NASA’s Voyager spacecraft are traveling on an escape trajectory from the Sun, and
are now on a journey that will take them through the outer reaches of the Solar System and
out into the Milky Way Galaxy.
They carry on board the Golden Records, a message from all humankind out into the cosmos.
In the thousands, millions and even billions of years of travel, where will they go?
What will they see?
Who might find them, and learn about us, long after we’re gone?
At the time I’m recording this video, NASA’s twin Voyager spacecraft are still fully operational,
flying away from the Solar System.
Voyager 1 was launched on September 5, 1977, and has now reached a distance of 144 astronomical
units, or 144 times the distance from the Earth to the Sun.
Light takes over 20 hours to travel from the spacecraft to Earth.
And its velocity compared to the Sun is more than 61,000 km/h.
Voyager 1 is on an escape trajectory, and it’s never coming back.
Voyager 2 was launched on August 20, 1977.
Because of a longer journey that took it past Jupiter, Saturn, Uranus and Neptune, it hasn’t
made the same distance.
It’s only 120 astronomical units from Earth.
Light merely takes 16 hours and 40 minutes to reach us.
Its velocity is a slower 55,000 km/h.
And Voyager 2 is also on an escape trajectory, charting a different path through the Milky
Way.
What does the future hold for these spacecraft?
The immediate answer, of course, is death.
Both spacecraft use radioisotope thermoelectric generators, batteries that convert the heat
from decaying chunks of plutonium into electricity.
It’s astounding to realize that they’ve already lasted over 40 years, but they’re
closer to the end of their lives than the beginning.
When they launched, the Voyagers enjoyed 470 watts of sweet electrical power.
But as the plutonium-238 decays, they’re down to about 249 watts.
Each drop in power means that NASA needs to turn off more and more of their science instruments.
And then, some time in the 2020s or 2030s, the power levels will get so low that their
transmitters will fail, and we’ll mark the moment we heard the last message from the
farflung Voyagers.
Their momentum will carry them onward and outward into the Milky Way.
But where?
Astronomers Coryn Bailer-Jones and Davide Farnocchia calculated the future paths of
the Voyagers, and calculated what stars they’ll encounter along their journey.
They made these calculations using the second data release from the European Space Agency’s
Gaia spacecraft.
This is the spacecraft that’s carefully calculating the location of 1% of the stars
in the entire Milky Way.
I’ve done a whole video celebrating this data release and warned you that this would
come up time and time again in fascinating ways.
And this is one of them.
In addition to charting the location to more than a billion stars, Gaia is measuring the
3D velocities of 7.2 million nearby stars.
In other words, Gaia tells us how all the stars around us are moving over the near future,
and the researchers looked at the paths the Voyagers will take over the upcoming tens
of thousands of years.
In about 16,700 years, Voyager 1 will make its closest flyby of Proxima Centauri, the
closest star to the Sun.
From our perspective, Proxima Centauri is 4.2 light-years away, and Voyager 1 will only
get a little closer, 3.5 light-years.
Proxima Centauri, is a smaller, red dwarf star and it’s known to have at least one
planet in the habitable zone.
But at 3.5 light-years away, Voyager 1 wouldn’t be able to give much of a better view.
Also, it would have been stone cold dead for tens of thousands of years.
Voyager 2 is going in roughly the same direction, and will cross its closest point at 20,300
years, getting within 2.87 light years of Proxima Centauri.
Assuming it doesn’t meet up with an alien probe and return to Earth as V’Ger, at the
42,000 year mark, Voyager 2 gets within 1.6 light-years of Ross 248.
This is a dim, red dwarf star with only 12% the mass of the Sun.
According to science fiction author Alastair Reynolds, Ross 248 has an ice planet called
Diadem with ice worms that have turned the entire planet into a thinking consciousness.
Voyager 2 won’t be able to conform Reynolds’ ice worm thinking planet hypothesis.
It’ll be long dead.
Super dead.
Then Voyager 1 gets within 1.86 light years of Gliese 445 on year 44,000 of its long journey.
To be honest, it’s really Gliese 445 that’s doing the heavy lifting here.
This main sequence star is hurtling in our direction.
It’s 17.6 light years away today, but when Voyager makes its flyby, it’ll be about
3.45 light-years from us.
And on that day, a person with perfect vision, with the darkest, least light polluted skies,
could, just barely see it in the sky.
But Voyager 1 could see it, if it wasn’t dead, which it will be, 44,000 years from
now.
More thrilling adventures await the Voyagers and even the Pioneer spacecraft, and we’ll
get to them in a second, but first I’d like to thank:
PumpAndHold Joel Adams
Erik Herrman Miguel
Andre Johnansson
And the rest of our 801 patrons for their generous support.
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I’ll spare you the play-by-play flybys of the missions.
Just know that at some point in the next 3.4 million years or so, Voyager 1 will get as
close as 1.27 light-years away from a star known only by a series of numbers.
Voyager 2 will make a similar flyby to a different star with a different string of numbers in
2.2 million years from now, getting within 1.83 light-years.
Bailer-Jones and Farnocchia plotted out the journeys of NASA’s Pioneer spacecraft too.
Pioneer 10 and 11 are also on escape trajectories from the Solar System.
They’ll also see a close flyby of Ross 248, Proxima Centauri and Gliese 445.
And 90,000 years from now, Pioneer 10 will get within 3 quarters of a light-year of HIP
117795, an orange-red star in the constellation Cassiopeia.
Beyond that, the future is hazy.
With future Gaia surveys, we could see a more accurate prediction of where the probes will
be.
Over the tens of millions, hundreds of millions and even billions of years of flight, they’ll
inevitably come closer to other stars in their journeys.
How long will the Voyagers last?
Their Golden records have been placed face-down on the spacecraft, and according to Cosmos,
should still be playable in a billion years from now.
Long enough for the spacecraft to complete 4 orbits around the Milky Way and encounter
many stars.
These calculations are, of course, nothing more than entertainment, to spark our imaginations.
The distances between stars are vast, and the fastest spacecraft ever sent by humanity
will still need tens of thousands of years to cross them.
Until then, we’ll work on faster and faster techniques for reaching other stars.
And maybe someday, we’ll send a future mission that will zip past the Voyagers and travelers
can see them out the windows.
Thinking back to the first times that humanity reached out beyond the Solar System.
What do you think?
Let me know your thoughts in the comments.
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