Six Caltech Professors Awarded Sloan Research Fellowships

PASADENA, Calif.— Six Caltech professors recently received Alfred P. Sloan Research Fellowships for 2003.

The Caltech recipients in the field of chemistry are Paul David Asimow, assistant professor of geology and geochemistry, Linda C. Hsieh-Wilson, Jonas C. Peters, and Brian M. Stoltz, assistant professors of chemistry. In mathematics, a Sloan Fellowship was awarded to Danny Calegari, associate professor of mathematics, and in neuroscience, to Athanassios G. Siapas, assistant professor of computation and neural systems.

Each Sloan Fellow receives a grant of $40,000 for a two-year period. The grants of unrestricted funds are awarded to young researchers in the fields of physics, chemistry, computer science, mathematics, neuroscience, computational and evolutionary molecular biology, and economics. The grants are given to pursue diverse fields of inquiry and research, and to allow young scientists the freedom to establish their own independent research projects at a pivotal stage in their careers. The Sloan Fellows are selected on the basis of "their exceptional promise to contribute to the advancement of knowledge."

From over 500 nominees, a total of 117 young scientists and economists from 50 different colleges and universities in the United States and Canada, including Caltech's six, were selected to receive a Sloan Research Fellowship.

Twenty-eight former Sloan Fellows have received Nobel prizes.

"It is a terrific honor to receive this award and to be a part of such a tremendous tradition of excellence within the Sloan Foundation," said Stoltz. Asimow commented that he will use his Sloan Fellowship to "support further investigation into the presence of trace concentrations of water in the deep earth... I'm pleased because funds that are unattached to any particular grant are enormously useful for seeding new and high-risk projects that are not quite ready to turn into proposals." On his research, Peters said, "The Sloan award will provide invaluable seed money for work we've initiated in the past few months regarding nitrogen reduction using molecular iron systems."

The Alfred P. Sloan Research Fellowship program was established in 1955 by Alfred P. Sloan, Jr., who was the chief executive officer of General Motors for 23 years. Its objective is to encourage research by young scholars at a time in their careers when other support may be difficult to obtain. It is the oldest program of the Alfred P. Sloan Foundation and one of the oldest fellowship programs in the country.

Contact: Deborah Williams-Hedges (626) 395-3227

Visit the Caltech Media Relations Web site at:


Exclude from News Hub: 

Antarctic landmarks named afterCaltech experts on glacier ice flow




For Immediate Release February 28, 2003

Antarctic landmarks named after Caltech experts on glacier ice flow

There aren't too many living individuals who can go to the mall and buy a globe with their name printed on it, but the California Institute of Technology just added two.

Barclay Kamb and Hermann Engelhardt, longtime researchers on the workings of the Antarctic ice streams, have been honored by the American Advisory Committee on Antarctic Names (ACAN) with the renaming of two features near the gigantic Ross Ice Shelf, a Texas-sized mass of floating ice. Hereafter, the feature informally called "ice stream C" will bear the formal name Kamb Ice Stream, and "ice ridge BC" will be formally named the Engelhardt Ice Ridge.

Kamb is the Rawn, Jr., Professor of Geology and Geophysics, Emeritus, at Caltech and is still active in attempting to understand the rapid flow of the Antarctic ice streams and its potential effects on the health of the great ice sheet that covers 98 percent of the Antarctic continent. If the ice sheet were to float rapidly outward into the circum-Antarctic Ocean and melt, the addition of the huge volume of meltwater to the oceans would raise the sea level and have a drastic impact on coastal cities throughout the world.

Engelhardt, a senior research associate in geophysics, emeritus, has collaborated with Kamb for years in the research. They have undertaken a number of expeditions to Antarctica to collect ice-stream data by drilling boreholes down through the ice to the bottom and sending down instruments such as temperature sensors, pressure gauges, ice corers, sediment corers, and borehole video. Previously, they had used these techniques to study surging ("galloping") glaciers in Alaska.

Actually, the news for the Caltech Division of Geological and Planetary Sciences is even better, because two of Kamb's former students were also honored with an Antarctic naming. Ice ridge CD has been formally named the Raymond Ice Ridge after Charlie Raymond, and ice stream F has been named the Echelmeyer Ice Stream after Keith Echelmeyer. Raymond, who earned his doctorate in 1969, is now on the University of Washington faculty; Echelmeyer, who finished his Ph.D. in 1983, is a faculty member at the University of Alaska at Fairbanks.

In announcing the namings on behalf of ACAN, glaciology professor Terry Hughes of the University of Maine said, jokingly, "It looks like Caltech made almost a clean sweep of the ice streams." . The ice streams in Antarctica move through the ice sheet somewhat like an ocean current, such as the Gulf Stream, moves through the ocean. Most of the ice sheet flows a few meters a year, but in those places where ice streams form, the flow of the ice is roughly a hundred times faster, approximately one meter per day. The ice streams are usually about 30 to 50 kilometers wide, 300 to 500 kilometers long, and 1 to 2 kilometers deep.

Why do they move so fast? "That's what we're trying to find out," says Kamb.

After 10 years of study, the researchers have demonstrated that the temperature at the base of the ice streams is at the melting point, whereas it is below freezing at the base of the ice sheet outside the ice streams. The ice streams' basal melting condition allows water pressure to build up under the ice, which tends to lift the ice mass above, and to weaken a layer of glacial sediment (clayey gravel called "till") that underlies the ice streams in a thickness of about one or two meters.

Both of these effects of pressure are capable of increasing flow of the ice streams, which are propelled downslope by gravity, with the soft, weak, till layer acting as a sort of basal "lubricant." The researchers believe that an increase in basal water pressure should result in a marked increase in ice-stream flow, but so far it has not been possible to observe and measure this expected effect in the actual ice streams.

It is believed that friction at the lateral shear margins and at bedrock humps under the ice (also called "sticky spots") prevent the velocity from getting out of control.

"The question is what will happen to the ice streams in the future," says Kamb. "Will they cause a big enough effect on the flow of the ice sheet to contribute appreciably to future sea-level rise? The big issue as to the future behavior of the Antarctic ice sheet is whether it will cause global sea level to rise."

To study the ice streams, Kamb and Engelhardt have made about a dozen National Science Foundation–funded expeditions during the Antarctic summer, in the period from late October to late January. Working in teams of about 13 or 14 people, including Caltech graduate students and support staff from the McMurdo base, the group drills a number of vertical holes, six inches in diameter to the bottom, at a depth of about 1,000 meters. Some of the holes are used to take core samples, while others are used to lower equipment like video cameras to study the character and distribution of till in the basal ice.

The instrumental work has to be completed within about three or four hours after borehole completion, because by that time, the borehole freeze-up process has already progressed to such an extent that the ice "grabs" the equipment still in the hole.

Neither Kamb nor Engelhardt anticipates going again to Antarctica for this particular project, though their studies continue. In fact, some of the equipment purposely left in the bore holes is still sending data.


Contact: Robert Tindol (626) 395-3631 t


Exclude from News Hub: 

The Martian polar caps are almost entirelywater ice, Caltech research shows

For future Martian astronauts, finding a plentiful water supply may be as simple as grabbing an ice pick and getting to work. California Institute of Technology planetary scientists studying new satellite imagery think that the Martian polar ice caps are made almost entirely of water ice—with just a smattering of frozen carbon dioxide, or "dry ice," at the surface.

Reporting in the February 14 issue of the journal Science, Caltech planetary science professor Andy Ingersoll and his graduate student, Shane Byrne, present evidence that the decades-old model of the polar caps being made of dry ice is in error. The model dates back to 1966, when the first Mars spacecraft determined that the Martian atmosphere was largely carbon dioxide.

Scientists at the time argued that the ice caps themselves were solid dry ice and that the caps regulate the atmospheric pressure by evaporation and condensation. Later observations by the Viking spacecraft showed that the north polar cap contained water ice underneath its dry ice covering, but experts continued to believe that the south polar cap was made of dry ice.

However, recent high-resolution and thermal images from the Mars Global Surveyor and Mars Odyssey, respectively, show that the old model could not be accurate. The high-resolution images show flat-floored, circular pits eight meters deep and 200 to 1,000 meters in diameter at the south polar cap, and an outward growth rate of about one to three meters per year. Further, new infrared measurements from the newly arrived Mars Odyssey show that the lower material heats up, as water ice is expected to do in the Martian summer, and that the polar cap is too warm to be dry ice.

Based on this evidence, Byrne (the lead author) and Ingersoll conclude that the pitted layer is dry ice, but the material below, which makes up the floors of the pits and the bulk of the polar cap, is water ice.

This shows that the south polar cap is actually similar to the north pole, which was determined, on the basis of Viking data, to lose its one-meter covering of dry ice each summer, exposing the water ice underneath. The new results show that the difference between the two poles is that the south pole dry-ice cover is slightly thicker—about eight meters—and does not disappear entirely during the summertime.

Although the results show that future astronauts may not be obliged to haul their own water to the Red Planet, the news is paradoxically negative for the visionary plans often voiced for "terraforming" Mars in the distant future, Ingersoll says.

"Mars has all these flood and river channels, so one theory is that the planet was once warm and wet," Ingersoll says, explaining that a large amount of carbon dioxide in the atmosphere is thought to be the logical way to have a "greenhouse effect" that captures enough solar energy for liquid water to exist.

"If you wanted to make Mars warm and wet again, you'd need carbon dioxide, but there isn't nearly enough if the polar caps are made of water," Ingersoll adds. "Of course, terraforming Mars is wild stuff and is way in the future; but even then, there's the question of whether you'd have more than a tiny fraction of the carbon dioxide you'd need."

This is because the total mass of dry ice is only a few percent of the atmosphere's mass and thus is a poor regulator of atmospheric pressure, since it gets "used up" during warmer climates. For example, when Mars's spin axis is tipped closer to its orbit plane, which is analogous to a warm interglacial period on Earth, the dry ice evaporates entirely, but the atmospheric pressure remains almost unchanged.

The findings present a new scientific mystery to those who thought they had a good idea of how the atmospheres of the inner planets compared to each other. Planetary scientists have assumed that Earth, Venus, and Mars are similar in the total carbon dioxide content, with Earth having most of its carbon dioxide locked up in marine carbonates and Venus's carbon dioxide being in the atmosphere and causing the runaway greenhouse effect. By contrast, the eight-meter layer on the south polar ice cap on Mars means the planet has only a small fraction of the carbon dioxide found on Earth and Venus.

The new findings further pose the question of how Mars could have been warm and wet to begin with. Working backward, one would assume that there was once a sufficient amount of carbon dioxide in the atmosphere to trap enough solar energy to warm the planet, but there's simply not enough carbon dioxide for this to clearly have been the case.

"There could be other explanations," Byrne says. "It could be that Mars was a cold, wet planet; or it could be that the subterranean plumbing would allow for liquid water to be sealed off underneath the surface."

In one such scenario, perhaps the water flowed underneath a layer of ice and formed the channels and other erosion features. Then, perhaps, the ice sublimated away, to be eventually redeposited at the poles.

At any rate, Ingersoll and Byrne say that finding the missing carbon dioxide, or accounting for its absence, is now a major goal of Mars research.

Contact: Robert Tindol (626) 395-3631



Clouds discovered on Saturn's moon Titan

Teams of astronomers at the California Institute of Technology and at the University of California, Berkeley, have discovered methane clouds near the south pole of Titan, resolving a fierce debate about whether clouds exist amid the haze of the moon's atmosphere.

The new observations were made using the W. M. Keck II 10-meter and the Gemini North 8-meter telescopes atop Hawaii's Mauna Kea volcano in December 2001. Both telescopes are outfitted with adaptive optics that provide unprecedented detail of features not seen even by the Voyager spacecraft during its flyby of Saturn and Titan.

The results are being published by the Caltech team in the December 19 issue of Nature and by the UC Berkeley and NASA Ames team in the December 20 issue of the Astrophysical Journal.

Titan is Saturn's largest moon, larger than the planet Mercury, and is the only moon in our solar system with a thick atmosphere. Like Earth's atmosphere, the atmosphere on Titan is mostly nitrogen. Unlike Earth, Titan is inhospitable to life due to the lack of atmospheric oxygen and its extremely cold surface temperatures (-183 degrees Celsius, or -297 degrees Fahrenheit). Along with nitrogen, Titan's atmosphere contains a significant amount of methane.

Earlier spectroscopic observations hinted at the existence of clouds on Titan, but gave no clue as to their location. These early data were hotly debated, since Voyager spacecraft measurements of Titan appeared to show a calm and cloud-free atmosphere. Furthermore, previous images of Titan had failed to reveal clouds, finding only unchanging surface markings and very gradual seasonal changes in the haziness of the atmosphere.

Improvements in the resolution and sensitivity achievable with ground-based telescopes led to the present discovery. The observations used adaptive optics, in which a flexible mirror rapidly compensates for the distortions caused by turbulence in Earth's atmosphere. These distortions are what cause the well-known twinkling of the stars. Using adaptive optics, details as small as 300 kilometers across can be distinguished at the enormous distance of Titan (1.3 billion kilometers), equivalent of reading an automobile license plate from 100 kilometers away.

The images presented by the two teams clearly show bright clouds near Titan's south pole.

"We see the intensity of the clouds varying over as little as a few hours," said post-doctoral fellow Henry Roe, lead author for the UC Berkeley group. "The clouds are constantly changing, although some persist for as long as a few days."

Titan experiences seasons much like Earth, though its year is 30 times longer due to Saturn's distant orbit from the sun. Titan is currently in the midst of southern summer, and the south pole has been in continuous sunlight for over six Earth years. The researchers believe that this fact may explain the location of the large clouds.

"These clouds appear to be similar to summer thunderstorms on Earth, but formed of methane rather than water. This is the first time we have found such a close analogy to the Earth's atmospheric water cycle in the solar system," says Antonin Bouchez, one of the Caltech researchers.

In addition to the clouds above Titan's south pole, the Keck images, like previous data, reveal the bright continent-sized feature that may be a large icy highland on Titan's surface, surrounded by linked dark regions that are possibly ethane seas or tar-covered lowlands.

"These are the most spectacular images of Titan's surface which we've seen to date," says Michael Brown, associate professor of planetary astronomy and lead author of the Caltech paper. "They are so detailed that we can almost begin to speculate about Titan's geology, if only we knew for certain what the bright and dark regions represented."

In 2004, Titan will be visited by NASA's Cassini spacecraft, which will look for clouds on Titan during its multiyear mission around Saturn. "Changes in the spatial distribution of these clouds over the next Titan season will help pin down their detailed formation process," says Imke de Pater, professor of astronomy at UC Berkeley. The Cassini mission includes a probe named Huygens that will descend by parachute into Titan's atmosphere and land on the surface near the edge of the bright continent.

The team conducting the Gemini observations consists of Roe and de Pater from UC Berkeley, Bruce A. Macintosh of Lawrence Livermore National Laboratory, and Christopher P. McKay of the NASA Ames Research Center. The team reporting results from the Keck telescope consists of Brown and Bouchez of Caltech and Caitlin A. Griffith of the University of Arizona.

The Gemini observatory is operated by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation, involving NOAO/AURA/NSF as the U.S. partner. The W.M. Keck Observatory is operated by the California Association for Research in Astronomy, a scientific partnership between the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. This research has been funded in part by grants from NSF and NASA.

Contact: Robert Tindol (626) 395-3631


New Theory Accounts for Existence of Binaries in Kuiper Belt

PASADENA, Calif.--In the last few years, researchers have discovered more than 500 objects in the Kuiper belt, a gigantic outer ring in the outskirts of the solar system, beyond the orbit of Neptune. Of these, seven so far have turned out to be binaries--two objects that orbit each other. The surprise is that these binaries all seem to be pairs of widely separated objects of similar size. This is surprising because more familiar pairings, such as the Earth/moon system, tend to be unequal in size and/or rather close together.

To account for these oddities, scientists from the California Institute of Technology have devised a theory of Kuiper belt binary formation. Their work is published in the December 12 issue of the journal Nature.

According to Re'em Sari, a senior research fellow at Caltech, the theory will be tested in the near future as additional observations of Kuiper belt objects are obtained and additional binaries are discovered. The other authors of the paper are Peter Goldreich, DuBridge Professor of Astrophysics and Planetary Physics at Caltech; and Yoram Lithwick, now a postdoc at UC Berkeley.

"The binaries we are more familiar with, like the Earth/moon system, resulted from collisions that ejected material," says Sari. "That material coalesced to form the smaller body. Then the interaction between the spin of the larger body and the orbit of the smaller body caused them to move farther and farther apart."

"This doesn't work for the Kuiper belt binaries," Sari says. "They are too far away from each other to have ever had enough spin for this effect to take place." The members of the seven binaries are about 100 kilometers in radius, but 10,000 to 100,000 kilometers from each other. Thus their separations are 100 to 1,000 times their radii. By contrast, Earth is about 400,000 kilometers from the moon, and about 6,000 kilometers in radius. Even at a distance of 60 times the radius of Earth, the tidal mechanism works only because the moon is so much less massive than Earth.

Sari and his colleagues think the explanation is that the Kuiper belt bodies tend to get closer together as time goes on -- exactly the reverse of the situation with the planets and their satellites, where the separations tend to increase. "The Earth/moon system evolves 'inside-out', but the Kuiper belt binaries evolved 'outside-in,'" explains Sari.

Individual objects in the Kuiper belt are thought to have formed in the early solar system by accretion of smaller objects. The region where the gravitational influence of a body dominates over the tidal forces of the sun is known as its Hill sphere. For a 100-kilometer body located in the Kuiper belt, this extends to about a million kilometers. Large bodies can accidentally pass through one another's Hill spheres. Such encounters last a couple of centuries and, if no additional process is involved, the "transient binary" dissolves, and the two objects continue on separate orbits around the sun. The transient binary must lose energy to become bound. The researchers estimate that in about 1 in 300 encounters, a third large body would have absorbed some of the energy and left a bound binary. An additional mechanism for energy loss is gravitational interaction with the sea of small bodies from which the large bodies were accreting. This interaction slows down the large bodies. Once in every 30 encounters, they slowed down sufficiently to become bound.

Starting with a binary of large separation a million kilometers apart, continued interaction with the sea of small objects would have led to additional loss of energy, tightening the binary. The time required for the formation of individual objects is sufficient for a binary orbit to shrink all the way to contact. Indeed, the research predicts that most binaries coalesced in this manner or at least became very tight. But if the binary system was formed relatively late, close to the time that accretion in the Kuiper belt ceased, a widely separated binary would survive. These are the objects we observe today. By this mechanism it can be predicted that about 5 percent of objects remain with large enough separation to be observed as a binary. The prediction is in agreement with recent surveys conducted by Caltech associate professor of planetary astronomy Mike Brown. The majority of objects ended up as tighter binaries. Their images cannot be distinguished from those of isolated objects when observed from Earth using existing instruments.

These ideas will be more thoroughly tested as additional objects are discovered and further data is collected. Further theoretical work could predict how the inclination of a binary orbit, relative to the plane of the solar system, evolves as the orbit shrinks. If it increases, this would suggest that the Pluto/Charon system, although tight, was also formed by the 'outside-in' mechanism, since it is known to have large inclination.

Robert Tindol

Caltech Professor to Explore Abrupt Climate Changes

PASADENA, Calif.—By analyzing stalagmites from caves in Sarawak, which is the Malaysian section of Borneo and the location of one of the world's oldest rain forests, and by studying deep-sea corals from the North Atlantic Ocean, California Institute of Technology researcher Jess Adkins will explore the vital link between the deep ocean, the atmosphere, and abrupt changes in global climates.

The project, "Linking the Atmosphere and the Deep Ocean during Abrupt Climate Changes," is funded by the Comer Science and Educational Foundation.

Because the Sarawak stalagmites and the deep-sea corals are uranium rich and can be dated precisely, and because they both accumulate continuously, uninterrupted by "bioturbation," the biological process that mixes the upper several centimeters of ocean sediments, they provide unique archives of climate history. By utilizing these archives, Adkins and his research group will be able to chart and link major climate variables, and thereby provide critical insight into understanding rapid climate changes that could impact the earth.

Adkins, an assistant professor of geochemistry and global environmental science, joined Caltech in 2000. He received his PhD in 1998 from the Massachusetts Institute of Technology Woods Hole Oceanographic Institute.

The Comer Science and Education Foundation was established to promote education and discovery through scientific exploration.

Contact: Deborah Williams-Hedges (626) 395-3227

Visit the Caltech Media Relations Web site at:



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


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


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.



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.



Subscribe to RSS - GPS