Mars orbit rendezvous

[4] This allowed the Mars DAV to be launched separately from the transit habitat, and without any crew.

[4] MOR is analogous to Lunar orbit rendezvous (LOR) used on the United States NASA Apollo program missions to Earth's moon during 1969 to 1972, as opposed to Earth orbit rendezvous (EOR) or Direct ascent.

[5] Mars flyby rendezvous was evaluated at NASA's Manned Spacecraft Center in the 1960s.

[5] At that time NASA developed designs for a combination of a Mars lander, short-stay surface habitat, and ascent vehicle called a Mars Excursion Module (MEM); the ascent stage performed the rendezvous.

[5] Compared to MOR, a flyby rendezvous means one spacecraft does not have to orbit Mars.