Humanity has always been fascinated by the sky above and the oceans below.
Curiosity is one of humanity's strengths and will continue to be a prominent trait.
Countless people have wondered what is beyond our world, and their inquiries have led to
new discoveries about the universe.
The universe is vast, and we know very little about it, but humanity is anxious to unravel
its greatest secrets.
Many missions, like as the National Aeronautics and Space Administration's Voyager, have been
carried out to increase our understanding of the cosmos.
However, if the stars had not aligned, two of the most remarkable spacecrafts ever launched
would never have launched.
The stars in this scenario were actually planets—the four largest in the solar system.
45 years later, both probes are still travelling across interstellar space.
Researchers, some of whom are younger than the spacecraft, are actively exploiting Voyager
data to solve riddles within and beyond our solar system.
And recently Voyager 1 came across something unusual; what is this most recent discovery?
What are the probes up to now?
What challenges will these spacecraft face in the coming years?
All of this will be revealed in today's video.
NASA's twin Voyager probes, launched in 1977, dazzled the world with historic journeys to
Jupiter, Saturn, Uranus, and Neptune.
Some 60 years ago, these planets were slowly wheeling into an arrangement that had last
occurred during Thomas Jefferson's presidency in the early years of the nineteenth century.
For a while, the rare planetary set piece went mostly unnoticed.
Gary Flandro, a doctoral student in aeronautics at the California Institute of Technology,
was the first to draw attention to it.
It was 1965, and the space age was just getting started—the Soviet Union had launched Sputnik
1, the first artificial satellite, only eight years before.
Flandro, who was working part-time at NASA's Jet Propulsion Laboratory in Pasadena, California,
was tasked with determining the most efficient way to send a space probe to Jupiter, or possibly
Saturn, Uranus, or Neptune.
He charted the orbital paths of those giant planets with a pencil, a favorite precision
tool of twentieth-century engineers, and discovered something intriguing: in the late 1970s and
early 1980s, all four would be strung like pearls on a celestial necklace in a long arc
with Earth.
As a result of this coincidence, a spacecraft may gain speed from the gravitational pull
of each large planet it passes through, as if it were being dragged along by an invisible
rope that suddenly snapped, sending the probe flying on its course.
One disadvantage was that the alignment occurred only once every 176 years.
To reach the planets while the lineup was still in effect, a spaceship would need to
be launched by the mid-1970s.
As it turned out, NASA designed two spacecraft to take advantage of this once-in-a-lifetime
opportunity.
In the summer of 1977, Voyager 1 and Voyager 2, which were identical in every manner, were
launched within 15 days of one another.
They've been in space for 45 years, sending data back to Earth every day from the Solar
System's most distant planets.
Earlier observations of Jupiter's and Saturn's moons by the Voyager spacecraft, which were
presented to shocked astronomers 40 years ago, revealed the presence of active volcanoes
and fissured ice fields on worlds that astronomers had imagined would be as dormant and crater
pocked as our own Moon.
In 1986, Voyager 2 was the first spacecraft to fly by Uranus, and three years later it
sailed by Neptune.
It is the only spacecraft that has gone in this manner thus far.
As pioneering Interstellar probes more than 14 billion miles from Earth, they are currently
startling physicists with a variety of unexpected discoveries concerning that unexplored region.
Finally, their incredible journey is drawing to an end; NASA has shut off heaters and other
non-essential components during the last three years in order to extend the spacecraft's
energy supplies as far as possible to 2030, which is the predicted end date.
It's a bittersweet occasion for the scientists working with the Voyagers, many of whom have
been with the mission since its inception.
They are now faced with completing a project that exceeds their wildest expectations.
Returning to Jupiter, the spacecraft began transmitting the first photographs of the
planet despite being three to four months distant.
It was completely unexpected for IO to appear in color; prior to the voyager expeditions,
it was assumed that all moons in the solar system would seem the same, dull and crated.
The extraordinary variety of moonscapes that the Voyagers discovered in the vicinity of
Jupiter and Saturn was not anticipated.
When the Voyagers were still approximately one million miles away from Jupiter, the first
clue that there may be more Moon kinds than scientists had expected arose.
The Low Energy Charged Particle (LECP) detection system, one of their equipment, noticed some
unusual signals.
The cameras on board the Voyagers revealed that IO has active volcanoes.
The little world, which is slightly larger than the Earth's moon, is now known to be
the most volcanically active body in the Solar System.
The components spewed by the moon's volcanoes are responsible for the colors of IO as well
as the anomalous ions that strike the detector.
Pele, the most powerful of IO's volcanoes, has emitted plumes 30 times the height of
Mount Everest, and its ash field is about the size of France.
Voyager 2 discovered ten new moons circling Uranus in 1986, increasing the planet's ringed
world count to an ever-increasing amount.
Three years later, as it flew around 2980 miles above Neptune's Azure methane atmosphere,
Voyager 2 saw the greatest wind speeds yet recorded for a planet in the solar system,
reaching up to 1000 miles per hour.
Triton, Neptune's largest moon, was determined to be one of the coldest places in the Solar
System, with a surface temperature of minus 391 degrees Fahrenheit (minus 235 degrees
Celsius).
Ice volcanoes blasted nitrogen gas and propelled particles five miles into the moon's atmosphere.
If Carl Sagan, an astronomer on the mission's imaging crew, had not been present, Voyager
2's images of Neptune and its moons would have been the last ever obtained by either
spacecraft.
NASA planned to turn off the cameras on both spacecraft after The Grand Tour was officially
completed.
Despite the fact that the project had been extended in the hopes that the Voyagers would
reach Interstellar space and had been renamed the Voyager Interstellar Mission, there would
have been no photo opportunities after Neptune, only continuous nothingness and impossibly
far-off stars.
Sagan urged NASA officials to order Voyager 1 to send another batch of images, and as
a result, on Valentine's Day in 1990, the probe directed its cameras back toward the
inner solar system and took 60 final images.
At a distance of 3.8 billion miles, Earth was captured by the most captivating of them
all, dubbed the 'Pale Blue Dot' by Sagan.
It is still the most distant representation of our planet ever obtained.
Earth is hardly visible in the shot because it is obscured by faint sunlight reflected
off the camera's optics; it doesn't even take up a whole pixel in the image.
However, as they moved into the interstellar portion of their journey, Voyager 1 picked
up on something that was out of the ordinary.
The interstellar medium, like the ocean, is full of turbulent 'waves.'
The largest are caused by the rotation of our Milky Way Galaxy, as space smears against
itself, creating undulations tens of light-years across.
Smaller ripples rush from supernova explosions, spanning billions of kilometers from crest
to crest.
The smallest waves are usually caused by our Sun, as solar eruptions send shockwaves through
space that permeate the lining of our heliosphere.
These crashing waves reveal information about the density of the interstellar medium, which
influences our understanding of the shape of our heliosphere, how stars form, and even
our own position in the Galaxy.
As these waves reverberate through space, they vibrate the electrons around them, which
ring out at different frequencies depending on how closely they are packed together.
The electron density increases as the pitch of the ringing increases.
The Plasma Wave System on Voyager 1, which includes two antennas protruding 10 meters
(30 feet) behind the spacecraft, was designed to detect that ringing.
“It’s very faint and monotone, because it is in a narrow frequency bandwidth,”
said Stella Koch Ocker, a Ph.D. student in the Department of Astronomy and the Cornell
Center for Astrophysics and Planetary Science at Cornell University.
“We’re detecting the faint, persistent hum of interstellar gas.”
This enables scientists to better understand how the interstellar medium interacts with
solar wind, as well as how the interstellar environment shapes and modifies the Solar
System's heliosphere.
Three months after leaving the heliosphere, Voyager 1 heard interstellar sounds for the
first time in November 2012.
Six months later, there was another 'whistle,' this time louder and higher in pitch.
The interstellar medium appeared to be getting thicker, and quickly.
These brief whistles can still be found in Voyager data at irregular intervals.
“They’ve only been seen about once a year, so relying on these kinds of fortuitous events
meant that our map of the density of interstellar space was kind of sparse,” Dr. Ocker explained.
Dr. Ocker and colleagues set out to fill in the gaps with a running measure of interstellar
medium density that does not rely on shockwaves propagating out from the Sun.
They discovered a promising candidate after filtering through the Voyager 1 data, looking
for weak but consistent signals.
It began to pick up around the time of another whistle in mid-2017.
The new signal is known as plasma wave emission, and it appears to track the density of interstellar
medium.
The tone of the emission rises and falls with the appearance of the abrupt whistles in the
data.
The signal is also similar to one observed in Earth's upper atmosphere, which is known
to track with electron density.
Based on the signal, electron density around Voyager 1 began to rise in 2013 and peaked
around mid-2015, representing a roughly 40-fold increase in density.
It is anticipated that the spacecraft will eventually leave these turbulent shores behind
and come into contact with something new in the Interstellar space.
The Voyagers have lasted longer and travelled farther than any other spacecraft in history.
They are the first objects created by humans to enter interstellar space, and they will
remain so for at least another few decades.
Overall, not a bad record considering the Voyager missions were only supposed to last
five years.
Voyager 1 will pass by Proxima Centauri, our nearest neighbor star, in 16,000 years, while
Voyager 2 will take 20,000 years.
They will then spend millions of years orbiting the galaxy, long after our sun has died.
Let us know what you think about the Voyagers in the comments section below.