An Interplanetary GPS Using Pulsar Signals
Spacecraft could determine their position anywhere in the solar system to within five kilometres using signals from x-ray pulsars, say astronomers.
Navigating in space is a tricky business. The usual method relies on Earth-based tracking stations to work out a spacecraft’s distance using radio waves, a process that is accurate to within a metre or so.
That’s fine for the radial distance, but tracking a spacecraft’s angular position is much harder because of the limited angular resolution of radio antennas. The current technology produces an uncertainty of about four kilometres per astronomical unit of distance between Earth and the spacecraft.
So for a spacecraft at the distance of Pluto, that’s an uncertainty of 200 kilometres and at the distance of Voyager 1, the uncertainty is 500 kilometres.
So a way for spacecraft to determine their own position accurately would clearly be useful.
Today, Werner Becker at the Max Planck Institute for Radio Astronomy in Germany and a couple of pals have worked out the practical details for an autonomous spacecraft navigation system using pulsars signals. They say that technology being developed now would allow spacecraft to work out their position to within five kilometres anywhere in the solar system.