SPACE IN MINIATURE

NASA planning in the 1960's envisioned a nuclear propelled ship entering Mars orbit and deploying a Mars Excursion Module (MEM) for a manned landing. Mission planning determined that a landing as early as 1982 would be possible.

Late 60's feasibility studies envisioned a Mars Excursion Module as a large 10 meter diameter version of the Apollo CM. This was used by North American Rockwell to simplify their Mars entry design. Paul Hudson's painting "Humans on Mars" illustrates a more evolved biconic design, with a large boat tail for better storage of propellants and equipment.

My version is 10 meters in diameter, and 11.3 meters tall, with an aft boat tail, as shown in Hudson's artwork. The boat tail would increase the internal volume for fuel, cargo, and a habitat/laboratory, compared to a pure cone. The parallels between this design and the Apollo Command Module and Lunar Module are many.

The MEM would carry four astronauts to the Martian surface in the silver Ascent Module. The Ascent Module has upward pointing windows for rendezvous and docking, and large side pointing windows for the pilots during landing.

During descent from orbit, a retro-pack would deorbit the lander, then be jettisoned. The large heat shield would protect the craft during atmospheric entry and then be jettisoned, freeing the folded landing legs and landing radar. A drogue parachute would further slow and stabilize the craft below Mach 1. At 10,000 feet altitude the drogue would be released and the descent engine would fire for the final descent. Two astronauts would climb from couches and take their places at the descent windows for the terminal phase of piloted control. Men would arrive on Mars.

After landing the astronauts would descend to the Habitat/Laboratory buried in the Descent Module. The Hab/Lab would provide living quarters and life support for a thirty-day stay, plus an airlock and small laboratory to study Martian samples.

The Descent Module would also carry a rover in a large equipment bay. Other storage bays would be accessible to astronauts on EVA for Mars surface experiments and equipment.

Early designs had six landing legs folded into the heat shield. Here the landing gear was reduced to four for a wider stance and reduced development cost. Compressible honeycomb struts and a wide stance would allow landing on a variety of rough surfaces.

After the thirty-day stay, the astronauts would load their samples and films into the Ascent Stage for ascent to orbit. A stage-and-a-half design, eight conical fuel tanks would be dropped after being drained, then the ascent engine would draw on internal tanks for final orbit insertion. Docking with the orbital Mars ship would follow for a nine-month trip back to Earth.

The Model

The lander body is made from a shortened plastic gasoline funnel. The boat tail is made of plywood bulkheads, covered with styrene skins. The Ascent Stage crew compartment is made from styrene sheet rolled into a cone.

The landing legs are made of brass and aluminum tubing. The spreader bars used paper clip wire to brace the legs to the descent stage. The landing pad is a 22 mm diameter button, covered in gold foil. The legs were detailed with copper candy foil. An HO gage ladder allows transfer from airlock to surface.

The airlock door is styrene, detailed with styrene strips and a staple for a handle. The rover ramp used styrene strip and sheet. The communication antenna is a plastic bubble from a Solo drink lid. Mounted on an extendable Astromast of wire and foil, it took an entire afternoon to build. A small stowage bay left of the ladder is open for access by EVA astronauts. It is loaded with surface tools, and is covered in gold foil.

The RCS thruster modules were wood and plastic. The 16 thrusters were turned from wood, painted and glued into a Water Putty filled plastic bubble, then covered with ultra bright Bare Metal Foil. The toughest part was making all 16 thrusters the same! Each is painted black inside, and silver outside.

Ultra bright Chrome Bare Metal Foil covers the boat tail and ascent stage. Gold Mylar gift wrap covers the descent/habitat structure. I used spray photo adhesive to glue the Mylar to the funnel. The glue went on in clumps, giving a small-scale wrinkled appearance to the Mylar, similar to real multi-layer insulation.

A paper US flag and "United States" were applied to the Descent and Ascent Stages using permanent glue stick.

A base with scratch built astronauts and rover was also built to display the MEM with exploration in progress. The base is plywood, covered in Syrofoam pieces covered with a painted layer of Durham's Water Putty. Assembled, the MEM stands 4 5/8 inches tall.

Sources:

• Definition of Experimental Tests for a Manned Mars Excursion Module: Final report, Vols I-IV, plus Briefing Brochure; North American Corporation Space Division; Jan.12, 1968 (courtesy of David Portree)
• David Portree; Humans to Mars - Fifty Years of Mission Planning; NASA SP-2001-4521; 2001