Posts tagged science
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/.
NSF AWARDS CU-BOULDER $5.9 MILLION GRANT FOR ALPINE ECOSYSTEM RESEARCH
Jun 16th
The National Science Foundation has awarded the University of Colorado Boulder a six-year, $5.9 million grant to continue intensive studies of long-term ecological changes in Colorado’s high mountains, both natural and human-caused, over decades and centuries.
Awarded to CU-Boulder’s Institute of Arctic and Alpine Research, the renewal grant will allow faculty and students, including undergraduates, to continue key environmental studies at the Niwot Ridge Long-Term Ecological Research, or LTER, site west of Boulder. The study site, considered extremely sensitive to climate change, is adjacent to CU-Boulder’s Mountain Research Station and encompasses several thousand acres of tundra, talus slopes, glacial lakes and wetlands stretching to the top of the Continental Divide.
The grant is the largest environmental sciences award in CU-Boulder history, said INSTAAR Fellow Mark Williams, principal investigator on the grant. In 2005, NSF awarded CU-Boulder a $4.9 million renewal grant for environmental studies at the Niwot Ridge site. As one of five initial LTER sites selected by NSF in 1980, Niwot Ridge is now one of 25 such sites in North America and the only one located in an alpine environment, said Williams.
“CU-Boulder has a worldwide reputation for monitoring global climate change from Greenland to Antarctica and its impacts on natural ecosystems and human populations,” said Vice Chancellor for Research Stein Sture. “To direct such a key program in our own backyard for the National Science Foundation is crucial from an environmental science standpoint and unique in that it provides a spectacular training ground for our students to work side-by-side with some of the world’s best climate change scientists.”
Recent climate studies have predicted the mountainous areas of the American West will become both hotter and drier in the coming years, and long-term meteorological measurements on Niwot Ridge indicate the alpine climate there has warmed slightly in recent decades, said Williams, also a professor in the geography department. The temperatures are significant because even small changes in alpine ecosystems can cascade down and have negative effects on other ecosystems, he said.
CU-Boulder researchers also have charted a doubling in atmospheric nitrogen deposition on Niwot Ridge in the past several decades — primarily from automobile, agriculture, ranching and industrial activity — that is now adversely affecting some aquatic and terrestrial life on the ridge, said Williams.
In addition, researchers are keeping a close eye on existing populations of the American pika, a potato-sized animal related to rabbits and found in rocky talus slopes as high as 13,000 feet on Niwot Ridge. Of 25 populations of pikas in the Great Basin of Nevada documented between 1898 to 1990, nine had disappeared by 2008, apparently the result of warming temperatures. Pikas in Colorado require deep snowpack during winter that serves to insulate them from extremely cold air temperatures, Williams said.
“Many consider the American pika a ‘sentinel species’ in terms of measuring the effects of climate change,” said Williams. “Niwot Ridge has a cold, short growing season, and the biological activity that occurs there is on the razor’s edge of environmental tolerance.”
Despite a long-term warming and drying trend in mountainous areas of the West, 2011 was a striking anomaly, said Williams. “What we have seen around here is one of the largest and latest snowfall years on record in the high country and extreme dryness accompanied by an inordinate amount of winter wildfires around Boulder, which is only 15 miles as the crow flies from the Niwot Ridge study area. What has happened from Boulder west to the Continental Divide has been a total disconnect in terms of weather.”
“The primary climate driver of the Niwot Ridge site is snow, and the mountains are our water towers,” said Williams. “As the alpine climate changes, one of the biggest impacts on humans will be a change in water resources. Even if we end up with the same amount of precipitation, in the form of less snow and more rain, we are going to end up with less usable water for municipalities.”
There already are some indications that the snowline in the Rocky Mountains is moving upward, which will affect the abundance and distribution of plants and animals and likely shorten the annual ski seasons at resorts throughout the West in the future, he said.
The Niwot Ridge site is a huge benefit to CU-Boulder students, said Williams. “I have five undergraduates working in my chemistry lab this summer. Not only do they get paid, but they learn valuable research skills.” The LTER grant funds research for about 15 CU-Boulder graduate students and 25 to 30 undergraduates annually, Williams said, and there are more than a dozen CU-Boulder faculty members that are co-investigators on the new Niwot Ridge LTER program grant.
CU-Boulder ecology and environmental biology department Professor William Bowman, director of CU-Boulder’s Mountain Research Station for the past 20 years, said the Niwot Ridge site has been gaining momentum in stature from its beginnings by the consistent, high-quality research that has resulted in many publications in top-tier science journals.
More than half of the research on Niwot Ridge is by scientists and students from around the world that are not associated with the LTER program, said Bowman, also an INSTAAR fellow and who leads a team studying how air pollution, including nitrogen deposition, threatens biological and aquatic communities in U.S. national parks. There are currently 12 undergraduates conducting research at the Niwot Ridge site as part of the NSF’s Research Experience for Undergraduates program, said Bowman, who also is mentoring a student researcher at Niwot Ridge from Fairview High School in Boulder.