Fifty Years Ago – the First Space Walks
Fifty years ago Soviet Cosmonaut Alexei Leonov and American Astronaut Edward H. White II performed the first extravehicular activities (EVAs), which are more popularly known as space walks. Leonov’s EVA, on March 18, 1965, lasted 12 minutes; White spent 23 minutes outside Gemini 4 on June 3, 1965. However tentative these initial forays outside the protective confines of a pressurized spacecraft may have been, they were the first steps towards establishing EVAs as necessary techniques for exploring and working in space.
Leonov carried a 45-minute oxygen supply in a backpack. The Voskhod spacecraft was a modified Vostok. The electronics inside the Voskhod were air cooled so Leonov could not depressurize the cabin for his EVA. He had to exit the Voskhod through an inflatable airlock attached to the side of the spacecraft. Leonov emerged from the airlock over north-central Africa. For the next 12 minutes he floated alongside Voskhod before crawling back into the airlock over eastern Siberia. When he first tried to get back into the airlock, Leonov discovered his space suit had inflated to such a degree that he almost wouldn’t fit through the hatch. He reduced the pressure in his suit twice, even to the point of risking decompression sickness, before he could climb back in. Leonov then had to turn around inside the airlock so he could close the outside hatch. By the time he managed to rejoin his crewmate Pavel Belyayev inside Voskhod 2, he was sweating profusely and was nearing exhaustion.
Two and a half months later, NASA was ready to try an EVA on the second piloted Gemini flight. The second piloted flight, Gemini 4, was crewed by James McDivitt and Edward H. White II. Rather than using a backpack like Leonov, American astronaut Ed White’s oxygen came from the spacecraft through a 25-foot umbilical. White carried a small Hand Held Maneuvering Unit (HHMU). The HHMU comprised two small oxygen bottles attached to a handle with three thruster nozzles. Squeezing the handle released pressurized oxygen through the nozzles to propel White forward or backward. He had enough oxygen in the HHMU to effect a total velocity change of six feet per second.
White opened the hatch and emerged from Gemini 4 over the Pacific Ocean, near Hawaii. He exhausted the gas in the HHMU after only three minutes. He continued to float alongside the spacecraft, twisting his body and tugging on the umbilical to maneuver. As Gemini 4 approached the Gulf of Mexico, the mission commander James McDivitt ordered White back into the spacecraft. White was having so much fun performing the EVA that he was at first reluctant to return. At last, White climbed back into Gemini 4 and closed the hatch. Later in the 4-day flight, White was supposed to reopen the hatch and dump the umbilical, HHMU, chest pack and other EVA equipment. However, the hatch proved difficult to secure so the astronauts decided to keep it sealed and brought the equipment back to Earth.