Pioneer 10, the first spacecraft to venture out of the solar system, has fallen silent after traveling billions of miles from Earth on a mission that has lasted nearly 31 years, NASA said Tuesday.

What was apparently the spacecraft's last signal was received January 22 by the Jet Propulsion Laboratory's Deep Space Network. At the time, Pioneer 10 was 7.6 billion miles from Earth; the signal, traveling at the speed of light, took 11 hours and 20 minutes to arrive.

The signal and the two previous signals were very faint. The Deep Space Network heard nothing from Pioneer 10 during a final attempt at contact on February 7. No more attempts are planned.

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