In February 1993, Kent Joosten, an engineer in the Exploration Program Office (ExPO) at NASA’s Johnson Space Center in Houston, Texas, proposed a plan for lunar exploration which, he hoped, would take into account the emerging realities of space exploration in the 1990s. His International Lunar Resources Exploration Concept would, he wrote, reduce "development and recurring costs of human exploration beyond low-Earth orbit" and "enable lunar surface exploration capabilities significantly exceeding those of Apollo." It would do these things by exploiting lunar oxygen as oxidizer for burning liquid hydrogen fuel brought from Earth, shipping most cargo to the moon separate from the crew, and relying on cooperation with Russia.
According to Joosten, a lunar lander making a direct flight from Earth's surface to the lunar surface that would arrive on the moon with empty oxidizer tanks and then reload with liquid oxygen mined and refined from lunar regolith (that is, surface material) would have half the mass of a lander that performed an Apollo-style Lunar-Orbit Rendezvous mission (itself a mass-saver) and brought to the moon oxidizer for the return trip from Earth. This would in turn permit a smaller launch vehicle, slashing costs.
One-way automated cargo landers, each rectangular in shape and capable of delivering 11 tons of payload to the moon's surface, would be assembled and packed in the U.S. and shipped to Russia in C-5 Galaxy or Antonov-124/225 transport planes, then launched on Russian Energia rockets from Baikonur Cosmodrome in Kazakstan. Joosten noted that launch teams at Baikonur could service two Energia rockets at the same time and that three Energia launch pads existed. An Energia would place a cargo lander into Earth orbit attached to a Russian "Block 14C40" upper stage that would then boost the lander toward the moon.
Shuttle-derived heavy-lift boosters would launch the piloted landers from Kennedy Space Center's twin Complex 39 Shuttle pads. The pads, monolithic Vehicle Assembly Building, and other KSC facilities would require modifications to support the new piloted lunar effort, but no wholly new facilities would need to be constructed, Joosten explained. The piloted lander, carrying an international crew and about two metric tons of cargo, would be placed into Earth orbit, then a new-design Trans-Lunar Injection Stage would put it on a direct trajectory to land near the pre-established automated oxygen production facilities.
Joosten's crew lander design outwardly resembled the "Eagle" transport in the 1970s TV series Space: 1999 (image at top of post). The crew compartment, a conical capsule modeled on the Apollo Command Module (but lacking a nose-mounted docking unit), would be mounted on the front of a horizontal, three-legged lander. At launch, the capsule would sit on top of the stack surmounted by a solid-propellant launch escape system. The three legs would fold against the lander's belly beneath a streamlined shroud during ascent from Earth. On the moon, the crew hatch would face downward, providing ready access to the surface via a ladder on the lander's single forward leg; on the launch pad, the hatch would permit horizontal access to the capsule interior much as did the Apollo Command Module hatch. The crew compartment windows would be inset into the hull and oriented to enable the pilot to view the landing site during descent.
The crew lander would land on and launch from the moon using four belly-mounted throttleable rocket motors. Soon after lunar touchdown, the lander would be reloaded with liquid oxygen from the automated oxygen plant. The entire lander would lift off the lunar surface for flight to Earth; no expendable descent stages would be left behind to clutter up the moon. Nearing Earth, the crew capsule would separate and orient itself for reentry by turning its Apollo-style bowl-shaped heat shield toward the atmosphere. The lander section, meanwhile, would steer toward a reentry point away from populated areas. The crew capsule would use a steerable parasail-type parachute. Joosten recommended recovering the crew capsule on land - perhaps at Kennedy Space Center - to avoid the greater cost of Apollo-style water recovery.
Joosten envisioned a three-phase lunar program, but provided details for only Phases 1 and 2. In Phase 1, three cargo landers would deliver to the target landing site a nuclear power system, an automated liquid oxygen production facility, robotic diggers, loaders, power supply, and propellant transport "carts," and a pressurized exploration rover and science equipment. The first piloted lander carrying two astronauts would then arrive for a two-week stay, during which they would check out the automated systems and explore using the pressurized rover. Several Phase 1 piloted missions to the same site would be possible.
In Phase 2, three cargo flights would deliver a second pressurized rover, an airlock module, consumables on a cart, and science equipment. A fourth cargo flight would deliver a four-person crew for a six-week stay. The crew would divide up two to a pressurized rover. The airlock module would include docking units so that the two rovers and the consumables cart could link to it, forming a small outpost. Phase 3 might see larger crew sizes and longer stay times; alternately, NASA might change direction and use technology developed for the lunar program (for example, the crew capsule and Shuttle-derived heavy-lifter) to send humans to Mars.