An artist's concept of Pioneer 10. Photo: NASA

The longest operating deep-space probe is getting at least one more chance for life as project managers have secured observation time with radio antennas to try to contact the spacecraft for the first time since last summer.

Controllers last communicated in real time with Pioneer 10 in July during an attempted maneuver to realign the spacecraft's antennas with Earth. Further communications were received from the distant satellite in August.

Pioneer 10 is currently 7.16 billion miles from Earth and the round-trip light time is 21 hours and 20 minutes. Its speed relative to the Sun is 27,380 mph.

The new batch of NASA Deep Space Network (DSN) communications attempts includes five downlink-only sessions and three two-way communications periods. The one-way downlink opportunities begin later this month, while the more complex two-way sessions will not take place until April.

Project officials say that obtaining these last few chances to contact Pioneer 10 was a difficult process. The DSN supports many other higher priority missions such as Galileo, Cassini and Ulysses, placing the time for lower priority missions like Pioneer 10 at a premium.

The DSN is a collection of large dish-like antennas with installations in Goldstone, California, Canberra, Australia, and Madrid, Spain.

The Arecibo radio telescope in Puerto Rico is also joining the hunt for Pioneer 10. Observations began on February 26 and will last through March 5 and another set of opportunities will begin on March 8, to last until March 18. Plans are to have Arecibo observe for around one hour on each of the listed nights.

"This should give us adequate coverage to contact the spacecraft or determine the reason why if contact has indeed been lost," a recent Pioneer 10 status report said of the DSN contact attempts set to occur between March and May.

Pioneer 10 was officially retired March 31, 1997. The craft now serves as a training tool for ground controllers and its faint signal provides a radio beacon used by DSN and other facilities to confirm station tracking and receiver performance.