ITHACA, N.Y. — Although sound does not travel through the vacuum of space, the universe is still making some kind of noise — according to one of the most famous space probes in history. Voyager 1 has detected what scientists are calling a constant humming sound from plasma, the fourth state of matter which makes up 99.9 percent of the universe.
The probe, launched from Earth 44 years ago, is currently 14 billion miles away. Its instruments recorded the “constant drone” after passing the edge of the solar system through the heliopause – our system’s border with interstellar space.
“It’s very faint and monotone, because it is in a narrow frequency bandwidth,” says astrophysicist Stella Ocker from Cornell University in a release. “We’re detecting the faint, persistent hum of interstellar gas.”
Voyager takes its mission into uncharted territory
The bizarre noises are like the special effects of a science fiction film, which scientists identified in data coming back from the probe. No manmade object has travelled further than NASA’s iconic spacecraft. The space agency launched Voyager 1 in 1977 to fly by Jupiter and Saturn but it has just kept going ever since. The probe crossed into interstellar space in August 2012 and now continues to collect data.
It carries a copy of the Golden Record, a “message to aliens” compiled by legendary astronomer Carl Sagan. There are greetings in 55 languages and pictures of people and places on Earth. It even includes music ranging from Beethoven to Chuck Berry’s “Johnny B. Goode.”
Currently, Voyager is in an area called the local “interstellar medium,” where the hum was detected. The study, appearing in Nature Astronomy, sheds fresh light this medium interactions with the sun’s wind.
After entering interstellar space, Voyager’s Plasma Wave System detected the gas bursts coming from our own roiling sun. In between the researchers uncovered a steady, persistent signature produced by the tenuous near-vacuum of space.
“The interstellar medium is like a quiet or gentle rain,” explains senior author James Cordes, Cornell’s George Feldstein Professor of Astronomy. “In the case of a solar outburst, it’s like detecting a lightning burst in a thunderstorm and then it’s back to a gentle rain.”
Is Voyager ‘swimming’ through cosmic noise?
Ocker believes there is more low-level activity in the gas than previously thought, enabling tracking of its spatial distribution.
“We’ve never had a chance to evaluate it. Now we know we don’t need a fortuitous event related to the sun to measure interstellar plasma,” co-author Shami Chatterjee adds.
“Regardless of what the sun is doing, Voyager is sending back detail. The craft is saying, ‘Here’s the density I’m swimming through right now. And here it is now.’… Voyager is quite distant and will be doing this continuously.”
Voyager 1 and its sister ship, Voyager 2, have been flying longer than any other spacecraft in human history. Their missions are providing humanity with observations of truly uncharted territory. They are also helping scientists understand the very nature of energy and radiation in space; key to protecting manned missions to Mars.
SWNS writer Mark Waghorn contributed to this report.