The Cassini spacecraft was hit by storms of dust as it passed through Saturn's rings twice just before going into orbit June 30.
Cassini sliced through known gaps in the rings so that it wouldn't be destroyed by huge icy boulders. But the gaps are not entirely empty, it turns out.
Cassini was peppered by microscopic bits of dust that slammed into it at about 45,000 mph (20 kilometers per second). At the peak of activity, 680 bits per second pummeled the probe, according to Science.NASA.gov.
The impacts were recorded and converted to a sound file that is available on the Internet.
"When we crossed the ring plane, we had roughly 100,000 total dust hits in less than five minutes," said Cassini science team member Don Gurnett, of the University of Iowa. Gurnett said the bits were about the size of particles in cigarette smoke.
Most of the dust hit the spacecraft's high-gain antenna, which was designed to handle such impacts. No apparent damage was done.
Each impacting particle generated a puff of superheated, ionized gas called plasma. Cassini's Radio and Plasma Wave Science (RPWS) instrument recorded the puffs.
"We converted these into audible sounds that resemble hail hitting a tin roof," said Gurnett, who is the instrument's principal investigator.
In other observations, the probe gained new insight into the composition of the icy, dirty rings. Cassini has begun a four-year tour of Saturn, with plans to study its rings and moons in several close flybys.
