After more than 30 years, it appears the venerable Pioneer 10 spacecraft has sent its last signal to Earth. Pioneer’s last, very weak signal was received on Jan. 22, 2003. NASA engineers report Pioneer 10’s radioisotope power source has decayed, and it may not have enough power to send additional transmissions to Earth. NASA’s Deep Space Network (DSN) did not detect a signal during the last contact attempt Feb. 7, 2003. The previous three contacts, including the Jan. 22 signal, were very faint with no telemetry received. The last time a Pioneer 10 contact returned telemetry data was April 27, 2002. NASA has no additional contact attempts planned for Pioneer 10.