Probes to the Outer Planets


Pioneer 10 was the first spacecraft to penetrate the asteroid belt between Mars and Jupiter and travel to the outer regions of the solar system. It returned the first close-up pictures of Jupiter, measured the temperature of Jupiter's atmosphere, and mapped its magnetic field. Pioneer 11 flew past Saturn and its moon Titan in 1979 during which the first close-up images of that planet and its rings were radioed to Earth. Pioneer 11's visit was followed by those of Voyager 1 and 2. In 1986, four and one-half years after visiting Saturn, Voyager 2 made the first close-up survey of Uranus. The Voyager 2 mission provided more information about Uranus and its moons than had been gathered since the planet's discovery. Uranus was previously thought to have nine rings. Voyager 2 revealed eleven rings. Voyager 2 completed its twelve year tour of the solar system with a visit to Neptune and its moons. In 1989, Galileo was launched to examine Jupiter and its four largest moons. Galileo has transmitted images of Jupiter's moon Europa which indicate that water may have existed, and might still exist, beneath Europa's crust. Other Galileo findings include new information about Jupiter's Great Red Spot and images of an eruption on Jupiter's moon Io. The probe took samples of Jupiter's atmosphere.

Pioneer at Jupiter
Pioneer at Jupiter
On October 15, 1997, the plutonium powered Cassini probe began what is anticipated to be a 7 year, 2 billion mile voyage to Saturn. Cassini is the largest, most complex and most expensive interplanetary probe launched to date. The spacecraft went into orbit around Saturn in July 2004, and will observe the planet, its ring system, and many of its moons for at least 4 years.


The StarChild site is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC.

StarChild Authors: The StarChild Team
StarChild Graphics & Music: Acknowledgments
StarChild Project Leader: Dr. Laura A. Whitlock
Responsible NASA Official: Phil Newman

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