NASA Assets Provide Orbital View to Study Phoenix Heat Waves

Where you live may say a lot about your socioeconomic status. It also may suggest how vulnerable you are to long periods of excessively hot weather.

Researchers at NASA’s Johnson Space Center, Arizona State University and the University of California at Riverside are studying the relationship between temperature variations and socioeconomic variables across metropolitan Phoenix. They have found that the urban poor are the most vulnerable to extreme heat.

Those in higher incomes tend to live in areas that are cooler due to the increased amount of vegetation, such as lush lawns and canopy trees, that surrounds homes or on higher-elevation hillslopes above the hotter Salt River valley floor. The urban poor tend to live in the urban core of metro Phoenix where the heat island effect is intense. These neighborhoods are located near industrial areas, commercial centers, and transportation corridors. There are few amenities, such as parks, and the landscaping has little or no grass or trees.

Propelled by a $1.4 million grant from the National Science Foundation as part of its Dynamics of Coupled Natural and Human Systems Program, the research team is compiling a history of the development of the metro Phoenix urban heat island. Urban heat islands result when existing soil and grass is replaced with materials such as asphalt and concrete that absorb heat during the day and reradiate it at night, thus causing increased temperatures especially during nighttime.

Sharon Harlan, a sociologist in the School of Human Evolution and Social Change at ASU, has pulled together the interdisciplinary team, which is comprised of social and natural scientists, public health experts, and educators.

Harlan is excited about the potential for this pioneering research.

“The problem of heat-related deaths and illnesses is very serious,” said Harlan. “Each year, heat fatalities in the U.S. occur in greater numbers than mortality from any other type of weather disaster. Global climate changes and rapidly growing cities are likely to compound and intensify the adverse health effects of heat islands around the world. Our research is integrating data with sophisticated modeling tools to analyze urban systems while keeping health equity considerations and the well-being of vulnerable populations at the center of attention. We want our research to be used to promote better decision-making about climate adaptation in cities.”

The primary objective of the research is to study high heat wave events—unexpected long-duration heat waves. Many cities including Chicago, Phoenix and Paris have encountered these events over the past several years.

Data from numerous sources, including remotely sensed imagery from NASA, are being used to create an historical record of how temperatures and vegetation patterns changed across metro Phoenix from the early 1970s to 2000. William Stefanov, senior geoscientist with Jacobs Technology in JSC’s Astromaterials Research and Exploration Science Directorate, is providing the orbital view of the metropolitan area.

The remotely sensed information is collected from satellites or airplanes and includes vegetation, temperature and land cover. Together it provides a map of the urban and suburban surface at a moment in time. In addition, researchers will use the data to do what is called change detection analysis. Images from one year or one season can be compared with those from another. The changes, such as those in vegetation, can be highlighted.

“We’re using a series of Landsat data for historical vegetation and surface temperature, high-resolution airborne imagery to get detailed maps of the land cover in our study neighborhoods and the Advanced Spaceborne Thermal Emission and Reflection Radiometer, or ASTER, a Japanese sensor on board the NASA Terra satellite, for current surface temperature data,” said Stefanov.

An airborne data flight over Phoenix by the NASA MODIS/ASTER Simulator, or MASTER, sensor is planned for next year to coincide with a ground data collection campaign. Among other biophysical information, high-resolution measurements of ground surface temperature will be obtained from the MASTER data throughout the metropolitan area to compare with and validate other airborne and satellite data sets used in the project.

According to several global climate change models, the southwestern United States is predicted to experience higher temperatures and more droughts over the coming century. If that happens, Phoenix is expected to experience more heat wave events.

The remotely sensed data are fed into high-resolution urban climate models to build predictive simulations of what will happen to the Phoenix metropolitan area if predicted climate change occurs there. Maps of “riskscapes” produced by this project will show where people in Phoenix are most vulnerable to high heat events.

“This project has theoretical aspects, but it also has an applied focus,” said Stefanov. “We are trying to develop tools that city planners and emergency responders can use. Urban planners also can use this data so that they can help plan the city’s growth and perhaps replace materials that absorb heat with those that are more reflective.”

“A lot of urban development is taking place around the world in arid or semiarid climates,” said Stefanov. “By studying Phoenix, researchers can better understand what these developing cities may face and how their environments may change as populations expand.”

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WISE Spies a Comet with its Powerful Infrared Eye

NASA's Wide-field Infrared Survey Explorer, or WISE, has discovered its first comet, one of many the mission is expected to find among millions of other objects during its ongoing survey of the whole sky in infrared light.

Officially named "P/2010 B2 (WISE)," but known simply as WISE, the comet is a dusty mass of ice more than 2 kilometers (1.2 miles) in diameter. It probably formed around the same time as our solar system, about 4.5 billion years ago. Comet WISE started out in the cold, dark reaches of our solar system, but after a long history of getting knocked around by the gravitational forces of Jupiter, it settled into an orbit much closer to the sun. Right now, the comet is heading away from the sun and is about 175 million kilometers (109 million miles) from Earth.

"Comets are ancient reservoirs of water. They are one of the few places besides Earth in the inner solar system where water is known to exist," said Amy Mainzer of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Mainzer is the principal investigator of NEOWISE, a project to find and catalog new asteroids and comets spotted by WISE (the acronym combines WISE with NEO, the shorthand for near-Earth object).

"With WISE, we have a powerful tool to find new comets and learn more about the population as a whole. Water is necessary for life as we know it, and comets can tell us more about how much there is in our solar system."

The WISE telescope, which launched into a polar orbit around Earth on Dec. 14, 2009, is expected to discover anywhere from a few to dozens of new comets, in addition to hundreds of thousands of asteroids. Comets are harder to find than asteroids because they are much more rare in the inner solar system. Whereas asteroids tour around in the "main belt" between the orbits of Mars and Jupiter, large numbers of comets orbit farther away, in the icy outer reaches of our solar system.

Both asteroids and comets can fall into orbits that bring them close to Earth's path around the sun. Most of these "near-Earth objects" are asteroids but some are comets. WISE is expected to find new near-Earth comets, and this will give us a better idea of how threatening they might be to Earth.

"It is very unlikely that a comet will hit Earth," said James Bauer, a scientist at JPL working on the WISE project, "But, in the rare chance that one did, it could be dangerous. The new discoveries from WISE will give us more precise statistics about the probability of such an event, and how powerful an impact it might yield."

The space telescope spotted the comet during its routine scan of the sky on January 22. Sophisticated software plucked the comet out from the stream of images pouring down from space by looking for objects that move quickly relative to background stars. The comet discovery was followed up by a combination of professional and amateur astronomers using telescopes across the United States.

A teacher also teamed up with an observer to measure comet WISE using a home-built telescope next to a cornfield in Illinois. Their research is part of the International Astronomical Search Collaboration, an education program that helps teachers and students observe comets and asteroids (more information is online at http://iasc.hsutx.edu/ ).

All the data are catalogued at the Minor Planet Center, in Cambridge, Mass., the worldwide clearinghouse for all observations and orbits of minor planets and comets.

Comet WISE takes 4.7 years to circle the sun, with its farthest point being about 4 astronomical units away, and its closest point being 1.6 astronomical units (near the orbit of Mars). An astronomical unit is the distance between Earth and the sun. Heat from the sun causes gas and dust to blow off the comet, resulting in a dusty coma, or shell, and a tail.

Though this particular body is actively shedding dust, WISE is also expected to find dark, dead comets. Once a comet has taken many trips around the sun, its icy components erode away, leaving only a dark, rocky core. Not much is known about these objects because they are hard to see in visible light. WISE's infrared sight should be able to pick up the feeble glow of some of these dark comets, answering questions about precisely how and where they form.

"Dead comets can be darker than coal," said Mainzer. "But in infrared light, they will pop into view. One question we want to answer with WISE is how many dead comets make up the near-Earth object population."

The mission will spend the next eight months mapping the sky one-and-a-half times. A first batch of data will be available to the public in the spring of 2011, and the final catalog a year later. Selected images and findings will be released throughout the mission.

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. The ground-based observations are partly supported by the National Science Foundation. The Minor Planet Center is funded by NASA.

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IBEX Finds Surprising Changes at Solar Boundary

When NASA launched the Interstellar Boundary Explorer (IBEX) on October 19, 2008, space physicists held their collective breath for never-before-seen views of a collision zone far beyond the planets, roughly 10 billion miles away. That’s where the solar wind, an outward rush of charged particles and magnetic fields continuously spewed by the Sun, runs into the flow of particles and fields that permeates interstellar space in our neighborhood of the Milky Way galaxy.

No spacecraft had ever imaged the collision zone, which occurs in a region known as the heliosheath, because it emits no light. But the two detectors on IBEX are designed to “see” what the human eye cannot. The interaction of the solar wind and interstellar medium creates energetic neutral atoms of hydrogen, called ENAs, that zip away from the heliosheath in all directions. Some of these atoms pass near Earth, where IBEX records their arrival direction and energy. As the spacecraft slowly spins, the detectors gradually build up pictures of the ENAs as they arrive from all over the sky.

Mission scientists got their first surprise six months after launch, once the spacecraft had scanned enough overlapping strips of sky to create a complete 360° map. Instead of recording a relatively even distribution all the way around, as expected, IBEX found that the counts of ENAs — and thus the strength of the interaction in the heliosheath — varied dramatically from place to place. The detectors even discovered a long, enhanced “ribbon,” accentuated by an especially intense hotspot or “knot,” arcing across the sky. (IBEX Explores Galactic Frontier, Releases First-Ever All-Sky Map)

Now scientists have finished assembling a second complete sweep around the sky, and IBEX has again delivered an unexpected result: the map has changed significantly. Overall, the intensity of ENAs has dropped 10% to 15%, and the hotspot has diminished and spread out along the ribbon. Details of these findings appear in the September 27th issue of Journal of Geophysical Research (Space Physics).

“We thought we might detect small changes occurring gradually throughout the Sun’s 11-year-long activity cycle, but not over just 6 months,” notes David McComas (Southwest Research Institute), principal investigator for the IBEX mission and the paper’s lead author. “These observations show that the interaction of the Sun with the interstellar medium is far more dynamic and variable than anyone envisioned.”

In the past, space physicists had little notion of what to expect along the boundary where the Sun’s own magnetic bubble, the heliosphere, meets interstellar space. Even though the solar wind travels outward at roughly a million miles per hour, it still takes about a year to reach the heliosphere’s edge. Also, the encounter zone within the heliosheath is believed to be several billion miles thick (roughly Pluto’s distance from the Sun). Finally, the ENAs take another six months to many years to complete the return trip back to Earth, depending on their direction and energy.

With ENAs starting out from such a wide range of distances and traveling back toward Earth at different speeds, IBEX mission scientists had expected that any highs and lows in intensity arising within the heliosheath would be hopelessly smeared out in the spacecraft’s all-sky maps. So they’re elated by the variations and changes seen so far by IBEX. These early results hint that the solar wind and the interstellar flow might be interacting in a thinner layer than many researchers had imagined possible.

McComas says the dropoff in intensity between the two all-sky maps perhaps makes sense, because the Sun is only now emerging from an unusually long period of very low activity and a correspondingly weak solar wind. The fewer the solar-wind particles that reached the heliosheath in recent years, the fewer the ENAs that got created. “We didn’t plan it this way,” says McComas, “but it’s an almost perfect situation, in that we’re seeing the interaction in its simplest state — before trying to interpret what turns out to be a much more complicated interaction than anticipated.”

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NASA Study Sees Earth's Water Cycle Pulse Quickening

Freshwater is flowing into Earth's ocean in greater amounts every year, thanks to more frequent and extreme storms related to global warming, according to a first-of-its-kind study by a team of NASA and university researchers.

The team, led by Tajdarul Syed of the Indian School of Mines, Dhanbad, India, and formerly with the University of California, Irvine, used NASA and other world-scale satellite observations to track total water volume flowing from the continents into the ocean each month. They found 18 percent more water fed into the world's ocean from rivers and melting polar ice sheets in 2006 than in 1994. The average annual rise was 1.5 percent.

"That might not sound like much – 1.5 percent a year – but after a few decades, it's huge," said Jay Famiglietti, UC Irvine Earth system science professor and principal investigator on the study, published this week in the Proceedings of the National Academy of Sciences. He noted that while freshwater is essential to humans and ecosystems, the rain is falling in all the wrong places, for all the wrong reasons.

"In general, more water is good," Famiglietti said. "But here's the problem: Not everybody is getting more rainfall, and those who are may not need it. What we're seeing is exactly what the Intergovernmental Panel on Climate Change predicted – that precipitation is increasing in the tropics and the Arctic Circle with heavier, more punishing storms. Meanwhile, hundreds of millions of people live in semiarid regions, and those are drying up."

Famiglietti said the evaporation and precipitation cycle taught in grade school is accelerating dangerously because of higher temperatures fueled by greenhouse gases. Hotter weather above the ocean causes freshwater to evaporate faster, which leads to thicker clouds unleashing more powerful storms over land. The resulting rainfall then travels via rivers to the sea in ever-larger amounts, and the cycle begins again.

"Many scientists and models have suggested that if the water cycle is intensifying because of climate change, then we should be seeing increasing river flow. Unfortunately, there is no global discharge measurement network, so we have not been able to tell," wrote Famiglietti and Syed.

Satellite records of sea-level rise, precipitation and evaporation were used to create a unique 13-year record – the longest and first of its kind. The trends the researchers found were all the same: increased evaporation from the ocean that led to increased precipitation on land and more flow back into the ocean.

Among the NASA data used in the ongoing study are measurements from the NASA/European Topex/Poseidon and Jason-1 satellite altimeters and the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE) satellites. The study is funded by NASA and Earth system science fellowships.

"As we turn up the thermostat on planet Earth, it's not just higher temperatures we have to think about," said co-author Josh Willis of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Long-term changes in rainfall will be a part of climate change too. What we've shown here is that we now have the tools to see global climate change as it occurs – not just the warming, but changes in the hydrological cycle as well."

The researchers cautioned that although they had analyzed more than a decade of data, it was still a relatively short time frame. Natural ups and downs that appear in climate data make detecting long-term trends challenging. Further study is needed, they said, and is underway.

Other authors of the study include Don Chambers of the University of South Florida, Tampa, Fla.; and Kyle Hilburn of Remote Sensing Systems, Santa Rosa, Calif.

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NASA Ames Scientists Train the Next Generation of Earth Explorers

South of the San Francisco Bay is a 100-year tidal floodplain near NASA Ames Research Center, Moffett Field, Calif. Because of the potential for flooding, Ames purchased a segment of the mud flats for flood storm management, and has used the area for field experiments to teach and train gifted science students about the practical benefits of studying the tidal salt marsh and its wildlife.

For the last eight years, NASA Ames Earth Science Division has been participating in a student internship program called DEVELOP. Funding comes through the Applied Sciences Program in the Earth Science Division in the Science Mission Directorate at NASA Head Quarters. It is a training and development program that provides an opportunity for talented science students to learn and use sophisticated NASA technology, while mentored by science advisors from NASA and partner agencies. At the completion of the program, students share their research results with local communities, demonstrating how NASA science measurements and predictions can be used to address local policy issues.

“Every summer is full of surprises. Our students usually work on some aspect of the South Bay Salt Ponds Restoration Project,” said Jay Skiles, a research scientist and program science mentor at NASA Ames. “This year, one of our student teams studied the sedimentation now taking place in the salt ponds after some of the levees were purposely breached. The DEVELOP program is a great way for students to learn science skills and meet professionals in the field.”

During the past two centuries, the San Francisco Bay has lost an estimated 85 percent of its historic wetlands to fill or alteration. This dramatic decline in the wetlands has caused a severe impact to tidal marsh habitats and the fish and wildlife. In addition, the changed environment has increased the risk of local floods, according to South Bay Salt Ponds Restoration Project literature.

To help restore the wetlands, one of the first defenses was to build levees that separate the ponds from the tides. It was expected that once the levees breach, the sediment from the ponds would evolve into tidal marsh. In addition, by phasing the restoration of tidal marsh over many years, the need for large volumes of sediment also would be reduced.

NASA scientists regularly mentor and teach students about the scientific method, using inquiry and data collecting as a means of assessment and resolution. At Ames, scientists have taken a proactive role monitoring and studying fluvial (stream) and coastal flood sources. In this case, they helped a team of students, ranging from high school to university graduates, model the sediment deposits to predict marsh habitat development.

“I heard about the internship program while I was attending San Francisco State University,” said Michelle Newcomer, a master’s student at SFSU and a DEVELOP team member. “I applied because it sounded really exciting. I wanted to apply my geographic information system (GIS) and remote sensing skills to a real-world project.”

The five-member team called themselves the Salt Pond Restoration Sedimentation Team. They identified four project objectives: (1) track sediment transport pathways to determine the source of sediment in the South Bay; (2) calibrate satellite imagery with the collected suspended sediment concentration measurements, using Landsat 5 imagery, and data and imagery from NASA satellite instruments Moderate Resolution Imaging Spectroradiometer (MODIS), and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER); (3) create a GIS model to predict sediment deposition and (4) assess the applicability of remote sensing for predicting sediment deposition during restoration.

“We focused on two salt ponds in the Alviso complex, one of which was referred to as Pond A21. Coyote Creek is the waterway that connects the pond to the Bay. We also were interested in Pond A6 because it is the next pond to be breached; we wanted to use our model to forecast marsh accumulation in A6,” said Newcomer.

To predict marsh accumulation, students used the marsh sedimentation model, called MarSed, which was implemented in a geographic information systems platform. The conceptual model has different variables that effect marsh accumulation, including the concentration of suspended sediments, how quickly sediment settles, and time of flooding. Field work was necessary to get the suspended sedimentation measurements.

Field work consisted of going out into the San Francisco Bay on pontoon boats, provided by NASA’s Disaster Assistance and Rescue Team (DART) facility. While on the boats, students collected water samples at the bay’s surface, and recorded their exact location using a Global Positioning System (GPS) device.

Once samples were collected, students began processing them at the U.S. Geological Survey laboratory in Menlo Park, Calif.

The team concluded that (1) the delta and Coyote Creek are primary sources of suspended sediment to the Alviso ponds, (2) suspended sediment concentrations could successfully be detected using remote sensing, (3) sediment deposition for Pond A21 was successfully predicted using remote sensing and GIS techniques, and (4) Pond A6 is predicted to reach equilibrium conditions stable enough for vegetation colonization after 60 months of tidal inundation.

The team reported that restoration managers can use these products as a tool for determining the locations of pond breaches, as well as understanding the time frame of future marsh development.

“We knew that we wanted our calibrated model to do well. At the end of the project, we were all very happy, and felt accomplished that we had actually got it to work,” said Newcomer.

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Hello, Saturn Summer Solstice: Cassini's New Chapter

Turning a midsummer night's dream into reality, NASA's Cassini spacecraft begins its new mission extension -- the Cassini Solstice Mission -- today. The mission extension will take Cassini a few months past Saturn's northern summer solstice (or midsummer) through September 2017. It will enable scientists to study seasonal changes and other long-term weather changes on Saturn and its moons.

Cassini had arrived just after Saturn's northern winter solstice in 2004, and the extension continues a few months past the northern summer solstice in May 2017. A complete seasonal period on Saturn has never been studied at this level of detail.

Cassini has revealed a bounty of scientific discoveries since its launch in 1997, including previously unknown characteristics of the Earth-like world of Saturn's moon Titan, and the plume of water vapor and organic particles spewing from another moon, Enceladus.

The Cassini Solstice Mission will enable continued study of these intriguing worlds. It will also allow scientists to continue observations of Saturn's rings and the magnetic bubble around the planet, known as the magnetosphere. Near the end of the mission, the spacecraft will make repeated dives between Saturn and its rings to obtain in-depth knowledge of the gas giant. During these dives, the spacecraft will study the internal structure of Saturn, its magnetic fluctuations and ring mass.

Cassini entered orbit around Saturn in 2004. Mission managers had originally planned for a four-year tour of the Saturnian system. In 2008, Cassini received a mission extension through September 2010 to probe the planet and its moons through equinox, when the sun was directly over the equator. Equinox, which occurred in August 2009, marked the turn from southern fall to northern spring. The second mission extension, called the Cassini Solstice Mission, was announced earlier this year.

"After nearly seven years in transit and six years in Saturn orbit, this spacecraft still just hums along," said Bob Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "With seven more years to go, the science should be just as exciting as what we've seen so far."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the project for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

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Wildfires: A Symptom of Climate Change

This summer, wildfires swept across some 22 regions of Russia, blanketing the country with dense smoke and in some cases destroying entire villages. In the foothills of Boulder, Colo., this month, wildfires exacted a similar toll on a smaller scale.

That's just the tip of the iceberg. Thousands of wildfires large and small are underway at any given time across the globe. Beyond the obvious immediate health effects, this "biomass" burning is part of the equation for global warming. In northern latitudes, wildfires actually are a symptom of the Earth's warming.

'We already see the initial signs of climate change, and fires are part of it," said Dr. Amber Soja, a biomass burning expert at the National Institute of Aerospace (NIA) in Hampton, Va.

And research suggests that a hotter Earth resulting from global warming will lead to more frequent and larger fires.

Human ignition

The fires release "particulates" -- tiny particles that become airborne -- and greenhouse gases that warm the planet.

A common perception is that most wildfires are caused by acts of nature, such as lightning. The inverse is true, said Dr. Joel Levine, a biomass burning expert at NASA Langley Research Center in Hampton, Va.

"What we found is that 90 percent of biomass burning is human instigated," said Levine, who was the principal investigator for a NASA biomass burning program that ran from 1985 to 1999.

Levine and others in the Langley-led Biomass Burning Program travelled to wildfires in Canada, California, Russia, South African, Mexico and the wetlands of NASA's Kennedy Space Center in Florida.

Biomass burning accounts for the annual production of some 30 percent of atmospheric carbon dioxide, a leading cause of global warming, Levine said.

Dr. Paul F. Crutzen, a pioneer of biomass burning, was the first to document the gases produced by wildfires in addition to carbon dioxide.

"Modern global estimates agree rather well with the initial values," said Crutzen, who shared the Nobel Prize in Chemistry 1995 with Mario J. Molina and F. Sherwood Rowland for their "work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone."

Northern exposure

Whether biomass burning is on the rise globally is not clear. But it definitely is increasing in far northern latitudes, in "boreal" forests comprised largely of coniferous trees and peatlands.

The reason is that, unlike the tropics, northern latitudes are warming, and experiencing less precipitation, making them more susceptible to fire. Coniferous trees shed needles, which are stored in deep organic layers over time, providing abundant fuel for fires, said Soja, whose work at the NIA supports NASA.

"That's one of the reasons northern latitudes are so important," she said, "and the smoldering peat causes horrible air quality that can affect human health and result in death."

Fires in different ecosystems burn at different temperatures due to the nature and structure of the biomass and its moisture content. Burning biomass varies from very thin, dry grasses in savannahs to the very dense and massive, moister trees of the boreal, temperate and tropical forests.

Fire combustion products vary over a range depending on the degree of combustion, said Levine, who authored a chapter on biomass burning for a book titled "Methane and Climate Change," published in August by Earthscan.

Flaming combustion like the kind in thin, small, dry grasses in savannahs results in near-complete combustion and produces mostly carbon dioxide. Smoldering combustion in moist, larger fuels like those in forest and peatlands results in incomplete combustion and dirtier emission products such as carbon monoxide.

Boreal fires burn the hottest and contribute more pollutants per unit area burned.


'Eerie experience'

Being near large wildfires is a unique experience, said Levine. "The smoke is so thick it looks like twilight. It blocks out the sun. It looks like another planet. It's a very eerie experience."

In Russia, the wildfires are believed caused by a warming climate that made the current summer the hottest on record. The hotter weather increases the incidence of lightning, the major cause of naturally occurring biomass burning.

Soja said she hopes the wildfires in Russia prompt the country to support efforts to mitigate climate change. In fact, Russia's president, Dmitri A. Medvedev, last month acknowledged the need to do something about it.

"What's happening with the planet's climate right now needs to be a wake-up call to all of us, meaning all heads of state, all heads of social organizations, in order to take a more energetic approach to countering the global changes to the climate," said Medvedev, in contrast to Russia's long-standing position that human-induced climate change is not occurring.

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Dust Models Paint Alien's View of Solar System

New supercomputer simulations tracking the interactions of thousands of dust grains show what the solar system might look like to alien astronomers searching for planets. The models also provide a glimpse of how this view might have changed as our planetary system matured.

"The planets may be too dim to detect directly, but aliens studying the solar system could easily determine the presence of Neptune -- its gravity carves a little gap in the dust," said Marc Kuchner, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md. who led the study. "We're hoping our models will help us spot Neptune-sized worlds around other stars."

The dust originates in the Kuiper Belt, a cold-storage zone beyond Neptune where millions of icy bodies -- including Pluto -- orbit the sun. Scientists believe the region is an older, leaner version of the debris disks they've seen around stars like Vega and Fomalhaut.

"Our new simulations also allow us to see how dust from the Kuiper Belt might have looked when the solar system was much younger," said Christopher Stark, who worked with Kuchner at NASA Goddard and is now at the Carnegie Institution for Science in Washington, D.C. "In effect, we can go back in time and see how the distant view of the solar system may have changed."

Kuiper Belt objects occasionally crash into each other, and this relentless bump-and-grind produces a flurry of icy grains. But tracking how this dust travels through the solar system isn't easy because small particles are subject to a variety of forces in addition to the gravitational pull of the sun and planets.

The grains are affected by the solar wind, which works to bring dust closer to the sun, and sunlight, which can either pull dust inward or push it outward. Exactly what happens depends on the size of the grain.

The particles also run into each other, and these collisions can destroy the fragile grains. A paper on the new models, which are the first to include collisions among grains, appeared in the Sept. 7 edition of The Astronomical Journal.

"People felt that the collision calculation couldn't be done because there are just too many of these tiny grains too keep track of," Kuchner said. "We found a way to do it, and that has opened up a whole new landscape."

With the help of NASA's Discover supercomputer, the researchers kept tabs on 75,000 dust particles as they interacted with the outer planets, sunlight, the solar wind -- and each other.

The size of the model dust ranged from about the width of a needle's eye (0.05 inch or 1.2 millimeters) to more than a thousand times smaller, similar in size to the particles in smoke. During the simulation, the grains were placed into one of three types of orbits found in today's Kuiper Belt at a rate based on current ideas of how quickly dust is produced.

From the resulting data, the researchers created synthetic images representing infrared views of the solar system seen from afar.

Through gravitational effects called resonances, Neptune wrangles nearby particles into preferred orbits. This is what creates the clear zone near the planet as well as dust enhancements that precede and follow it around the sun.

"One thing we've learned is that, even in the present-day solar system, collisions play an important role in the Kuiper Belt's structure," Stark explained. That's because collisions tend to destroy large particles before they can drift too far from where they're made. This results in a relatively dense dust ring that straddles Neptune's orbit.

To get a sense of what younger, heftier versions of the Kuiper Belt might have looked like, the team sped up the dust production rate. In the past, the Kuiper Belt contained many more objects that crashed together more frequently, generating dust at a faster pace. With more dust particles came more frequent grain collisions.

Using separate models that employed progressively higher collision rates, the team produced images roughly corresponding to dust generation that was 10, 100 and 1,000 times more intense than in the original model. The scientists estimate the increased dust reflects conditions when the Kuiper Belt was, respectively, 700 million, 100 million and 15 million years old.

"We were just astounded by what we saw," Kuchner said.

As collisions become increasingly important, the likelihood that large dust grains will survive to drift out of the Kuiper Belt drops sharply. Stepping back through time, today's broad dusty disk collapses into a dense, bright ring that bears more than a passing resemblance to rings seen around other stars, especially Fomalhaut.

"The amazing thing is that we've already seen these narrow rings around other stars," Stark said. "One of our next steps will be to simulate the debris disks around Fomalhaut and other stars to see what the dust distribution tells us about the presence of planets."

The researchers also plan to develop a more complete picture of the solar system's dusty disk by modeling additional sources closer to the sun, including the main asteroid belt and the thousands of so-called Trojan asteroids corralled by Jupiter's gravity.

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Spring on Titan Brings Sunshine and Patchy Clouds

The northern hemisphere of Saturn's moon Titan is set for mainly fine spring weather, with polar skies clearing since the equinox in August last year. The visual and infrared mapping spectrometer (VIMS) aboard NASA's Cassini spacecraft has been monitoring clouds on Titan regularly since the spacecraft entered orbit around Saturn in 2004. Now, a group led by Sébastien Rodriguez, a Cassini VIMS team collaborator based at Université Paris Diderot, France, has analyzed more than 2,000 VIMS images to create the first long-term study of Titan's weather using observational data that also includes the equinox. Equinox, when the sun shone directly over the equator, occurred in August 2009.

Rodriguez is presenting the results and new images at the European Planetary Science Congress in Rome on Sept. 22.

Though Titan's surface is far colder and lacks liquid water, this moon is a kind of "sister world" to Earth because it has a surface covered with organic material and an atmosphere whose chemical composition harkens back to an early Earth. Titan has a hydrological cycle similar to Earth's, though Titan's cycle depends on methane and ethane rather than water.

A season on Titan lasts about seven Earth years. Rodriguez and colleagues observed significant atmospheric changes between July 2004 (early summer in Titan's southern hemisphere) and April 2010 (the very start of northern spring). The images showed that cloud activity has recently decreased near both of Titan's poles. These regions had been heavily overcast during the late southern summer until 2008, a few months before the equinox.

Over the past six years, the scientists found that clouds clustered in three distinct latitude regions of Titan: large clouds at the north pole, patchy clouds at the south pole and a narrow belt around 40 degrees south. "However, we are now seeing evidence of a seasonal circulation turnover on Titan – the clouds at the south pole completely disappeared just before the equinox and the clouds in the north are thinning out," Rodriguez said. "This agrees with predictions from models and we are expecting to see cloud activity reverse from one hemisphere to another in the coming decade as southern winter approaches."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate, Washington, D.C. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson.

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NASA Study Shows Desert Dust Cuts Colorado River Flow

PASADENA, Calif. – Snowmelt in the Colorado River basin is occurring earlier, reducing runoff and the amount of crucial water available downstream. A new study shows this is due to increased dust caused by human activities in the region during the past 150 years.

The study, led by a NASA scientist and funded by the agency and the National Science Foundation, showed peak spring runoff now comes three weeks earlier than before the region was settled and soils were disturbed. Annual runoff is lower by more than five percent on average compared to pre-settlement levels.

The findings have major implications for the 27 million people in the seven U.S. states and Mexico who rely on the Colorado River for drinking, agricultural and industrial water. The results were published in this week's Proceedings of the National Academy of Sciences.

The research team was led by Tom Painter, a snow hydrologist at both NASA's Jet Propulsion Laboratory in Pasadena, Calif., and UCLA. The team examined the impact of human-produced dust deposits on mountain snowpacks over the Upper Colorado River basin between 1915 and 2003. Studies of lake sediment cores showed the amount of dust falling in the Rocky Mountains increased by 500 to 600 percent since the mid-to-late 1800s, when grazing and agriculture began to disturb fragile but stable desert soils.

The team used an advanced hydrology model to simulate the balance of water flowing into and out of the river basin under current dusty conditions, and those that existed before soil was disturbed. Hydrologic data gathered from field studies funded by NASA and the National Science Foundation, and measurements of the absorption of sunlight by dust in snow, were combined with the modeling.

More than 80 percent of sunlight falling on fresh snow is typically reflected back into space. In the semi-arid regions of the Colorado Plateau and Great Basin, winds blow desert dust east, triggering dust-on-snow events. When dark dust particles fall on snow, they reduce its ability to reflect sunlight. The snow also absorbs more of the sun's energy. This darker snow cover melts earlier, with some water evaporating into the atmosphere.

Earlier melt seasons expose vegetation sooner, and plants lose water to the atmosphere through the exhalation of vapor. The study shows an annual average of approximately 35-billion cubic feet of water is lost from this exhalation and the overall evaporation that would otherwise feed the Colorado River. This is enough water to supply Los Angeles for 18 months.

"The compressed mountain runoff period makes water management more difficult than a slower runoff," Painter said. "With the more rapid runoff under dust-accelerated melt, costly errors are more likely to be made when water is released from and captured in Colorado River reservoirs."

Prior to the study, scientists and water managers had a poor understanding of dust-on-snow events. Scientists knew from theory and modeling studies that dust could be changing the way snowfields reflect and absorb sunlight, but no one had measured its full impact on snowmelt rates and runoff over the river basin. The team addressed these uncertainties by making systematic measurements of the sources, frequency and snowmelt impact of dust-on-snow events.

"These researchers brought together their collective expertise to provide a historical context for how the Colorado River and its runoff respond to dust deposition on snow," said Anjuli Bamzai, program director in the National Science Foundation's Division of Atmospheric and Geospace Sciences in Arlington, Va. "The work lays the foundation for future sound water resource management."

Painter believes steps can be taken to reduce the severity of dust-on-snow events in the Colorado River basin. He points to the impact of the Taylor Grazing Act of 1934 for potential guidance on how dust loads can be reduced. The act regulated grazing on public lands to improve rangeland conditions. Lake sediment studies show it decreased the amount of dust falling in the Rocky Mountains by about one quarter.

"Restoration of desert soils could increase the duration of snow cover, simplifying water management, increasing water supplies and reducing the need for additional reservoir storage of water. Peak runoff under cleaner conditions would then come later in summer, when agricultural and other water demands are greater," Painter said.

"It could also at least partially mitigate the expected regional impacts of climate change, which include reduced Colorado River flows, increased year-to-year variability in its flow rate, and more severe and longer droughts," he added. "Climate models project a seven to 20 percent reduction in Colorado River basin runoff in this century due to climate change."

Other institutions participating in the study include the National Snow and Ice Center in Boulder, Colo.; U.S. Geological Survey Southwest Biological Center in Moab, Utah; University of Washington in Seattle; Center for Snow and Avalanche Studies in Silverton, Colo.; and the University of Colorado-NOAA Western Water Assessment in Boulder.

For more information about NASA and agency programs, visit: http://www.nasa.gov . JPL is managed for NASA by the California Institute of Technology in Pasadena.

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Five Things About NASA's Mars Curiosity Rover

Mars Science Laboratory, aka Curiosity, is part of NASA's Mars Exploration Program, a long-term program of robotic exploration of the Red Planet. The mission is scheduled to launch from Cape Canaveral, Fla., in late 2011, and arrive at an intriguing region of Mars in August 2012. The goal of Curiosity, a rolling laboratory, is to assess whether Mars ever had an environment capable of supporting microbial life and conditions favorable for preserving clues about life, if it existed. This will help us better understand whether life could have existed on the Red Planet and, if so, where we might look for it in the future.

1. How Big Is It?: The Mini Cooper-sized rover is much bigger than its rover predecessors, Spirit, Opportunity and Pathfinder. Curiosity is twice as long (about 2.8 meters, or 9 feet) and four times as heavy as Spirit and Opportunity, which landed in 2004. Pathfinder, about the size of a microwave oven, landed in 1997.

2. Landing--Where and How: In November 2008, possible landing sites were narrowed to four finalists, all linked to ancient wet conditions. NASA will select a site believed to be among the most likely places to hold a geological record of a favorable environment for life. The site must also meet safe-landing criteria. The landing system is similar to a sky crane heavy-lift helicopter. After a parachute slows the rover's descent toward Mars, a rocket-powered backpack will lower the rover on a tether during the final moments before landing. This method allows landing a very large, heavy rover on Mars (instead of the airbag landing systems of previous Mars rovers). Other innovations enable a landing within a smaller target area than previous Mars missions.

3. Toolkit: Curiosity will use 10 science instruments to examine rocks, soil and the atmosphere. A laser will vaporize patches of rock from a distance, and another instrument will search for organic compounds. Other instruments include mast-mounted cameras to study targets from a distance, arm-mounted instruments to study targets they touch, and deck-mounted analytical instruments to determine the composition of rock and soil samples acquired with a powdering drill and a scoop.

4. Big Wheels: Each of Curiosity's six wheels has an independent drive motor. The two front and two rear wheels also have individual steering motors. This steering allows the rover to make 360-degree turns in-place on the Mars surface. The wheels' diameter is double the wheel diameter on Spirit and Opportunity, which will help Curiosity roll over obstacles up to 75 centimeters (30 inches) high.

5. Rover Power: A nuclear battery will enable Curiosity to operate year-round and farther from the equator than would be possible with only solar power.

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Missing Piece Inspires New Look at Mars Puzzle

PASADENA, Calif. -- Experiments prompted by a 2008 surprise from NASA's Phoenix Mars Lander suggest that soil examined by NASA's Viking Mars landers in 1976 may have contained carbon-based chemical building blocks of life.

"This doesn't say anything about the question of whether or not life has existed on Mars, but it could make a big difference in how we look for evidence to answer that question," said Chris McKay of NASA's Ames Research Center, Moffett Field, Calif. McKay coauthored a study published online by the Journal of Geophysical Research - Planets, reanalyzing results of Viking's tests for organic chemicals in Martian soil.

The only organic chemicals identified when the Viking landers heated samples of Martian soil were chloromethane and dichloromethane -- chlorine compounds interpreted at the time as likely contaminants from cleaning fluids. But those chemicals are exactly what the new study found when a little perchlorate -- the surprise finding from Phoenix -- was added to desert soil from Chile containing organics and analyzed in the manner of the Viking tests.

"Our results suggest that not only organics, but also perchlorate, may have been present in the soil at both Viking landing sites," said the study's lead author, Rafael Navarro-González of the National Autonomous University of Mexico, Mexico City.

Organics can come from non-biological or biological sources. Many meteorites raining onto Mars and Earth for the past 5 billion years contain organics. Even if Mars has never had life, scientists before Viking anticipated that Martian soil would contain organics from meteorites.

"The lack of organics was a big surprise from the Vikings," McKay said. "But for 30 years we were looking at a jigsaw puzzle with a piece missing. Phoenix has provided the missing piece: perchlorate. The perchlorate discovery by Phoenix was one of the most important results from Mars since Viking." Perchlorate, an ion of chlorine and oxygen, becomes a strong oxidant when heated. "It could sit there in the Martian soil with organics around it for billions of years and not break them down, but when you heat the soil to check for organics, the perchlorate destroys them rapidly," McKay said.

This interpretation proposed by Navarro-González and his four co-authors challenges the interpretation by Viking scientists that Martian organic compounds were not present in their samples at the detection limit of the Viking experiment. Instead, the Viking scientists interpreted the chlorine compounds as contaminants. Upcoming missions to Mars and further work on meteorites from Mars are expected to help resolve this question.

The Curiosity rover that NASA's Mars Science Laboratory mission will deliver to Mars in 2012 will carry the Sample Analysis at Mars (SAM) instrument provided by NASA Goddard Space Flight Center, Greenbelt, Md. In contrast to Viking and Phoenix, Curiosity can rove and thus analyze a wider variety of rocks and samples. SAM can check for organics in Martian soil and powdered rocks by baking samples to even higher temperatures than Viking did, and also by using an alternative liquid-extraction method at much lower heat. Combining these methods on a range of samples may enable further testing of the new report's hypothesis that oxidation by heated perchlorates that might have been present in the Viking samples was destroying organics.

One reason the chlorinated organics found by Viking were interpreted as contaminants from Earth was that the ratio of two isotopes of chlorine in them matched the three-to-one ratio for those isotopes on Earth. The ratio for them on Mars has not been clearly determined yet. If it is found to be much different than Earth's, that would support the 1970s interpretation.

If organic compounds can indeed persist in the surface soil of Mars, contrary to the predominant thinking for three decades, one way to search for evidence of life on Mars could be to check for types of large, complex organic molecules, such as DNA, that are indicators of biological activity. "If organics cannot persist at the surface, that approach would not be wise, but if they can, it's a different story," McKay said.

The Phoenix mission was led by Principal Investigator Peter H. Smith of the University of Arizona, Tucson, with project management at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Phoenix finding of perchlorate was reported by JPL's Michael Hecht and co-authors. JPL, a division of the California Institute of Technology, Pasadena, also manages Mars Science Laboratory for the NASA Exploration Missions Directorate, Washington.

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NASA Data Shed New Light About Water and Volcanoes on Mars

HOUSTON -- Data from NASA's Phoenix Mars Lander suggest liquid water has interacted with the Martian surface throughout the planet's history and into modern times. The research also provides new evidence that volcanic activity has persisted on the Red Planet into geologically recent times, several million years ago.

Although the lander, which arrived on Mars on May 25, 2008, is no longer operating, NASA scientists continue to analyze data gathered from that mission. These recent findings are based on data about the planet's carbon dioxide, which makes up about 95 percent of the Martian atmosphere.

"Atmospheric carbon dioxide is like a chemical spy," said Paul Niles, a space scientist at NASA's Johnson Space Center in Houston. "It infiltrates every part of the surface of Mars and can indicate the presence of water and its history."

Phoenix precisely measured isotopes of carbon and oxygen in the carbon dioxide of the Martian atmosphere. Isotopes are variants of the same element with different atomic weights. Niles is lead author of a paper about the findings published in Thursday's online edition of the journal Science. The paper explains the ratios of stable isotopes and their implications for the history of Martian water and volcanoes.
"Isotopes can be used as a chemical signature that can tell us where something came from, and what kinds of events it has experienced," Niles said.

This chemical signature suggests that liquid water primarily existed at temperatures near freezing and that hydrothermal systems similar to Yellowstone’s hot springs have been rare throughout the planet's past. Measurements concerning carbon dioxide showed Mars is a much more active planet than previously thought. The results imply Mars has replenished its atmospheric carbon dioxide relatively recently, and the carbon dioxide has reacted with liquid water present on the surface.

Measurements were performed by an instrument on Phoenix called the Evolved Gas Analyzer. The instrument was capable of doing more accurate analysis of carbon dioxide than similar instruments on NASA's Viking landers in the 1970s. The Viking Program provided the only previous Mars isotope data sent back to Earth.

The low gravity and lack of a magnetic field on Mars mean that as carbon dioxide accumulates in the atmosphere, it will be lost to space. This process favors loss of a lighter isotope named carbon-12 compared to carbon-13. If Martian carbon dioxide had experienced only this process of atmospheric loss without some additional process replenishing carbon-12, the ratio of carbon-13 to carbon-12 would be much higher than what Phoenix measured. This suggests the Martian atmosphere recently has been replenished with carbon dioxide emitted from volcanoes, and volcanism has been an active process in Mars' recent past. However, a volcanic signature is not present in the proportions of two other isotopes, oxygen-18 and oxygen-16, found in Martian carbon dioxide. The finding suggests the carbon dioxide has reacted with liquid water, which enriched the oxygen in carbon dioxide with the heavier oxygen-18.

Niles and his team theorize this oxygen isotopic signature indicates liquid water has been present on the Martian surface recently enough and abundantly enough to affect the composition of the current atmosphere. The findings do not reveal specific locations or dates of liquid water and volcanic vents, but recent occurrences of those conditions provide the best explanations for the isotope proportions.

The Phoenix mission was led by principal investigator Peter H. Smith of the University of Arizona in Tucson, with project management at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The University of Arizona provided the lander's Thermal and Evolved Gas Analyzer

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NASA's Next Mars Rover Rolls Over Ramps

PASADENA, Calif. -- The rover Curiosity, which NASA's Mars Science Laboratory mission will place on Mars in August 2012, has been rolling over ramps in a clean room at NASA's Jet Propulsion Laboratory to test its mobility system.

Curiosity uses the same type of six-wheel, rocker-bogie suspension system as previous Mars rovers, for handling uneven terrain during drives. Its wheels are half a meter (20 inches) in diameter, twice the height of the wheels on the Spirit and Opportunity rovers currently on Mars.

Launch of the Mars Science Laboratory is scheduled for 2011 during the period from Nov. 25 to Dec. 18. The mission is designed to operate Curiosity on Mars for a full Martian year, which equals about two Earth years.

A public lecture by Mars Science Laboratory Chief Scientist John Grotzinger, of the California Institute of Technology in Pasadena, will take place at JPL on Thursday, Sept. 16, beginning at 7 p.m. PDT Time (10 p.m. EDT). Live video streaming, supplemented by a real-time web chat to take public questions, will air on Ustream at http://www.ustream.tv/channel/nasajpl .

JPL, a division of Caltech, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington. More information about the mission is online at: http://mars.jpl.nasa.gov/msl/ .

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NASA and NOAA's Newest GOES Satellite Ready for Action

GREENBELT, Md. -- NASA and NOAA's latest Geostationary Operational Environmental Satellite, GOES-15, has successfully completed five months of on-orbit testing and has been accepted into service. The satellite has demonstrated operational readiness of its subsystems, spacecraft instruments and communications services. GOES-15 is the third and final spacecraft in the GOES N-P Series of geostationary environmental weather satellites.

The GOES fleet help NOAA forecasters track life-threatening weather and solar activity that can impact the satellite-based electronics and communications industry. During the checkout period, GOES-15 delivered high-resolution images from space, including the first visible and infrared images of Earth taken by its imager instrument, and the first image of the sun taken by its solar X-ray imager instrument.

"NASA is ecstatic that we were able to deliver on our promise to provide NOAA and this Nation with three geosynchronous weather satellites," said Andre Dress, GOES Deputy Project Manager at NASA's Goddard Space Flight Center, Greenbelt, Md. "From the very beginning, we set the bar high and we have attained all our goals. It is something that NASA and its contractors (Boeing Space & Intelligence Systems, Lockheed Martin, ITT and United Launch Alliance) can be very proud of."

NOAA operates GOES-13 in the east and GOES-11 in the west -- both provide weather observations covering more than 50 percent of the Earth's surface. The GOES-15 spacecraft, designed and built by Boeing Space and Intelligence Systems, will be placed in an on-orbit storage location at 105 degrees west longitude should one of the operational GOES satellites degrade or exhaust their fuel. It will share a parking space with GOES-14, currently in the same storage orbit. Both satellites can be made operational within 24 hours to replace an older satellite.

"With more than 35 million Americans living in hurricane-prone areas, we need the reliable, accurate data GOES provide," said Gary Davis, director of the Office of Systems Development at NOAA’s Satellite and Information Service.

A six-minute view of the 2009 Atlantic hurricane season as seen from space by GOES-12, formerly the East Coast GOES sentinel, is available online. The video highlights NASA technology and NOAA satellite data.

NOAA manages the GOES program, establishes requirements, provides all funding and distributes environmental satellite data for the United States. NASA Goddard procures and manages the design, development and launch of the satellites for NOAA on a cost reimbursable basis.

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Deadly Tides Mean Early Exit for Hot Jupiters

Bad news for planet hunters: most of the "hot Jupiters" that astronomers have been searching for in star clusters were likely destroyed long ago by their stars. In a paper accepted for publication by the Astrophysical Journal, John Debes and Brian Jackson of NASA's Goddard Space Flight Center in Greenbelt, Md., offer this new explanation for why no transiting planets (planets that pass in front of their stars and temporarily block some of the light) have been found yet in star clusters. The researchers also predict that the planet hunting being done by the Kepler mission is more likely to succeed in younger star clusters than older ones.

"Planets are elusive creatures," says Jackson, a NASA Postdoctoral Program fellow at Goddard, "and we found another reason that they're elusive."

When astronomers began to search for planets in star-packed globular clusters about 10 years ago, they hoped to find many new worlds. One survey of the cluster called 47 Tucanae (47 Tuc), for example, was expected to find at least a dozen planets among the roughly 34,000 candidate stars. "They looked at so many stars, people thought for sure they would find some planets," says Debes, a NASA Postdoctoral Program fellow at Goddard. "But they didn't."

More than 450 exoplanets (short for "extrasolar planets," or planets outside our solar system) have been found, but "most of them have been detected around single stars," Debes notes.

"Globular clusters turn out to be rough neighborhoods for planets," explains Jackson, "because there are lots of stars around to beat up on them and not much for them to eat." The high density of stars in these clusters means that planets can be kicked out of their solar systems by nearby stars. In addition, the globular clusters surveyed so far have been rather poor in metals (elements heavier than hydrogen and helium), which are the raw materials for making planets; this is known as low metallicity.

Debes and Jackson propose that hot Jupiters—large planets that are at least 3 to 4 times closer to their host stars than Mercury is to our sun—are quickly destroyed. In these cramped orbits, the gravitational pull of the planet on the star can create a tide—that is, a bulge—on the star. As the planet orbits, the bulge on the star points a little bit behind the planet and essentially pulls against it; this drag reduces the energy of the planet's orbit, and the planet moves a little closer to the star. Then the bulge on the star gets bigger and saps even more energy from the planet's orbit. This continues for billions of years until the planet crashes into the star or is torn apart by the star's gravity, according to Jackson's model of tidal orbital decay.

"The last moments for these planets can be pretty dramatic, as their atmospheres are ripped away by their stars' gravity," says Jackson. "It has even been suggested recently the hot Jupiter called WASP-12B is close enough to its star that it is currently being destroyed."

Debes and Jackson modeled what would have happened in 47 Tuc if the tidal effect were unleashed on hot Jupiters. They recreated the range of masses and sizes of the stars in that cluster and simulated a likely arrangement of planets. Then they let the stars' tides go to work on the close-in planets. The model predicted that so many of these planets would be destroyed, the survey would come up empty-handed. "Our model shows that you don't need to consider metallicity to explain the survey results," says Debes, "though this and other effects will also reduce the number of planets."

Ron Gilliland, who is at the Space Telescope Science Institute in Baltimore and participated in the 47 Tuc survey, says, "This analysis of tidal interactions of planets and their host stars provides another potentially good explanation—in addition to the strong correlation between metallicity and the presence of planets—of why we failed to detect exoplanets in 47 Tuc."

In general, Debes and Jackson's model predicts that one-third of the hot Jupiters will be destroyed by the time a cluster is a billion years old, which is still juvenile compared to our solar system (about 4-1/2 billion years old). 47 Tuc has recently been estimated to be more than 11 billion years old. At that age, the researchers expect more than 96% of the hot Jupiters to be gone.

The Kepler mission, which is searching for hot Jupiters and smaller, Earth-like planets, gives Debes and Jackson a good chance to test their model. Kepler will survey four open clusters—groups of stars that are not as dense as globular clusters—ranging from less than half a billion to nearly 8 billion years old, and all of the clusters have enough raw materials to form significant numbers of planets, Debes notes. If tidal orbital decay is occurring, Debes and Jackson predict, Kepler could find up to three times more Jupiter-sized planets in the youngest cluster than in the oldest one. (An exact number depends on the brightness of the stars, the planets' distance from the stars, and other conditions.)

"If we do find planets in those clusters with Kepler," says Gilliland, a Kepler co-investigator, "looking at the correlations with age and metallicity will be interesting for shaping our understanding of the formation of planets, as well as their continued existence after they are formed."

If the tidal orbital decay model proves right, Debes adds, planet hunting in clusters may become even harder. "The big, obvious planets may be gone, so we'll have to look for smaller, more distant planets," he explains. "That means we will have to look for a much longer time at large numbers of stars and use instruments that are sensitive enough to detect these fainter planets."

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Extreme Effects: Seven Things You Didn't Know About Mercury

Pity poor Mercury. The tiny planet endures endless assaults by intense sunlight, powerful solar wind and high-speed miniature meteoroids called micrometeoroids. The planet's flimsy covering, the exosphere, nearly blends in with the vacuum of space, making it too thin to offer protection. Because of this, it's tempting to think of Mercury's exosphere as just the battered remains of ancient atmosphere. Really, though, the exosphere is constantly changing and being renewed with sodium, potassium, calcium, magnesium and other species that are liberated from Mercury's soil by barrages of particles. Because both these particles and Mercury's surface materials respond to sunlight, the solar wind, Mercury's own magnetic sheath (the magnetosphere) and other dynamic forces, the exosphere may not look the same from one observation to the next. Far from being dead, Mercury's exosphere is a place of amazing activity that can tell astronomers a lot about the planet's surface and environment.

Three related papers written by scientists at NASA's Goddard Space Flight Center in Greenbelt, Md., and their colleagues offer insight into the details of how the exosphere gets replenished and show that new modeling of the magnetosphere and exosphere can explain some intriguing observations of the planet. These papers are published as part of Icarus's September 2010 special issue devoted to observations of Mercury during the first and second flybys of the MESSENGER (short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft.

1. Mercury's substitute. No spacecraft have been able to land on Mercury, so astronomers have to figure out indirectly what's in the planet's soil. One approach is to study Earth's moon. Like Mercury, the moon has a very thin exosphere, and on both bodies, the same processes drive species from the surface and into the exosphere. So when Goddard's Rosemary Killen, an expert on both exospheres, and her colleagues wanted to find out what kind of soil could give rise to the concentrations of sodium and potassium found in Mercury's exosphere, they looked at lunar samples. Their best match? Samples brought back by Russia's Luna 16 spacecraft.


2. Going their separate ways. The atoms and molecules in Earth's atmosphere bounce around and collide all the time, but this doesn't happen much in Mercury's exosphere. Instead, the species tend to follow their own paths and are actually more likely to collide with the planet's surface than with each other. A combination of observations from Earth-based telescopes and recent MESSENGER data show that sodium, calcium and magnesium are released from the surface by different processes and behave very differently in the exosphere, notes Killen, a member of the MESSENGER science team.

3. The power of sunlight. New modeling revealed a surprising force releasing most of the sodium into Mercury's exosphere and tail. Researchers had expected the main factor to be charged particles hitting the surface and releasing sodium in a process called ion sputtering. Instead, the main factor seems to be photons releasing sodium in a process called photon-stimulated desorption (PSD), which may be enhanced in regions impacted by ions. This modeling was done by Matthew Burger, a University of Maryland Baltimore County (UMBC) research scientist working at Goddard with Killen, and colleagues using data from the first and second MESSENGER flybys. Sunlight pushes sodium atoms away from the planet's surface to form the long comet-like tail. "The radiation acceleration is strongest when Mercury is at a middle distance from the sun," says Burger. "That's because Mercury is traveling fastest at that point in its orbit, and this is one of the factors that determines how much pressure the sun's radiation exerts on the exosphere." Impacts by micrometeoroids also contribute up to 15% of the sodium observed.

4. Harsher in the north. Much of the sodium is observed at the north and south poles of Mercury, but a lopsided distribution was found during the first MESSENGER flyby: sodium emissions were 30% stronger in the northern hemisphere than the southern one. Modeling of Mercury's magnetosphere done by Mehdi Benna, a UMBC scientist working at Goddard and a member of the MESSENGER science team, and colleagues may help explain this observation. The model reveals four times more protons hitting Mercury near the north pole than near the south pole. More strikes means that more sodium atoms could be liberated by ion sputtering or PSD; it's enough of a difference to explain the observations. "This happens because the magnetic field coming from the sun was tilted during the Mercury flyby. The field wasn't symmetric when it wrapped around Mercury," Benna says. "This configuration exposed the north polar region of the planet to more solar wind particles than the south polar region."

5. Shifting into high gear. Burger adds that the increase in charged particles near the north pole works together with the photons involved in PSD. "PSD affects just the outer surface of the grains of soil. The surfaces become depleted quickly and release a limited amount of sodium," he explains. More sodium has to travel from the inside of each grain to the surface, and that takes some time. "But the increase in charged particles at the north pole speeds up this whole process, so more sodium is released more quickly."

6. Particles in the groove. After protons from the solar wind bombard Mercury's surface and free species from the soil, intense sunlight can strike those liberated materials and convert them into positive ions (the process of photoionization). Modeling by Benna and colleagues reveals that some of these ions may be able to travel around the planet in a "drift belt," perhaps making half a loop or perhaps going around several times before exiting the belt. "If this drift belt exists and if the concentration of ions in the drift belt is high enough, it may create a magnetic depression in this region," he explains. MESSENGER science team members noticed a dip in the magnetic field on both sides of the planet. "But so far, we can't say that a drift belt caused this dip," Benna notes. "Models by us and by other researchers tell us that a drift belt can form, but are there enough ions there to cause a dip in the magnetic field? We don't know yet."

7. Maverick magnesium. The MESSENGER spacecraft was the first to find magnesium in Mercury's exosphere. Killen, a member of the MESSENGER science team, says that astronomers expected the concentration of magnesium to be greatest at the surface and to taper off with distance in the usual manner (exponential decay). Instead, she and her colleagues found that the concentration of magnesium over the north pole during the third flyby "was hanging there at a constant density, and then all of the sudden, it dropped like a rock," she says. "This was just a total surprise, and it's the only time we've seen this odd distribution." What's more, Killen says, the temperature of this magnesium can reach tens of thousands of degrees Kelvin, which is far above the surface temperature of 800 °F. The processes that were expected to be at work on the planet's surface probably can't account for this. "Only a very high-energy process can produce magnesium that is so hot," she adds, "and we don't know what that process is yet."

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NASA Selects Science Investigations for Solar Probe Plus

WASHINGTON -- NASA has begun development of a mission to visit and study the sun closer than ever before. The unprecedented project, named Solar Probe Plus, is slated to launch no later than 2018.

The small car-sized spacecraft will plunge directly into the sun's atmosphere approximately four million miles from our star's surface. It will explore a region no other spacecraft ever has encountered. NASA has selected five science investigations that will unlock the sun's biggest mysteries

"The experiments selected for Solar Probe Plus are specifically designed to solve two key questions of solar physics -- why is the sun's outer atmosphere so much hotter than the sun's visible surface and what propels the solar wind that affects Earth and our solar system? " said Dick Fisher, director of NASA's Heliophysics Division in Washington. "We've been struggling with these questions for decades and this mission should finally provide those answers."

As the spacecraft approaches the sun, its revolutionary carbon-composite heat shield must withstand temperatures exceeding 2550 degrees Fahrenheit and blasts of intense radiation. The spacecraft will have an up close and personal view of the sun enabling scientists to better understand, characterize and forecast the radiation environment for future space explorers.

NASA invited researchers in 2009 to submit science proposals. Thirteen were reviewed by a panel of NASA and outside scientists. The total dollar amount for the five selected investigations is approximately $180 million for preliminary analysis, design, development and tests.

The selected proposals are:

-- Solar Wind Electrons Alphas and Protons Investigation: principal investigator, Justin C. Kasper, Smithsonian Astrophysical Observatory in Cambridge, Mass. This investigation will specifically count the most abundant particles in the solar wind -- electrons, protons and helium ions -- and measure their properties. The investigation also is designed to catch some of the particles for direct analysis.

-- Wide-field Imager: principal investigator, Russell Howard, Naval Research Laboratory in Washington. This telescope will make 3-D images of the sun's corona, or atmosphere. The experiment will also provide 3-D images of solar wind and shocks as they approach and pass the spacecraft. This investigation complements instruments on the spacecraft providing direct measurements by imaging the plasma the other instruments sample.

-- Fields Experiment: principal investigator, Stuart Bale, University of California Space Sciences Laboratory in Berkeley, Calif. This investigation will make direct measurements of electric and magnetic fields, radio emissions, and shock waves that course through the sun's atmospheric plasma. The experiment also serves as a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna.

-- Integrated Science Investigation of the Sun: principal investigator, David McComas of the Southwest Research Institute in San Antonio. This investigation consists of two instruments that will monitor electrons, protons and ions that are accelerated to high energies in the sun's atmosphere.

-- Heliospheric Origins with Solar Probe Plus: principal investigator, Marco Velli of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Velli is the mission's observatory scientist, responsible for serving as a senior scientist on the science working group. He will provide an independent assessment of scientific performance and act as a community advocate for the mission.


"This project allows humanity's ingenuity to go where no spacecraft has ever gone before," said Lika Guhathakurta, Solar Probe Plus program scientist at NASA Headquarters, in Washington. "For the very first time, we'll be able to touch, taste and smell our sun."

The Solar Probe Plus mission is part of NASA's Living with a Star Program. The program is designed to understand aspects of the sun and Earth's space environment that affect life and society. The program is managed by NASA'S Goddard Space Flight Center in Greenbelt, Md., with oversight from NASA's Science Mission Directorate's Heliophysics Division.The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., is responsible for formulating, implementing and operating the Solar Probe Mission.

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Space Station Crew Talks With Students At Florida Science Center

WASHINGTON -- Approximately 500 middle school students and teachers at the Pinellas County Science Center in St. Petersburg, Fla., will have an out-of-this-world phone conversation with NASA astronauts aboard the International Space Station.

Flight Engineers Doug Wheelock, Tracy Caldwell Dyson, and Shannon Walker will make the long-distance phone call on Thursday, Sept. 9, from 11:45 a.m. to 12:05 p.m. EDT.

Students have prepared for the downlink by using data from NASA's satellite network to complete lessons in robotics and marine science. NASA astronaut Robert Springer will be on hand at the center to speak with the students and answer questions. NASA education staffers also will conduct experiments with the students.

The downlink is one in a series with educational organizations in the U.S. and abroad to improve teaching and learning in science, technology, engineering and mathematics. It is an integral component of Teaching From Space, a NASA Education Office program. It promotes learning opportunities and builds partnerships with the education community using the unique environment of human spaceflight.

The center is celebrating its 50th year as a non-profit educational facility with programs focused on science, technology, engineering and mathematics. The center houses an observatory, planetarium, marine touch tank, weather station, wetlands and labs for cyber security, forensics, chemistry, robotics, energy, petrology and computers.

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NASA Sets Briefing About Assistance To Trapped Miners In Chile

HOUSTON -- A NASA team sent to Chile to aid trapped miners will hold a news conference about their work at the San Jose gold and copper mine near Copiapo at noon CDT, Tuesday, Sept. 7. The conference will be at NASA's Johnson Space Center in Houston, and it will air live on NASA Television and the agency's website.

The participants also will answer questions from reporters at participating NASA centers. For journalists not able to attend at a NASA center, a limited number of phone lines are available by calling 281-483-5111 by 11:45 a.m. on Tuesday.

U.S. news media planning to attend the briefing in person must contact the Johnson newsroom at 281-483-5111 by 10 a.m. Tuesday. Reporters interested in a one-on-one interview must contact the Johnson newsroom by 11:30 a.m. Tuesday.

NASA responded to a request from the government of Chile, submitted through the U.S. Department of State, to provide technical advice that might assist the trapped miners. The NASA team of two medical doctors, a psychologist and an engineer arrived in Chile Aug. 31.

Dr. Michael Duncan, deputy chief medical officer in the Space Life Sciences Directorate at Johnson, led the team. The other members are physician James Polk and psychologist Albert Holland from Johnson; and Clint Cragg, principal engineer with the NASA Engineering and Safety Center located at NASA's Langley Research Center in Hampton, Va.

The team will participate in the news conference. Afterward, Duncan will be available for one-on-one interviews.

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NASA Selects Investigations For First Mission To Encounter The Sun

WASHINGTON -- NASA has begun development of a mission to visit and study the sun closer than ever before. The unprecedented project, named Solar Probe Plus, is slated to launch no later than 2018.

The small car-sized spacecraft will plunge directly into the sun's atmosphere approximately four million miles from our star's surface. It will explore a region no other spacecraft ever has encountered. NASA has selected five science investigations that will unlock the sun's biggest mysteries.

"The experiments selected for Solar Probe Plus are specifically designed to solve two key questions of solar physics -- why is the sun's outer atmosphere so much hotter than the sun's visible surface and what propels the solar wind that affects Earth and our solar system? " said Dick Fisher, director of NASA's Heliophysics Division in Washington. "We've been struggling with these questions for decades and this mission should finally provide those answers."

As the spacecraft approaches the sun, its revolutionary carbon-composite heat shield must withstand temperatures exceeding 2550 degrees Fahrenheit and blasts of intense radiation. The spacecraft will have an up close and personal view of the sun enabling scientists to better understand, characterize and forecast the radiation environment for future space explorers.

NASA invited researchers in 2009 to submit science proposals. Thirteen were reviewed by a panel of NASA and outside scientists. The total dollar amount for the five selected investigations is approximately $180 million for preliminary analysis, design, development and tests.
The selected proposals are:

-- Solar Wind Electrons Alphas and Protons Investigation: principal investigator, Justin C. Kasper, Smithsonian Astrophysical Observatory in Cambridge, Mass.

This investigation will specifically count the most abundant particles in the solar wind -- electrons, protons and helium ions -- and measure their properties. The investigation also is designed to catch some of the particles in a special cup for direct analysis.

-- Wide-field Imager: principal investigator, Russell Howard, Naval Research Laboratory in Washington. This telescope will make 3-D images of the sun's corona, or atmosphere. The experiment actually will see the solar wind and provide 3-D images of clouds and shocks as they approach and pass the spacecraft. This investigation complements instruments on the spacecraft providing direct measurements by imaging the plasma the other instruments sample.

-- Fields Experiment: principal investigator, Stuart Bale, University of California Space Sciences Laboratory in Berkeley, Calif. This investigation will make direct measurements of electric and magnetic fields, radio emissions, and shock waves that course through the sun's atmospheric plasma. The experiment also serves as a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna.

-- Integrated Science Investigation of the Sun: principal investigator, David McComas of the Southwest Research Institute in San Antonio. This investigation consists of two instruments that will take an inventory of elements in the sun's atmosphere using a mass spectrometer to weigh and sort ions in the vicinity of the spacecraft.

-- Heliospheric Origins with Solar Probe Plus: principal investigator, Marco Velli of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Velli is the mission's observatory scientist, responsible for serving as a senior scientist on the science working group. He will provide an independent assessment of scientific performance and act as a community advocate for the mission.

"This project allows humanity's ingenuity to go where no spacecraft has ever gone before," said Lika Guhathakurta, Solar Probe Plus program scientist at NASA Headquarters, in Washington. "For the very first time, we'll be able to touch, taste and smell our sun."

The Solar Probe Plus mission is part of NASA's Living with a Star Program. The program is designed to understand aspects of the sun and Earth's space environment that affect life and society. The program is managed by NASA'S Goddard Space Flight Center in Greenbelt, Md., with oversight from NASA's Science Mission Directorate's Heliophysics Division. The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., is the prime contractor for the spacecraft.

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NASA Selects University Finalists for Inflatable Loft Competition

WASHINGTON -- NASA and the National Space Grant Foundation have selected university teams from Maryland, Oklahoma and Wisconsin as finalists in a competition to design, manufacture, assemble and test an inflatable loft.

NASA is challenging college students to design and rapidly develop prototype concepts for inflatable habitat lofts for the next generation of space explorers. The loft will be integrated onto an existing NASA operational hard-shell prototype habitat. The winning concepts may be applied to space exploration habitats of the future.

"This competition gives these students the opportunity of a lifetime," said NASA Chief Technologist Bobby Braun at NASA Headquarters in Washington. "They'll design and build new hardware. If their team wins, they'll get the chance to integrate their designs into a NASA hard shell habitat and see it field tested next summer."

The inaugural eXploration Habitat, or X-Hab, Academic Innovation Challenge finalists are:

Oklahoma State University
University of Wisconsin-Madison
University of Maryland

The competition is a university-level challenge designed to encourage studies in spaceflight-related engineering and architecture disciplines. This design competition requires undergraduate and graduate students to explore NASA's work to develop space habitats, while also helping the agency gather new and innovative ideas to complement current research and development.

In June 2011 at NASA's Johnson Space Center in Houston, the NASA-Habitat Demonstration Unit project will conduct a head-to-head competition among the three teams to successfully demonstrate an attachable inflatable habitat "loft" concept, based on a list of NASA requirements for the design.

The Houston competition will determine the winning team, which will be awarded additional funds to integrate their design with the NASA habitat during field testing in August and September 2011.

The National Space Grant Foundation will award the three teams $48,000 each to cover the costs of their design development and participation in the head-to-head competition. An additional $10,000 will be awarded to the team that wins the competition to offset their costs of participating in the integrated field testing.

NASA's Exploration Mission Directorate and the Innovative Partnerships Program are sponsoring this new technology challenge. NASA is dedicated to supporting research that enables sustained and affordable human and robotic exploration. This educational competition contributes to the agency's efforts to train and develop a highly skilled scientific, engineering and technical workforce for the future.

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