Three space probes are leaving our solar system — yet are still functioning. After the two Voyager space probes, New Horizons "was launched in 2006, initially to study Pluto," remembers New Scientist. But "it has since travelled way beyond this point, ploughing on through the Kuiper belt, a vast, wide band of rocks and dust billions of miles from the sun. It is now speeding at tens of thousands of kilometres per hour..." And it's just performed the first ever example of interstellar navigation...As it hurtles out of our solar system, NASA's New Horizons spacecraft is so far from Earth that the stars in the Milky Way appear in markedly different positions compared with our own view... due to the parallax effect. This was demonstrated in 2020 when the probe beamed back pictures of two nearby stars, Proxima Centauri and Wolf 359, to Earth. Now, Tod Lauer at the US National Optical-Infrared Astronomy Research Laboratory in Arizona and his colleagues have used this effect to work out the position of New Horizons... Almost all spacecraft calculate their bearings to within tens of metres using NASA's Deep Space Network, a collection of radio transmitters on Earth that send regular signals out to space. In comparison, the parallax method was far less accurate, locating New Horizons within a sphere with a radius of 60 million kilometres, about half the distance between Earth and the sun. "We're not going to put the Deep Space Network out of business — this is only a demo proof of concept," says Lauer. However, with a better camera and equipment they could improve the accuracy by up to 100 times, he says. Using this technique for interstellar navigation could offer advantages over the DSN because it could give more accurate location readings as a spacecraft gets further away from Earth, as well as being able to operate autonomously without needing to wait for a radio signal to come from our solar system, says Massimiliano Vasile at the University of Strathclyde, UK. "If you travel to an actual star, we are talking about light years," says Vasile. "What happens is that your signal from the Deep Space Network has to travel all the way there and then all the way back, and it's travelling at the speed of light, so it takes years." Just like a ship's captain sailing by the stars, "We have a good enough three-dimensional map of the galaxy around us that you can find out where you are," Lauer says. So even when limiting your navigation to what's on-board the spacecraft, "It's a remarkable accuracy, with your own camera!"Read more of this story at Slashdot.