John Howard Casper (born July 9, 1943) is a former American astronaut and retired United States Air Force pilot.

After F-100 Super Sabre training at Luke Air Force Base, Arizona, he flew 229 combat missions with the 35th Tactical Fighter Wing in the Vietnam War.

Following his tour in Vietnam, Casper flew F-100 and F-4 Phantom aircraft while assigned to the 48th Tactical Fighter Wing, Royal Air Force Lakenheath, United Kingdom.

His technical assignments while assigned to the Astronaut Office included Chief of the Operations Development Branch; lead for improvements to the nosewheel steering, brakes, tires, and development of a landing drag chute; astronaut team leader for the Shuttle Avionics Integration Laboratory (SAIL); and ascent/entry spacecraft communicator (CAPCOM) in the Mission Control Center.

After 72 orbits of the Earth, the STS-36 mission concluded with a lakebed landing at Edwards Air Force Base, California, on March 4, 1990, after traveling 1.87 million miles.

A highly successful extravehicular activity (EVA) resulted in many lessons learned that benefited the International Space Station assembly.

These payloads included experiments to understand the process of semiconductor crystal growth, investigating the process of metal alloys as they solidify, studying materials at their critical point (where they exist as both a liquid and gas), and testing new technology for use on future spacecraft, such as advanced solar arrays, radiators, heat sinks, and radiation shielding.

The flight also tested new technology for aligning the Remote Manipulator System arm and for grasping payloads with a new magnetic end effector.

Columbia flew at a record low altitude of 195 km (105 nautical miles) to gather data on spacecraft glow and erosion caused by atomic oxygen and nitrogen molecules.

[3] In 2022, Casper published an autobiography of his experience in space titled The Sky Above: An Astronaut’s Memoir of Adventure, Persistence, and Faith.