New study describes workings of deep oceanduring the Last Glacial Maximum

Scientists know quite a bit about surface conditions during the Last Glacial Maximum (LGM), a period that peaked about 18,000 years ago, when ice covered significant portions of Canada and northern Europe.

But to really understand the mechanisms involved in climate change, scientists need to have detailed knowledge of the interaction between the ocean and the atmosphere. And until now, a key component of that knowledge has been lacking for the LGM because of limited understanding of the glacial deep ocean.

In a paper published in the November 29 issue of the journal Science, researchers from the California Institute of Technology and Harvard University report the first measurements for the temperature-salinity distribution of the glacial deep ocean. The results show unexpectedly that the basic mechanism of the distribution was different during icy times.

"You can think of the global ocean as a big bathtub, with the densest water at bottom and the lightest at top," explains Jess Adkins, an assistant professor of geochemistry and global environmental science at Caltech and lead author of the paper. Because water that is cold or salty--or both--is dense, it tends to flow downward in a vertical circulation pattern, much like water falling down the sides of the bathtub, until it finds its correct density level. In the ocean today, this circulation mechanism tends to be dominated by the temperature of the water.

In studying chlorine data from four ocean drilling program sites, the researchers found that the glacial deep ocean's circulation was set by the salinity of the water. In addition, a person walking on the ocean bottom from north to south, 18,000 years ago, would have found that the water tended to get saltier as he proceeded (within an acceptable margin of error, both north and south waters were the same temperature). Taking that into account, the water in the north would have been less dense. The exact reverse is true today, with the waters at low southern latitudes being very cold and relatively fresh, while those in the high northern latitudes being warmer and saltier.

Adkins says there is a good explanation for the change. The seawater "equation of state" dictates that the density of water near the freezing point is about two-to-three times more sensitive to changes in salinity relative to changes in temperature, as compared to today's warmer deep waters.

So, the equation demands that the density-layering of the ocean "bathtub" be set by the water's salt content at the last glacial maximum. Temperature is still crucial, in that colder waters are more sensitive to salinity changes than warmer water, but Adkin's results show that the deep water circulation mechanism must have operated in a fundamentally different manner in the past.

"This observation of the deep ocean seems like a strange place to go to study Earth's climate, but this is where you find most of the mass and thermal inertia of the climate system," Adkins says.

The ocean's water temperature enters into the complex mechanism affecting the climate, with water moving about in order for the ocean to equalize its temperature. Too, the water and air interact to further complicate the weather equation.

Thus, the results from the glacial deep ocean shows that the climate in those days was operating in a very different way, Adkins says. "Basically, the purpose of this study is to understand the mechanisms of climate change."

In addition to Adkins, the other authors are Katherine McIntyre, a postdoctoral scholar in geochemistry at Caltech; and Daniel P. Schrag of the Department of Earth and Planetary Sciences at Harvard University.

Contact: Robert Tindol (626) 395-3631

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RT

Rupture of Denali fault responsible for 7.9-magAlaskan earthquake of November 3

Geologists just back from a reconnaissance of the 7.9-magnitude Alaska earthquake of November 3 confirm that rupture of the Denali fault was the principal cause of the quake.

According to Caltech geology professor Kerry Sieh, Central Washington University geological sciences professor Charles Rubin, and Peter Haeussler of the U.S. Geological Survey, investigations over a week-long period revealed three large ruptures with a total length of about 320 kilometers. The principal rupture was a 210-kilometer-long section of the Denali fault, with horizontal shifts of up to nearly 9 meters (26 feet). This places the rupture in the same class as those that produced the San Andreas fault's two historical great earthquakes in 1906 and 1857. These three ruptures are the largest such events in the Western Hemisphere in at least the past 150 years.

Like California's San Andreas, the Denali is a strike-slip fault, which means that the blocks on either side of the fracture move sideways relative to one another. Over millions of years, the cumulative effect of tens of thousands of large shifts has been to move southern Alaska tens of kilometers westward relative to the rest of the state. These shifts have produced a set of large aligned valleys that arch through the middle of the snowy Alaska range, from the Canadian border on the east to the foot of Mount McKinley on the west. Along much of its length the great fracture traverses large glaciers. Surprisingly, the fault broke up through the glaciers, offsetting large crevasses and rocky ridges within the ice.

At the crossing of the Trans-Alaska pipeline, approximately in the center of the 320-kilometer rupture, the horizontal shift was about 4 meters. Fortunately, geological studies of the fault prior to construction led to a special design that would have allowed for shifts greater than this without failure of the pipeline.

The earthquake shook loose thousands of snow avalanches and rock falls in the rugged terrain adjacent to the fault. Although most of these measured only a few tens of meters in dimension, many were much larger. In some places enormous blocks of rock and ice fell onto glaciers and valley floors, skidding a kilometer or more out over ice, stream, and tundra.

The team of investigators included geologists from several organizations, including Caltech's Division of Geological and Planetary Sciences, the U.S. Geological Survey, Central Washington University, and the University of Alaska. The rugged range is traversed by just two highways, and so the scientists used helicopters to access the fault ruptures in the remote and rugged terrain.

Before departing for the field, the geologists had learned from seismologists the basic character of the rupture. Within a day of the quake, Caltech seismologist Chen Ji had determined that the shift along the fault was principally horizontal, but that the initial 20 seconds of the eastward-propagating crack was along a fault with vertical motion. This fault was discovered midweek, near the western end of the principal horizontal shift. Along this 40-kilometer-long fault, a portion of the Alaska range has risen several meters.

Perhaps the most surprising discovery in the field was that the fault rupture propagated only eastward from the epicenter and left the western half of the great fault unbroken. Several members of the team wonder if, in fact, this great earthquake is the first in a series of large events that will eventually include breaks farther west toward Mount McKinley and Denali National Park.

Contact: Robert Tindol (626) 395-3631

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Caltech scientists find largest object in solar system since Pluto's discovery

Planetary scientists at the California Institute of Technology have discovered a spherical body in the outskirts of the solar system. The object circles the sun every 288 years, is half the size of Pluto, and is larger than all of the objects in the asteroid belt combined.

The object has been named "Quaoar" (pronounced KWAH-o-ar) after the creation force of the Tongva tribe who were the original inhabitants of the Los Angeles basin, where the Caltech campus is located. Quaoar is located about 4 billion miles from Earth in a region beyond the orbit of Pluto known as the Kuiper belt. This is the region where comets originate and also where planetary scientists have long expected to eventually find larger planet-shaped objects such as Quaoar. The discovery, announced at the meeting of the Division of Planetary Sciences of the American Astronomical Society in Birmingham, Alabama, today, is by far the largest object found so far in that search.

Currently detectable a few degrees northwest of the constellation Scorpio, Quaoar demonstrates beyond a doubt that large bodies can indeed be found in the farthest reaches of the solar system. Further, the discovery provides hope that additional large bodies in the Kuiper belt will be discovered, some as large, or even larger than Pluto. Also, Quaoar and other bodies like it should provide new insights into the primordial materials that formed the solar system some 5 billion years ago.

The discovery further supports the ever-growing opinion that Pluto itself is a Kuiper belt object. According to recent interpretations, Pluto was the first Kuiper belt object to be discovered, long before the age of enhanced digital techniques and charge-coupled (CCD) cameras, because it had been kicked into a Neptune-crossing elliptical orbit eons ago.

"Quaoar definitely hurts the case for Pluto being a planet," says Caltech planetary science associate professor Mike Brown. "If Pluto were discovered today, no one would even consider calling it a planet because it's clearly a Kuiper belt object."

Brown and Chad Trujillo, a postdoctoral researcher, first detected Quaoar on a digital sky image taken on June 4 with Palomar Observatory's 48-inch Oschin Telescope. The researchers looked through archived images taken by a variety of instruments and soon found images taken in the years 1983, 1996, 2000, and 2001. These images not only allowed Brown and Trujillo to establish the distance and orbital inclination of Quaoar, but also to determine that the body is revolving around the sun in a remarkably stable, circular orbit.

"It's probably been in this same orbit for 4 billion years," Brown says.

The discovery of Quaoar is not so much a triumph of advanced optics as of modern digital analysis and a deliberate search methodology. In fact, Quaoar apparently was first photographed in 1982 by then-Caltech astronomer Charlie Kowal in a search for the postulated "Planet X." Kowal unfortunately never found the object on the plate—much less Planet X—but left the image for posterity.

Because the precise location of Quaoar on the old plates is highly predictable, the orbit is thought to be quite circular for a solar system body, and far more circular than that of Pluto. In fact, Pluto is relatively easy to spot—at least if one knows where to look. Because Pluto comes so close to the sun for several years in its 248-year eccentric orbit, the volatile substances in the atmosphere are periodically heated, thereby increasing the body's reflectance, or albedo, to such a degree that it is bright enough to be seen even in small amateur telescopes.

Quaoar, on the other hand, never approaches the sun in its circular orbit, which means that the volatile gases never are excited enough to kick up a highly reflective atmosphere. As is the case for other bodies of similar rock-and-ice composition, Quaoar's surface has been bathed by faint ultraviolet radiation from the sun over the eons, and this radiation has slowly caused the organic materials on the body's surface to turn into a dark tar-like substance.

As a result, Quaoar's albedo is about 10 percent, just a bit higher than that of the moon. By contrast, Pluto's albedo is 60 percent.

As for spin rate, the researchers know that Quaoar is rotating because of slight variations in reflectance in the six weeks they've observed the body. But they're still collecting data to determine the precise rate. They will also probably be able to figure out whether the spin axis is tilted relative to the ecliptical plane.

Inclination is about 7.9 percent, which means that the plane of Quaoar's orbit is tilted by 7.9 degrees from the relatively flat orbital plane in which all the planets except Pluto are to be found. Pluto's orbital inclination is about 17 degrees, which presumably resulted from whatever gravitational interference originally thrust it into an elliptical orbit.

Quaoar's orbital inclination of 7.9 degrees is not particularly surprising, Brown says, because the Kuiper belt is turning out to be wider than originally expected. The Kuiper belt can be thought of as a band extending around the sky, superimposed on the path of the sun. Brown and Trujillo's research, in effect, is to take repeated exposures of a several-degree swath of this band and then use digital equipment to check and see if any tiny point of light has moved relative to the stellar background.

Brown and Trujillo are currently using about 10 to 20 percent of the available time on the 48-inch Oschin Telescope, which was used to obtain both the Palomar Sky Survey and the more recent Palomar Digital Sky Survey. The latter was completed just last year, thus freeing up the Oschin Telescope to be refitted by the Jet Propulsion Laboratory for a new mission to search for near-Earth asteroids. About 80 percent of the telescope time is now designated for the asteroid survey, leaving the remainder for scientific studies like Brown and Trujillo's.

Since the discovery, the researchers have also employed other telescopes to study and characterize Quaoar, including the Hubble Space Telescope (related news release available at link below) and the Keck Observatory on Mauna Kea, Hawaii. Information derived from these studies will provide new insights into the precise composition of Quaoar and may answer questions about whether the body has a tenuous atmosphere.

But the good news for the serious amateur astronomer is that he or she doesn't necessarily need a space telescope or 10-meter reflector to get a faint image of Quaoar. Armed with precise coordinates and a 16-inch telescope fitted with a CCD camera—the kind advertised in magazines such as Sky and Telescope and Astronomy—an amateur should be able to obtain images on successive nights that will show a faint dot of light in slightly different positions.

As for Brown and Trujillo, the two are continuing their search for other large Kuiper-belt bodies. Some, in fact, may be even larger than Quaoar.

"Right now, I'd say they get as big as Pluto," says Brown.

 

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MacArthur Foundation certifies two Caltech professors as geniuses

Two members of the California Institute of Technology faculty have been named MacArthur Fellows, a prestigious honor bestowed each year on innovators in a variety of fields and commonly known as the "genius grants."

Charles Steidel, an astronomer, and Paul Wennberg, an atmospheric scientist, are two of the 24 MacArthur Fellows announced today by the John D. and Catherine T. MacArthur Foundation of Chicago. Each of the 24 recipients will receive a $500,000 "no strings attached" grant over the next five years.

Steidel's expertise is cosmology, a field to which he has made numerous contributions in the ongoing attempt to understand the formation and evolution of galaxies and the development of large-scale structure in the universe. In particular, Steidel is known for the development of a technique that effectively locates early galaxies at prescribed cosmic epochs, allowing for the study of large samples of galaxies in the early universe.

Access to these large samples, which are observed primarily using the Keck telescopes on Mauna Kea on the Big Island of Hawaii, allows for the mapping of the distribution of the galaxies in space and for detailed observations of many individual galaxies. These are providing insights into the process of galaxy formation when the universe was only 10 to 20 percent of its current age.

Steidel says he hasn't yet decided what to do with the grant money. "I'm giving it some thought, but I'm still in the disbelief phase—it took me completely by surprise!" he said.

"The unique nature of the fellowship makes me feel like I should put a great deal of thought into coming up with a creative use for the money. It does feel a bit odd to be recognized for work that is by its nature collaborative and dependent on the hard work of many people, but at the same time I am very excited by the possibilities!"

A graduate of Princeton University and the California Institute of Technology, Steidel was a faculty member at MIT before returning to Caltech, where he is now a professor of astronomy. He is also a past recipient of fellowships from the Sloan and Packard foundations, and received a Young Investigator Award from the National Science Foundation in 1994. In 1997 he was presented the Helen B. Warner Prize by the American Astronomical Society for his significant early-career contributions to astronomy.

Wennberg holds joint appointments as a professor of atmospheric chemistry and a professor of environmental science and engineering. A specialist in how both natural and human processes affect the atmosphere, Wennberg is particularly interested in measuring a class of substances known as radicals and how they enter into atmospheric chemical reactions. These radicals are implicated in processes that govern the health of the ozone layer as well as the presence of greenhouse gases.

Wennberg has earned recognition in the field for developing airborne sensors to study radicals and their chemistry. One of the early scientific results from these measurements demonstrated that conventional thinking was incorrect about how ozone is destroyed in the lower stratosphere, affecting assessments of the environmental impacts of chlorofluorocarbons and stratospheric aircraft.

Wennberg said he was "blown over by the award" when he received notification. "It is a wonderful recognition of the work that I have done in association with the atmospheric scientists working on NASA's U-2 aircraft chemistry program."

"I have been pondering how I might use the funds, but have no concrete plans at the moment. It will certainly enable me to do things I wouldn't have thought possible—perhaps even take up the bassoon again! "

A graduate of Oberlin College and Harvard University, Wennberg was a research associate at Harvard before joining the Caltech faculty. In 1999 he was named recipient of a Presidential Early Career Award in Science and Engineering.

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Caltech geophysicists find four active volcanoes in Andes with innovative satellite radar survey

Four volcanoes in the central Andes mountains of South America, all previously thought to be dormant, must now be considered active due to ground motions detected from space, geophysicists say.

In a paper appearing in the July 11 issue of the journal "Nature", California Institute of Technology geophysics graduate student Matt Pritchard and his faculty adviser, Mark Simons, unveil their analysis of eight years of radar interferometry data taken on 900 volcanoes in the Andes. The data were gathered from 1992 to 2000 by the European Space Agency's two remote-sensing satellites, ERS 1 and ERS 2.

Of the four centers of activity, Hualca Hualca volcano in southern Peru is especially worth close observation because of the population density in the area and because it is just a few miles from the active Sabancaya volcano. A second volcano now shown to be active, Uturuncu in Bolivia, is bulging vertically about 1-to-2 centimeters per year, according to the satellite data, while a third, Robledo caldera in Argentina, is actually deflating for unknown reasons. A fourth region of surface deformation, on the border between Chile and Argentina, was unknown prior to the study, so the authors christened it "Lazufre" because it lies between the two volcanoes Lastarria and Cordon del Azufre.

While the study provides important new information about volcanic hazards in its own right, Pritchard, the lead author, says it also proves the mettle of a new means of studying ground deformation that should turn out to be vastly superior to field studies. The fact that none of the four volcanoes were known to be active—and thus probably wouldn't have been of interest to geophysicists conducting studies using conventional methods—shows the promise of the technique, he says.

"Achieving this synoptic perspective would have been an impractical undertaking with ground-based methods, like the GPS system," Pritchard says.

The sensitive data is superior to ground-based results in that a huge amount of subtle information can be accumulated about a large number of geological features. The satellites bounce a radar signal off the ground, and then accurately measure the time it takes the signal to return. On a later pass, when the satellite is again in approximately the same spot, it sends another signal to the ground.

If the two signals are out of phase, then the distance from the satellite to the ground is either increasing or decreasing, and if the features are volcanic, then the motion can be assumed to have been caused by movement of magma in the subsurface or by hydrothermal activity.

"You can think of a magma chamber as a balloon beneath the surface inflating and deflating. So if the magma is building up underground, you expect a swelling upward, and this is what we can detect with the satellite data."

Given the appropriate satellite mission, all the world's subaerial volcanoes could be easily monitored for active deformation on a weekly basis. Such a capability would have a profound impact on minimizing volcanic hazards in regions lacking necessary infrastructure for regular geophysical monitoring.

Another unusual finding from the study that shows its promise in better understanding volcanism is the Lascar volcano's lack of motion. Lascar has had three major eruptions since 1993, as well as several minor ones, and many volcanologists assume there should have been some ground swelling over the years of the study, Pritchard says.

"But we find no deformation at the volcano," he explains. "Some people find it curious, others think it's not unexpected. But it's a new result, and regardless of what's going on, it could tell us interesting things about magma plumbing."

There are several possible explanations to account for the lack of vertical motion at the Lascar volcano, Pritchard says. The first and most obvious is that the satellite passes took place at times between inflations and subsequent deflations, so that no net ground motion was recorded. It could also be that magma is somehow able to get from within Earth to the atmosphere without deforming surfaces at all; or that a magma chamber might be deep enough to allow an eruption without surface deformations being visible, even though deformation is occurring at depth.

The study is also noteworthy in that Simons and Pritchard were able to do their work without leaving their offices on the Caltech campus. The data analysis was done with software developed at Caltech and the Jet Propulsion Laboratory, and the authors say this software was critical to the study's success.

Simons, an assistant professor of geophysics at Caltech, and Pritchard are scheduled to attend a geophysics conference in Chile in October, and will try to see some or all of the four volcanoes at that time.

Contact: Robert Tindol (626) 395-3631

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RT

Geophysicists Find Sharp-Sides to the African Superplume

Scientists at the California Institute of Technology have discovered that the African superplume-a massive, hot upwelling of rock beneath southern Africa-has edges that are sharp and distinct, not diffuse and blurred as previously thought. Such sharp, lateral boundaries have never been found in the Earth's mantle before, and they challenge scientist's understanding of the interior.

In a paper to be published in the June 7 issue of the journal Science, a team of geophysicists at Caltech's Seismological Laboratory used a fortuitous set of seismic waves from distant earthquakes to show that the boundary of the African superplume appears to be sharp, with a width of about 30 miles. The sharp boundary is not vertical but somewhat tilted, somewhat like a rising plume of smoke that is tilted by the wind. This suggests that the plume is unstable. Using dynamic computer modeling, the scientists provide further evidence of what they and other geologists suspected, that the superplume has a dense chemical core that differs from the scalding hot rock that comprises the surrounding mantle.

The team of scientists from Caltech includes Sidao Ni, the paper's lead author and a staff scientist in the seismology lab; graduate student Eh Tan; Michael Gurnis, professor of geophysics; and Don Helmberger, the Smits Family Professor of Geophysics and Planetary Science and director of the Caltech seismology lab.

About 20 years ago, scientists developed a way to make three-dimensional "snapshots" of the earth's interior using the seismic waves, or vibrations, that travel through the earth following an earthquake. By measuring the time it takes for these waves to travel from an earthquake's epicenter to a recording station, they can infer the temperatures and densities in a given segment of the mantle, the middle layer of the earth. In the mid-1980s, they noticed a huge area under Africa where seismic waves passed through slowly implying that the solid rock was at a substantially higher temperature.

Some 750 miles across and more than 900 miles tall, the region was initially thought to be a giant anomaly, with broad, diffuse edges, that was hotter than the mantle's surrounding rock. The so-called African superplume was slowly rising upwards, much like the thermal convection that occurs in a pot of boiling water. As seismic instrumentation improved, other evidence suggested that the structure might be more than thermal, possibly having a different chemical composition from the surrounding mantle rock.

If there were heavy and dense material associated with this anomalous mantle, the scientists reasoned, then it would either lie underneath or within the vast majority of the hot, rising African superplume. "So we said if that's the case, there should actually be a sharp boundary between the two materials, instead of a diffuse boundary," says Gurnis. The researchers went looking.

By pure chance, other unrelated work had placed a series of seismic detectors in southern Africa. This allowed the Caltech team to study and interpret the fine-scale structure of earthquake seismic waves recorded by the arrays. The energy from the earthquakes emanated from South America and passed through the African superplume.

It turned out, says Gurnis, that a clear pattern of waves developed that grazed the east edge of the plume, creating a peculiar pattern that was indicative of being an incredibly sharp boundary-a boundary that probably extends nearly 900 miles above the core. The findings startled the researchers. "No one expected this," says Gurnis. "Everybody thought there'd be these very broad, diffuse structures. Instead what we've found is a structure that is much bigger, much sharper, and extends further off the core mantle boundary."

They also found that the structure, instead of having a dome-like appearance predicted by their computer models, tilts toward the northeast. Gurnis speculates that's probably due to its dynamic state-"It's a completely different observation from what we expected to see," he says.

At this point, the team can only speculate on the causes. "One of the ideas, and it's not perfect, is that the rock composition of the plume is more iron rich, and thus denser," Gurnis suggests. "It will be interesting to see what observations other scientists can make. The idea of sharp, near-vertical edges was not on people's agendas before now, so this may change people's perspectives on the interior.

"I don't particularly like this idea," Gurnis admits; "it's strange. I guess that's why we find it so interesting."

The interdisciplinary team of researchers was funded by the National Science Foundation's Cooperative Studies of Earth's Deep Interior program.

 

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Researchers find new clue why Martian wateris found on the north pole, not the south

When astronauts finally land on Mars, a safe bet is that they'll head for northern climes if they intend to spend much time there. That's because nearly all the available water is frozen as ice at the north pole. Planetary scientists have been aware of this for some time, but they now have a new clue why it is so.

In the March 21 issue of the journal Nature, California Institute of Technology researcher Mark Richardson and his colleague John Wilson of the National Oceanic and Atmospheric Administration reveal that the higher average elevation of the Red Planet's southern hemisphere ultimately tends to drive water northward.

Their evidence is based on a computer model the two have worked on for years (Wilson since 1992, Richardson since 1996), coupled with data returned by NASA's Mars Global Surveyor.

"We've found a mechanism in the Martian climate that introduces annual average hemispheric asymmetry," explains Richardson, an assistant professor of planetary science at Caltech. "The circulation systems of Mars and Earth are similar in certain ways, but Mars is different in that water is not available everywhere."

The key to understanding the phenomenon is a complicated computer modeling of the Hadley circulation, which extends about 40 degrees of latitude each side of the Martian equator. A topographical bias in circulation pretty much means there will be a bias in the net pole-to-pole transport of water, Richardson explains.

A plausible explanation is that water ice is found at the north pole and carbon dioxide ice is found at the south for reasons having to do with the way the sun heats the atmosphere. As the Martian orbit changes on time scales of 50,000 years and more, these effects tend to cancel, with no pole claiming the water ice cap over geological time. It has been suggested that topography determines where carbon dioxide forms, and hence, where water ice can form, but the processes controlling carbon dioxide ice caps are poorly understood.

However, the mechanism Richardson and Wilson describe is independent of this occasional realignment of the pole's precession and the planet's eccentric orbit. The mechanism means that, while there is never a time in the past when water ice can be discounted at the south pole, one is more likely to find it more frequently at the north pole.

The importance of the study is its furthering of our understanding of the Martian climate and Martian water cycle. A better understanding of how water is transported will be particularly important to determining whether life once existed on Mars, and what happened to it if it ever did.

The Web address for the journal Nature is http://www.nature.com.

Contact: Robert Tindol (626) 395-3631

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Caltech astronomer to search for "hot Jupiters"with off-the-shelf camera lens

In an age when nearly all astronomical work requires really big telescopes, David Charbonneau is something of an anomaly. The Caltech astronomer will soon begin a multiyear survey for extrasolar planets at Palomar Observatory—not with the 200-inch Hale telescope, but with a tiny desktop-sized device he and JPL researcher John Trauger assembled largely from parts bought at a camera shop.

Basing his instrument on a standard 300-millimeter telephoto lens for a 35-millimeter camera, Charbonneau will begin sweeping the skies this spring in hopes of catching a slew of "hot Jupiters" as their fast orbits take them in front of other stars. Admittedly, the charge-coupled device at the camera-end of the lens is a good bit more costly than the lens itself, but the total budget for the project—$100,000—is still a paltry sum when one considers that the next generation of earthbound telescopes will likely cost upwards of $400 million apiece.

Charbonneau, a recent import to the Caltech astronomy staff from the Harvard-Smithsonian Center for Astrophysics, is one of the world's leading authorities on the search for "transiting planets," or planets that should be detectable as they pass into the line of sight between their host star and Earth. In November, Charbonneau and his colleagues made international news when they discovered the first planetary atmosphere outside our own solar system. But that work was done with the Hubble Space Telescope. The yet-to-be-formally-named telescope at Palomar Observatory will certainly be more modest in cost, but every bit as ambitious a program for searching out other worlds.

"Basically, the philosophy of this project is that, if we can buy the stuff we need off the shelf, we'll buy it," the Canadian native said recently in his new campus office.

At the fore-end of the new instrument is a standard 300-millimeter camera lens. Charbonneau settled on a telephoto lens because he reasoned that the optics have been honed to a fine degree of precision over the years. Too, he assumed that the lens would be robust enough for the duration of the three-year project.

The charge-coupled device (CCD), a standard imaging tool in astronomy for the last couple of decades, is a $22,000 item that accounts for the largest part of the instrument budget. The CCD will be mounted in a specially constructed camera housing to fit at the back of the lens, and the entire device will be fitted onto an inexpensive equatorial mount—also available at many stores carrying amateur astronomical equipment.

Meanwhile, the Palomar staff has stored away a 20-inch telescope so Charbonneau will have a small dome for his new instrument, and are also doing other preparations to mechanize the actual observing so that a telescope operator will not have to be on site at all times.

Palomar Observatory engineer Hal Petrie says the mountain crew is currently busy linking the new telescope with an existing weather-monitoring system at the nearby 48-inch dome, where another automated telescope is located. The system monitors the atmospheric conditions to determine whether the dome should be opened.

"The new telescope is a very good use of space," says Petrie. "The potential for results is very exciting."

Charbonneau will be able to photograph a single square of sky, about 5 degrees by 5 degrees. That's a field of view in which about 100 full moons could fit. Or, if one prefers, a field of view in which an entire constellation can be seen at one time.

With special software Charbonneau helped develop during his time at Harvard-Smithsonian and at the National Center for Atmospheric Research, he will compare many pictures of the same patch of sky to see if any of the thousands of stars in each field have slightly changed. If the software turns up a star that has dimmed slightly, the reason could well be that a planet passed in front of the star between exposures.

Repeated measurements will allow Charbonneau to measure the orbital period and physical size of each planet, and further work with the 10-meter telescopes at the Keck Observatory will allow him and his colleagues to get spectrographic data, and thus, the mass and composition of each planet.

"Once you get the mass and size, you have the density," he says. Weather permitting, Charbonneau will be able to get up to 300 images during an ideal night. Assuming that he can have 20 good nights per month, he should have about 6,000 images each month show up in his computer.

The ideal time will be in the fall and winter, when the Milky Way is in view, and an extremely high number of stars can be squeezed into each photograph. This, too, is an anomaly in astrophysical research, particularly to cosmologists, for whom the Milky Way is pretty much a blocked view of the deep sky.

"It's estimated that about one in three stars in our field of view will be like the sun, and that one percent of sunlike stars will have a hot Jupiter, or a gas giant that is so close to the star that its orbit is about four or five days," he says.

"One-tenth of this 1 percent will be inclined in the right direction so that the planet will pass in front of its star, so that maybe one in 3,000 stars will have a planet we can detect," Charbonneau adds. "Or if you want to be conservative, about one in 6,000."

Compared to other research programs in astronomy, the search for hot Jupiters is fairly simple and straightforward to explain to the public, Charbonneau says.

"An amateur could do this, except maybe for the debugging of the software, which requires several people working 10 hours a day.

"But it's easy to understand what's going on, and cheap to build the equipment. That's why everyone thinks it's an ideal project—if it works."

The new Palomar telescope is the final instrument in a network of three. Of the other two, one is located in the Canary Islands and operated by the National Center for Atmospheric Research; the other is near Flagstaff, Arizona, and is operated by Lowell Observatory.

The large span in longitude of the three-instrument network will allow Charbonneau and his colleagues to observe a patch of sky with one telescope while the patch is above the horizon in the night sky, and then pass it off to the next westward telescope as the sun comes up.

Contact: Robert Tindol (626) 395-3631

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Caltech's Joseph Kirschvink Receives Feynman Prize for Excellence in Teaching

"I was shocked and stunned," laughed Joseph Kirschvink, a professor of geobiology at the California Institute of Technology, upon hearing he had been awarded the 2002 Richard P. Feynman Prize for Excellence in Teaching. But, to hear his students tell it, it's clear the honor is an appropriate one.

Indeed, Kirschvink was nominated by two of his current students, Ben Weiss, who will graduate with his Ph.D. in planetary science in 2002, and Tim Raub, a forthcoming 2002 graduate (BS, geology; MS, geobiology). In their nominating letter, they point out that among undergrads, Kirschvink's stature is "legendary," and his earth history and introduction to geobiology classes are popular even among non-majors. "This popularity," they wrote, "reflects Joe's fundamental teaching philosophy: he treats students like colleagues."

To his students it is "Joe," not Dr. Kirschvink. The informality invites questions, they write, and it is those questions that Kirschvink thrives on. Students may interrupt him at any time, and he explains and re-explains concepts, holding to a standard of unanimous understanding among his pupil-colleagues. "Joe's unique philosophy echoes Caltech's purpose to create the 100th scientist," wrote Weiss and Raub, "yet it combines this, successfully, with the noble and perhaps even more difficult goal to 'leave no student behind.' "

The Feynman Prize is presented each year to a Caltech professor who demonstrates exceptional ability, creativity, and innovation in both laboratory and classroom instruction. It consists of a cash award of $3,500, matched by an equivalent raise in the annual salary of the awardee. Kirschvink was specifically selected, said Caltech provost Steve Koonin, for "his innovative teaching style and outstanding mentorship, which have inspired a generation of Caltech students."

Kirschvink believes it was his own experience as a Caltech alum—BS and MS in 1975—that contributes to his classroom rapport. "As an undergrad here I know the capabilities of the students," he says. In all his classes, he employs the Socratic method of doubting and questioning statements. It's a technique he learned, he says, from the late Gene Shoemaker (codiscoverer of the Shoemaker-Levy comet that hit Jupiter) one of his professors from his own days as an undergrad.

Kirschvink frequently gets his undergraduates involved in his science projects as well. His research is aimed at increasing our understanding of how biological evolution has influenced, and has been influenced by, major events on the surface of the earth. His major contributions include the "snowball" Earth theory, the theory that the entire Earth may have actually frozen over several times in its history, potentially causing some of the most severe crises in the history of life on Earth, and perhaps stimulating evolution. Another original concept concerns the Cambrian evolutionary explosion, that he believes may have been precipitated in part by a large burst of true polar wander, in which the earth's rotational axis moved to the equator in a geologically short interval of time. The common thread in his research efforts is the study of paleomagnetism and rock magnetism, for which Kirschvink maintains laboratories dedicated to the study of weakly magnetic biological and geological materials.

The Feynman Prize is made possible by the generosity of an endowment from Ione and Robert E. Paradise, along with additional contributions from Mr. and Mrs. William H. Hurt. It is named in honor of the late Caltech Nobel laureate and popular science author, who was lauded for his innovative classroom lectures on physics.

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Caltech Professor Emeritus Receives Prestigious German Scientific Honor

PASADENA, Calif.— Peter Wyllie, professor of geology, emeritus, at the California Institute of Technology, recently received the Leopold von Buch Medal, one of the highest scientific awards presented by the German Geological Society. This award, which was presented during the annual meeting in Kiel, Germany, is accompanied by honorary membership in the German Geological Society.

The Leopold von Buch Medal is awarded annually, usually to a foreign scholar in recognition of outstanding scientific contributions and for special services to the geological sciences.

Wyllie received the medal "in recognition of his scientific research on the petrology of crystalline rocks, and also for his service in publicizing the importance of the geosciences for society."

Wyllie is an internationally known authority on the formation of igneous rocks—those created when molten material solidifies. His primary research covers experimental petrology of magmas and volatiles that erupt as lavas from volcanoes or form the granites of the Sierra Nevada Mountains.

Throughout his career, Wyllie has been a "global ambassador" for the geosciences. He served as chairman of the U.S. National Academy committee that published, in 1993, the first national survey of Earth sciences, Solid-Earth Sciences and Society. Wyllie has given numerous international lectures on the impact of Earth sciences on society, including such subjects as resources (oil, minerals, and water supply), hazards (earthquakes, volcanic eruptions, and landslides), and global climatic change. He has been elected fellow or foreign member of national science academies in the United States, the United Kingdom (the Royal Society), Russia, China, and India (Delhi and Allahabad), and of Academia Europaea.

He has served as president of the Mineralogical Society of America, the International Mineralogical Association, and the International Union of Geodesy and Geophysics.

Wyllie has received numerous honors and awards throughout his career, including the 2001 Mineralogical Society of America's Roebling Medal, the Wollaston Medal of the Geological Society of London in 1982, and the Abraham-Gottlob-Werner Medaille of the German Mineralogical Society in 1987.

Wyllie joined Caltech in 1983 as chair of the Division of Geological and Planetary Sciences. In 1987, Wyllie returned to teaching and research, then was appointed division academic officer in 1994. He served in this capacity until his retirement in 1999.

Contact: Deborah Williams-Hedges (626) 395-3227 debwms@caltech.edu

Visit the Caltech Media Relations Web site at: http://pr.caltech.edu/media

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