Astronaut Bruce McCandless, II, mission specialist, participates in an extravehicular activity (EVA) a few meters away from the cabin of the shuttle Challenger. McCandless approaches his maximum distance from the Challenger. He is framed by the blackness of space and below him a cloudy earth. He is floating without tethers connecting him to the shuttle.

In this iconic moment captured by a 70mm camera aboard the Space Shuttle Challenger, astronaut Bruce McCandless II was captain of mission STS-41-B, donning a specialised propulsion unit (MMU) to move independently in space, entirely untethered from the spacecraft for the first time in history. The mission objective was to deploy two communications satellites and associated testing of computer programming. With over 300 hours of flight training, McCandless performed the operation with exceptional dexterity and calm.

Since the first NASA spacewalk by Ed White (Gemini IV mission) on June 3, 1965, spacewalks had been conducted while attached to a long tether serving as an umbilical cord between astronaut and spacecraft. With the MMU, McCandless was able to travel further from the spacecraft than any astronaut before him.

The momentous occasion was not lost on McCandless. He had served on the Apollo 11 mission 15 years prior, as capsule communicator at mission control. Writing in 2015, he recalled his space flight and how "my wife was at mission control, and there was quite a bit of apprehension. I wanted to say something similar to Neil [Armstrong] when he landed on the moon, so I said, 'It may have been a small step for Neil, but it’s a heck of a big leap for me.' That loosened the tension a bit."