Space telescope Hubble Space Telescope, which was launched on April 24, 1990 by the Space Shuttle "Discovery" (STS-31). Performing astronomy from ground-based observatories on Earth is limited by the filtering and distortion of electromagnetic radiation (scintillation or twinkling) due to the atmosphere. Some terrestrial telescopes can reduce atmospheric effects with adaptive optics. A telescope orbiting Earth outside the atmosphere is subject neither to twinkling nor to light pollution from artificial light sources on Earth. As a result, the angular resolution of space telescopes is often much smaller than a ground-based telescope with a similar aperture. Space-based astronomy is even more important for
Space Shuttle program launched on September 29, 1988. The longest Shuttle mission was STS-80 lasting 17 days, 15 hours. The final flight of the Space Shuttle program was STS-135 on July 8, 2011. Since the Shuttle's retirement in 2011, many of its original duties are performed by an assortment of government and private vessels. The European ATV Automated Transfer Vehicle supplied the ISS between 2008 and 2015. Classified military missions are being flown by the US Air Force's unmanned space plane, the X-37B. By 2012, cargo to the International Space Station was already being delivered commercially under NASA's Commercial Resupply Services by SpaceX's