As NASA’s Cassini spacecraft embarked on its Grand Finale, scientists have discovered a “big empty” space between Saturn and its rings. In the first leg of its Grand Finale, the spacecraft has just been exploring the rings of Saturn.
In addition to taking stunning photographs, Cassini will make detailed maps of the magnetic and gravitational fields of the rings. It will also take samples of them. Finally, the probe will be examining how much material is in these rings. On April 26, Cassini’s first dive revealed something surprising about the Saturn’s ring plane: “the big empty.”
The Music of Space and The Big Empty
As Cassini plunged through the gap between Saturn and its rings, engineers used the spacecraft’s antennas to protect it from dust particles. One element of the antennas is the Radio and Plasma Wave Science (RPWS) instrument. This can detect even the tiniest of particles hitting the spacecraft.
On December 18, 2016, the probe passed through the plane of Saturn’s rings, just outside the main ring. In doing so, RPWS picked up hundreds of particle hits per minute. However, when the spacecraft passed through the gap between the planet and its inner rings, RPWS barely detected any particles at all.
Data from RPWS can be converted to an audio format, so the particles hitting Cassini sound like tiny pops and cracks. NASA scientists expected to hear many such sounds in the audio from April 26th. But instead, they heard space music full of eerie whistles and squeaks. These were produced by waves in the charged particle environment.
The mission team was surprised by this new development.
“It was a bit disorienting – we weren’t hearing what we expected to hear,” said William Kurth, RPWS team leader at the University of Iowa, Iowa City.
This news, however, looks good for the future of Saturn’s exploration. The spacecraft should encounter fewer threats in the gap, the big empty. Plus, the gap is offering a new mystery for scientists to explore.
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