The Distant Alien Stars That NASA’s Voyager and Pioneer Probes Will Visit

Astronomers have determined the star systems that NASA’s Voyager and Pioneer probes are likely to find as they move through the Milky Way in the next thousand years.

The missions which have already made history will continue to do so in coming centuries.

Advertisement

During the early 1990s, NASA’s Pioneer 10 and 11 spacecraft became the first robotic missions to travel beyond Neptune.

In 2012 and 2018, the Voyager 1 and 2 missions went even farther by moving beyond the heliopause and entering interstellar space.

But history will continue being written as NASA’s spacecraft venture further out into space.

Now, a study published in the journal Research Notes of the American Astronomical Society (RNAAS), data from the second publication of data from the ESA Gaia mission (GDR2) and the astronomical database SIMBAD were used to determine the destination of Voyager and Pioneer.

The Voyager 1 & 2 Mission timeline. To infinity and beyond. Image Credit: NASA.
The Voyager 1 & 2 Mission timeline. To infinity and beyond. Image Credit: NASA.

“They will just continue to orbit through the Galaxy,” Coryn Bailer-Jones of the Max Planck Institute for Astronomy told Universe Today via email.

“They are extremely unlikely to ever collide with a star. They are likely to be deflected a little bit now and again by stars and molecular clouds but would remain bound to the Galaxy for many, many billions of years.”

Pioneer 10 and 11 made headlines around the globe when in 1972 and 73, respectively, when both were launched towards Jupiter. As the very first spacecraft to cross the main asteroid belt separating the inner planets from the outer planets of our solar system, Pioneer 10 and 11 found Jupiter and its moon system, Saturn and its moons, and achieved escape velocity that would allow them to eventually leave the Solar System.

But the Voyager probes are also making headlines and writing history as they continue to travel into outer space.

On 25 August 2012, data from Voyager 1 indicated that it had become the first human-made object to enter interstellar space, traveling “further than anyone, or anything, in history”.

NASA's Voyager 2 probe, currently on a journey toward interstellar space. Image Credit: NASA
NASA’s Voyager 2 probe, currently on a journey toward interstellar space. Image Credit: NASA

As of 2013, Voyager 1 was moving with a velocity of 17 kilometers per second (11 mi/s) relative to the Sun.

On 5 November 2018, data from Voyager 2 indicated that it also had entered interstellar space.

And since both the Pioneer as well as the Voyager mission always had the intention to explore what lies beyond our Solar System, acting as possible interstellar messengers, one can not help but be curious where they might end up in the near future. What star systems will they visit? And will they continue exploring space?

Although NASA has already lost contact with Pioneer 10 and 11 in 2003 and 1995, respectively, the trajectory that Pioneer and Voyager will follow can be determined by astronomers.

To find their trajectory, Bailor-Jones and his colleague Davide Fornocchia from JPL relied on the same techniques used in a previous study to trace the origin and future trajectory of the interstellar object ‘Oumuamua.

As Bailer-Jones explained, this consisted of three steps:

“[One,] identify in what direction and with what speed the spacecraft are leaving the solar system. (This is done by taking into account the gravity of all the planets in the solar system, as well as the Sun.) [Two,]map the motions of the spacecraft and the stars from Gaia into the future over millions of years. This takes into account a model for the gravity of the Galaxy as a whole. [Third,] identify which stars the spacecraft come close to, and when.”

Each Voyager spacecraft carries a golden record on board which includes sounds from Earth as well as pictures and messages. Image Credit: NASA
Each Voyager spacecraft carries a golden record on board which includes sounds from Earth as well as pictures and messages. Image Credit: NASA

As noted in the study, the scientists determined the asymptotic trajectories of the four spacecraft by starting from their ephemerides from JPL’s Horizons system, propagating them numerically to the year 2900, and then extrapolating to the asymptote.

Then, using a linear motion approximation they identified stars which approach within 15 pc of each spacecraft (~4500 stars in each case).

Here’s a table with the most notable flybys.

machine-readable version of the full table is available.

Source
The American Astronomical Society