Future stellar flybys of the Voyager and Pioneer spacecraft

C.A.L. Bailer-Jones, D. Farnocchia

Following their encounters with the outer planets in the 1970s and 1980s, Pioneers 10 and 11 and Voyagers 1 and 2 are now on escape trajectories out of the solar system. Although they will cease to operate long before encountering any stars (the Pioneers already have), it is nonetheless interesting to ask which stars they will pass closest to in the next few million years. We answer this here using the accurate 3D positions and 3D velocities of 7.2 million stars in the second Gaia data release.

The animations below trace the orbits of the Sun (in yellow), one of the spacecraft ("s/c", in blue) and some close encountering stars (in red) forward in time. The coordinate system is Cartesian with the Galactic centre at (0,0,0) and is inertial with respect to that. Left is the view from the north Galactic pole (the z-axis is perpendicular to the Galactic plane); right is the view from l=90 (the direction of Galactic rotation). The Sun and spacecraft are at (x,y,z) = (8000,0,10) at t=0. Note that the scales on the axes are different, so total speeds for objects cannot easily be compared.
Above: Voyager 1 flybys with (in order) Proxima Centauri (16kyr), Gl 445 (44kyr), TYC 3135-52-1 (303kyr; the closest encounter), and HD 28343 (488kyr). These are four of the five stars listed in Table 1 in the paper. Gaia DR2 2091429484365218432 is excluded because its flyby is much later, but this is included in the panel below (which covers a longer timespan).
Above: Pioneer 10 flybys with (in order) Ross 248 (33.8kyr), Proxima Centauri (34.1kyr), and HIP 117795 (90kyr, the closest encounter). These are three of the four stars listed in Table 1 in the paper.

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Coryn Bailer-Jones, calj at mpia.de
Last modified: 10 December 2019