cold fjord writes with an excerpt from Science Codex: "CSIRO scientists have written software that could guide spacecraft to Alpha Centauri ... Dr George Hobbs (CSIRO) and his colleagues study pulsars — small spinning stars that deliver regular 'blips' or 'pulses' of radio waves and, sometimes, X-rays. Usually the astronomers are interested in measuring, very precisely, when the pulsar pulses arrive in the solar system. Slight deviations from the expected arrival times can give clues about the behaviour of a pulsar itself ... 'But we can also work backwards,' said Dr Hobbs. 'We can use information from pulsars to very precisely determine the position of our telescopes.' 'If the telescopes were on board a spacecraft, then we could get the position of the spacecraft.' Observations of at least four pulsars, every seven days, would be required. ... A paper (paywalled) describing in detail how the system would work has been accepted for publication by the journal Advances in Space Research."
(Here is a related story
from the same source.)