Mars Excursion Module

[1] A MEM formed part of Mars orbit rendezvous (MOR) and flyby-rendezvous mission profiles studied at NASA's Manned Spacecraft Center in the 1960s.

The Mars-bound vehicle was designed to weigh approximately 3.97 million kg in a 323 km parking orbit, with a trans-Mars injection (TMI) burn scheduled for May 1986.

After a 200-day journey, the ROMBUS would enter a 555 km orbit around Mars, with a reduced mass of 984.75 tons after jettisoning empty fuel tanks.

[3] This ruled out many of the lifting body and glider designs that were being considered based on estimates of a thicker Mars atmosphere than revealed by Mariner IV.

[3] Gordon Woodcock at the NASA Marshal Space Flight Center worked on the basis of a thinner Mars atmosphere (0.5 percent of Earth's), and developed design for a MEM (a more Apollo-like "gumdrop" style design), and also a pure-lander variant that would deliver a pressurized crewed Mars rover called Molab.