There is much surprise from the results of NASA Cassini spacecraft's fist dive into the gap between Saturn and its rings.
Details of the orbiter's debut dive on April 26 are showing that the region is bereft of charged particles, contrary to all expectations.
In fact, an eerie silence exists between the space of Saturn and its rings with surprisingly little dust and debris. The lack of impacts is obvious in the new NASA sound video of the first dive.
In the words of Cassini Project Manager Earl Maize, the gap is a "big empty." The soundscape generated has reinforced the emptiness more intensely with freaky sounds all around.
"The region between the rings and Saturn is 'the big empty,' apparently," he said.
The data of the mission into the "big empty" was made into a soundtrack. which was picked up by the Radio and Plasma Wave Science (RPWS) instrument of the spacecraft.
Particle Expectations Dashed
The converted RPWS data into audio files give the sounds resembling white noise.
To safeguard against the particles during the first dive, Cassini had raised a large antenna as a shield at the front. However, that is looking unwarranted as the spacecraft encountered very few particles, and none were larger than 1 micron across, according to NASA.
Maize said scientists are going to analyze the mystery in the gap contrary to expectations.
Prior to dive, RPWS had "detected hundreds of ring particles hitting per second" with the particles being vaporized into electrically-excited gas outside the rings of the planet.
Earlier images by Cassini had given the impression that ring particles will be in abundance at the approximately 1,200-mile-wide region between Saturn and the rings. There was also the likelihood of the spacecraft facing challenges from them.
Though Cassini engineers are delighted at the apparent lack of particles, ring scientists are puzzled by the region's apparent dust-free nature.
Considering the fact that it is the first time a spacecraft is venturing into the region, Cassini engineers had oriented the spacecraft in such a way that its 13-foot-wide antenna is pointing to the direction of incoming ring particles to shield the sensitive instruments.
Radio Waves, Plasma Waves, And Particle Impact
In the audio files, audible pops and cracks are the sounds of dust particles hitting the instrument's antenna. They are engulfing the normal whistles and squeaks.
Obviously, the swooping Cassini at the gap between Saturn and the innermost ring was tuning into radio waves and plasma waves, around Saturn. The whistles and squeaks represent the waves in the environment of charged particles.
"It was a bit disorienting - we weren't hearing what we expected to hear," said William Kurth, the instrument's team lead at the University of Iowa.
The new data are of immense use to scientists. According to NASA, the sound data will offer new insights into Saturn's relationship with its moons and rings as well as its interaction with the solar wind.
The dives are part of Cassini spacecraft's 'grand finale' with the epic journey ending on Sept. 15. After taking 20 more dives, Cassini will plunge into Saturn's atmosphere and mark the mission's end.