This article is pretty intersting in the fact that CSIRO scientist's are saying "Pulsar" readings are reliable enough to use as a GPS like measurment for spacecraft, and also the mention of the idea in 1974.
Quote16 August 2013
CSIRO scientists have written software that could guide spacecraft to Alpha Centauri, show that the planet Nibiru doesn't exist ... and prove that the Earth goes around the Sun.
SNIP
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, or whether it is orbiting another star, for instance.
"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. "Each pulsar would have to be observed for about an hour," Dr Hobbs said. "Whether you can do them all at the same time or have to do them one after the other depends on where they are and exactly what kind of detector you use."
A paper describing in detail how the system would work has been accepted for publication by the journal Advances in Space Research.
/SNIP
SOURCE:
http://www.csiro.au/Portals/Media/Pulsars-make-a-GPS-for-the-cosmos.aspx