Pulsars as accelerometers in space–towards solving the “lost in space” problem

Navigation in space using x-ray pulsars has been frequently suggested as a means by which a spacecraft may determine its position in space independent of Earth-based measurements. Most research towards practical x-ray navigation has focused on using time-difference of arrival of signals to determine the range of the spacecraft along the line-of-sight to the pulsar. In this paper, we show that pulsar signals may be used to measure the spacecraft’s acceleration along the line-of-sight to the pulsar. Given a sufficient number of acceleration measurements, the full three-dimensional acceleration vector of the spacecraft may be determined. Since acceleration is a function of the spacecraft’s position in the solar system, this acceleration vector may be used to determine the position of the spacecraft, even if no prior position estimation is known.