Posts tagged NASA
C.U. Team on a 2 Year effort to research environment factors
Jan 25th
Jan. 25, 2012
CU-BOULDER-LED TEAM TO ASSESS DECLINE OF
ARCTIC SEA ICE IN ALASKA’S BEAUFORT SEA
A national research team led by the University of Colorado Boulder is embarking on a two-year, multi-pronged effort to better understand the impacts of environmental factors associated with the continuing decline of sea ice in the Arctic Ocean.
The team will use tools ranging from unmanned aircraft and satellites to ocean buoys in order to understand the characteristics and changes in Arctic sea ice, which was at 1.67 million square miles during September 2011, more than 1 million square miles below the 1979-2000 monthly average sea ice extent for September — an area larger than Texas and California combined. Critical ocean regions north of the Alaskan coast, like the Beaufort Sea and the Canada Basin, have experienced record warming and decreased sea ice extent unprecedented in human memory, said CU-Boulder Research Professor James Maslanik, who is leading the research effort.
The team will be targeting the Beaufort Sea, considered a “marginal ice zone” where old and thick multiyear sea ice has failed to survive during the summer melt season in recent years, said Maslanik of CU-Boulder’s Colorado Center for Astrodynamics Research in CU’s engineering college. Such marginal ice zones are characterized by extensive ice loss and a strong “ice-albedo” feedback.
“Sea ice is lost when the darker ocean absorbs more sunlight in the form of heat in the summers, resulting in potentially thinner sea ice that re-forms the following winter,” Maslanik said. “This positive feedback between heat absorption by the ocean and accelerated melting becomes reinforcing in itself.” Marginal ice zones also are characterized by significant human and marine mammal activity, he said.
There was a record loss of sea ice cover over the Arctic in 2007, he said. “In some areas of the Arctic Ocean the multiyear ice rebounded, but in the Beaufort Sea we did not see that kind of multiyear ice persistence like we used to see,” said Maslanik, who also is a research professor in the aerospace engineering sciences department.
“The biggest question is whether places like the Beaufort Sea and adjacent Canada Basin have passed a ‘tipping point’ and now are essentially sub-Arctic zones where ice disappears each summer,” he said. Such ice loss could be causing fundamental changes in ocean conditions, including earlier annual blooms of phytoplankton, which are microscopic plant-like organisms that drive the marine food web.
The vast majority of climate scientists believe shrinking Arctic sea ice in recent decades is due to rising temperatures primarily caused by human activities that pump huge amounts of heat-trapping gases like carbon dioxide into the atmosphere. The new $3 million study led by Maslanik, “The Marginal Ice Zone Observations and Processes EXperiment,” or MIZOPEX, is being funded by NASA.
The team will undertake extensive airborne surface mapping using a variety of Unmanned Aircraft Systems, or UAS, comparing the results with data collected by a fleet of satellites from NASA, the National Oceanic and Atmospheric Administration and the Japanese space agency. Unlike satellites, small, unmanned aircraft can fly below the clouds, observe the same location continuously for hours and make more precise measurements of sea ice composition and sea surface temperatures. Maslanik and his CU-Boulder team previously used unmanned aircraft to assess ice conditions both in the Arctic and in Antarctica.
The MIZOPEX arsenal also will include floating buoys that measure ocean temperatures. CU-Boulder engineering faculty members Scott Palo and Dale Lawrence and their graduate students are converting miniaturized versions of dropsondes — standard weather reconnaissance devices designed to be dropped from aircraft and capture data as they fall toward Earth — into the buoys that will be deployed by the UAS.
The modified dropsondes, which were developed at CU-Boulder for use in Antarctica, will be combined with CU-designed miniature unmanned aircraft that will land on the ocean near sea ice floes. Such floes are critical to several species of Arctic wildlife, including polar bears, walruses and seals.
The buoys and unmanned craft will collect sea surface and subsurface temperatures to about a meter deep, while the overflying unmanned planes and satellites measure temperatures at the surface, Maslanik said. “We want to know if the warming is just at the ocean surface or if there is additional heat getting into the mixed layers of the upper ocean, either from absorbed sunlight or from ocean currents, that could be contributing to sea ice melt.”
The team plans to gather information over 24-hour cycles to determine how the ocean and ice are reacting to atmospheric changes. “Understanding what’s happening in the water is critical to forecasting what will happen to ice in the near term, as well as in the decades to come,” said MIZOPEX team scientist Betsy Weatherhead of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences.
“We’ve never had the data before,” Weatherhead said. “With this new instrumentation, we’ll be able to ask questions and test theories about the drivers of ice melt.”
The MIZOPEX effort involves CU-Boulder, NASA, Fort Hays State University in Kansas, Brigham Young University, the University of Alaska-Fairbanks, NOAA, the University of Washington and Columbia University. Ball Aerospace Systems Group of Boulder also is collaborating on the project.
Other MIZOPEX project scientists from CU include Brian Argrow, Sandra Castro, Ian Crocker, William Emery, Eric Frew and Mark Tschudi. Argrow directs the CU-headquartered Research and Engineering Center for Unmanned Vehicles, a university-government-industry partnership for the development and application of unmanned vehicle systems.
For more information on MIZOPEX visit http://ccar.colorado.edu/mizopex/index.html.
For more information on CU-Boulder’s Research and Engineering Center for Unmanned Vehicles visit http://recuv.colorado.edu/.
Young galaxies are 13-billion light years from home
Jan 10th
DEVELOPING GALAXY CLUSTER EVER FOUND
A team of researchers led by the University of Colorado Boulder has used NASA’s Hubble Space Telescope to uncover a cluster of galaxies in the initial stages of construction — the most distant such grouping ever observed in the early universe.
In a random sky survey made in near-infrared light, Hubble spied five small galaxies clustered together 13.1 billion light-years away. They are among the brightest galaxies at that epoch and very young, living just 600 million years after the universe’s birth in the Big Bang. One light-year is about 6 trillion miles.
Galaxy clusters are the largest structures in the universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster, or protocluster, presumably will grow into one of today’s massive galactic “cities” comparable to the nearby Virgo cluster, a collection of more than 2,000 galaxies.
The composite image at right, taken in visible and near-infrared light, reveals the location of five tiny galaxies clustered together 13.1 billion light-years away. The circles pinpoint the galaxies. The Wide Field Camera 3 aboard NASA’s Hubble Space Telescope spied the galaxies in a random sky survey. The developing cluster is the most distant ever observed. The young galaxies lived just 600 million years after the universe’s birth in the Big Bang. The average distance between them is comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and Andromeda, and a few dozen small dwarf galaxies. The close-up images at right, taken in near-infrared light, show the puny galaxies. The letters “a” through “e” correspond to the galaxies’ location in the wide-field view at left. Simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo cluster’s M87. Galaxy clusters are the largest structures in the universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster presumably will grow into a massive galactic city, similar in size to the nearby Virgo cluster, a collection of more than 2,000 galaxies. Credit: NASA, ESA, M. Trenti (University of Colorado Boulder and Institute of Astronomy, University of Cambridge, U.K.), L. Bradley (Space Telescope Science Institute, Baltimore), and the BoRG team
or more information on the galaxies visit the news center at http://hubblesite.org/.
“These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together,” says the study’s leader, Michele Trenti, a research associate at CU-Boulder’s Center for Astrophysics and Space Astronomy and a newly appointed scientist at the Institute of Astronomy at the University of Cambridge in the United Kingdom. “The result confirms our theoretical understanding of the buildup of galaxy clusters. And Hubble is just powerful enough to find the first examples of them at this distance.”
Trenti will present his results Jan. 10 at the American Astronomical Society meeting in Austin, Texas. The study will appear in the Feb. 10 issue of The Astrophysical Journal.
Most galaxies in the universe live in groups and clusters, and astronomers have probed many mature “galactic cities” in detail as far as 11 billion light-years away. But finding clusters in the early phases of construction has been challenging because they are rare, dim and widely scattered across the sky.
“Records are always exciting, and this is the earliest and the most distant developing galaxy cluster that has ever been seen,” said CU-Boulder Professor Michael Shull of the astrophysical and planetary sciences department, a member of the observing team. “We have seen individual galaxies this old and far away, but we have not seen groups of them in the construction process before.”
Last year, a group of astronomers uncovered one distant developing cluster. Led by Peter L. Capak of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena, the astronomers discovered a galactic grouping 12.6 billion light-years away with a variety of telescopes, including Hubble. Spectroscopic observations were made with the W.M. Keck Observatory in Hawaii to confirm the cluster’s distance by measuring how much its light has been stretched by the expansion of space.
Trenti’s team used the sharp-eyed Wide Field Camera 3 to hunt for the elusive catch. “We need to look in many different areas because the odds of finding something this rare are very small,” Trenti said. “It’s like playing a game of Battleship: The search is hit and miss. Typically a region has nothing, but if we hit the right spot we can find multiple galaxies.”
Because these distant, fledgling clusters are so dim, the team hunted for the systems’ brightest galaxies. These bright lights act as billboards, advertising cluster construction zones, according to the team. Galaxies at early epochs don’t live alone. From simulations, the astronomers expect galaxies to be clustered together.
Because brightness correlates with mass, the most luminous galaxies pinpoint the location of developing clusters. These powerful light beacons live in deep wells of dark matter, which form the underlying structure in which galaxy clusters form, Trenti said. The team expects many fainter galaxies that were not seen in these observations to inhabit the same neighborhood.
The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness. The galaxies are bright and massive because they are being fed lots of gas through mergers with other galaxies, Trenti said. The team’s simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo Cluster’s M87.
The observations demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly, in which small objects accrete mass, or merge, to form bigger objects over a smooth and steady but dramatic process of collision and agglomeration. Astronomers have likened the process to streams merging into tributaries, then into rivers and to a bay.
Hubble looked in near-infrared light because ultraviolet and visible light from distant objects have been stretched into near-infrared wavelengths by the expansion of space in these extremely distant galaxies. The observations are part of the Brightest of Reionizing Galaxies or BoRG survey, which is using Hubble’s Wide Field Camera 3 to search for the brightest galaxies around 13 billion years ago, when light from the first stars burned off a fog of cold hydrogen in a process called reionization.
The team estimated the distance to the newly spied galaxies based on their colors, but the astronomers plan to follow up with spectroscopic observations to confirm their distance.
Without spectroscopic observations, it’s not clear whether the observed galaxies are gravitationally bound yet. The average distance between them is likely comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and Andromeda, and a few dozen small dwarf galaxies.
These observations are pushing Hubble to the limit of its ability. This region, however, will be prime country for future telescopes such as NASA’s James Webb Space Telescope, an infrared observatory scheduled to launch later this decade. Webb will see farther into the infrared, allowing it to hunt for even earlier stages of galaxy assembly within 300 million years of the Big Bang.
Shull, also a faculty member at CU-Boulder’s Center for Astrophysics and Space Astronomy, said the research team will receive an additional 260 orbits of observation time on Hubble to continue the search for more of the fledgling galaxy clusters as part of the BoRG survey. “There is high interest right now in learning if Earth is unique in the universe in its ability to host life,” he said. “Similarly, we are interested to see if these ancient, forming galaxy clusters we have identified are unique, or if there are others out there. I expect that we may find a few more.”
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute, or STScI, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc., in Washington, D.C.
For more information on the galaxies visit the news center at http://hubblesite.org/. For more information on CU-Boulder’s CASA visit http://casa.colorado.edu/.
For more information on CU-Boulder’s CASA visit http://casa.colorado.edu/.