24 YEARS AGO this famous photo was taken
Written by Paul Suba on February 7, 2018
SOURCE: THE LEARNING NETWORK
On Feb. 7, 1984, two Challenger space shuttle astronauts, Capt. Bruce McCandless II and Col.l Robert L. Stewart, performed the first untethered spacewalk during the STS-41B mission. “Free of any lifeline and propelled into the dark void by tiny jets, they became, in effect, the first human satellites, ” reported the Feb. 8 New York Times.
Astronauts in every previous spacewalk, or extra-vehicular activity, had been attached to the spacecraft by a long cable. Captain McCandless and Colonel Stewart used 300-pound nitrogen-propelled backpacks known as manned maneuvering units to make their way through space. The men made two spacewalks during the mission, the second occurring on Feb. 9. The first lasted 5 hours 55 minutes and the second was 6 hours 17 minutes.
The two astronauts used the extra-vehicular activity to simulate the procedures that were planned for the capture and repair of a malfunctioning satellite on a future mission. That objective was carried out in April 1984, when two astronauts successfully repaired the Solar Max satellite while using manned maneuvering units. In November of that same year, two STS-51A astronauts used their manned maneuvering units to retrieve two malfunctioning communications satellites, the Westar VI and Palapa B2.
The manned maneuvering units used by Captain McCandless and Colonel Stewart were not used again after 1984, as NASA decided to perform only tethered spacewalks for safety reasons. In 1994, NASA unveiled a new backpack called Simplified Aid for EVA Rescue, or Safer, and tested it with an untethered spacewalk, the fourth, and thus far last untethered extra-vehicular activity it has performed. Every astronaut at the International Space Station wears Safer, which is smaller and lighter than the manned maneuvering units, for use during an emergency.