Voyager 1 hears a plasma hum in deep space

Voyager 1 is one of a pair of NASA spacecraft launched 44 years ago. Voyager 1 is the most distant human-made object in space, and it's still working and getting further from home every day. The spacecraft entered interstellar space after exiting our solar system's heliopause.

A team of researchers led by Cornell recently published a study outlining something new and interesting instruments aboard the spacecraft have detected. According to the team, Voyager 1's instruments have detected the constant drone of interstellar gas plasma waves. Data scientists working on the project examined traveled back to Earth from 14 billion miles away.

Researcher Stella Koch Ocker from Cornell discovered the emission. Ocker says the sound is very faint and monotone because it's in a narrow frequency bandwidth. The scientists are detecting the faint and persistent hum of interstellar gas.

The discovery helps scientists understand how the interstellar medium interacts with the solar wind and how the protective bubble of the solar system's heliosphere is shaped and modified by the interstellar environment. Voyager 1 has been heading ever further from Earth since it launched in September 1977. The spacecraft passed by Jupiter in 1979 and flew by Saturn in 1980.

Currently, Voyager 1 is traveling at about 38,000 mph and crossed the solar system's heliopause in August 2012. One senior author on the paper, James Cordes, says that the interstellar medium is like a quiet or gentle rain. Researchers believe there is more low-level activity within the interstellar gas than scientists previously thought possible. The activity has allowed scientists to track the spatial distribution of plasma when it's not being impacted by solar flares. Ocker said Voyager 1 is an engineering gift to science that keeps on giving.