Space: SPACE The Fuel-Cell Flight

(See Cover)

It was scheduled to be the longest space flight on record. It almost became one of the shortest. And the threat to the ambitious mission became doubly dramatic as the fortunes of Gemini 5 oscillated wildly last week between disaster and promise, perfection and near-fatal flaw.

Lift-off from Cape Kennedy, when it finally came, was timed to the second. The countdown clock had not been stopped once−a truly remarkable demonstration of cooperation between men and intricate machines. Rising above its roaring tail in textbook exactitude, the booster flung its capsule aloft with a heart-stopping burst of power. Ahead were eight orbital days−eight days that would, if all went well, teach man more than he had ever known before about the problems and possibilities of flight in space.

Bad luck seemed behind the spacecraft at last. Forgotten for the moment was the mare's nest of trouble that had postponed the flight for two days. Fuel cells running low on fuel, liquid hydrogen boiling uselessly away, telemetering equipment turned suddenly unreliable, fire near the launch pad, thunderstorms aloft−all seemed problems of the past. Now everything was going well; Gemini's orbit was incredibly exact. "Everything is fine," reported Command Pilot Gordon Cooper. "You are go! You are go!" exulted Astronaut Jim McDivitt, capsule communicator in the Mission Control Center near Houston.

Dropping Pressure. At 56 minutes after launch, Cooper began the mission's first important maneuver. By firing his aft thrusters at just the right moment for just the right length of time, he gave his craft a "kick in the apogee" and moved it into an even more precise orbit. Curving between 107 and 217 miles above the earth, Gemini was now ready for its next test: release of the 76-Ib. Radar Evaluation Pod (REP). Fitted with bright, flashing lights and radar transponders, the REP would be an orbiting target for a carefully planned attempt to check the techniques of docking vehicles in space.

But even before REP could be released, there was an ominous hint that the mission might be going sour once more. In the final minutes of the first revolution, as Gemini 5 came within range of the Guaymas tracking station in Mexico, Astronaut Pete Conrad made a calm, almost routine report. The pressure, he said, was dropping in the fuel cells' oxygen supply. The gauge that normally should have read 800 to 900 Ibs. per sq. in. was dropping fast. Since the fuel cells were the main source of power for the spacecraft's communications, computer and environment control system, they were, in effect, the heart of the Gemini mission.

As yet untried in orbit, fuel cells were installed in Gemini 5 because they were smaller and lighter than the conventional batteries used on all previous space flights. Unlike conventional batteries, they can supply electricity for as long as they are fed their fuel−an ideal trait for long-duration power supplies. They produce electricity through the continuous chemical reaction of oxygen and hydrogen, and in the process they form water, a most valuable byproduct.