April 25, 2013
Meteoroids Slam Into Saturn’s Rings, Captured By Cassini Orbiter
Lee Rannals for redOrbit.com — Your Universe Online
NASA said on Thursday that its Cassini spacecraft provided the first direct evidence of small meteoroids crashing into Saturn's rings.Previously, scientists had only witnessed impacts on Earth, the moon and Jupiter as they occurred. Studying the impact rate of meteorites outside the Saturnian system helps scientists understand how different planetary systems in our Solar System formed.
The meteoroids that impacted Saturn are estimated to range from about one-half inch to several yards in size, according to the study published in the journal Science.
"These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth -- two very different neighborhoods in our solar system -- and this is exciting to see," Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement. "It took Saturn's rings acting like a giant meteoroid detector -- 100 times the surface area of the Earth -- and Cassini's long-term tour of the Saturn system to address this question."
Scientists know a very large meteoroid impact occurred in 1983 because of the ripples left 12,000 miles across the innermost rings. NASA said the summer of 2009 on Saturn was a great time to see the debris left by meteoroid impacts, because the angle of the sun caused the clouds of debris to look bright against the darkened rings in pictures from Cassini's imaging science subsystem.
"We knew these little impacts were constantly occurring, but we didn't know how big or how frequent they might be, and we didn't necessarily expect them to take the form of spectacular shearing clouds," said Matt Tiscareno, lead author of the paper and a Cassini participating scientist at Cornell University in Ithaca, NY. "The sunlight shining edge-on to the rings at the Saturnian equinox acted like an anti-cloaking device, so these usually invisible features became plain to see."
The team believes meteoroids of this size probably break up on a first encounter with the rings, creating smaller, slower pieces that enter orbit around the planet.
"Saturn's rings are unusually bright and clean, leading some to suggest that the rings are actually much younger than Saturn," said Jeff Cuzzi, a co-author of the paper and a Cassini interdisciplinary scientist specializing in planetary rings and dust at NASA's Ames Research Center in Moffett Field, California. "To assess this dramatic claim, we must know more about the rate at which outside material is bombarding the rings. This latest analysis helps fill in that story with detection of impactors of a size that we weren't previously able to detect directly."
Researchers published a paper in The Astrophysical Journal in March about how Saturn's moons and rings help tell the tale of how our Solar System formed. He said these bodies around Saturn date back more than four billion years, and they are from a time that the planetary bodies in our neighborhood formed.