RE: Which Space Shuttle had the longest mission and why?
The Space Shuttle with the longest mission was Columbia as part of the STS-80 mission. This mission lasted nearly 17.5 days, from November 19 to December 7 in 1996. STS-80 was a marathon science mission during which the shuttle's crew operated a variety of experiments in a self-contained module in the shuttle's cargo bay, known as the Spacelab module. Most Spacelab investigations were staffed by double-shift crews to ensure 24-hour operations, contributing to the lengthy mission time. The mission had multiple objectives. Two significant goals were deploying and later retrieving the Wake Shield Facility and the Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer-Shuttle Pallet Satellite II (ORFEUS-SPAS II), both of which were separate deployable payloads designed to study novel aspects of space science. The Wake Shield Facility was designed to create an ultra-vacuum environment in its wake (hence the name), suitable for growing thin semiconductor films for use in various technologies, while the ORFEUS was an astrophysics payload designed to observe the life cycle of stars and understand the gases surrounding them better. Lengthly missions like STS-80 allow for extended observation and data collection times, which can provide more comprehensive outcomes and meaningful insights in such scientific investigations. It's also a testament to the increasingly long-duration spaceflight capabilities NASA was developing at the time, preparatory to stays aboard the International Space Station.