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Some bottled oxygen will be taken along (so that it can be used, among other things, to repressurize the cabin in the event of a meteorite hit), but most of the oxygen will be produced by the electrolysis of water. Although the ships will also carry a supply of fresh water, a large portion of the water consumed by the astronauts will be produced by passing exhaled carbon dioxide through a reactor that separates oxygen from the CO<sub>2</sub> and combines it with hydrogen. Other water will come from recycled urine and wash water. Earlier plans to grow algae on board to supplement the food supply have now been shelved. "Algae cookies taste pretty horrible," explains NASA's Robert Lohman. Instead, the food supply will consist largely of frozen and freeze-dried food.
To counteract the possibly damaging effects of weightlessness on such a long voyage, the joined spaceships will be slowly spun around to create artificial gravity on board. In addition each craft will have a shielded compartment in which crew members can sit out dangerous barrages of radiation during solar storms. There will also be exercising facilities, games, a library and other diversions to while away the hours. One problem has not been resolved: what to do about the crew members' sexual drives. NASA psychologists agree that pornography (which suffices as an escape mechanism for nuclear submarine crews on 60-day missions) may not be enough. With an all-male Mars crew, they believe, homosexual activity is inevitable. Including women on the crew poses other problems. As one psychologist put it: "Sex will be more of a public relations problem than a medical problem for NASA."
When the linked-up ships finally approach Mars, they will separate, fire their main engines to enter an orbit around the planet, and reunite. Before any manned landing takes place, the expedition will send down several small unmanned probes to scout landing sites and scoop up soil before returning to the mother ship.
When sites have been selected, three astronauts will descend in a lander, which will contain a Mars rover, scientific gear and supplies for a month's stay. The surface activities—televised up to the mother ship and relayed to earth—will resemble the familiar rock gathering and experimenting of lunar exploration. The astronauts will wear oxygen packs to survive in the thin carbon dioxide atmosphere, and space suits to weather Martian temperatures (from 75° F. at the equator at noon to —180° F. in the polar regions). But there will be significant differences. Since Martian gravity is one-third of the earth's (compared with the moon's one-sixth G), the astronauts will walk with a more normal gait. They may be buffeted by the high winds of Martian dust storms, which often exceed hurricane force. They will also be on the lookout for things that do not exist on the moon: water and primitive life forms.
During the stay, several expeditions will be sent to the surface. Finally, after 40 days in orbit, the twin ships will separate, fire their engines to boost them away from Mars, and redock for the long voyage home. After slipping back into earth orbit 186 days later, the astronauts will transfer to a waiting space shuttle for the descent to earth. Above them in orbit will be the empty Mars ships, awaiting the next crew of interplanetary travelers.