Right now, the two Voyager spacecrafts are hurtling through interstellar space
at 35,000 miles an hour.
The space is so far away that it took 35 years to get there, and now we need new
science to understand it.
I couldn't believe how nature was fooling us.
It made us rethink everything we knew about the shape of our solar system.
I think I discovered that the tail has a croissant shape.
And even where the edge of our solar system actually is.
There was a lot of confusion.
Actually, the confusion lasted almost a year.
Even just to understand what Voyager is trying to say requires a very special
set of skills.
It's really like a Swiss watchmaker.
It needs to be a trained eye to tell me, can I trust this data or not?
What's even more extraordinary is how Voyager, the old spacecraft from 1977,
with 64 kilobytes of memory, was able to make this journey at all.
3, 2, 1.
.. We have ignition and we have liftoff.
Both Voyager 1 and Voyager 2 were launched in 1977, and it had to be then,
thanks to an extremely rare planetary alignment that happens once every 175
years.
Well, we could fly past Jupiter, get a gravity kick and go to Saturn, get a
gravity kick and get to Uranus, and another gravity kick and go past
Neptune.
Within just two years, Voyager 1 had reached Jupiter.
Voyager showed us a planet which looks so serene through a telescope, was
actually rocked by hundreds of raging hurricanes, a glowing aurora at the
North Pole, and three thin rings.
Voyager took 33,000 images of Jupiter and its major moons that captured the
world.
And we get to see these pictures and go whoa, look at that!
What's this? What's going on?
It was fantastic.
On a night like tonight, our eyes, our minds, our souls, our blood are moving
out through the universe.
We're part of history, and that means that we have to replace the old myths
with new ones.
Just one year later and Voyager 1 had already sped past Saturn, spying
intricate details in the planet's rings .
From Earth, scientists could only see five or six of Saturn's rings.
Voyager showed us that there were more than 100.
And I can remember those first pictures as we flew away, looking back at that
system and seeing the reflected sunlight in that structured ring system
. Was just so beautiful.
Then the Voyagers parted ways.
Voyager 1 headed straight for the edge of our solar system.
Voyager 2 took a more scenic route, reaching Uranus in 1986.
And eventually Neptune in 1989, showing us yet more outstanding views of the
green and blue planet and spotted geysers on Neptune's large moon, Triton.
And that was the main mission.
The first human made object to reach the distant worlds of our solar system.
But the Voyagers weren't done yet.
They were about to embark on the journey to search for the edge of our
solar system, and before they left, there was one last thing to do.
Carl Sagan convinced NASA to turn the cameras towards Earth and take that very
famous picture, the pale blue dot.
On that blue dot.
That's where everyone you know, and everyone you ever heard of, and every
human being who ever lived, lived out their lives.
It's a very small stage in a great cosmic arena.
These images were the last of 67,000 images taken by the two Voyager
spacecraft. Their cameras were then turned off to save power as they carried
on their journey towards interstellar space, the boundary where our Sun's
solar wind ends, and the rest of our universe begins.
Problem was, nobody actually knew where it really was.
Scientists thought that sooner or later, the charged particles that create
solar wind were going to run out and Voyager would enter a pristine
environment of interstellar space.
We thought that would happen, oh, maybe just beyond Neptune.
But no, that didn't happen.
Well, we said to NASA, give us a bit more money, another five years.
Well, this kept happening year after year.
NASA, please give us a little bit more money, a little bit longer, soon we'll
be there.
As Voyagers 1 and 2 continue to move out into the outer reaches of the Solar
System, they remarkably continued to send very faint signals back to Earth.
And this is what makes it so interesting and so fragile.
The whole instrumentation of Voyager was designed to visit the outer planets
that are, that have very strong magnetic fields.
So now you're dealing with a signal that is almost at the noise of the
instrument, and because Voyager was not designed for that, it's a miracle feat
that all this team is able to go mine the data, and pull out the signal, and
tell us what's going on.
Just five instruments were still operating on the spacecraft, and in
2012, almost 35 years since Voyager 1 left Earth, scientists started to see
the first signs that they were crossing into interstellar space through the
boundary known as the heliopause.
Think about the heliopause as your walls of your house.
This is what separates the environment that is dominated by the solar wind from
environment that is dominated from other winds, from other stars outside of
our bubble, the heliosphere.
The expectation was that there would be a sudden shock, a burst of activity that
would make it obvious we had finally reached this sharp boundary.
But the reality was much stranger.
All of the detectors on Voyager were seeing particles suddenly appear and
then disappear, and appear and then disappear, and nobody had a clue why.
These strange particles seemed to be coming from elsewhere in the galaxy.
Did we cross or not?
The data was so confusing.
On one hand, Voyager was still being affected by the Sun's magnetic field,
but the particles were suggesting we had crossed.
It turns out, what really tipped the scale in the team, was the radio data.
The data was stored on the spacecraft using a tape recorder.
So ancient technology, it's extraordinary, but it worked.
And the data we gathered, and sent back bit by bit.
And six months later, we played.
We turned to the radio station of Voyager and guess what we heard
.
These plasma waves converted into sound that we can hear were the final proof
that we had crossed the boundary into interstellar space.
The first human made object to venture into interstellar space.
Even more extraordinary than crossing the boundary into interstellar space was
what the data said about the shape of the solar system.
I was tasked to create a computer model with all the physics that we know to
kind of predict this shape of the heliosphere.
It turned out that the solar system's heliosphere is not round like you'd
think. It has a tail from whizzing around the galaxy.
And more than that...
I was finding that it has a croissant shape, two horns with a void in the
middle.
Was just a shock to realise that something such basic as the shape of our
home is completely different.
And all of this was discovered by a small, extremely low-tech probe, more
than 10 billion miles away, and they're still going.
In 2018, NASA's Voyager 2 spacecraft crossed the boundary.
Finally, both Voyager spacecrafts, with their 1970s technology, had reached
where no human-made object had ever been before, interstellar space.
There's very little material.
Very empty.
Space can be very, very empty.
The environment out there is colder and denser, and of course it's dark.
There's not a lot of light.
You're far away from the Sun.
Voyager has also discovered that our Solar System's impact is much bigger
than we thought before.
We would have liked to get to a region where the heliosphere doesn't influence
anymore the interstellar medium.
What we call a pristine interstellar medium.
What we're measuring now is a medium highly disturbed by the Sun.
The Voyagers are still sending us ever fainter signals, still teaching us new
things about interstellar space.
But they're running out of time.
We probably have two, three, maybe four more years of power to communicate with
Voyager.
But there are still so many mysteries left to be solved.
What is the environment outside?
What's happening at the nearby stars that are influencing our system?
And so on.
So one of the beauties of the Voyager mission is that it started as a
planetary mission, gave us the first images of our planets, discovered
volcanoes in the Solar System, and then it's went to discover our heliosphere,
our vast regions of our solar system, and enter into the galaxy.
Long after their power has gone, the Voyagers will continue to rush away from
us. Monuments to human endeavour and exploration, heading out towards the
stars.
Voyager will continue its little journey in the interstellar space way past when
we maybe as a species will cease to exist, when we might move to a different
planet.
It'll keep going and going and going and going and going forever.