Humans have spent millennia navigating through our wonderful world just by using the stars as a guide, and while we have abandoned those methods on Earth, we have to go back to the stars if we want to know where we are in the universe. This, at least, is the suggestion of British physicists.
A team from the National Physical Laboratory (NPL) and University of Leicester has developed a method that uses pulsars so that any spacecraft can find its position with an accuracy of 30 kilometers (19 miles) in three dimensions when sailing all the way to the orbit of Neptune.
The method, published in Experimental Astronomy, uses a well-known theoretical approach to planning X-ray navigation, XNAV, a compact navigational system. The set-up requires a small X-ray telescope working together with an atomic clock. The telescope will detect signals from three specific pulsars, neutron stars that spin many times per second and emit pulses of radiation. Having correctly found the pulsars, the craft could then use the known distances of these stars to find out where it is.
“Up until now, the concept of pulsar-based navigation has been seen just as that – a concept,” said Dr John Pye, from the University of Leicester, in a statement. “This simulation uses technology in the real world and proves its capabilities for this task. “Our X-ray telescope can be feasibly launched into space due to its low weight and small size; indeed, it will be part of a mission to Mercury [ESA's BepiColombo] in 2018.”
This proposal is an improvement on the current methods employed by space agencies to keep track of spacecraft exploring the Solar System. Both the Deep Space Network and European Space Tracking use radio waves to communicate with space probes, so they are limited by both the number of missions they can follow simultaneously and by the time delay it takes the signal to reach the spacecraft.
“Our capability to explore the Solar System has increased hugely over the past few decades; missions like Rosetta and New Horizons are testament to this. Yet how these craft navigate will in future become a limiting factor to our ambitions,” Dr Setnam Shemar of NPL added. “The use of these dead stars in one form or another has the potential to become a new method for navigating in deep space and, in time, beyond the Solar System.”
The system is very much in the early stages, and it takes hours for the telescope to provide an accurate position, but if the 2018 mission is successful, the XNAV might soon become the standard for every probe.