2013年5月30日星期四

Cassini finds hints of activity at Saturn moon Dione

Cassini finds hints of activity at Saturn moon Dione

"A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn's geyser moon Enceladus or perhaps a weaker copycat Enceladus," said Bonnie Buratti of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. "There may turn out to be many more active worlds with water out there than we previously thought."

Other bodies in the solar system thought to have a subsurface ocean -- including Saturn's moons Enceladus and Titan and Jupiter's moon Europa -- are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.

Hints of Dione's activity have recently come from Cassini, which has been exploring the Saturn system since 2004. The spacecraft's magnetometer has detected a faint particle stream coming from the moon, and images showed evidence for a possible liquid or slushy layer under its rock-hard ice crust. Other Cassini images have also revealed ancient, inactive fractures at Dione similar to those seen at Enceladus that currently spray water ice and organic particles.

The mountain examined in the latest paper -- published in March in the journal Icarus -- is called Janiculum Dorsa and ranges in height from about 0.6 to 1.2 miles (1 to 2 kilometers). The moon's crust appears to pucker under this mountain as much as about 0.3 mile (0.5 kilometer).

"The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed," said Noah Hammond, the paper's lead author, who is based at Brown University, Providence, R.I.

Dione gets heated up by being stretched and squeezed as it gets closer to and farther from Saturn in its orbit. With an icy crust that can slide around independently of the moon's core, the gravitational pulls of Saturn get exaggerated and create 10 times more heat, Hammond explained. Other possible explanations, such as a local hotspot or a wild orbit, seemed unlikely.

Scientists are still trying to figure out why Enceladus became so active while Dione just seems to have sputtered along. Perhaps the tidal forces were stronger on Enceladus, or maybe the larger fraction of rock in the core of Enceladus provided more radioactive heating from heavy elements. In any case, liquid subsurface oceans seem to be common on these once-boring icy satellites, fueling the hope that other icy worlds soon to be explored -- like the dwarf planets Ceres and Pluto -- could have oceans underneath their crusts. NASA's Dawn and New Horizons missions reach those dwarf planets in 2015.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Hammond's work was funded through a NASA Outer Planets Research grant.

For more information about Cassini, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .


Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.


CRCW0805158RFKEA CRCW0805158KFKTA CRCW0805158KFKEA CRCW0805154RFKTA CRCW0805154RFKEA CRCW0805154KFKTA CRCW0805154KFKEA CRCW0805150RJNTA CRCW0805150RJNEB CRCW0805150RJNEA CRCW080516R9FKEA CRCW080516R5FKTA CRCW080516R5FKEA CRCW080516R2FKTA CRCW080516R2FKEA CRCW080516R0JNTA CRCW080516R0JNEA CRCW080516R0FKTA CRCW080516R0FKEA CRCW080516K9FKTB CRCW080516K9FKTA CRCW080516K9FKEB CRCW080516K9FKEA CRCW080516K5FKTA CRCW080516K5FKEA CRCW080516K2FKTA CRCW080516K2FKEB CRCW080516K2FKEA CRCW080516K0JNTA CRCW080516K0JNEA CRCW080516K0FKTA CRCW080516K0FKEA CRCW0805169RFKTA CRCW0805169RFKEA CRCW0805169KFKTA CRCW0805169KFKEA CRCW0805165RFKTA CRCW0805165RFKEA CRCW0805165KFKTA CRCW0805165KFKEA
http://www.suvsystem.com/a/1957.aspx