[4] Hartsfield was a rookie astronaut who had transferred to NASA in 1969 after the cancellation of the Air Force's Manned Orbiting Laboratory (MOL) program.

The decision on whether to appoint a reserve crew member was made on a per-flight basis by flight management teams at Johnson Space Center.

STS-4 launched from Kennedy Space Center (KSC) on June 27, 1982, at 15:00:00 UTC, with Ken Mattingly as commander and Henry Hartsfield as pilot.

Mattingly, an active-duty naval officer, later described the classified payload – two sensors for detecting missile launches – as a "rinky-dink collection of minor stuff they wanted to fly".

They also operated the Remote Manipulator System (Canadarm) with an instrument called the Induced Environment Contamination Monitor mounted on its end, designed to obtain information on gases or particles being released by the orbiter in flight.

The flight lasted 7 days, 1 hour, 9 minutes, and 31 seconds, and covered a total distance of 4,700,000 km (2,900,000 mi) in 112 complete orbits.

The mission achieved all objectives except for the Air Force payload, but the SRBs were lost when their main parachutes failed, causing the empty casings to impact the ocean at high velocity and sink.