Space: Inside While Outside

By the time Astronaut Charles Bassett climbs out of the Gemini 9 some time next year to take a walk in space, the very name of his mission—EVA (for extravehicular activity)—may have to be changed. Bassett will be not so much outside one vehicle as inside another. His air-conditioned suit with its $6,000,000 backpack containing 166 lbs. of assorted gadgetry will amount to a spacecraft in itself.

Perfected after six years of research, the sophisticated AMU (for Astronaut Maneuvering Unit) that is built into the space walker’s backpack will give Bassett singular agility. It is powered by twelve small hydrogen peroxide thrusters that can propel it in any direction; it has its own fuel tanks, running lights, gyroscopes, and an alarm system that warns the wearer by flashing lights and sounding beeps in his earphones if fuel or oxygen is running low. With its own hour-long oxygen supply, storage batteries and radio and telemetry systems, the AMU does not even need the “umbilical cord” that was used to supply oxygen and radio communication to Astronaut Ed White when he walked outside Gemini 4.

Flying by Eyeball. An AMU-equipped astronaut will maneuver through space by manipulating control knobs at the end of each of two projecting arms—the right knob for attitude, the left for direction of motion. Should he want to turn to the left, for example, he will turn the right knob to the left, automatically firing two thrusters that rotate AMU counterclockwise around its own axis. To move backwards, he will pull back on the left control knob and activate forward-firing thrusters. If an astronaut has to use both hands for other jobs, he will move into the proper atti tude, then throw a stabilizer switch and use his AMU’s gyro-controlled stabilizer system to “park” in space.

Despite AMU’s elaborate controls, maneuvering in space without the radar and computer guidance available in full-size spacecraft—called “eyeballing” by astronauts—can be both difficult and dangerous.

A three-second burn from the backward-firing thrusters, for example, will increase an astronaut’s forward velocity by one foot per second. Because there is no air friction to slow him down, the astronaut will have to use his forward-firing thrusters for exactly three seconds to stop his forward motion as he approaches his destination. If his timing is inaccurate, he may crash into his target or wind up bouncing back and forth like a celestial ping pong ball.

Tethered by Nylon. Mastering orbital mechanics, the physical laws that govern the motion of an orbiting satellite, will be even more difficult. When an astronaut is behind his Gemini capsule he cannot simply increase his speed to catch up with it. Increased speed will put him into a higher orbit, which will make him fall farther behind. To overtake his Gemini capsule, he will have to fire his downward and forward thrusters alternately until he edges close to his target.

Aware of the risks, NASA has insisted that Astronaut Bassett remain attached to Gemini 9 by a 200-ft. nylon tether. If both Bassett and AMU perform satisfactorily, however, the astronaut who leaves Gemini 12 in an AMU may well be allowed to sever his last connection with the mother ship and strike out into empty space on his own.