Astronomers improve "cosmic yardstick" by measuringdistance to star in Gemini with Palomar Testbed Interferometer

Researchers using the testbed interferometer at Palomar Observatory have achieved the best-ever distance measurement to a type of star known as a Cepheid variable. The new results improve the "cosmic yardstick" used to infer the size and age of the universe.

In the September 28 issue of the British journal Nature, a group of astronomers from the California Institute of Technology, the Jet Propulsion Laboratory, and the Infrared Processing and Analysis Center announce that the distance to the star Zeta Geminorum in the Gemini constellation is 1,100 light years. The degree of accuracy in the measurement is about 13 percent, meaning that the star could be as close as 960 or as far away as 1,240 light-years. This represents an improvement of a factor of three over previous measurements.

The improvement is due to the use of the Palomar Testbed Interferometer, of which JPL engineer Mark Colavita is the principal investigator and codesigner. "This has been a bit of a Holy Grail in the field," says Benjamin Lane, a graduate student in Caltech's planetary science program and the lead author of the study. "The measurement of accurate distances to Cepheids is widely considered to be a principal limitation in determining the Hubble constant."

Cepheid variables for several decades have been an important link in the chain of measurements that allow astronomers to estimate the distances to the farthest objects in the universe—and ultimately, the overall size and expansion rate of the universe itself.

Cepheid variables are stars that have very predictable relationships between their absolute brightness and the frequency with which they brighten up. A Cepheid is useful for measuring distances because, if it is known how bright the star really is, then it is a simple task to measure how bright it appears on Earth and then calculate the distance.

A good analogy is a light bulb shining at an unknown distance. If we are certain that only 100-watt light bulbs brighten once a day, and we observe that the light indeed brightens once daily, then we can calculate its distance by measuring the brightness of the light reaching us and comparing it to the known absolute brightness of a 100-watt light bulb.

"Zeta Geminorum is known to grow larger and smaller," says Lane. "We already knew this because we can see the Doppler effect." In other words, astronomers can measure a slight difference in light coming from the star because the surface of the star moves toward us and away from us as the star expands and contracts.

In the Nature study, the researchers couple this information with new data collected with the Palomar Testbed Interferometer. The interferometer combines the images from two 16-inch telescope mirrors in such a way that images are as sharp as they would be if the telescope mirror were 360 feet in diameter.

Data from the interferometer showed that Zeta Geminorum went through a change in angular size of about five hundred-millionths of a degree during its 10-day cycle. "That's roughly the size of a basketball on the moon, as seen from Earth," says Colavita.

From previous Doppler measurements, the researchers already knew that the change in the star's diameter was about 4.2 million kilometers. By combining that information with the newly measured change in angular size, they were able to deduce the distance to the Cepheid.

The direct measurement of distance to Zeta Geminorum shows that the basic technique works, Lane says. "As a graduate student, it has been exciting to be at the leading edge of this field."

The Palomar Testbed Interferometer was designed and built by a team of researchers from the Jet Propulsion Laboratory in Pasadena led by Colavita and Michael Shao. Funded by NASA, the interferometer is located at the Palomar Observatory near the historic 200-inch Hale Telescope.

The device is intended as an engineering testbed for the interferometer that will soon link the 10-meter Keck Telescopes atop Mauna Kea in Hawaii.

The Keck Interferometer has been funded to find and study extrasolar planets. The Navy and the NSF are also funding the development of interferometers for astrometry and stellar astronomy.

"The current precision is a significant improvement over the previous determinations, but we expect to achieve distance measurements at the level of a few percent in the near future," says Shri Kulkarni, a professor of astronomy and planetary science at Caltech and a coauthor of the paper.

In addition to Lane and Kulkarni, the other authors are Marc Kuchner, a Caltech graduate student in astronomy; Andrew Boden of the Infrared Processing and Analysis Center (IPAC), and Michelle Creech-Eakman, a postdoctoral scholar at JPL.

Writer: 
Robert Tindol
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Packard Foundation Gives Caltech $1 Million

PASADENA—In order to further a better understanding of Earth's history, the David and Lucile Packard Foundation Science Program has awarded the California Institute of Technology a $1 million grant.

This funding will help scientists investigate how microorganisms and Earth's near-surface environments have interacted over billions of years. The project, led by Dianne Newman, the Clare Boothe Luce Assistant Professor of Geobiology and Environmental Engineering Science at Caltech, will bring together investigators from a wide range of disciplines that do not traditionally overlap. They will work on a well-defined problem in the new discipline of geobiology.

The project, "The Geobiology of Anaerobic Fe(II) Oxidation: Biological, Geochemical, and Field Studies," integrates molecular microbiology with geochemistry and field geology. These scientists will try to identify chemical signatures of early life in the geologic record.

"We believe that the potential for discoveries that could come from any of the individual components alone is extraordinary, and we think that this is just the kind of challenge that the Packard Foundation had in mind when it conceived the interdisciplinary project program," said Caltech president David Baltimore.

The David and Lucile Packard Foundation was created in 1964 to support and encourage nonprofit organizations dependent on private funding and volunteer leadership. It awards grants in six main program areas: conservation; population; science, children, families, and communities; arts; and organizational effectiveness and philanthropy.

Founded in 1891, Caltech has an enrollment of some 2,000 students, and a faculty of about 275 professorial members and 130 research members. The Institute has more than 19,000 alumni. Caltech employs a staff of more than 2,100 on campus and 4,800 at JPL.

Over the years, 28 Nobel Prizes and four Crafoord Prizes have been awarded to faculty members and alumni. Forty-five Caltech faculty members and alumni have received the National Medal of Science; and eight alumni (two of whom are also trustees), two additional trustees, and one faculty member have won the National Medal of Technology. Since 1958, 13 faculty members have received the annual California Scientist of the Year award. On the Caltech faculty there are 77 fellows of the American Academy of Arts and Sciences; and on the faculty and Board of Trustees, 70 members of the National Academy of Sciences and 48 members of the National Academy of Engineering. ###

Contact: Jill Perry (626) 395-3226 jperry@caltech.edu

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

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JP
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East and West Antarctica once began separating but then stopped, new research shows

PASADENA—Earth was well on its way to having two Antarcticas long ago, but a tectonic separation between the eastern and western portions of the continent suddenly stopped after 17 million years of spreading, researchers say.

In the March 9 issue of Nature, lead author Steve Cande of the Scripps Institution of Oceanography, Joann Stock of Caltech, and their colleagues in Australia and Japan report that the rift between East and West Antarctica began about 43 million years ago, then ended 17 million years later, after the seafloor had spread about 180 kilometers. The researchers discovered the motion after making several cruises over a period of years in the waters off the Antarctic coast and after gathering data on the seafloor itself.

"The two pieces of Antarctica pulled apart and then stopped," says Stock, a professor of geology and geophysics at Caltech. "If it had kept on going, there would eventually have been two Antarcticas."

The primary scientific value of the study is that it answers some nagging questions about the "missing" motion in the Antarctic region. For a variety of reasons, geophysicists have had a hard time getting a handle on the precise directions and amounts of motion there, and how the motion fits into the grand scheme of global plate tectonics.

"It's like a jigsaw puzzle," Stock says. "You have to know how one piece moved relative to the other pieces to understand how it all fits together.

"A lot of the tectonic plate history for western North America, for example, depends on what happened in Antarctica. You wouldn't think so, but that's the way plate tectonic movements work."

The key to the new results was the researchers' discovery of an underwater feature off Cape Adare that they have named the Adare Trough. This trough is about 230 kilometers long and runs roughly northwest-southeast near the 170th meridian. The sharp break in the direction of the magnetic lines on either side of the trough allows the researchers to infer the ancient relative motions of the plates, and the age and shape of the trough and seafloor around it indicates the period when the spreading occurred.

Seafloor spreading in the area accounts for the "missing" motion in the plate circuit linking the Australia, Antarctic, and Pacific plates, the researchers also found. Too, the 180-kilometer-wide zone of extension is most likely related to the uplift that has occurred in the Transantarctic Mountains to the west, and explains other geological features that have hitherto been puzzling.

And finally, the new results could shed new light on global issues such as the motion between hotspots in the Pacific and Indo-Atlantic oceans.

In addition to Cande and Stock, the other authors are Dietmar Müller of the University of Sidney and Takemi Ishihara of the Geological Survey of Japan.

Writer: 
Robert Tindol
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Astrobiologists should look for both water and energy sources when searching for life on other worlds, researcher says

PASADENA—When planetary scientists first saw evidence of a water ocean beneath the frozen surface of Europa, everyone immediately began pondering the likelihood that the Jovian moon could harbor advanced life forms—perhaps even fishlike creatures.

But last summer a group of planetary scientists from the California Institute of Technology and Jet Propulsion Laboratory threw water on the theory—so to speak—when they took a novel approach and concluded that advanced life forms were not likely.

"Water is a good place to look for life, but is only one ingredient for life," says Kenneth Nealson, an astrobiologist who holds joint appointments at Caltech and JPL, and who was a coauthor of the 1999 paper on Europa.

"You also need energy and, probably, organic carbon."

Nealson and his colleagues Eric Gaidos and Joseph Kirschvink (both of Caltech) wrote in the controversial 1999 Science paper that life on Earth is not necessarily the best analogy for life on another world. In other words, astrobiologists should be prepared to use chemistry and physics to analyze the possibilities for extraterrestrial life, rather than merely assuming life will exist wherever there is water.

Specifically, the authors showed that nearly all forms of energy used by life on Earth would be unavailable to the organisms that might live beneath Europa's surface ice layer. This did not preclude primitive unicellular organisms, but boded poorly for anyone hoping to someday see Europan creatures with gills and backbones.

"There is a trap in the thinking, because on Earth, virtually everywhere you find water you also find life," Nealson says. "And conversely, on Earth, about the only thing you can associate with lifelessness is the lack of water.

"But on another planet, just because you find water doesn't mean you're necessarily going to find life there."

Nealson says that a very likely place to look for life forms is any place where there is an energy gradient of some sort. Some potential energy gradients that might be available on Europa might arise from the gravitational and magnetic fields of Jupiter, which would almost certainly grind things around inside the moon and result in a heat source.

But when Nealson and his colleagues last year analyzed the closed system beneath Europa, they concluded that this source of energy alone was probably insufficient for multicellular life to survive. Also, they concluded that the redox energy (or available chemical energy) of the moon would also be inadequate for complex life of the kind we are familiar with on Earth.

"Still, I think Europa is a great place to look for very simple organisms," Nealson says today.

Another salubrious way to look for life is to look carefully at any place there is a water cycle, however small. If any of the other Jovian moons, such as Ganymede or Callisto, have a hydrological cycle in which moisture precipitates and runs underground, is heated by an internal source, and ultimately is returned to the surface, then the planet or moon would have the potential for energy gradients, energy flow, and geochemical cycling. All of these may be key to the existence of global life.

And the water cycle could be entirely subterranean and could even be a very limited, closed loop, Nealson says. For example, Mars may still have frozen subterranean waters that are occasionally melted by the planet's internal heat, but never result in water vapor actually surfacing. In such a case, there could be bacterial life that has lived in a closed loop beneath the Martian surface for billions of years.

"There's certainly no present-day atmospheric water cycle on Mars—no rain, no aquifers to collect the rainfall, no recycling," he says. "So if there's life on Mars, it has a hard time existing, and we'd have a hard time finding it without drilling."

While a drilling excavation to Mars is still a few decades in the future, Nealson hopes that one of the orbiters to Mars will soon include a deep-sounding radar instrument. Such an instrument can detect either liquid or frozen water beneath the surface.

The Mars orbiter scheduled for launch in 2003 by the European Space Agency (in conjunction with scientists from JPL) is scheduled to have deep-sounding radar for the detection of subsurface liquid water. A similar device will eventually be sent to Europa.

Perhaps later, the search could be extended to other Jovian moons, as well as the moons of Saturn and even Uranus.

"The moons of Jupiter have changed the way I feel about life in the solar system," Nealson says. "Each of the four large moons has different properties, different energy flows, different likelihoods of water.

"It's important to keep an open mind," he says.

Writer: 
Robert Tindol
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Snowball Earth episode 2.4 billion years ago was hard on life, but good for modern industrial economy, research shows

PASADENA-For the primitive organisms unlucky enough to be around 2.4 billion years ago, the first global freeze was a real wipeout, likely the worst in the history of life on Earth. Few of the organisms escaped extinction, and those that did were forced into an evolutionary bottleneck that altered the diversity of life for eons.

But 2.4 billion years later, an unlikely winner has emerged from that first planetary deep-freeze, and it's none other than us modern industrial humans. New research from the California Institute of Technology reveals that the world's largest deposit of manganese (a component of steel) was formed by the cascade of chemical reactions caused when the planet got so cold that even the equators were icy-a condition now known as "Snowball Earth."

In a special issue of the Proceedings of the National Academy of Sciences on global climatic change published February 14, Caltech geobiology professor Joe Kirschvink and his team show that the huge Kalahari Manganese Field in southern Africa was a consequence of a long Snowball Earth episode. Kirschvink, who originated the Snowball Earth concept more than a decade ago, says the new study explains how the drastic climatic changes in a Snowball Earth episode can alter the course of biological evolution, and can also account for a huge economic resource.

According to Kirschvink and his team, the planet froze over for tens of millions of years, but eventually thawed when a greenhouse-induced effect kicked in. This warming episode led to the deposit of iron formations and carbonates, providing nutrients to the blue-green algae that were waiting in the wings for a good feeding.

The algae bloom during the melting period resulted in an oxygen spike, which in turn led to a "rusting" of the iron and manganese. This caused the manganese to be laid down in a huge 45-meter-thick deposit in the Kalahari to await future human mining and metallurgy. Today, about 80 percent of the entire world's known manganese reserves are found in that one field, and it is a major economic resource for the Republic of South Africa.

The Snowball Earth's cascade of climatic chemical reactions also probably forced the living organisms of the time to mutate in such a way that they were protected from the excess oxygen. Because free radicals can cause DNA damage, the organisms adapted an enzyme known as the superoxide dismutase to compensate.

Kirschvink points out that the enzyme and its evolutionary history are well known to biologists, but that a global climate change apparently has never been suggested as a cause of the enzyme's diversification.

"To our knowledge, this is the first biochemical evidence for this adaptation," says Kirschvink, adding that the data shows that the adaptation can be traced back to the Snowball Earth episode 2.4 billion years ago.

Kirschvink, his former doctoral student Dave Evans (now at the University of Western Australia in Perth), and Nicolas J. Beukes of Rand Afrikaans University proposed the Snowball Earth episode in a 1997 paper in Nature. Their evidence for the freeze of 2.4 billion years ago was based on their finding evidence of glacial deposits in a place in southern Africa that in ancient times was within 11 degrees of the equator, according to magnetic samples also gathered there.

The other authors of the PNAS paper are Eric Gaidos of the Jet Propulsion Laboratory, who also holds an appointment in geobiology at Caltech; L. Elizabeth Bertani and Rachel E. Steinberger, both of the Division of Biology at Caltech; and Nicholas J. Beukes and Jans Gutzmer, both of Rand Afrikaans University in Johannesburg.

The work was supported by the NASA National Astrobiology Institute.

A detailed article on the Snowball Earth phenomenon was published in the January 2000 issue of Scientific American.

Writer: 
Robert Tindol
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Thunderstorms found to be an energy source for Jupiter's Great Red Spot

PASADENA-Using data from the Galileo spacecraft currently in orbit around Jupiter, scientists have discovered that thunderstorms beneath the upper cloud cover are supplying energy to the planet's colorful large-scale weather patterns-including the 300-year-old Great Red Spot.

In two articles in the February 10 issue of the British journal Nature and an article in the current issue of the journal Icarus, Caltech planetary science professor Andrew Ingersoll and his colleagues from Cornell, NASA, and UCLA write that lightning storms on the giant planet are clearly associated with the eddies that supply energy to the large-scale weather patterns.

Their conclusion is possible because Galileo can provide daytime photos of the cloud structure when lightning is not visible, and nighttime photos of the same area a couple of hours later clearly showing the lightning.

"You don't usually see the thunderstorms or the lightning strikes because the ammonia clouds in the upper atmosphere obscure them," says Ingersoll.

"But when Galileo passes over the night side, you can see bright flashes that let you infer the depth and the intensity of the lightning bolts."

Especially fortuitous are the Jovian nights when there is a bit of moonshine from one of the large moons such as Io, says Ingersoll. When there is no moonshine, the Galileo images show small blobs of glow from the lightning flashes, but nothing else. But when the upper cloud covers are illuminated at night by moonshine, the pictures show both the glow from the lightning some 100 kilometers below as well as eddies being roiled by the turbulence of the thunderclouds.

The association of the eddies with lightning is especially noteworthy in the new papers, Ingersoll says. Planetary scientists have known for some years that Jupiter had lightning; and in fact they have known since the Voyager flyby that the zonal jets and long-lived storms are kept alive by soaking up the energy of smaller eddies. But they did not know until now that the eddies themselves were fed by thunderstorms below.

"The lightning indicates that there's water down there, because nothing else can condense at a depth of 80 or 100 kilometers," he says. "So we can use lightning as a beacon that points to the place where there are rapidly falling raindrops and rapidly rising air columns-a source of energy for the eddies.

"The eddies, in turn, get pulled apart by shear flow and give up their energy to these large-scale features. So ultimately, the Great Red Spot gets its energy and stays alive by eating these eddies."

Adding credence to the interpretation is the fact that the anticyclonic rotation (clockwise in the northern hemisphere and counterclockwise in the southern) of the eddies is consistent with the outflow from a convective thunderstorm. Their poleward drift is consistent with anticyclones being sucked into Jupiter's powerful westward jets.

Ingersoll is lead author of the Nature paper that interprets the new Galileo data. The other authors are Peter Gierasch and Don Banfield of Cornell University; and Ashwin Vasavada of UCLA. (Banfield and Vasavada are Ingersoll's former doctoral students at Caltech).

Gierasch is lead author of the other Nature paper, which announces the discovery of moist convection on Jupiter. The other authors are Ingersoll; Banfield; Vasavada; Shawn Ewald of Caltech; Paul Helfenstein and Amy Simon-Miller, both of Cornell; and Herb Breneman and David Senske, both of NASA's Jet Propulsion Laboratory (JPL).

The authors of the Icarus paper are Ingersoll; Vasavada; Senske; Breneman; William Borucki of NASA Ames Research Center; Blane Little and Clifford Anger, both of ITRES Research in Calgary, Alberta; and the Galileo SSI Team.

The Galileo spacecraft has been orbiting Jupiter and its moons for the past four years, and the mission has begun an additional one-year extension.

JPL, a division of Caltech, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.

Writer: 
Robert Tindol
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Largest Explosions in the Universe May Come from the Death of Massive Stars

PASADENA-Cosmic gamma-ray bursts, the brightest known explosions in the universe, may come from the fiery deaths of very massive stars in supernova explosions, a team of astronomers said today.

In a paper to appear today in the international journal Nature, the international team led by the California Institute of Technology presents evidence that the gamma-ray burst of March 26, 1998 (GRB 980326) is apparently associated with a supernova explosion.

This would then indicate that some gamma-ray bursts are associated with the formation of black holes during the fiery deaths of very massive stars. If true, this would be some of the first direct evidence for what produces gamma-ray bursts.

As a consequence, the team suggests that a burst of gamma rays are seen when one of the jets from the supernova's central black hole is pointed directly toward Earth. Gamma-ray bursts are brilliant flashes of high-energy radiation that occur at seemingly random times and from random places in the sky.

While these objects have been known since 1967, it was only recently demonstrated that these bursts originate from galaxies in the very distant universe and are by far the most brilliant bursts in the universe. This breakthrough was made possible due to the launch of the Italian-Dutch satellite BeppoSAX in 1996, which for the first time pinpointed the location of the bursts with a sufficient accuracy to enable their detailed studies with ground-based telescopes such as the W. M. Keck Telescope.

Despite the strides, scientists were still left wondering what produces these spectacular explosions. Various theories of their possible origins are still vigorously debated.

There are currently two popular models, both suggesting that the bursts originate in a formation of a black hole. In one model, two massive objects such as neutron stars or black holes (both of which may be end-products of previous supernova explosions) coalesce, forming a single massive black hole.

In the second model, such a black hole is produced in a catastrophic collapse of the core of a massive star. In this model, one then expects two sources of light: the "afterglow'' emission from the gamma-ray burst itself and light from the exploding star, a supernova. The afterglow rapidly declines whereas the supernova explosion gains in brightness over a period of a few weeks, and then gradually fades away.

The new study reports on the observations of GRB 980326 carried out at the W. M. Keck Observatory's 10-m telescope located atop Mauna Kea, Hawaii. As in many other cases, a visible light afterglow was found following the burst, which then rapidly faded away. However, the Caltech-led team discovered something never previously observed-a dramatic rebrightening of optical emission at the position of the gamma-ray burst.

Normally, the optical light of a gamma-ray burst vastly outshines its host galaxy for weeks. When the light from the gamma-ray burst fades, the apparent total brightness remains constant: all that remains is the light from the host galaxy.

Shrinivas R. Kulkarni of the Caltech team explains, "A month after GRB 980326, it looked as though the host galaxy was dominating the light." However, the next time the team observed, some eight months after the burst, the "galaxy" was gone.

"Galaxies do not just disappear, so we were astonished," Kulkarni said. "Clearly, what we were seeing is a new source of light brightening one month and then fading away. This is something quite new."

This unexpected rebrightening is now believed to be due to the underlying supernova created in the explosion of the massive star. The team had also obtained spectra of the object at different times, and that provided additional clues.

"The spectrum of the source right after the burst was blue, which is common," said S. George Djorgovski of Caltech. "But after a month it was very red, which was unexpected.

"That alone suggested that we were looking at some different phenomenon happening at the same location, but with a time delay of a few weeks."

Both the rebrightening and the spectrum changes are naturally explained by the presence of a supernova. The intensity of the apparent re-burst matches the peak brightness of a supernova seen in a distant galaxy, and its red spectrum also has the right color.

This represents the most direct evidence to date in favor of the massive supernova model. In this scenario, a black hole is quickly formed in the center of a massive star whose core is unable to support itself against gravity.

When the star explodes, powerful jets from the central black hole emerge along the original axis of rotation, and gamma rays are created by the jets. If the jets are not pointed toward Earth, then we see only a supernova and the effects of the exploding star. But gamma rays as well as the light from the supernova arrive at Earth if the jets are pointing in our direction.

Joshua S. Bloom, a graduate student at Caltech and lead author of the paper said, "This appears to be the smoking gun for the origin of some gamma-ray bursts, a perfect marriage of the two brightest events in the universe. It is wonderful to be a part of such a discovery."

Gamma-ray bursts, since their discovery some 30 years ago, have over 150 theoretical models about their possible origins, but only a handful can come close to describing the true trigger of the bursts.

"It is possible that there are other causes for gamma-ray bursts such as the coalescence of neutron stars," Bloom said. "Undoubtedly, astronomers will focus on unearthing new classes in the years to come."

Early reports of the results created some excitement in the astronomical community. Two other groups, from universities of Amsterdam and Chicago, in view of the work presented by the Caltech team, have reanalyzed the data on some other gamma-ray bursts. They appear to find good evidence for an underlying supernova in another well-studied gamma-ray burst.

"It is encouraging to have had such a resounding reception to an unexpected result," said Kulkarni. "Even some of the initial skeptics seem to be converted by these results."

Other members of the Caltech team are graduate student A. C. Eichelberger; postdoctoral scholars P. Côté, J. P. Blakeslee, and S. C. Odewahn; and Assistant Professor F. A. Harrison.

In addition to the members of the Caltech team, the other coauthors include M. Feroci of the BeppoSAX team; D. A. Frail of the National Radio Observatory; A. V. Filippenko, D. C. Leonard, A. G. Reiss, H. Spinrad, D. Stern, A. Bunker, B. Grossan, S. Perlmutter, and R. A. Knop of the University of California at Berkeley; A. Dey of the National Optical Astronomy Observatory; and I. M. Hook of the European Southern Observatory.

Writer: 
Robert Tindol
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Clare Boothe Luce Professorship Awarded to Caltech

PASADENA—The California Institute of Technology is pleased to announce a recent grant of $498,427, in support of a five-year Clare Boothe Luce Professorship in geobiology from the Henry Luce Foundation. Dr. Dianne Newman has been appointed to the position.

Newman's expertise in microbiology and geochemistry will allow her to explore a wide range of problems, as well as collaborate with a variety of faculty members.

"Encouraging women in science and engineering is a top priority for me personally, as well as for the Institute. The Clare Boothe Luce Professorship at Caltech helps us in a very substantial way toward that goal," says Caltech president David Baltimore.

Newman received her bachelor's degree in German studies from Stanford University in 1993, and her Ph.D. in environmental engineering from the Massachusetts Institute of Technology in 1997. In addition, she was an exchange scholar at Princeton University from 1995 to 1997, and is currently a postdoctoral fellow at Harvard.

Newman has received a number of awards, including the W.B. Dickman Writing Prize in Engineering, the American Chemical Society Award, and the NASA Planetary Biology Internship Grant. An accomplished writer and teacher, she has been recognized nationally for her research work.

The Clare Boothe Luce Program is administered by the Henry Luce Foundation, which was established by Mrs. Luce's husband, Henry R. Luce. The program was created "to encourage women to enter, study, graduate and teach" in scientific and technological fields in which they are underrepresented. Mrs. Luce established the program "in recognition that women have already entered the fields of medicine, law, business and the arts, and in order to encourage more women to enter the field of science."

Founded in 1891, Caltech has an enrollment of some 2,000 students, and an academic staff of about 280 professorial faculty and 130 research faculty. The Institute has more than 19,000 alumni. Caltech employs a staff of more than 1,700 on campus and 5,300 at JPL.

Over the years, 27 Nobel Prizes and four Crafoord Prizes have been awarded to faculty members and alumni. Forty-four Caltech faculty members and alumni have received the National Medal of Science; and eight alumni (two of whom are also trustees), two additional trustees, and one faculty member have won the National Medal of Technology. Since 1958, 13 faculty members have received the annual California Scientist of the Year Award. On the Caltech faculty there are 77 fellows of the American Academy of Arts and Sciences; and on the faculty and Board of Trustees, 69 members of the National Academy of Sciences and 49 members of the National Academy of Engineering.

Contact: Joanna Layton (626) 395-3227

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JL

Caltech joins effort to extend capabilities of major observatories

PASADENA—The California Institute of Technology will participate in a multi-institutional effort, funded by the National Science Foundation, to advance the field of adaptive optics, which promises to revolutionize astronomy.

The National Science Foundation's governing body, the National Science Board, has approved a proposal to establish a Center for Adaptive Optics at the University of California, Santa Cruz. As a partner institution, Caltech will bring together faculty from astronomy, planetary science, and physics to advance the use of existing adaptive optics technology at the 200-inch Hale Telescope at Palomar Observatory in California and the two 10-meter Keck Telescopes in Hawaii.

According to Mike Brown, assistant professor of planetary astronomy and leader of the Caltech team, "This effort will breathe new life into ground-based observing by giving us more sophisticated tools to view distant planetary systems." Depending on the size of the telescope, adaptive optics technology will make images 10 to 20 times sharper, giving scientists a much better view of space. "We plan on making Palomar the best at seeing very faint things next to very bright things, possible indicators of planetary systems. We can learn and experiment at Palomar, then utilize Keck for the really big discoveries."

Very few astronomers have any experience using adaptive optics. "We're hoping to quickly learn how to optimize the technology currently available and pass on that knowledge to other scientists. I expect this to bring about some exciting discoveries," said Brown.

Adaptive optics is a method to actively compensate for changing distortions that cause blurring of images. It is used in astronomy to correct for the blurring effect of turbulence in the earth's atmosphere. For astronomers, adaptive optics can give ground-based telescopes the same clarity of vision that space telescopes achieve by orbiting above the earth's turbulent atmosphere.

Astronomers have already started to reap the benefits of applying adaptive optics to their research. A team headed by Dr. Richard Dekany at the Jet Propulsion Laboratory recently conducted a highly successful first test of an adaptive optics system on the 200-inch Hale Telescope at Palomar Observatory. Enhanced high-resolution images of excellent quality were obtained of the ring system of Uranus and of the Lagoon Nebula.

The 27 partner institutions of the Center for Adaptive Optics will include Caltech, UC Berkeley, UC San Diego, UCLA, UC Irvine, the University of Chicago, the University of Rochester, the University of Houston, Indiana University, Lawrence Livermore National Laboratory, and 17 other national laboratory, industry, and international partners.

The center will provide the sustained effort needed to bring adaptive optics from promise to widespread use. It will conduct research, educate students, develop new instruments, and disseminate knowledge about adaptive optics to the broader scientific community.

Caltech participants will include Shri Kulkarni, Chuck Steidel, Mark Metzger, and Keith Matthews from astronomy, and Christopher Martin from physics.

Palomar Observatory is located near San Diego, Calif., and is owned and operated by Caltech. Caltech and the University of California jointly operate the W. M. Keck Observatory, which houses the world's two largest optical and infared telescopes and is located on Mauna Kea, Hawaii.

Writer: 
Sue Pitts McHugh
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Caltech Question of the Month: If the sun ceased to exist right now, how long would mankind survive?" Would the oceans freeze?

Question: If the sun ceased to exist right now, how long would mankind survive?" Would the oceans freeze?

Submitted by Joseph Canale, La Crescenta.

Answered by Dave Stevenson, George Van Osdol Professor of Planetary Science, Caltech.

The sun provides more than just energy, it provides the gravitational force that keeps us in orbit. But I interpret the question to mean "What if the sun stopped shining?"

In that situation, Earth's surface would cool down to a state in which the outgoing infrared radiation is balanced only by conductive heat from Earth's interior. The heat content of the atmosphere is negligible except on the very short time scale of a few days.

Within days to a week, Earth's surface would cool to below the freezing point of salty water, and the oceans would begin to form a complete ice cap. In a year or so the temperature would be down below 200 degrees absolute at the surface (that's roughly minus 100 Fahrenheit). The water in the deepest part of Earth's oceans would freeze after 1,000 years. Earth's surface would not cool all the way to its new stable state of around 30 degrees absolute (approaching minus 400 Fahrenheit) until millions of years had elapsed.

This state is one in which the radioactive heat in Earth's interior balances outgoing radiation. In the interim period of several million years, Earth's subsurface would be kept warm because of the slowness of heat conduction through solid rock or ice. So the inside would stay warm even as Earth's atmosphere was freezing out as solid oxygen and nitrogen. Interestingly, this means that bacteria that live well beneath Earth's surface might survive for a while, though life right at Earth's surface would be extinguished very rapidly on a time scale of years or less. A small number of people could survive a long time by drilling and creating a habitat deep down (miles below Earth's surface).

Writer: 
RT
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