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STRONGEST EVIDENCE YET INDICATES ICY SATURN MOON HIDING SALTWATER OCEAN
Jun 22nd
The new discovery was made during the Cassini-Huygens mission to Saturn, a collaboration of NASA, the European Space Agency and the Italian Space Agency. Launched in 1997, the mission spacecraft arrived at the Saturn system in 2004 and has been touring the giant ringed planet and its vast moon system ever since.
The plumes shooting water vapor and tiny grains of ice into space were originally discovered emanating from Enceladus — one of 19 known moons of Saturn — by the Cassini spacecraft in 2005. The plumes were originating from the so-called “tiger stripe” surface fractures at the moon’s south pole and apparently have created the material for the faint E Ring that traces the orbit of Enceladus around Saturn.
During three of Cassini’s passes through the plume in 2008 and 2009, the Cosmic Dust Analyser, or CDA, on board measured the composition of freshly ejected plume grains. The icy particles hit the detector’s target at speeds of up to 11 miles per second, instantly vaporizing them. The CDA separated the constituents of the resulting vapor clouds, allowing scientists to analyze them.
The study shows the ice grains found further out from Enceladus are relatively small and mostly ice-poor, closely matching the composition of the E Ring. Closer to the moon, however, the Cassini observations indicate that relatively large, salt-rich grains dominate.
“There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than the salt water under Enceladus’ icy surface,” said Frank Postberg of the University of Germany, lead author of a study being published in Nature on June 23. Other co-authors include Jürgen Schmidt from the University of Potsdam, Jonathan Hillier from Open University headquartered in Milton Keynes, England, and Ralf Srama from the University of Stuttgart.
“The study indicates that ‘salt-poor’ particles are being ejected from the underground ocean through cracks in the moon at a much higher speed than the larger, salt-rich particles,” said CU-Boulder faculty member and study co-author Sascha Kempf of the Laboratory for Atmospheric and Space Physics.
“The E Ring is made up predominately of such salt-poor grains, although we discovered that 99 percent of the mass of the particles ejected by the plumes was made up of salt-rich grains, which was an unexpected finding,” said Kempf. “Since the salt-rich particles were ejected at a lower speed than the salt-poor particles, they fell back onto the moon’s icy surface rather than making it to the E Ring.”
According to the researchers, the salt-rich particles have an “ocean-like” composition that indicates most, if not all, of the expelled ice comes from the evaporation of liquid salt water rather than from the icy surface of the moon. When salt water freezes slowly the salt is “squeezed out,” leaving pure water ice behind. If the plumes were coming from the surface ice, there should be very little salt in them, which was not the case, according to the research team.
The researchers believe that perhaps 50 miles beneath the surface crust of Enceladus a layer of water exists between the rocky core and the icy mantle that is kept in a liquid state by gravitationally driven tidal forces created by Saturn and several neighboring moons, as well as by heat generated by radioactive decay.
According to the scientists, roughly 440 pounds of water vapor is lost every second from the plumes, along with smaller amounts of ice grains. Calculations show the liquid ocean must have a sizable evaporating surface or it would easily freeze over, halting the formation of the plumes. “This study implies that nearly all of the matter in the Enceladus plumes originates from a saltwater ocean that has a very large evaporating surface,” said Kempf.
Salt in the rock dissolves into the water, which accumulates in a liquid ocean beneath the icy crust, according to the Nature authors. When the outermost layer of the Enceladus crust cracks open, the reservoir is exposed to space. The drop in pressure causes the liquid to evaporate into a vapor, with some of it “flash-freezing” into salty ice grains, which subsequently creates the plumes, the science team believes.
“Enceladus is a tiny, icy moon located in a region of the outer Solar System where no liquid water was expected to exist because of its large distance from the sun,” said Nicolas Altobelli, ESA’s project scientist for the Cassini-Huygens mission. “This finding is therefore a crucial new piece of evidence showing that environmental conditions favorable to the emergence of life may be sustainable on icy bodies orbiting gas giant planets.”
The Huygens probe was released from the main spacecraft and parachuted through the atmosphere to the surface of Saturn’s largest moon, Titan, in 2005.
The Cassini spacecraft is carrying 12 science instruments, including a $12.5 million CU-Boulder ultraviolet imaging spectrograph designed and built by a LASP team led by Professor Larry Esposito.
LINGUISTICS INSTITUTE TO OFFER FREE FILMS, WORKSHOPS AT CU-BOULDER
Jun 20th
The biennial event has never been held in Colorado and is expected to attract about 500 people to CU-Boulder. The previous three institutes were held at the University of California, Berkeley (2009), Stanford (2007) and Massachusetts Institute of Technology (2005).
In addition to the free and public events, the institute will offer 80 courses taught by distinguished faculty, with enrollment available to the public through CU-Boulder’s Continuing Education and Professional Studies.
For one class, Field Methods in Linguistics, a speaker of the Idi language of Papua New Guinea will travel to Boulder. The Idi language is spoken by only about 1,600 people and is barely documented. Students in the class led by Professor Nicholas Evans of Australian National University will work intensively for one month to provide the first extensive documentation of this language.
On July 13 at 7 p.m. in Muenzinger Psychology and Biopsychology room E050 will be a free showing of “We Are Still Here,” a film examining language and culture revitalization efforts of the Wampanoag Native Americans in Massachusetts.
And on July 20 at 7 p.m. in Muenzinger Psychology and Biopsychology room E050 there will be a free showing of “Speaking in Tongues,” a film following four children through the world of bilingualism and bilingual education in the United States.
“Language is fundamental to virtually everything we do in life, and it is perhaps the single most important thing that separates humans from all other life forms,” said Andrew Cowell, associate director of the institute and a CU-Boulder professor of linguistics. “We take it for granted so much of the time until someone makes the smallest misstatement, a machine translation produces something goofy or we pick up on a subtle accent we recognize — and then political careers can be compromised, corporate initiatives can become the target of worldwide mockery or lifelong friendships can be initiated.
“The institute will focus specifically on ‘Language in the World’ and the interdisciplinary connections between linguistics and other fields such as psychology, sociology, anthropology, law, computer science and the media,” he said.
The institute is sponsored by the Linguistic Society of America, which is the main professional body for linguists in the United States, with major support from CU-Boulder.
Students enrolled in a Colorado university, college or community college are eligible to register for the institute at about half the usual price, as are Colorado faculty. Information about this offer is posted at https://verbs.colorado.edu/LSA2011/registration-cofund.html.
For more information and a complete schedule of events visit
http://verbs.colorado.edu/LSA2011/.
Fourmile Canyon Fire aerial mulching to begin Thursday, April 7 (weather permitting)
Apr 5th
Aerial mulching treatments will consist of certified weed-free straw and WoodStrawÓ being dropped in pre-determined areas from helicopters. Target areas were determined by a set of criteria that includes slope, burn severity, flood/debris flow risk, and values downstream (including human life, safety and property). In total, approximately 1,960 acres will be aerially mulched inside the fire boundary.
Aerial operations will begin on April 7 (weather permitting) in the vicinity of Sugarloaf Road and Fourmile Canyon Drive and move to areas within Sunshine Canyon on or after April 12. Flights will operate for about two weeks (up until April 23) depending on weather conditions throughout the mulching period.
Helicopters will be flying during daylight hours only beginning as early as 7 a.m., and residents can expect temporary road closures as helicopters fly overhead. Additionally, heavy truck equipment will be used in the vicinity of Sugarloaf Road and Sunshine Canyon to deliver straw and support equipment for the aerial flights.
Hand seeding is taking place along roads and driveways in areas that were moderately to severely burned, and with less than 60 percent slope. Roads and driveways are targeted because vehicles are a common way that weed seeds are transported. In total, approximately 500 acres will be seeded utilizing the help of volunteers.
Call the Fourmile Rehabilitation Hotline at 303-413-7010 for the latest updates on seeding and aerial mulching activities. Message boards or flaggers will be located in the vicinity of work being performed to alert residents of any delays or modifications to traffic patterns.
Safety issues
Due to safety regulations and FAA requirements, no one can be in the immediate areas where mulch is being dropped.
Residents and workers in the mulching areas for Gold Hill, Four Mile Canyon, Sugar Loaf and Sunshine Canyon will be asked to leave the area for the day, and bring in pets/livestock while their specific block or neighborhood is being mulched.
Boulder County Sheriff’s patrols will be active in the area to maintain public safety for the duration of the treatments. The Sheriff’s Office asks everyone to be mindful of the following privacy and public safety rules:
- Motorists must not block traffic on any public right of way.
- Everyone must stay at least 200 feet outside of the perimeter of active aerial mulching treatment areas at all times so as not to impede operations.
- No trespassing is allowed on private property including driveways, turn-offs, private roads or other private property.
- Cyclists are asked to avoid Sugarloaf Road, Fourmile Canyon Drive, and Sunshine Canyon Drive while helicopter flights are occurring (April 7-23).
Information resources
For additional information and maps showing the treatment areas go to: www.bouldercounty.org/fourmilefire.