Later Missions

After the Challenger accident in 1986, more than 80 shuttle missions were completed with no serious mishaps. The most notable of these were the scientific missions that launched these exploratory spacecraft: Magellan (launched May 1989), the probe designed for radar mapping of the planet Venus; Galileo (launched October 1989), the unmanned spacecraft that reached Jupiter in December 1995; Ulysses (launched October 1990), a probe designed for study of the Sun; and the Hubble Space Telescope (launched April 1990), a high-powered telescope designed to make astronomical observations from space, away from the interference of Earth's atmosphere. In December 1993 the first Hubble Telescope Servicing Mission was successfully completed, correcting the telescope's optics and improving the electronic systems.

In July 1995 the shuttle Atlantis linked up with the Russian space station Mir. This mission was the first of nine shuttle/Mir linkups between 1995 and 1998. These flights were the precursors to assembly of the International Space Station that began to be constructed in orbit in late 1998. The first docking with Mir was perhaps the most significant event in the history of spaceflight since the symbolic joining of Apollo and Soyuz spacecraft 20 years earlier (see Apollo program). It signaled a new age of cooperation in space, where exploration of the universe would be measured more in terms of what a coalition of nations had accomplished rather than what a single nation had achieved. See also Space Station.

After the ceremonies following the rendezvous and docking of Atlantis to Mir, the two groups of astronauts undertook several days of joint scientific investigations inside the Spacelab module tucked in Atlantis's large cargo bay. Research in seven different medical and scientific disciplines, begun previously at Mir, also was concluded on the July 1995 mission. All of these experiments took advantage of the unique microgravity environment present on the spacecraft. Scientists hope to learn more about changes in the human body caused by spaceflight; the data collected in these experiments also may advance understanding of conditions such as anemia, high blood pressure, osteoporosis, kidney stones, balance disorders, and immune deficiencies that often occur on Earth.

In March 1996 Atlantis docked again with Mir, carrying 860 kg (1,900 lb) of supplies to the space station. Atlantis also left Shannon Lucid, an American astronaut, on Mir for a planned stay of five months. Because of delays caused by problems with Atlantis, Lucid stayed aboard Mir for 188 days (more than 6 months), breaking the U.S. record for long duration spaceflight. Five more U.S. astronauts stayed aboard Mir on extended stays before shuttle/Mir missions ended in 1998, when both the United States and Russia began concentrating on International Space Station plans. Spacelab missions also ended in 1998, in hopes that the ISS will provide a new and more permanent laboratory in space.

The majority of space shuttle missions in the early 2000s were devoted to construction of the ISS. In 1998 the orbiter Atlantis was overhauled to make it more compatible with the ISS. Atlantis received new displays, navigation equipment, and an airlock with which to connect to the station. Its power and cooling systems were also improved.

In February 2000 Endeavour completed a mission that focused on mapping Earth’s terrain. Scientists used two antennas—one located at the end of a long mast and the other in the shuttle’s payload bay—to obtain high-quality, three-dimensional images that give information about topography (features such as mountains and rivers).