LOS ANGELES -- 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 Jan. 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. HoustonChronicle.com - Lonely Pioneer 10 phones home for last time | 
