Using Pulsars For Spacecraft Navigation

Jimme Blue writes "The use of pulsars as a GPS analogue holds the promise of fixing a spacecraft's location to within 5 km, anywhere in the galaxy. While not ready for immediate use, it may be ready for use within the Solar System in the next 10-15 years. From the article: '"The principle is so simple that it will definitely have applications," said Prof Werner Becker from the Max-Planck Institute for Extraterrestrial Physics in Garching. "These pulsars are everywhere in the Universe and their flashing is so predictable that it makes such an approach really straightforward," he told BBC News.'"

Comments

Visibility is an issue

[gstrickler]

Within the solar system, visibility to a known set of pulsars shouldn't be an issue, but as you venture outside the solar system, which pulsars are visible may begin to change as pulsars don't emit in all directions. In practice, most pulsars in a given galaxy probably rotate/emit more or less in the galactic plane, so, even within a galaxy, it's probably a good reference. But that's definitely a risky method if you start moving out of the galactic plane.

Re:Visibility is an issue

[busyqth]

even within a galaxy, it's probably a good reference. But that's definitely a risky method if you start moving out of the galactic plane.

Now that's too bad because I was planning on moving out of the galactic plane sometime later this year.

Re:Visibility is an issue

[Alain Williams]

As the spaceship moves some pulsars will drop out of visibility and others will become visible - so the spacecraft can lock on to the new ones, using the old ones to calibrate them. That would work unless we develop some kind of 'jump' technology where we appear at great distance from our last position and have no pulsars in common between the two places, but that would be an interesting problem to have.

Re:Visibility is an issue

[Yetihehe]

I, for one, would like to know how to get my exact position BEFORE I'm teleported to some random corner of galaxy.

Re:Visibility is an issue

[gstrickler]

Your logic is flawed. The Milky Way doesn't follow lie along the equator because the earth is tilted on it's axis.

The fact that we can see other pulsars (many of them) from within the Milky Way means that those pulsars are either rotating on an axis nearly perpendicular to the galactic plane (aka galactic equator), or they're tilted relative to to the galactic plane and we happen to be nearly perpendicular to their axis of rotation. Since we know that not all stars rotate in the galactic plane (e.g. the solar systems ecliptic plane is inclined about 60 degrees from the galactic plane, and we have now observed enough other planetary systems to know that isn't uncommon), then it's likely that some of the pulsars we can see are spinning approximately in the galactic plane, and that some are not. But given there are many more random orientations that are not on an axis perpendicular to the galactic plane, it's probable that most of the ones we can observe from earth are nearly perpendicular to the galactic plane, and will thus be visible throughout most of the galaxy. As we travel around the galaxy within the vicinity of the galactic plane, the pulsars we can see from any given point will be those that spin on an axis nearly perpendicular to the galactic plane, plus some smaller number at other orientations that happen to have an axis of rotation approximately perpendicular to a line between that point and the pulsar.

Really old idea

[GryMor]

This has been in use in sci-fi since the dawn of space opera. It gained sufficient use that it was internalized to the point that it's rarely mentioned anymore, you could even say it's why most sci-fi expects a reliable knowledge of location and date even in the face of miss-folds and unplanned time travel.

Re:Too Late.

[Samantha Wright]

I assume you took this prior art as inspiration? (Incidentally, I also tend to recall Sagan mentioning pulsars in the first episode of Cosmos being once believed to be a form of alien navigation. Guess that's why he and Drake put them on the plaque.)

Re:Take Jersey Shore with you

[Anonymous Coward]

Take Jersey Shore with you

Prior art

[hawguy]

This isn't exactly a new idea:

http://en.wikipedia.org/wiki/Pioneer_plaque#Relative_position_of_the_Sun_to_the_center_of_the_Galaxy_and_14_pulsars

Re:Prior art

[TooMuchToDo]

I think its awesome that while we had to build a GPS constellation for earth, the Universe has naturally provided a system usable for precision guidance for interstellar travel. Science is fucking awesome.