Item — HN Reader

> There are lots of naturally occurring ones such as pulsars, enough to the point they could be used for 3D navigation, if you can find your distance to them.

There's work towards this, from the X-ray emission of pulsars[0]. I don't think you'd need a precise distance to the pulsars to measure your own position, as long as you're measuring your own position relative to some other object (e.g., Solar System barycenter). If it's a relative measurement then you should be able to determine that by comparing the time-of-arrival (TOA) of the pulsed emission from multiple pulsars with the TOAs at Earth.

[0] https://en.wikipedia.org/wiki/X-ray_pulsar-based_navigation

1 comments

Pulsar glitches are a thing, here's a great resource: http://www.jb.man.ac.uk/pulsar/glitches.html

I'd worry about pulse identification over any significant period of time.

And pulsars spin rates slowly change over time do to energy losses.

But I don't think these things would cripple a pulsar-based navigation system. Presumably any network of pulsars used for this purpose would be regularly monitored and timing solutions would be updated regularly. The updated timing solutions could be transmitted as-needed.

At any rate, a robust navigation network of pulsars would need a sufficient number of sources to guard against glitches breaking the navigation system.

Also, in context of an alien civilization finding our XX century probes a million years from now, I think they could reconstruct the location anyway - I'd assume there would be only one combination of pulsars you could pattern-match to what's on Voyager plaques, even if each of them shifted in frequency a bit.