Spaceships could use blinking dead stars to chart their way

Like GPS satellites, pulsars could help ships pinpoint their place in space

illustration of SEXTANT

SPACE PLACE  NASA’s SEXTANT experiment demonstrated a stellar version of GPS, finding the experiment’s location with an apparatus consisting of 52 X-ray telescopes (illustrated) on the International Space Station.

NASA's Goddard Space Flight Center

OXON HILL, Md. — Future spacecraft could navigate by the light of dead stars.

Using only the timing of radiation bursts from pulsating stellar corpses, an experiment on the International Space Station was able to pinpoint its location in space in a first-ever demonstration. The technique operates like a stellar version of GPS, researchers with the Station Explorer for X-ray Timing and Navigation Technology experiment, SEXTANT, reported at a news conference January 11 during a meeting of the American Astronomical Society.

Known as pulsars, the dead stars emit beams of radiation that sweep past Earth at regular intervals, like the rotating beams from a lighthouse. Those radiation blips could allow a spaceship to find its location in space (SN: 12/18/10, p. 11). It’s similar to how GPS uses the timing of satellite signals to determine the position of your cell phone – and it would mean spacecraft would no longer have to rely on radio telescope communications to find their coordinates. That system becomes less accurate the further a spaceship gets from Earth.

SEXTANT used an array of 52 X-ray telescopes to measure the signals from five pulsars. By analyzing those signals, the researchers were able to locate SEXTANT’s position to within 10 kilometers as it orbited Earth on the space station, astronomer Keith Gendreau of NASA’s Goddard Space Flight Center in Greenbelt, Md., reported.

On Earth, knowing your location within 10 kilometers isn’t that impressive — GPS can do much better. But “if you’re going out to Pluto, there is no GPS navigation system,” Gendreau said. Far from Earth, pulsar navigation could improve upon the position estimates made using radio telescopes.

Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.

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