rushtobugment shares a report from ScienceAlert: Using the positions and shifting light of stars, both near and far, astronomer Coryn A.L. Bailer-Jones has demonstrated the feasibility of autonomous, on-the-fly navigation for spacecraft traveling far beyond the Solar System. “When traveling to the nearest stars, signals will be far too weak and light travel times will be of order years,” Bailer-Jones wrote in his paper, which is currently available on the preprint server arXiv, where it awaits peer review from the astronomy community. “An interstellar spacecraft will therefore have to navigate autonomously, and use this information to decide when to make course corrections or to switch on instruments. Such a spacecraft needs to be able to determine its position and velocity using only onboard measurements.”
With a catalog of stars, Bailer-Jones was able to show that it’s possible to work out a spacecraft’s coordinates in six dimensions — three in space and three in velocity — to a high accuracy, based on the way the positions of those stars changes from the spacecraft’s point of view. “As a spacecraft moves away from the Sun, the observed positions and velocities of the stars will change relative to those in a Earth-based catalog due to parallax, aberration, and the Doppler effect,” he wrote. “By measuring just the angular distances between pairs of stars, and comparing these to the catalog, we can infer the coordinates of the spacecraft via an iterative forward-modeling process.”
Bailer-Jones tested his system using a simulated star catalog, and then on nearby stars from the Hipparcos catalog compiled in 1997, at relativistic spacecraft speeds. Although this is not as accurate as Gaia, that’s not terribly important – the aim was to test that the navigation system can work. With just 20 stars, the system can determine the position and velocity of a spacecraft to within 3 astronomical units and 2 kilometers per second (1.24 miles per second). This accuracy can be improved inverse to the square root of the number of stars; with 100 stars, the accuracy came down to 1.3 astronomical units and 0.7 kilometers per second. […] The system hasn’t taken stellar binaries into consideration, nor has it considered the instrumentation. The aim was to show that it could be done, as a first step towards actualizing it. It’s even possible that it could be used in tandem with pulsar navigation so that the two systems might be able to minimize each other’s flaws.
Read more of this story at Slashdot.