Exploring the Solar System

Exploring the Outer Planets

What was the Galileo mission?

Voyager 2 is more than 101 astronomical units (9.4 billion miles) away from Earth, heading in a direction roughly perpendicular to Voyager 1. Although it is closer to Earth than Voyager 1, it is still more than twice as far away as Pluto, and is also likely to be in the heliosheath. If all goes well, both Voyager spacecraft will continue to send valuable scientific data back to eager astronomers until at least the year 2020.

Galileo was a major, multi-billion dollar mission to Jupiter and its four largest moons: Io, Europa, Ganymede, and Callisto. Along the way, it also tested space probe flight strategies—in particular, large-scale gravitational slingshots—and even studied Earth as if it were a distant planet. This highly successful mission overcame a great many obstacles to achieve, and exceed, its scientific expectations; it was therefore called “the little spacecraft that could.”


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