(Press-News.org) Simulations performed at Southwest Research Institute may explain how Saturn's majestic rings and icy inner moons formed following the collision of a Titan-sized satellite with the planet, according to a paper published in Nature magazine's Dec. 12 Advance Online Publication.
Saturn's rings are at present 90 to 95 percent water ice. Because dust and debris from rocky meteoroids have polluted the rings, the rings are believed to have consisted of pure ice when they formed. This composition is unusual compared to the approximately half-ice and half-rock mixture expected for materials in the outer Solar System. Similarly, the low densities of Saturn's inner moons show that they too are, as a group, unusually rich in ice.
The previous leading ring origin theory suggests the rings formed when a small satellite was disrupted by an impacting comet. "This scenario would have likely resulted in rings that were a mixture of rock and ice, rather than the ice-rich rings we see today," says the paper's author, Dr. Robin M. Canup, associate vice president of the SwRI Planetary Science Directorate in Boulder.
The new theory links the formation of the rings to the formation of Saturn's satellites. While Jupiter has four large satellites, Saturn has only one, Titan. Previous work suggests that multiple Titan-sized satellites originally formed at Saturn, but that those orbiting interior to Titan were lost as their orbits spiraled into the planet.
As the final lost satellite neared Saturn, heating caused by the flexing of its shape by the planet's gravity would cause its ice to melt and its rock to sink to its center. Canup uses numerical simulations to show that as such a satellite crosses the region of the current B ring, planetary tidal forces strip material from its outer icy layers, while its rocky core remains intact and eventually collides with the planet. This produces an initial ice ring that is much more massive than Saturn's current rings.
Over time, collisions in the ring cause it to spread radially and decrease in mass. Inwardly spreading ring material is lost, while material spreading past the ring's outer edge accumulates into icy moons with estimated masses consistent with the inner moons seen today.
"The new model proposes that the rings are primordial, formed from the same events that left Titan as Saturn's sole large satellite, " says Canup. "The implication is that the rings and the Saturnian moons interior to and including Tethys share a coupled origin, and are the last remnants of a lost companion satellite to Titan."
During its extended mission, the Cassini spacecraft will measure the rings' current mass and will indirectly measure the pollution rate of the rings. This should provide an improved estimate of the rings' age and a test of the new ring origin model.
INFORMATION:
NASA's Outer Planets Research Program funded this research. The paper, "Origin of Saturn's Rings and Inner Moons by Mass Removal from a Lost Titan-Sized Satellite," by Dr. R.M. Canup, was published in Nature magazine's Dec. 12 Advance Online Publication.
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CINCINNATI –For the first time, scientists have created functioning human intestinal tissue in the laboratory from pluripotent stem cells.
In a study posted online Dec. 12 by Nature, scientists from Cincinnati Children's Hospital Medical Center say their findings will open the door to unprecedented studies of human intestinal development, function and disease. The process is also a significant step toward generating intestinal tissue for transplantation, researchers say.
"This is the first study to demonstrate that human pluripotent stem cells in a petri dish can be ...
A team led by Massachusetts General Hospital (MGH) researchers has developed a faster way to engineer synthetic enzymes that target specific DNA sequences for inactivation, repair or alteration. The report from the MGH Molecular Pathology Unit, being published online in Nature Methods, describes a highly effective but less labor-intensive way to generate powerful tools called zinc-finger nucleases (ZFNs).
"With our approach, called context-dependent assembly, any scientist can use either standard molecular biology techniques or commercial DNA synthesis to design ZFNs ...
BIRMINGHAM, Ala. – University of Alabama at Birmingham researchers have pinpointed a protein that compromises the kidney's filtering ability, causing nephrotic syndrome, and demonstrated that a naturally occurring precursor of an acid in the body offers potential for treating some forms of the condition.
The research was published online Dec. 12 in Nature Medicine.
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RIVERSIDE, Calif. – Researchers at the University of California, Riverside have identified components in pomegranate juice that both inhibit the movement of cancer cells and weaken their attraction to a chemical signal that promotes the metastasis of prostate cancer to the bone. The research could lead to new therapies for preventing cancer metastasis.
Performed in the lab of Manuela Martins-Green, a professor of cell biology, the research was presented today (Dec. 12, 2010) at the 50th annual meeting of the American Society for Cell Biology taking place in Philadelphia.
Prostate ...
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Demand for newsprint in North American has declined by 50% over the past decade, and despite recent price increases the future remains bleak for producers. Strategic Analysts has released their latest white paper discussing the decline and analyzing the cost competitiveness and financial viability of AbitibiBowater and the other major producers.
Springboro, OH - December 3, 2010 - Back in 2000, newsprint demand in North America was at an all time high. Daily circulation was at its record levels and the newspapers themselves were reporting record advertising revenue. ...
California-based Pizza.com has announced the addition of Shay Traynor to the company's sales staff.
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Piracini will continue to travel throughout New England several times a year visiting companies ...
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LightBoxes4Sale.com is a niche website that focuses on a very specific sector of the display fixture market: light boxes. This narrow scope means more specialized, targeted customer care and a wider selection.
Explains ADG sales and marketing director Craig Abrams, "If you're a designer or corporate buyer and you are looking for a light box, LightBoxes4Sale.com will have the perfect style and size for you."
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Lisa Calkins, CEO of custom application development company Amadeus Consulting is nominated as one of the most influential women in tech for 2011. The awards are put on by Fast Company, a magazine that is at the forefront of exciting emerging technology and innovation in growing companies.
The annual award is given to female power players in the technology industry who bring a unique brand thought leadership and proven success to technology companies in all sectors including: custom software development, consumer product, mobile application development, etc. The award ...
