus-3a is a large complex vehicle that requires eight launches to deliver the various elements to LEO. From the initial launch of the NTPS until the last drop tank is attached to the star truss (via orbital assembly) could take ~7 months assuming 30 days between SLS/HLV launches. Failure to deliver the elements on time and in the prescribed order could delay vehicle assembly and jeopardize mission departure within the specified launch window. Using the Copernicus-2 spacecraft plus its three key components—the NTPS, in-line tank and integrated saddle truss/drop tank assembly—now configured as an Earth Return Vehicle (ERV), a “split crewed mission” architecture can be utilized that can reduce vehicle size and complexity, eliminate the need for orbital assembly and an extra engine, and can achieve transit times as low as 90 days. Use of a pre-deployed ERV is not a new idea. In NASA’s DRM 1.0 study in 1993 (Ref. 22), the ERV was one of the key transportation system elements used in the mission architecture. The split crewed architecture for very fast 1-way transit missions is outlined in Figure 13. Using the Copernicus-2 spacecraft plus an ERV, a 2033 landing mission would require a round trip time of ~857 days with ~667 days spent in Mars orbit and on the surface. The outbound transit time on Copernicus-2 is 100 days and the inbound transit time using the ERV is 90 days. In this split mission, the ERV is pre-deployed to Mars orbit in advance of the crew. It departs from LEO in December 2030 (departure C3 ~10.794 km2/s2, VTMI ~3.662 km/s), on a 283-day “minimum-energy” trajectory out to Mars. The ERV then arrives at Mars (arrival Vinf ~3.480 km/s) and propulsively captures into a 24-hr elliptical Mars orbit (~250 by 33,793 km, VMOC ~1.34 km/s) in October 2031 where it remains until the crewed Copernicus-2 MTV arrives during the next opportunity ~26 months later. Copernicus-2 departs LEO with its four crew on May 25, 2033 and arrives at Mars 100 days later. It then captures into the same parking orbit as the ERV on September 2, 2033. In the process, Copernicus-2 uses up ~97 percent of its available propellant. To return to Earth, Copernicus-2 rendezvous with the ERV and the forward crewed PL element is switched over to the ERV (shown in Fig. 13). No propellant transfer is required just a R&D maneuver. The reconfigured ERV then rendezvous with the orbiting Hab lander, followed by crew transfer, then EDL near the cargo lander at which point the surface exploration phase of the missions begins. After ~653 days on the surface, the crew lifts off using the MAV and returns to the ERV. Following the transfer of the crew and samples, the MAV is jettisoned. Before leaving Mars orbit, the crew finally jettisons the exterior consumables container and connecting tunnel from the PL element to reduce vehicle mass and propellant consumption. The ERV then performs the TEI burn on July 1, 2035 and begins the 90-day transfer back to Earth. On the final approach to Earth, the ERV does a final slowdown burn (V ~2.257 km/s) after which the crew separates and re-enters using the Orion MPCV capsule. The ERV flies past Earth at a sufficiently high altitude and is disposed of into heliocentric space.

[Figure: Figure 13.—Copernicus-2 MTV and components configured for a very fast split crewed mission.]