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The Journey to Jupiter
The Cruise - The Winding Road to Jupiter

Galileo didn't have enough fuel to fly directly to Jupiter, but the spacecraft could borrow enough energy from Venus and Earth to make the long journey. Mission planners designed a flight path nicknamed "VEEGA" -- Venus-Earth-Earth Gravity Assist. Galileo would slingshot once by Venus, and twice by Earth, gathering enough momentum to reach distant Jupiter.

Galileo looks back at Earth and the Moon.
Galileo looks back at Earth and the Moon.

First stop: Venus. The Galileo team tried out the spacecraft's instruments and study of the thick, toxic clouds that cloak our sister planet. Flying by our home planet twice, we saw the Earth and Moon together -- as someone from another world might view us.

After the first Earth flyby, Galileo's umbrella-shaped high-gain antenna did not open as planned. But the Galileo team worked hard to reprogram the spacecraft to send back data through a smaller antenna. Engineers at NASA's Deep Space Network upgraded their antennas as well. The result allowed scientists to capture almost all the information originally planned.

Asteroid Ida and its moon, Dactyl.
Asteroid Ida and its moon, Dactyl.

On Galileo's first trip through the asteroid belt, the spacecraft took detailed images of an asteroid named Gaspra - the first close approach to an asteroid. On a second pass through the asteroid belt, Galileo discovered a miniature moon orbiting asteroid Ida. This tiny body was named Dactyl.

In 1994, Galileo was perfectly positioned to watch the fragments of comet Shoemaker-Levy 9 crash into Jupiter. The spacecraft made the only direct observations of the impact. Earth-based telescopes had to wait to see the impact sites as they rotated into view.

Cruise Timeline:

  • Venus Flyby: 2/10/1990 (16,000 km distance)
  • Earth-1 Flyby: 10/8/1990 (960 km distance)
  • Gaspra Flyby: 10/29/1991 (1600 km distance)
  • Earth-2 Flyby: 12/8/1992 (305 km distance)
  • Ida Flyby:
    8/28/1993 (2400 km distance)
      Discovery: Dactyl, first known moon of an asteroid
  • Comet S/L-9 Jupiter Impact: July 16-22, 1994

Next: Arrival at Jupiter and the Probe Mission Next

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Last Updated: 9 Jul 2010