Pioneer 10 Mission Ends With Whisper

On the edge of the solar system, 6.2 billion miles from home, mankind’s most distant interplanetary explorer transmitted its last breath of science data as NASA pulled the plug on its 25-year mission. A 230-foot radio dish near Madrid captured the probe’s final science transmission at about 2:45 p.m. EST, said Larry Lasher, the project manager. The signal had taken more than nine hours to reach Earth and was one-billionth of one-trillionth of a watt strong. With Pioneer 10’s radioactive power source ebbing away, NASA decided the scientific return did not justify the expense of operating the spacecraft. Of its original 11 instruments only one remained operational, and that was expected to be starved of power by the end of the year. The spacecraft will fall silent a few months later.