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Saturn's rings show evidence of a modern-day collision NASA/JPL NEWS RELEASE Posted: October 11, 2006 Scientists with NASA's Cassini mission have spied a new, continuously changing feature that provides circumstantial evidence that a comet or asteroid recently collided with Saturn's innermost ring, the faint D ring.
These findings are being presented today at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Pasadena, Calif. "This structure in the D ring reminds us that Saturn's rings are not eternal, but instead are active, dynamical systems, which can change and evolve," said Dr. Matt Hedman, Cassini imaging team associate at Cornell University, Ithaca, N.Y. When Cassini researchers viewed the D ring along a line of sight nearly parallel to the ringplane, they observed a pattern of brightness reversals: a part of the ring that appears bright on the far side of the rings appeared dark on the near side of the rings, and vice versa. This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material. Both the changes over time and the "corrugated" structure of this region could be explained by a collision of a comet or meteoroid into the D ring, which then kicked out a cloud of fine particles. This cloud might have inherited some of the tilt of the colliding object's path as it slammed into the rings. An alternate explanation could be that the object struck an already inclined moonlet, shattering it to bits and leaving its debris in an inclined orbit. In either case, the researchers speculate the aftermath of such a collision would be a ring slightly tilted relative to Saturn's equatorial plane. Over a period of time, as the inclined orbits of the ring particles evolve, this flat sheet of material would become a corrugated spiral that appears to wind up like a spring over time, which is what was observed. Based on observations between 1995 and 2006, scientists reconstructed a timeline and estimated that the collision occurred in 1984. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo. |
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Dazzling images from Mars are revealed by scientists. The robotic rover Opportunity has reached the massive Victoria crater with its steep cliffs and layers of rock exposing the planet's geologic history. Meanwhile, the new Mars Reconnaissance Orbiter has photographed the rover and its surroundings from high above.
Loaded with a package of telescopes in its payload bay, shuttle Columbia soared into space for the first ASTRO mission in December 1990. The crew narrates this highlights film from the STS-35 mission in which the astronauts worked around the clock in two shifts to operate the observatory. The flight launched and then landed at night, and included the astronauts teaching from space.
n this news conference from NASA Headquarters, scientists announce the Hubble Space Telescope's discovery of 16 extrasolar planet candidates orbiting a variety of distant stars in the central region of our Milky Way galaxy. Five of the newly found planets represent a new extreme type of planet not found in any nearby searches.