A couple of researchers, one at the Max Planck Institute for Astronomy and the other at the Jet Propulsion Laboratory at CIT, have found a way to estimate how long it will take for already launched spacecraft to reach other star systems. This couple, Corinne Beiler-Jones and David Farnocchia, wrote an article describing their results and uploaded it to the arXiv preprint server.
Back in the 1970s, NASA sent four unmanned space probes - Pioneer 10 and Voyager 1 and Voyager 2, which continued to operate after the completion of their missions - all four are on their way out of the solar system or have already left. But what will happen to them? Will they be able to reach other star systems, and if so, how long will it take?
This is what Beiler-Jones and David Farnocchia were interested in. They used the Gaia Space Telescope to find some possible answers. It was launched by the European Space Agency back in 2013 and was placed at a point just outside the Earth's orbit around the Sun. It collects information on billions of stars, including their trajectories in space. The latest dataset, published last year, contained information on 7.2 million stars.
With data describing the trajectories of four spacecraft and data describing the trajectories of many stars, the researchers were able to determine when the trajectories of four spacecraft could approach very distant star systems.
The researchers found that four spacecraft will approach about 60 stars over the next 1 million years - and approach about 10 of them within two parsecs. They also found that Pioneer 10 is likely to be the first to pass a star system called HIP 117795. It is in the constellation Cassiopeia. Their calculations show that the spacecraft will pass within 0.231 parsecs of the star in about 90,000 years. They also found that all four spacecraft would travel for a very long time before they collide or are captured by a star system - on the order of 1020 years.