Using Pulsars As GPS For Starships

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.)

Unpaywalled

[Anonymous Coward]

The paper is available free from the arXiv (http://arxiv.org/abs/1307.5375)

Re:Paywalled?

[bartron]

Only partially. CSIRO gets some funding from the government but the rest it needs to make up from revenue by selling stuff (IP or services), setting up research partnerships etc.

Re:The past called..

[Anonymous Coward]

The abstract of the paper (unpaywalled version [arxiv.org]) has a better summary.

We demonstrate how observations of pulsars can be used to help navigate a spacecraft travelling in the solar system. We make use of archival observations of millisecond pulsars from the Parkes radio telescope in order to demonstrate the effectiveness of the method and highlight issues, such as pulsar spin irregularities, which need to be accounted for. We show that observations of four millisecond pulsars every seven days using a realistic X-ray telescope on the spacecraft throughout a journey from Earth to Mars can lead to position determinations better than ~20 km and velocity measurements with a precision of ~0.1 m/s.

In other words, they're not just saying that it's a theoretical possibility. They're saying "this is the type of telescope you need", "this is how you have to process the data", and "this is how precisely you can measure your position". Next step, I guess, is building the hardware.

Re:Visibility

[Anonymous Coward]

Are the pulses from pulsars visible from all directions, or just from the plane of rotation?

Not from all directions, but not always from the plane of rotation either. The pulse sweeps around at a fixed angle from the plane of rotation, which may not be 90 degrees.

But you're right: if we went far enough, we'd stop seeing some pulsars, and start seeing some new ones. So if we start travelling more than a thousand light years or so, we'll need another means of navigation.

The original paper [arxiv.org] only talks about using it as a means of navigation within the solar system, though, for which it's perfectly fine, and much more precise than existing methods.