Going Farther

NASA has achieved an impres­sive record of exploring the Solar System and beyond with unmanned probes, satellites, and space telescopes. In the 1970s, Pioneer 10 and 11 flew past Jupiter and Saturn. They were followed by Voyager 1 and 2, record-breaking probes that made a tour of the outer planets before eventually leav­ing the solar system. In 1976,

NASA landed two Viking spacecraft on the surface of Mars, and these landers sent the first pictures from the surface of the red planet back to Earth.

Not even NASA’s highly trained and experienced engineers are infallible, however. Sometimes spacecraft disap­pear. In 1993, the Mars Observer space­craft disappeared from tracking screens just three days before it was scheduled to go into orbit around Mars. A succes­sor spacecraft, Mars Global Surveyor, made it into orbit safely in 1998.

NASA often has proved itself adapt­able to challenges. After the Hubble Space Telescope was launched in 1990,
scientists discovered that it had a faulty mirror. NASA designed a rescue package to deal with the unexpected problem in such a costly piece of space hardware. The agency sent Shuttle astronauts to correct the fault, which they did, and Hubble began to provide Earth-based astronomers with their clearest view yet of the heavens.