Tracking Earth Changes with Satellite Images

SAN FRANCISCO, Calif.--For the past two decades, radar images from satellites have dominated the field of geophysical monitoring for natural hazards like earthquakes, volcanoes, or landslides. These images reveal small perturbations precisely, but large changes from events like big earthquake ruptures or fast-moving glaciers remained difficult to assess from afar, until now.

Sebastien Leprince, a graduate student in electrical engineering at the California Institute of Technology, working under the supervision of geology professor and director of Caltech's Tectonics Observatory (TO), Jean-Philippe Avouac, wrote software that correlates any two optical images taken by satellite. It has proved extremely reliable in tracking large-scale changes on Earth's surface, like earthquake ruptures, the mechanics of "slow" landslides, or defining the fastest-moving sections of glaciers that, due to global warming, have recently increased their pace.

Leprince will describe his software and results of many of its applications on December 14 at the annual meeting of the American Geophysical Union (AGU) in San Francisco. His research will also be featured in the January 1 issue of Eos, AGU's weekly newspaper.

When the technique called InSAR, which uses radar images to reveal details about ground displacement, was introduced, it was quickly embraced. No longer did geoscientists have to rely solely on measurements made by troupes of field geologists or by ground-based devices that might not have been optimally placed. But, says Leprince, "InSAR is physically limited: it's good for small displacements but not for large ones. The radar resolution isn't enough to look at deformation with a large gradient."

Using optical images to complement the radar-based InSAR technique seemed like a natural step. When Leprince began grappling with the idea in 2003, he found several baby steps had been taken. "Satellite image correlation was not a science yet, it was more like an art," he says. The first attempts, reported in 1991, were inconclusive but promising. Since then, several teams of scientists had worked on the problem independently. Some had even developed it well enough to monitor glacier flow.

The major obstacle Leprince faced in developing optical image correlation software was that there were several steps involved but no one knew in which order to take them. "Errors came from everywhere, but where exactly?" he noted. "And we found at least one major flaw in each step."

Three of the four main steps involve correcting geometric distortions innate to taking pictures from space and projecting them onto a surface. The first step matches coordinates of the satellite image with coordinates on the ground. "This is not new, but the approximations being made were not okay," says Leprince. The second step describes the satellite's position in its orbit at the time it took the photo. This is just like in everyday life--you need to know how your camera was oriented when you show off a photo you snapped. In the next step, which Leprince says people never knew they were doing wrong, the image is correctly wrapped onto topography. Finally, the images are precisely combined-or coregistered-in order to measure surface displacements accurately.

"What is important is that we identified the steps and took each one independently and did an error analysis for each step to see how errors propagated," says Leprince. His program, which he calls COSI-Corr and which was packaged by the TO's software engineer Francois Ayoub for official release this year, takes all of these steps automatically in just a few hours of processing time. "You start the program, you go home, you have a nice weekend on the beach, and it's done."

The paper describing the software Leprince developed appeared in the June 2007 issue of the journal IEEE Transactions on Geoscience and Remote Sensing. COSI-Corr can now combine any images taken by different satellite imagers from different incidence views. For example, to analyze displacement from the 1999 Hector Mine earthquake near Twenty-Nine Palms in California, Leprince correlated a SPOT 4 image with an ASTER image. This had never been done before. It takes only a few hours to process.

Using his technique, Leprince has precisely measured offset from several notable recent earthquakes, including 2005 Kashmir, Pakistan; 2002 Denali, Alaska; 1999 Hector Mine and Chi Chi, Taiwan; and 1992 Landers, California. In the case of earthquakes, the image correlation technique can be used to map in detail all fault ruptures and to measure displacements both along and across the fault. Uncertainties, typically within centimeters for 10-15-meter-resolution images, are extremely low.

The day after Leprince released his software through the TO website, he was contacted by a geologist in Canada asking how the technique could be used to study glacier flow. Radar images cannot analyze glaciers because they move too fast and ice melting poses a problem. "The tectonic application was pretty well set up and we'd tested it thoroughly," says Leprince. "So we extended it to glaciology." And then to other studies as well.

What's tricky about studying glacier flow is that not only has their pace picked up in recent years due to climate change, but glaciers have a natural yearly cycle of ice gain and loss. The two signals can be discerned with cross-correlation of optical imagery. Leprince's method was used to study Mer de Glace glacier in the Alps, which flows at around 90 meters per year. The optical images provide a full view of the ice flow field, pinpointing exactly where the glacier is moving fastest. The same approach was taken with a landslide above the Alpine town of Barcelonnette in eastern France. Benchmarks had been planted to monitor the landslide's flow, and Leprince's correlation methods showed that all 38 of them missed the fastest-moving region. While the landslide is moving slow now, the town will be threatened when the landslide detaches and descends rapidly.

There are many more applications for correlating optical images to monitor Earth surface changes. Caltech geologists and their collaborators began to apply it to studying dunes, which radars cannot image, after they were contacted by labs in Egypt who need information on dune migration for urban planning.

"Radar interferometry is a huge technique, but you can only measure half of the world with it. Now we can measure the other half with this technique," comments Leprince. "The biggest thing is what's to come."

COSI-Corr and many of its applications will be presented by Leprince on Friday morning, December 14, in Moscone South Exhibit Hall B. To learn more about the technique, visit http://www.tectonics.caltech.edu/slip_history/spot_coseis/

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Elisabeth Nadin
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Earthquake Season in the Himalayan Front

SAN FRANCISCO, Calif.--Scientists have long searched for what triggers earthquakes, even suggesting that tides or weather play a role. Recent research spearheaded by Jean-Philippe Avouac, professor of geology and director of the Tectonics Observatory at the California Institute of Technology, shows that in the Himalayan mountains, at least, there is indeed an earthquake season. It's winter.

For decades, geologists studying earthquakes in the Himalayan range of Nepal had noted that there were far more quakes in the winter than in the summer, but it was difficult to assign a cause. "The seasonal variation in seismicity had been noticed years ago," says Avouac. Now, over a decade of data from GPS receivers and satellite measurements of land-water storage make it possible to connect the monsoon season with the frequency of earthquakes along the Himalaya front. The analysis also provides key insight into the timescale of earthquake nucleation in the region.

Avouac will present the results of the study on December 12 at the annual meeting of the American Geophysical Union (AGU) in San Francisco. They are also available online through the journal Earth and Planetary Science Letters, and will appear in print early next year.

The world's tallest mountain range, the Himalaya continues to rise as plate tectonic activity drives India into Eurasia. The compression from this collision results in intense seismic activity along the front of the range. Stress builds continually along faults in the region, until it is released through earthquakes.

Avouac and two collaborators from France and Nepal--Laurent Bollinger and Sudhir Rajaure--began their earthquake seasonality investigation by analyzing a catalog of around 10,000 earthquakes in the Himalaya. They saw that, at all magnitudes above this detection limit, there were twice as many earthquakes during the winter months--December through February--as during the summer. That is, in winter there are up to 150 earthquakes of magnitude three per month, and in summer, around 75. For magnitude four, the winter average is 16 per month, while in summer the rate falls to eight per month. They ran the numbers through a statistical calculation and ruled out the possibility that the seasonal signal was due merely to chance.

"The signal in the seismicity is real; there is no discussion," Avouac says. "We see this seasonal cycle," he adds. "We didn't know where it came from but it is really strong. We're looking at something that is changing on a yearly basis-the timescale over which stress changes in this region is one year."

Earlier studies suggested that seasonal variations in atmospheric pressure set off earthquakes, and this had been proposed for seasonal seismicity following the 1992 Landers, California, quake.

The scientists turned to satellite measurements of water levels in the region. Using altimetry data from TOPEX/Poseidon, a satellite launched in 1992 by NASA and the French space agency CNES (Centre National d'Etudes Spatiales), they evaluated the water level in major rivers of the Ganges basin to within a few tens of centimeters. They found that the water level over the whole basin begins its four-meter rise at the onset of the monsoon season in mid-May, reaching a maximum in September, followed by a slow decrease until the next monsoon season.

They combined river level measurements with data from NASA's GRACE--Gravity Recovery and Climate Experiment--mission, which studies, among other things, groundwater storage on landmasses. The data revealed a strong signal of seasonal variation of water in the basin. Paired with the altimetry data, these measurements paint a complete picture of the hydrologic cycle in the region.

In the Himalaya, monsoon rains swell the rivers of the Ganges basin, increasing the pressure bearing down on the region. As the rains stop, the river water soaks through the ground and the built-up load eases outward, toward the front of the range. This outward redistribution of stress after the rains end leads to horizontal compression in the mountain range later in the year, triggering the wintertime earthquakes.

The final piece connecting winter earthquake frequency to season, and lending insight into the process by which earthquakes nucleate, lay in GPS data. Installation of GPS instruments across the Himalayan front began in 1994, and now they provide a decade's worth of measurements showing land movement across the region. Instead of looking at vertical motions, which are widely believed to be sensitive to weather and the same forces that cause tides on Earth, the scientists concentrated on horizontal displacements. The lengthy records, analyzed by Pierre Bettinelli during his graduate work at Caltech, show that horizontal motion is continuous in the range front. Stress constantly builds in the region. But just as water levels near their lowest in the adjacent Ganges basin and earthquakes begin their doubletime, horizontal motion reaches its maximum speed.

"We had been staring at [the seasonal signal] for years, and then the satellite data came in and we deployed the GPS network and suddenly it became crystal clear," says Avouac. "It's like something you dream of."

While many scientists have suggested that changing water levels can influence the earthquake cycle, a definitive mechanism had yet to be pinpointed. "There are two main avenues by which people have tried to understand the physics of earthquakes: Earth tides and aftershocks," says Avouac. With the water level data, he could show that the rate at which stress builds along the rangefront, rather than the absolute level of stress, triggers earthquakes.

Although Earth tides induce stress levels similar to what builds up during seasonal water storage, they only vary over a 12-hour period. The Himalayan signal shows that it is more likely that earthquakes are triggered after stress builds for weeks to months, which matches the timescale of seasonal stress variation in that region.

About other earthquake-prone regions Avouac says, "seasonal variation has been reported in other places, but I don't know any other place where it is so strong or where the cause of the signal is so obvious."

Other authors on the paper are Pierre Bettinelli, Mireille Flouzat, and Laurent Bollinger of the Commissariat a l'Énergie Atomique, France; Guillaume Ramillien of the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, France; and Sudhir Rajaure and Som Sapkota of the National Seismological Centre in Nepal.

Avouac will present details of the group's findings at AGU on Wednesday, December 12, at 2 p.m., Moscone West room 3018, in session T33F: Earthquake geology, active tectonics, and mountain building in south and east Asia.

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Elisabeth Nadin
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Tracing the Roots of the California Condor

Pasadena, Calif.--At the end of the Pleistocene epoch some 10,000 years ago, two species of condors in California competed for resources amidst the retreating ice of Earth's last major glacial age. The modern California condor triumphed, while its kin expired.

In the past century, paleontologists have been unsure whether the modern California condor is different enough from a larger, extinct condor that lived during Pleistocene time to classify the two as distinct species. Now, after the most extensive study of condor fossils and skeletal remains to date, Caltech senior undergraduate Valerie Syverson has documented evidence that confirms the two are different enough for the distinction.

Her findings will be presented on October 28 at the annual meeting of the Geological Society of America in Denver.

To solve the puzzle, Syverson teamed up with Donald Prothero, a paleontologist at Occidental College and a guest lecturer in geobiology at Caltech. They studied bones from recently dead condors and compared them with those found in the extensive bone pile of Los Angeles's Pleistocene-aged La Brea tar pits. What they found, Syverson says, is that "there's definitely one species distinction, and possibly two."

Syverson began her study by examining bones from condor skeletons housed at the Los Angeles Museum of Natural History, the Museum of Vertebrate Zoology at UC Berkeley, and the Santa Barbara Museum of Natural History. One interesting finding was that among these modern birds, Gymnogyps californianus, there was no distinction in bone size between males and females.

After looking at modern condors, Syverson turned to La Brea. She examined Pleistocene specimens from various tar pits, the oldest 35,000 and the youngest 9,000 years old. The record thus provides a glimpse into a long time variation within a species restricted to one location. Over the entire 26,000-year record, Syverson found no change in condor morphology. Although this had been previously discovered in a similar study of golden eagles from La Brea, Syverson says it's remarkable to see that the drastic climate change accompanying the end of the last ice age had no impact on the size of the species that lived through it.

When Syverson plotted her measurements of modern and Pleistocene condor bones, she found there was a definite size distinction between the two. "The ancients are decidedly bigger," she says, and the difference is especially notable in the femur, or thigh bone. These birds were heavier, with a longer, narrower skull and beak than the modern California condor. At first blush, they seem to belong to the species Gymnogyps amplus, first described in 1911 based on a broken tarsometatarsus, a bone found in the lower leg of birds.

In fact, that type specimen suggests that the Pleistocene condors at La Brea may be a third distinct condor species. The broken tarsometatarsus--housed in the Berkeley collection--is larger than any other condor bone Syverson studied. "It would've been an outlier from either species," she says. "Based on the fact that the type specimen is outside the range for both of the groups, I wonder if we need to define a third species for the extinct La Brea condor."

This study also documents evidence that ancient and modern condors coexisted for some time, and that the Pleistocene species may have lived at the same time as humans in western North America. Several tarsometatarsi of the older, bigger species were found in the youngest pit at La Brea. This pit also contains the remains of the La Brea woman, the only prehistoric human discovered in the tar pits. Another piece of evidence pointing to the same conclusion comes from the Berkeley museum collection. It is a bone from a Native American midden--a garbage heap--in Oregon, and it falls into the size range of the ancient group. Although its age is unknown, it must have lived at the same time as the people who disposed of it.

Syverson hopes to use radiocarbon dating to determine the age of the Oregon specimen. She'd also like to apply the technique to date the G. amplus type specimen, to see if its age does indeed distinguish a third condor species.

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Elisabeth Nadin
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Caltech's Ingersoll Receives Achievement Award

PASADENA, Calif.-- Andrew P. Ingersoll of the California Institute of Technology has been awarded the 2007 Gerard P. Kuiper Prize by the Division for Planetary Sciences (DPS) of the American Astronomical Society in honor of his outstanding contributions to planetary science. The award was presented this week during the annual DPS meeting in Orlando, Florida.

Ingersoll, the Earle C. Anthony Professor of Planetary Science at Caltech, has been a leader in the investigation of planetary atmospheres for more than four decades. His research has included studies of the runaway greenhouse effect on Venus, the occurrence of liquid water on Mars, the supersonic winds on Jupiter's moon Io, and the atmospheric dynamics of Jupiter, Saturn, Uranus, and Neptune. He participated on the instrument teams for many NASA/JPL missions including Pioneer Venus, Pioneer Saturn, Voyager, Mars Global Surveyor, Galileo, and Cassini.

Ingersoll is a recipient of NASA's Exceptional Scientific Achievement Medal and is a Fellow of the American Academy of Arts and Sciences, the American Association for the Advancement of Science, the American Geophysical Union, and the American Astronomical Society.

The Gerard P. Kuiper Prize has been given annually since 1984 to scientists "whose achievements have most advanced our understanding of the planetary system," among them Carl Sagan, James Van Allen and Eugene Shoemaker. The award is named after the pioneering Dutch-born astronomer, who is considered the father of modern planetary science. In 1951, Kuiper proposed the existence of a belt of minor planets at the edge of the solar system; after its discovery, the region was named the Kuiper Belt in his honor. He also discovered the atmosphere of Saturn's moon Titan, the carbon dioxide atmosphere of Mars, Uranus's satellite Miranda, and Neptune's moon Nereid.

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Kathy Svitil
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New Method of Studying Ancient Fossils Points to Carbon Dioxide As a Driver of Global Warming

PASADENA, Calif.—A team of American and Canadian scientists has devised a new way to study Earth's past climate by analyzing the chemical composition of ancient marine fossils. The first published tests with the method further support the view that atmospheric CO2 has contributed to dramatic climate variations in the past, and strengthen projections that human CO2 emissions could cause global warming.

In the current issue of the journal Nature, geologists and environmental scientists from the California Institute of Technology, the University of Ottawa, the Memorial University of Newfoundland, Brock University, and the Waquoit Bay National Estuarine Research Reserve report the results of a new method for determining the growth temperatures of carbonate fossils such as shells and corals. This method looks at the percentage of rare isotopes of oxygen and carbon that bond with each other rather than being randomly distributed through their mineral lattices.

Because these bonds between oxygen-18 and carbon-13 form in greater abundance at low temperatures and lesser abundance at higher temperatures, a precise measurement of their concentration in a carbonate fossil can quantify the temperature of seawater in which the organisms lived. By comparing this record of temperature change with previous estimates of past atmospheric CO2 concentrations, the study demonstrates a strong coupling of atmospheric temperatures and carbon dioxide concentrations across one of Earth's major environmental shifts.

According to Rosemarie Came, a postdoctoral scholar in geochemistry at Caltech and lead author of the article, only about 60 parts per million of the carbonate molecular groups that make up the mineral structures of carbonate fossils are a combination of both oxygen-18 and carbon-13, but the amount varies predictably with temperature. Therefore, knowing the age of the sample and how much of these exotic carbonate groups are present allows one to create a record of the planet's temperature through time.

"This clumped-isotope method has an advantage over previous approaches because we're looking at the distribution of rare isotopes inside a single shell or coral," Came says. "All the information needed to study the surface temperature at the time the animal lived is stored in the fossil itself."

In this way, the method contrasts with previous approaches that require knowledge of the chemistry of seawater in the distant past--something that is poorly known.

The study contrasts the growth temperatures of fossils from two times in the distant geological past. The Silurian period, approximately 400 million years ago, is thought to have been a time of highly elevated atmospheric CO2 (more than 10 times the modern concentration), and was found by the researchers to be a time of exceptionally warm shallow-ocean temperatures—nearly 35 degrees C. In contrast, the Carboniferous period, roughly 300 million years ago, appears to have been characterized by far lower levels of atmospheric carbon dioxide (similar to modern values) and had shallow marine temperatures similar to or slightly cooler than today-about 25 degrees C. Thus, the draw-down of atmospheric CO2 coincided with strong global cooling.

"This is a huge change in temperature," says John Eiler, a professor of geochemistry at Caltech and a coauthor of the study. "It shows that carbon dioxide really has been a powerful driver of climate change in Earth's past."

The title of the Nature paper is "Coupling of surface temperatures and atmospheric CO2 concentrations during the Paleozoic era." The other authors are Jan Veizer of the University of Ottawa, Karem Azmy of Memorial University of Newfoundland, Uwe Brand of Brock University, and Christopher R. Weidman of the Waquoit National Estuarine Research Reserve, Massachusetts.

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Robert Tindol
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Caltech, JPL, Northrop Grumman to Celebrate 50 Years of Space Exploration

PASADENA, Calif.--Before October 1957, space flight was a thing of fantasy. Today we are experienced space explorers with unlimited voyages to undertake. Where is space flight's next horizon? What constitutes sensible space investment? How did the space pioneers accomplish their goals? These topics will be addressed at "50 Years in Space: An International Aerospace Conference Celebrating 50 Years of Space Technology," which will take place from September 19 to 21 at the California Institute of Technology.

The conference is hosted by Caltech, the Graduate Aeronautical Laboratories at Caltech (GALCIT), Northrop Grumman Corporation, and the Jet Propulsion Laboratory.

NASA Administrator Michael Griffin, astronaut Harrison "Jack" Schmitt, space industry pioneers and experts, and representatives from foreign space programs will speak on the history of space exploration, sensible space investment, and the future of space exploration from the perspectives of the aerospace industry, academia, government, and science. The opening keynote speaker will be the chairman of Northrop Grumman, Ronald Sugar.

"Our speakers represent all the institutions that essentially created and successfully sustained space exploration," said Ares Rosakis, Theodore von Karman Professor of Aeronautics and Mechanical Engineering and GALCIT director, and co-organizer of the conference with Dwight Streit, vice president, foundation technologies in Northrop Grumman's Space Technology sector. "This group crosses international and institutional boundaries. Each of our speakers is a preeminent expert in at least one of the many disciplines required for space travel. Their passion for space science and technology will make this conference the definitive observance worldwide commemorating 50 years in space," Streit noted.

"Many technologies developed as a result of space exploration have become integral terrestrial technologies--and our efforts benefit society in surprising ways that are completely separate from their initial impetus. As we look to the future, we will see how this important aspect of aeronautics continues--especially in the areas of tracking weather changes, global temperatures, and greenhouse gases, as well as the formations of the earth's crust related to seismic activity," Rosakis said.

The launch of Sputnik on October 4, 1957, began the space age. Within weeks, the Ramo-Wooldridge Corporation spun off Space Technology Laboratories (STL), with Simon Ramo as its president. STL and Ramo-Wooldridge became part of TRW Inc. in 1958, and then eventually part of Northrop Grumman in 2002.

In 1958, the JPL-built Explorer 1 put the U.S. in the space race, followed soon thereafter by Pioneer 1, built by TRW and the first spacecraft launched by NASA.

Ramo, the "R" in TRW, earned his PhD at Caltech in 1936. TRW's Space and Electronics Group became the Space Technology sector at Northrop Grumman. The president of the company's Space Technology sector, Alexis Livanos (also a Caltech graduate, having earned his bachelor's, master's, and PhD at Caltech), will give a special tribute to Ramo, 94, at the conference.

Livanos will join JPL director Charles Elachi (who earned his MS and PhD at Caltech), and Caltech president Jean-Lou Chameau as chairs of the conference. Elachi and Chameau will also be speaking.

Caltech alumnus Harrison "Jack" Schmitt, a geologist, one of the last two men to walk on the moon, and a NASA adviser, will be joined by Ed Stone, former director of JPL, and Gentry Lee, chief engineer for the Planetary Flight Systems Directorate at JPL, for a "look back" at the accomplishments of the past 50 years, many of which they bravely spearheaded. JPL, which became part of NASA after its formation in 1958, remains at the center of robotic planetary exploration and Earth-observing science. JPL is managed by Caltech.

Representatives of the top-tier space programs around the globe will also be present, including NASA's Griffin; European Space Agency Director General Jean-Jacques Dordain; President of Centre National d'Études Spatiales Yannick d'Escatha; and Masato Nakamura of the Japanese Institute of Space and Astronautical Science, all of whom will discuss the future of space exploration.

Miles O'Brien, CNN chief technology and environment correspondent, will moderate a panel discussion titled "Space and the Environment: Sensible Space Investment." Participating in the panel, and also presenting a separate talk, is A.P.J. Abdul Kalam, the 11th president of India and a noted scientist and aeronautical engineer.

Other distinguished guests include keynote speaker John C. Mather, James Webb Space Telescope senior project scientist; Elon Musk, SpaceX CEO; Burt Rutan, founder of Scaled Composites; and Hayden Planetarium Director Neil deGrasse Tyson. Mather was awarded the 2006 Nobel Prize in Physics for his work in the areas of black body form, cosmic microwave background radiation, and Big-Bang theory. PayPal creator Musk, whose space-transportation company, SpaceX, has opened up a whole new segment of the aerospace industry, will be speaking on a panel discussing the future of space exploration from an industry perspective. Closing keynote speaker Tyson is the recipient of eight honorary doctorates and was named one of Time magazine's 100 Most Influential People of 2007.

Several speakers will address the aerospace industry's perspective on the future of space flight. These include Musk; David Thompson, chairman and CEO of Orbital Science Corporation; Joanne Maguire, executive vice president, space systems, at Lockheed Martin; and David Whelan, corporate vice president, Boeing.

The perspective from academia will come from, among others, Caltech alumna and president of Purdue University France Córdova and Charles Kennel, the former director of Scripps Institution of Oceanography. Ronald Sega, undersecretary, United States Air Force, and the Defense Department's executive agent for space, will also speak on the future of space exploration.

Participants will be able to view large replicas of spacecrafts, rovers, and satellites. "This is more than a sit-and-listen event," said Rosakis. "It is an interactive learning experience. Guests will meet and exchange ideas with like-minded people and professionals in between formal presentations. The displays and replicas will also add to the guests' visual understanding of space exploration. They will be able to understand what the presence of these structures really feels like."

Full registration is $550. To register, go to http://www.galcit.caltech.edu/space50/. Registration is on a first-come, first-served basis, and seating is limited.

Caltech, JPL, Northrop Grumman, California Space Authority employees, Southern California high-school and college students and teachers with ID are welcome to attend the talks free of charge, but they must register via the website. 

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Jill Perry
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NASA'S Spitzer Finds Water Vapor on Hot, Alien Planet

It may not be a waterworld that would field many of Kevin Costner's dreams, but the exoplanet HD 189733b has just been found to have water vapor in its atmosphere. The observation provides the best evidence to date that water exists on worlds outside our own solar system.

The discovery was made by NASA's Spitzer Space Telescope, which possesses a particularly keen ability to study nearby stars and their exoplanets. HD 189733b is located 63 light-years away in the constellation Vulpecula.

"Water is the quintessence of life as we know it," says Yuk Yung, a professor of planetary science at the California Institute of Technology and one of the authors of a paper appearing in this week's journal Nature. "It is exciting to find that it is as abundant in another solar system as it is in ours."

The Spitzer observations show that HD 189733b swelters as it zips closely around its star every two days or so. Astronomers had predicted that planets of this class, termed "hot Jupiters," would contain water vapor in their atmospheres. Yet finding solid evidence for this has been slippery. These latest data are the most convincing yet that hot Jupiters are "wet." "We're thrilled to have identified clear signs of water on a planet that is trillions of miles away," said Giovanna Tinetti, a European Space Agency fellow at the Institute d'Astrophysique de Paris in France.

A former postdoctoral scholar at the Virtual Planetary Laboratory at Caltech, Tinetti is lead author of the Nature paper.

Coauthor, Mao-Chang Liang of Caltech and the Research Center for Environmental Changes in Taiwan said, "The discovery of water is the key to the discovery of alien life."

Although water is an essential ingredient for life as we know it, wet hot Jupiters are not likely to harbor any creatures. Previous measurements from Spitzer indicate that HD 189733b is a fiery 1,000 degrees Kelvin (1,340 degrees Fahrenheit) on average. Ultimately, astronomers hope to use instruments like those on Spitzer to find water on rocky, habitable planets like Earth. "Finding water on this planet implies that other planets in the universe, possibly even rocky ones, could also have water," said coauthor Sean Carey of the Spitzer Science Center ,which is headquartered at Caltech. "I'm excited to tell my nephew and niece about the discovery."

The new findings are part of a brand-new field of science that is concerned with investigating the climate on exoplanets, or planets outside our solar system. Such faraway planets cannot be seen directly; however, in the past few years, astronomers have begun to glean information about their atmospheres by observing a subset of hot Jupiters that transit, or pass in front of ,their stars as seen from Earth. Earlier this year, Spitzer became the first telescope to analyze, or break apart, the light from two transiting hot Jupiters, HD 189733b and HD 209458b. One of its instruments, called a spectrometer, observed the planets as they dipped behind their stars in what is called the secondary eclipse. This led to the first-ever "fingerprint," or spectrum, of an exoplanet's light. Yet, the results indicated the planet was dry, probably because the structure of these planets' atmospheres makes finding water with this method difficult.

Later, a team of astronomers found hints of water on HD 209458b by analyzing visible-light data taken by NASA's Hubble Space Telescope. The Hubble data were captured as the planet crossed in front of the star, an event called the primary eclipse. Now, Tinetti and her team have captured the best evidence yet for wet hot Jupiters by watching HD 189733b's primary eclipse in infrared light with Spitzer. In this method, changes in infrared light from the star are measured as the planet slips by, filtering starlight through its outer atmosphere. The astronomers observed the eclipse with Spitzer's infrared-array camera at three different infrared wavelengths and noticed that each time a different amount of light was absorbed by the planet. The pattern by which this absorption varies with wavelength matches that created by water.

"Water is the only molecule that can explain that behavior," said Tinetti. "Observing primary eclipses in infrared light is the best way to search for this molecule in exoplanets."

The water on HD 189733b is too hot to condense into clouds; however, previous observations of the planet from Spitzer and other ground- and space-based telescopes suggest that it might have dry clouds, along with high winds and a hot, sun-facing side that is warmer than its dark side. Other authors of the Nature paper include Alfred Vidal-Madjar, Jean-Phillippe Beaulieu, David Sing, Nicole Allard, and Roger Ferlet of the Institute d'Astrophysique de Paris; Robert J. Barber and Jonathan Tennyson of University College London in England; Ignasi Ribas of the Institut de Ciències de l'Espai, Spain; Gilda E. Ballester of the University of Arizona, Tucson; and Franck Selsis of the Ecole Normale Supérieure, France.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington, D.C. JPL is a division of Caltech. Spitzer's infrared-array camera was built by NASA's Goddard Space Flight Center, Greenbelt, MD. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. For graphics about this research and more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer

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Robert Tindol
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The Dwarf Planet Known as Eris is More Massive than Pluto, New Data Shows

PASADENA, Calif.—Die-hard Pluto fans still seeking redemption for their demoted planet have cause for despair this week. New data shows that the dwarf planet Eris is 27 percent more massive than Pluto, thereby strengthening the decree last year that there are eight planets in the solar system and a growing list of dwarf planets.

According to Mike Brown, the discoverer of Eris, and his graduate student Emily Schaller, the data confirms that Eris weighs 16.6 billion trillion kilograms. They know this because of the time it takes Eris's moon, Dysnomia, to complete an orbit.

"This was Pluto's last chance to be the biggest thing found so far in the Kuiper belt," says Brown, a professor of planetary astronomy at the California Institute of Technology. "There was a possibility that Pluto and Eris were roughly the same size, but these new results show that it's second place at best for Pluto."

Eris was discovered in 2005 with Palomar Observatory's 48-inch Samuel Oschin Telescope, an instrument specially adapted to do comprehensive searches for objects in the sky.

When it became apparent that Eris was similar in size if not larger than Pluto, Brown and others called for the International Astronomical Union to rule on its planetary status. The end result was demotion of Pluto and the redesignation of it and other Kuiper-belt objects as dwarf planets.

Schaller says that the new results, obtained with Hubble Space Telescope and Keck Observatory data, indicate that the density of the material making up Eris is about two grams per cubic centimeter. This means that Eris very likely is made up of ice and rock, and thus is very similar in composition to Pluto. Past results from the Hubble Space Telescope had already allowed planetary scientists to determine that its diameter is 2,400 kilometers, also larger than Pluto's.

"Pluto and Eris are essentially twins—except that Eris is slightly the pudgier of the two," says Brown. "And a little colder," adds Schaller.

The reason for Eris's blustery surface conditions is its sheer distance from the sun. Currently 97 astronomical units from the sun (an astronomical unit being the distance between the sun and Earth), Eris hovers at temperatures well below 400 degrees Fahrenheit and is pretty dark.

However, things get a little better on Eris now and then. Orbiting the sun on a highly elliptical 560-year journey, Eris sweeps in as close to the sun as 38 astronomical units. But at present it is nearly as far away as it ever gets.

Pluto's own elliptical orbit takes it as far away as 50 astronomical units from the sun during its 250-year revolution. This means that Eris is sometimes much closer to Earth than Pluto, although never closer than Neptune.

Based on spectral data, the researchers think Eris is covered with a layer of methane that has seeped from the interior and frozen on the surface. As in the case of Pluto, the methane has undergone chemical transformations, probably due to the faint solar radiation, causing the methane layer to redden. But the methane surface on Eris is somewhat more yellowish than the reddish-yellow surface of Pluto, perhaps because Eris is farther from the sun.

As for Dysnomia, the tiny satellite remains the only moon discovered orbiting Eris so far. Dysnomia is about 150 kilometers in diameter, is about 37,000 kilometers from Eris, and has a lunar "month" that lasts 16 days.

"But every year is 560 Earth-years," says Brown. "So on Eris they have a lot more months in their calendar."

Like the Earth-moon system, Eris-Dysnomia probably formed about 4.5 billion years ago following a massive collision.

Brown and Schaller are the authors of a paper, "The Mass of Dwarf Planet Eris," appearing in the June 15 issue of the journal Science.

The search for new planets and other bodies in the Kuiper belt is funded by Caltech and NASA. For more information on the program, see the Samuel Oschin Telescope's website at http://www.astro.caltech.edu/palomarnew/sot.html.

For more information on Mike Brown's research, see http://www.gps.caltech.edu/~mbrown.

To learn more about Eris, see http://www.planeteris.com.

An Eris image is available at http://www.gps.caltech.edu/~mbrown/planetlila/moon/hst.jpg

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Robert Tindol
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Caltech Astrophysicist Peter Goldreich Wins $1 Million International Shaw Prize

PASADENA, Calif.—Peter Goldreich, the Lee A. DuBridge Professor of Astrophysics and Planetary Physics, Emeritus, has been named winner of the 2007 Shaw Prize for astronomy by the Shaw Prize Foundation of Hong Kong. The announcement was made Tuesday, June 12, at foundation headquarters in Hong Kong.

Goldreich is one of four winners of the prize, which is awarded each year in the fields of astronomy, life sciences and medicine, and the mathematical sciences. This year's other recipients are Robert Lefkowitz of Duke University Medical Center, Robert Langlands of the Institute for Advanced Study, and Richard Taylor of Harvard University.

Goldreich, who spends half his time at the Institute for Advanced Study, was cited by the Shaw Prize Foundation for his "lifetime achievements in theoretical astrophysics and planetary sciences." A native of New York, Goldreich joined the Caltech faculty in 1966 and took emeritus status in 2002, although he remains active in research.

Goldreich once described himself as a "general-purpose theoretician in astrophysics." His work has involved fundamental research into phenomena such as the dynamics of planetary rings, pulsars, masers, the spiral arms of galaxies, the rotation of planets as well as their orbital resonances, and the oscillations of the sun. His past papers have covered a range of topics, from why Saturn's rings have sharp edges, to how stars send out coherent microwaves, or masers, in a manner similar to lasers on Earth, to how the moon Io affects the radio bursts of Jupiter.

His current research is focused on planet formation and turbulence in magnetized fluids.

Among Goldreich's past honors is the 1995 National Medal of Science, which is generally regarded as America's highest scientific honor.

The Shaw Prize is an international award to honor individuals who are currently active in their respective fields and who have achieved distinguished and significant advances, who have made outstanding contributions in culture and the arts, or who in other domains have achieved excellence. The award is dedicated to furthering societal progress, enhancing quality of life, and enriching humanity's spiritual civilization. Each recipient of the Shaw Prize receives an award of $1 million.

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Robert Tindol
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Caltech Seismologist Hiroo Kanamori Awarded Kyoto Prize by Inamori Foundation

PASADENA, Calif.—Hiroo Kanamori, one of the world's leading authorities on earthquakes, has been awarded the 23rd annual Kyoto Prize by the Inamori Foundation of Japan. The announcement was made today in Kyoto.

According to the Inamori Foundation, Kanamori is being awarded the honor for his "significant contributions to understanding the physical processes of earthquakes and developing seismic hazard mitigation systems to protect human life."

Kanamori is the John E. and Hazel S. Smits Professor of Geophysics, Emeritus, at the California Institute of Technology. A former director of the Seismological Laboratory at Caltech, he is widely known among earthquake scientists for a variety of important contributions. In 1977 he devised a moment-magnitude scale for determining the magnitudes of very large earthquakes, based on the amount of energy they release. Known as energy magnitude measurements, the method accounted for the effect of seismic waves with very long periods that were not accounted for by earlier methods.

Using the improved method, scientists were able to obtain more precise measurements of the energy of large earthquakes that occurred in the past, such as the 1960 Chilean earthquake and the 1964 Alaskan earthquake, as well as a better means of studying and analyzing seismic events when they occur.

Kanamori has also worked on the nature of tsunamis, particularly the relationship between ground motion and generation of giant sea waves that can have devastating consequences for coastline habitation. These "tsunami earthquakes" release most of their energy in very long-period seismic waves that do not necessarily cause precipitous shaking, but can nonetheless create huge ocean waves. He has also been a longtime advocate of automated early-warning systems to let populations know when a seismic event has occurred that could result in a tsunami.

Kanamori earned his doctorate in geophysics at the University of Tokyo in 1964. He came to Caltech as a postdoctoral researcher the following year, and after stints at MIT and the University of Tokyo, returned to Caltech as a full professor in 1972.

He is a member of the American Academy of Arts and Sciences, a past president of the Seismological Society of America, and winner of the National Academy of Sciences Day Prize and the Japan Academy Prize.

Kanamori will share this year's Kyoto Prize with Pina Bausch, director and choreographer of the Tanztheater Wuppertal Pina Bausch, and Hiroo Inokuchi, a materials scientist who has made fundamental contributions to organic molecular electronics. Kanamori, Inokuchi, and Bausch will each receive a cash gift of 50 million yen (approximately $410,000 at the current exchange rate), a Kyoto Prize Medal of 20-karat gold, and a diploma, and will be feted at a special weeklong event at Kyoto beginning November 9.

The Inamori Foundation was established in 1984 by Kazuo Inamori, founder and chairman emeritus of Kyocera and KDDI Corporation. The prize was created in 1985, in line with Inamori's belief that individuals have "no higher calling than to strive for the greater good of society," and that humanity's future "can be assured only when there is a balance between our scientific progress and our spiritual depth."

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Robert Tindol
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