Meanwhile, NASA was developing the Columbia Space Shuttle, the first of four reusable ships about the size of an airliner with a large cargo bay and each designed for 100 flights. It would be launched into Earth orbits at 150-400 miles altitude, serve a multitude of purposes for typical durations of 6-16 days, and reenter the atmosphere to land as a glider. Delays due to technical challenges and funding, however, resulted in a six-year hiatus in US manned spaceflight before the first Columbia flight in April, 1981. During this delay, I was assigned to provide astronaut oversight of development and testing of several Space Shuttle systems, including cockpit Displays and Controls (D&C). One of my major tasks was to introduce, evaluate, and promote the installation of a Head-Up Display (HUD) to meet the approach and landing piloting challenges presented by this large, heavy, fast, and high sink-rate glider in a variety of weather, night, and runway conditions. Although this design change was met with strong management resistance, it was finally retrofitted into the Colombia and installed into the remaining Space Shuttles still under construction.
The first four Columbia flights would be Orbital Flight Tests (OFT), manned by only two pilots to minimize the risk, and would test the Space Shuttle's operational and engineering performance. If successful, remaining missions would each be staffed by two pilots and up to six "Mission Specialists" who were primarily scientists and engineers. In 1979, flight crews for the four OFT missions were announced. I was assigned to the third OFT, initially termed the "Skylab Reboost" mission because, after serving its useful purpose in 1974, Skylab was abandoned and became a derelict with no other attention than to track its orbital position. Tracking demonstrated it was losing altitude more rapidly than expected, and designed without retro-rocket capability, it would make an uncontrolled reentry into the atmosphere at an unknown location. Not all of Skylab's components would disintegrate in the atmosphere, so some of we occupants of "Spacecraft Earth" could be endangered. The "magicians" in Mission Control, however, were able to make contact with Skylab, reenergize some of its systems, monitor its status, and exert limited control over its rotation but not its orbital decay. The only safe solutions were to boost Skylab to a higher "holding pattern" orbit, or to deboost it to a controlled ocean splashdown.
A booster module, about the size of a dump truck, was being developed by Martin Marietta Corporation. It would be installed in the cargo bay of the third Columbia Space Shuttle mission. The booster module had an Apollo docking probe, television camera for docking, a reaction control system, and a large booster engine. After rendezvous with Skylab, the booster module would be released from the Columbia's cargo bay. Its short transfer flight to Skylab would be controlled manually using hand-controllers and a television display mounted in the Columbia's aft flight deck. After docking, the Columbia would move away to a safe location, and the booster module's main engine would be fired to send the Skylab either higher or lower. The latter decision was never made because, after nearly a year of preparation, the Skylab's orbit was decaying faster than expected, and the Columbia could not be ready to intercept Skylab's entry into the atmosphere. Nevertheless, it would have been a doable and exciting "Buck Rogers" type of mission!
The sun's influence on Earth's atmospheric density on the fringes of space was not well-known at that time. It was discovered that ejection of solar mass during more intense stages of the sun's activity was absorbed in Earth's upper atmosphere causing it to swell and expand outward. This atmospheric expansion phenomenon caused increased drag on orbiting objects at higher altitudes than expected. Mission Control, however, had learned how to exert a slight influence over Skylab's altitude by maneuvering its axes to change its descent rate. It was difficult to precisely predict the effect of axial-rotation versus altitude changes due to the long time-delays in between the maneuvers and their effect. Mission Control tried to target Skylab's reentry into the Indian Ocean and did an admirable job under the circumstances. Most of the Skylab components that did not disintegrate hit the Indian Ocean target, although a few damaged parts were found by farmers in a very remote Southwestern region of Australia; but no harm done!