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Q. What becomes of old deep space probes? — Laura Y.
A. Eventually, they fall into the Sun.
Old spacecraft sent out from Earth travel around and around the Sun. The powerful gravity of our star draws them ever closer. Eventually, they will burn up as they come too close to the Sun's great heat.

As they travel around the Sun, those human-built spacecraft are in the heliosphere, which simply is the region of space around the Sun. From our point of view, the heliosphere encompasses our Solar System.

To an astronomer, the heliosphere is the region of space through which the solar wind extends. The solar wind is a stream of high-speed, ionized particles ejected by the Sun, primarily from the corona.

Heliospheric objects are bodies traveling within the heliosphere. They include natural bodies such as planets and moons, but they also can be human constructions such as spacecraft.

Here are some of the human-built heliospheric objects still out there traveling around the Sun:

Spacecraft	Launch
GALILEO	1989
GIOTTO	1992
HELIOS 1	1974
HELIOS 2	1976
ICE	1984
PHOBOS 2	1988
PIONEER 10	1972
PIONEER 11	1973
SAKIGAKE	1985
SUISEI	1989
ULYSSES	1990
VOYAGER 1	1977
VOYAGER 2	1977

Learn more...

• Heliospheric objects  »»
• Cosmic and Heliospheric Learning Center  »»

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