Pulsars could form GPS for space

Small, spinning stars may provide the key to form a kind of GPS to the stars, with the radio and X-rays emitted by the so-called "pulsars" providing useful positioning information to potential space travelers.

Dr. George Hobbs and his colleagues at the Commonwealth Scientific and Industrial Research Organisation in Australia say they may have figured out how to reverse engineer the the 'blips' emitted by pulsing stars -- pulsars -- to help spacecraft navigation.

In a process similar to kind of terrestrial triangulation our Earth-bound GPS uses, spacecraft could use telescopes to observe four different pulsars every seven days to calculate precise locations.

For now, spacecraft are monitored from Earth, but those measurements get less and less accurate the further the craft gets from home.

Hobbs says a pulsar-powered GPS could solve that problem, describing the process in a paper accepted for publication in the journal Advances in Space Research.

"We can use information from pulsars to very precisely determine the position of our telescopes," Hobbs said, and "if the telescopes were on board a spacecraft, then we could get the position of the spacecraft."

"The spacecraft can determine its position to within about 20 km, and its velocity to within 10 cm per second," said Hobbs. "To our knowledge, this is the best accuracy anyone has ever been able to demonstrate."

Hobbs and his team said the system would use the measurements from pulsars that have been observed for years, so the timing of their pulses is well known. The development of smaller, lighter X-ray telescopes makes the possibility of putting the system aboard a spacecraft possible.