Pulsar star X-rays could aid autonomous space navigation

Long-distance space missions could navigate autonomously using X-rays from pulsar stars.

The European Space Agency (ESA) has commissioned scientists at the National Physical Laboratory (NPL) and Leicester University to investigate the feasibility of using pulsars to navigate in deep space.

Spacecraft navigation currently relies on radio transmissions between a distant craft and a network of ground stations on Earth. This means that the craft has to wait for an instruction from Earth to guide it through space and with the large distances involved this could take hours, days or even longer.

This time delay affects a spacecraft’s ability to react rapidly according to its location. Furthermore, the ground infrastructure is increasingly difficult and expensive to maintain due to the size of the radio antennas.

Pulsars are highly compact and rapidly rotating neutron stars that emit intense electromagnetic radiation observed as pulses, similar to the rotating beam of light seen from a lighthouse. In some cases these pulses can be highly regular, making them suitable sources for navigation using a technique similar to GPS.

The traditional form of ground-based space navigation can only support a limited number of spacecraft as only one set of measurements can be processed at any one time. If feasible, this new technique could allow a greater number of complex space missions to take place simultaneously in deep space as craft become capable of navigating autonomously.

‘Using on-board X-ray detectors, spacecraft could measure the times of pulses received from pulsars to determine the position and motion of the craft,’ said Setnam Shemar who is leading the project on behalf of NPL’s Time and Frequency Team. ‘The University of Leicester will use its experience in X-ray astronomy to come up with potential designs of the device and NPL will develop timing and navigation algorithms to determine the potential accuracy of this technique.’

The university is currently building a lightweight X-ray telescope for flight on the European Space Agency’s BepiColombo mission to Mercury, due for launch in 2015.