Voyager 1 buffeted by "tsunami wave", 19.5 billion kms away from Earth
NEW
DELHI: Messages received from Voyager 1, the Nasa spacecraft
travelling 19.5 billion kms away from Earth, show that it is continuing
to experience a "tsunami wave" as it penetrates the interstellar medium
beyond the solar System.
The spacecraft launched in 1977 is the farthest a manmade object has gone from Earth ever. So far, signals from its instruments travelling at the speed of light take 36 hours and 14 minutes to reach Earth.
"Most people would have thought the interstellar medium would have been smooth and quiet. But these shock waves seem to be more common than we thought," said Don Gurnett, professor of physics at the University of Iowa in Iowa City. Gurnett presented the new data Monday, Dec. 15 at the American Geophysical Union meeting in San Francisco.
A "tsunami wave" occurs when the sun emits a coronal mass ejection, throwing out a magnetic cloud of plasma from its surface. This generates a wave of pressure. When the wave runs into the interstellar plasma -- the charged particles found in the space between the stars -- a shock wave results that perturbs the plasma.
"The tsunami causes the ionized gas that is out there to resonate -- "sing" or vibrate like a bell," said Ed Stone, project scientist for the Voyager mission based at California Institute of Technology in Pasadena.
This is the third shock wave that Voyager 1 has experienced. The first event was in October to November of 2012, and the second wave in April to May of 2013 revealed an even higher plasma density. Voyager 1 detected the most recent event in February, and it is still going on as of November data. The spacecraft has moved outward 250 million miles (400 million kilometers) during the third event.
It is unclear to researchers what the unusual longevity of this particular wave may mean. They are also uncertain as to how fast the wave is moving or how broad a region it covers.
The second tsunami wave helped researchers determine in 2013 that Voyager 1 had left the heliosphere, the bubble created by the solar wind encompassing the sun and the planets in our solar system. Denser plasma "rings" at a higher frequency, and the medium that Voyager flew through, was 40 times denser than what had been previously measured. This was key to the conclusion that Voyager had entered a frontier where no spacecraft had gone before: interstellar space.
"The density of the plasma is higher the farther Voyager goes," Stone said. "Is that because the interstellar medium is denser as Voyager moves away from the heliosphere, or is it from the shock wave itself? We don't know yet." Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is currently at a distance of about 16 billion kms from Earth. It is the longest continuously operated spacecraft and is expected to enter interstellar space in a few years.
The spacecraft launched in 1977 is the farthest a manmade object has gone from Earth ever. So far, signals from its instruments travelling at the speed of light take 36 hours and 14 minutes to reach Earth.
"Most people would have thought the interstellar medium would have been smooth and quiet. But these shock waves seem to be more common than we thought," said Don Gurnett, professor of physics at the University of Iowa in Iowa City. Gurnett presented the new data Monday, Dec. 15 at the American Geophysical Union meeting in San Francisco.
A "tsunami wave" occurs when the sun emits a coronal mass ejection, throwing out a magnetic cloud of plasma from its surface. This generates a wave of pressure. When the wave runs into the interstellar plasma -- the charged particles found in the space between the stars -- a shock wave results that perturbs the plasma.
"The tsunami causes the ionized gas that is out there to resonate -- "sing" or vibrate like a bell," said Ed Stone, project scientist for the Voyager mission based at California Institute of Technology in Pasadena.
This is the third shock wave that Voyager 1 has experienced. The first event was in October to November of 2012, and the second wave in April to May of 2013 revealed an even higher plasma density. Voyager 1 detected the most recent event in February, and it is still going on as of November data. The spacecraft has moved outward 250 million miles (400 million kilometers) during the third event.
It is unclear to researchers what the unusual longevity of this particular wave may mean. They are also uncertain as to how fast the wave is moving or how broad a region it covers.
The second tsunami wave helped researchers determine in 2013 that Voyager 1 had left the heliosphere, the bubble created by the solar wind encompassing the sun and the planets in our solar system. Denser plasma "rings" at a higher frequency, and the medium that Voyager flew through, was 40 times denser than what had been previously measured. This was key to the conclusion that Voyager had entered a frontier where no spacecraft had gone before: interstellar space.
"The density of the plasma is higher the farther Voyager goes," Stone said. "Is that because the interstellar medium is denser as Voyager moves away from the heliosphere, or is it from the shock wave itself? We don't know yet." Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is currently at a distance of about 16 billion kms from Earth. It is the longest continuously operated spacecraft and is expected to enter interstellar space in a few years.
Sid Harth (USA)
12/18/2014
Voyager
1 Rides Cosmic Tsunami Wave
Voyager 1 Rides 'Tsunami Wave' in Interstellar Space
It turns out that sailing through interstellar space isn't so peaceful.
NASA's Voyager 1 spacecraft — the only object made by humans to reach
interstellar space — might still be caught what scientists have
described as a cosmic "tsunami wave," a shock wave that first hit the
probe in February, according to new research. You can hear the eerie
interstellar vibrations in a video, courtesy of NASA.
"Most people would have thought the interstellar medium would have been
smooth and quiet," study researcher Don Gurnett, professor of physics at
the University of Iowa, and the principal investigator of Voyager 1's
plasma wave instrument, said in a statement from NASA. "But these shock
waves seem to be more common than we thought." [Photo Timeline: Voyager 1
in Interstellar Space]
Sid Harth (USA)
Such
a shock wave was what helped scientists determine that Voyager 1, which
launched in 1977 on a "grand tour" of the outer planets, had officially
left the solar system.
Last year, researchers keeping tabs on the car-sized spacecraft (12
billion miles away) analyzed measurements the Voyager 1 made in the
aftermath of a powerful eruption from the sun known as a coronal mass
ejection, or CME. This solar blast occurred in March 2012 and hit
Voyager 1 from April to May 2013. The shock wave caused the particles
around the spacecraft to vibrate substantially. Based on the frequency
of these vibrations, scientists could measure the density of the probe's
surroundings.
The density of the particles around Voyager 1 was 40 times higher than
scientists had previously observed when the space probe was still in the
outer layers of the heliosphere, the giant bubble of charged particles
and magnetic fields that surrounds the sun and the planets in our solar
system. Voyager 1 team members concluded that the spacecraft had exited
the heliosphere and entered a new cosmic realm. After researchers went
back and looked at old data, they concluded that Voyager 1 crossed into
interstellar space on August 25, 2012.
Sid Harth (USA)
Voyager
1 detected its third and most recent interstellar shock wave in
February. The vibrations were still going on as of November data,
according to NASA. That's remarkable considering that over the course of
this event, the spacecraft has traveled 250 million miles (400 million
kilometers).
The researchers say they are not sure how fast the wave is moving or how
big a region it covers. And they're still trying to understand what
they can learn from these waves.
"The density of the plasma is higher the farther Voyager goes," Ed
Stone, project scientist for the Voyager mission from the California
Institute of Technology, said in a statement from NASA. "Is that because
the interstellar medium is denser as Voyager moves away from the
heliosphere, or is it from the shock wave itself? We don't know yet."
The latest findings were presented Monday (Dec. 15) at the American
Geophysical Union meeting in San Francisco.
Follow Megan Gannon on Twitter. Follow us @Spacedotcom, Facebook or
Google+. Originally published on Space.com.
Copyright © 2014 All Rights Reserved.
...and I am Sid Harth
Source: TOI
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