OUR SKY - News

New NASA Moon mission begins integration of science instruments.

Astronomy on 04/24/2008 at 12:45pm (UTC)

Several instruments that will help NASA characterize the Moon's surface have been installed on the Lunar Reconnaissance Orbiter, or LRO. The powerful equipment will bring the Moon into sharper focus and reveal new insights about the celestial body nearest Earth.

Engineers and technicians on the LRO Integration and Test Team work almost around the clock in a clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland, to ready the spacecraft for testing and eventual launch later this year. "The spacecraft really is coming together now," says Cathy Peddie, LRO deputy project manager at Goddard. "We are in the space assembly homestretch and making solid progress. You can begin to see what LRO will look like in all of its glory."

Four of six instruments have been mated to the spacecraft, with one to be installed soon and one to arrive in the near future. The instruments are:

The Lyman-Alpha Mapping Project was built and developed at the Southwest Research Institute in San Antonio. The instrument will map the entire lunar surface in the far ultraviolet spectrum and search for surface ice and frost in the polar regions. It will provide images of permanently shadowed regions that are illuminated only by starlight.

The Cosmic Ray Telescope for the Effects of Radiation, or CRaTER, was built and developed by Boston University and the Massachusetts Institute of Technology in Boston. CRaTER will characterize the lunar radiation environment, allowing scientists to determine potential impacts to astronauts and other life. It also will test models on the effects of radiation and measure radiation absorption by a type of plastic that is like human tissue. The results could aid in the development of protective technologies to help keep future lunar crewmembers safe.

Diviner Lunar Radiometer Experiment was built and developed by the University of California, Los Angeles, and the Jet Propulsion Laboratory in Pasadena, California Diviner will measure surface and subsurface temperatures from orbit. It will identify cold traps and potential ice deposits as well as rough terrain and other landing hazards.

The Lunar Orbiter Laser Altimeter was conceived and built by scientists and engineers at Goddard. The instrument will measure landing site slopes and lunar surface roughness and generate high-resolution three-dimensional maps of the moon. The instrument also will measure and analyze the lunar topography to identify both permanently illuminated and shadowed areas.

The Russian-built Lunar Exploration Neutron Detector has arrived from the Institute for Space Research in Moscow. The detector will create high-resolution maps of hydrogen distribution and gather information about the neutron component of lunar radiation. Its data will be analyzed for evidence of water ice near the Moon's surface.

The remaining instrument, the Lunar Reconnaissance Orbiter Camera from Arizona State University in Tempe, Arizona, will provide high-resolution imagery to help identify landing sites and characterize the Moon's topography and composition. It should arrive at Goddard in May.

Also on board will be the Mini-RF Technology Demonstration experiment sponsored by NASA's Exploration Systems and Space Operations Mission Directorates. The miniaturized radar will be used to image the polar regions and search for water ice. The communications capabilities of the system also will be tested during the mission.

The satellite is scheduled to launch from NASA's Kennedy Space Center, Florida, in late 2008 on an Atlas V rocket. It will spend 1 year in low polar orbit on its primary exploration mission, with the possibility of 3 more years to collect additional detailed scientific information about the Moon and its environment. That information will help ensure a safe and productive human return to the Moon.

The spacecraft is being built and managed by Goddard for the Exploration Systems Mission Directorate at NASA Headquarters in Washington. It will transition to the Science Mission Directorate in 2010.

Command of ISS changed

Astronomy on 04/24/2008 at 12:44pm (UTC)

Expedition 16 Commander Peggy Whitson officially handed over command of the International Space Station to Expedition 17 Commander Sergei Volkov. Thursday's ceremony took place inside the U.S. Harmony Node.

The station crews have shifted their sleep schedules in preparation for Saturday morning's Soyuz TMA-11 undocking. Whitson and Flight Engineer Yuri Malenchenko will return to Earth with South Korean spaceflight participant So-yeon Yi.

Whitson broke Michael Foale's cumulative time-in-space record on Wednesday. She will have accumulated 377 days in space by the time she lands in Kazakhstan.

Meanwhile, the station occupants continue their normal activities as they resize U.S. spacesuits, work on science experiments and stow gear for Expedition 16's return home. Whitson and Malenchenko also are proceeding with their increased exercise routines to condition their bodies for their return to Earth's gravity.

Command of ISS changed

Astronomy on 04/24/2008 at 12:44pm (UTC)

New research finds that the ice is more vulnerable to sunny weather.

astronomy on 04/24/2008 at 12:43pm (UTC)

The shrinking expanse of Arctic sea ice is increasingly vulnerable to summer sunshine. Unusually sunny weather contributed to last summer's record loss of Arctic ice, while similar weather conditions in past summers did not appear to have comparable impacts, new research concludes.

"The relative importance of solar radiation in the summer is changing," says Jennifer Kay of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, who is lead author of the study. "The amount of sunshine reaching the Arctic is increasingly influential, as there is less ice to reflect it back into space," she says.

The findings by Kay and colleagues at NCAR and Colorado State University (CSU) in Fort Collins indicate that the presence or absence of clouds now has greater implications for sea ice loss.

"A single unusually clear summer can now have a dramatic impact," Kay says.

A report on the new results will be published April 22, 2008 in Geophysical Research Letters, a journal of the American Geophysical Union (AGU).

Last summer's loss of Arctic sea ice set a modern-day record, with the ice extent shrinking in September to a minimum of about 4.1 million square kilometers (1.6 million square miles). That was 43 percent less ice coverage than in 1979, when accurate satellite observations began.

The study draws on observations from new NASA satellite radar and lidar instruments. Lidar devices make measurements using lasers. Looking at the first 2 years of satellite data from those sensors, Kay and her colleagues found that total 2007 summertime cloud cover was 16 percent less than the year before, largely because of a strong high-pressure system centered north of Alaska that kept skies clear.

Over a 3-month period in the summer, the increased sunshine was strong enough to melt about a foot of surface ice. Over open water, it was sufficient to increase sea-surface temperatures by 2.4° C (4.3° F). Warmer ocean waters can contribute to sea ice loss by melting the ice from the bottom, thereby thinning it and making it more susceptible to future melt.

"Satellite radar and lidar measurements allow us to observe Arctic clouds in a new way," says CSU's Tristan L'Ecuyer, a co-author of the study. "These new instruments not only provide a very precise view of where clouds exist but also tell us their height and thickness, which are key properties that determine the amount of sunlight clouds reflect back to space."

The research team also examined longer-term records of Arctic cloud and weather patterns, including a 62-year-long record of cloudiness from surface observations at Barrow, Alaska. The scientists found that the 2007 weather and cloud pattern was unusual but not unprecedented. Five other years — 1968, 1971, 1976, 1977, and 1991 — appeared to have lower summertime cloud cover than 2007, but without the same impact on sea ice.

"In a warmer world, the thinner sea ice is becoming increasingly sensitive to year-to-year variations in weather and cloud patterns," Kay says.

The research suggests that warmth from the Sun will increasingly affect Arctic climate in the summer. As the ice shrinks, incoming sunshine triggers a feedback mechanism: the newly exposed dark ocean waters, much darker than the ice, absorb the Sun's radiation instead of reflecting it. This warms the water and melts more ice, which in turn leads to more absorption of radiation and still more warming.

The authors note that, in addition to solar radiation, other factors such as changes in wind patterns and, possibly, shifts in ocean circulation patterns also influence sea ice loss. In particular, strong winds along regions of sea ice retreat were important to last year's loss of ice. The relative importance of these factors, and the precise extent to which global climate change is driving them, are not yet known.

GLOBE at Night 2008 results a solid step toward IYA 2009

Astronomy on 04/24/2008 at 12:42pm (UTC)

The international star-hunting activity known as GLOBE at Night inspired 6,838 measurements of night-sky brightness by citizen scientists around the world, including 660 digital measurements using handheld sky-quality meters.

The third edition of GLOBE at Night was held from February 25-March 8, with assistance from the educational outreach networks of the Astronomical Society of the Pacific (ASP) to help spread the campaign to amateur astronomers and science centers.

The 2008 campaign received measurements from 62 countries, surpassing last year's total of 60 countries. Just over 4,800 of the measurements came from the United States (with 48 states and the District of Columbia reporting at least one measurement). Observers in Hungary submitted the most measurements (380) from outside the U.S., followed by Romania, the Czech Republic, Costa Rica, and Spain, all with over 100 observations; Canada was next largest, with 95 measurements reported.

These basic numbers fall roughly midway between the 2007 and 2006 results from GLOBE at Night, which may result from several factors.

"While we have just begun to analyze the data, we have strong anecdotal evidence from our citizen-scientist network in North America that they experienced abnormally cloudy skies this year," says Connie Walker, GLOBE at Night project manager at the National Optical Astronomy Observatory (NOAO) in Tucson. "The timing of the March new Moon this year — which is required to give everyone sufficiently dark skies to properly observe the constellation Orion — also fell further into summer vacation for our partners in Chile and some other Southern Hemisphere countries, which made it more difficult to attract large numbers of students."

The classic GLOBE at Night program directs students, families, and the general public on how to observe and record the number of stars visible in the constellation Orion, as seen from different locations. Observers report their results online by comparing their view of Orion with a set of template images on the program's Web site, which shows the number of stars in the constellation for a range of visibilities from bright skies to very dark.

The digital version of GLOBE at Night takes advantage of low-cost digital sky-quality meters manufactured by Unihedron of Ontario, Canada, which can make a highly repeatable direct measurement of integrated sky brightness.

Both the "classic" GLOBE at Night exercise that anyone can have fun doing with their unaided eyes, and a digital effort to obtain precise measurements of urban dark skies will be conducted again in March 2009, as one of several start-hunting efforts connected to the "dark-skies awareness" cornerstone program of the International Year of Astronomy (IYA) 2009.

GLOBE at Night 2009 will occur in the latter half of March. These dates should provide better conditions for schools in the Southern Hemisphere, and will likely coincide with Earth Hour 2009 as well, Walker says.

A first-look at results from GLOBE at Night 2008 was presented by project leaders who attended the March 2008 meeting of the National Science Teachers Association in Boston. More detailed analysis of the GLOBE at Night 2008 data will be presented at the May 31-June 4 annual meeting of the Astronomical Society of the Pacific in St. Louis, to be held jointly with the American Astronomical Society. The meeting's primary focus is national and regional training and planning related to IYA 2009.

Michigan telescopes help give astronomers insights into blazars.

Astronomy on 04/24/2008 at 12:41pm (UTC)

For the first time, astronomers have observed a blazar in action, substantiating a prevailing theory about how these luminous and energetic galactic cores work.

Two University of Michigan astronomers contributed to the research, which was led by Alan Marscher of the Institute for Astrophysical Research at Boston University. A paper on the observations is published in the April 24 issue of Nature.

Blazars, among the most energetic objects in the universe, are fueled by supermassive black holes at the core of certain giant elliptical galaxies. Periodically, they emit jets of high-energy plasma at almost the speed of light. Competing theoretical models sought to explain how this phenomenon occurs.

One model predicted that the jets were propelled by magnetic fields that were twisted by the gravity of the black hole and the materials falling into it. This is the behavior the astronomers detected.

"What we've observed is the mechanism by which the acceleration of relativistic particles in the emanating jets occurs. Knowing that mechanism enhances our understand of the physics that goes into the acceleration process," says Hugh Aller, a professor in the U-M Department of Astronomy.

Relativistic particles are particles traveling close to the speed of light.

"Often, we'd observe blazars, but they didn't do anything. It's been difficult to catch these outbursts when they occur," he adds.

Scientists from across the globe aimed a variety of telescopes at the blazar BL Lacertae, about 950 million light-years away from Earth. Optical, X-ray and radio telescopes monitored the galaxy at different electromagnetic wavelengths periodically for several years. U-M recorded radio light curves at the Radio Astronomy Observatory at Peach Mountain in Dexter.

"This is the first observational evidence that really fits with the picture that the theoreticians have had," says Margo Aller, a research scientist and lecturer in the U-M Department of Astronomy. "The reason we have this evidence is a very fine sampling of a large number of instruments, including the Michigan radio telescopes."

Scientists hope to get a closer look at blazar jets when NASA launches its Gamma-ray Large Area Space Telescope (GLAST) satellite observatory in May.

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