May 11 Event Will Mark 90th Anniversary for GPS

Caltech's Division of Geological and Planetary Sciences marks milestone with daylong celebration
News Writer: 
Robert Perkins

photo of two row boats on a Grand Canyon expedition in 1939

Grand Canyon expedition (Caltech and Carnegie Institution), 1939
Credit: Courtesy of the Archives, California Institute of Technology

On May 11, Caltech’s Division of Geological and Planetary Sciences (GPS) will celebrate its 90th anniversary with a daylong symposium and celebration featuring speakers who contributed to the division throughout its history as well as lab tours and posters about current research.

Speakers will include alumni from the 1930s to the present—among them centenarians Mel Levet (BS ’39, MS ’40) and Walter Munk (BS ’39, MS ’40). Levet is a geologist (who also pitched for and coached the Beavers baseball team in the 1930s) and Munk is a physical oceanographer who is renowned for his work on ocean circulation and tides. Throughout the day, tours will be conducted of three facilities: the media center of the Caltech Seismological Laboratory, more colloquially called the Seismo Lab, an internationally recognized earthquake research facility; the Earth Surface Dynamics Laboratory (or “Flume Lab”), a tilting flume used to study erosion and debris flows; and the Bruce Murray Laboratory for Planetary Visualization, a state-of-the-art image processing and data visualization lab. The tours will offer alumni and friends a firsthand look at the division’s ongoing research. The following day, a 195-mile round-trip, nine-hour excursion has been scheduled to explore the San Andreas Fault. The bus tour will include stops at the Cajon Pass, Lost Lake, Devil’s Punchbowl Natural Area, and several other locations.

“Caltech excels at reinventing itself to create new research directions while also strengthening strong programs at the core of Earth and planetary science. Our students, alumni and faculty across many generations have collaborated to establish these outstanding programs. This event is a celebration of those collaborations and the accomplishments and distinguished careers of our alumni and current students,” says John Grotzinger, the Ted and Ginger Jenkins Leadership Chair of GPS and the Fletcher Jones Professor of Geology. 

GPS began as the Department of Geology in 1926. The department originally partnered with the then-independent Seismological Laboratory, which was established in 1921 in the hills above Pasadena and managed jointly by Caltech and the Carnegie Institution of Washington until Caltech took full charge of its administration in 1937. (The Seismo Lab finally moved onto Caltech’s campus in 1974 with the construction of the Seeley G. Mudd Building of Geophysics and Planetary Sciences, also known as South Mudd.) Since the 1920s, Caltech has collaborated with the United States Geological Survey on the Southern California Seismic Network (SCSN), which monitors ground motion in the region via seismometers at 410 sites and provides timely information about earthquakes to first responders.

The department made significant early advances in earthquake science, including the development of a formula for measuring the magnitude of earthquakes—the Richter Scale—by Caltech’s Charles Richter (PhD ’28) and Beno Gutenberg, the Seismo Lab’s founding director, in 1935. (The Richter Scale was replaced in 1977 with the invention of the Moment Magnitude Scale by Caltech’s Hiroo Kanamori, the John E. and Hazel S. Smits Professor of Geophysics, Emeritus.) More recently, earthquake scientists at GPS have collaborated with researchers in the Division of Engineering and Applied Science to roll out a network of low-cost, easy-to-install seismometers. The goal of the project, known as the Community Seismic Network, is to collect highly granular and detailed information about how tremors shake the Los Angeles area and how different buildings respond to those quakes. Such information would be crucial to first responders in the aftermath of a major earthquake, directing them to the hardest-hit areas.

Another early focus of research for GPS was paleontology. Indeed, paleontologist Chester Stock served as division chair from 1947-50, and also as chief science curator at the Los Angeles County Museum of History, Science, and Art (now the Natural History Museum of Los Angeles County) for several years. The museum still retains a collection of specimens from Stock, who excavated dinosaur and mammal fossils throughout the American West and northern Mexico.

As the United States entered the space race in the 1950s, the division shifted away from paleontology and toward geochemistry and planetary science. Led by chair Robert Sharp (BS ’34, MS ’35, and namesake of Mars’s Mount Sharp, the base of which served as the landing site for the Mars Curiosity rover in 2012), the division changed its name to Geological and Planetary Sciences in 1960 and forged a partnership with the Jet Propulsion Laboratory (JPL), which is managed by Caltech for NASA. The division worked with JPL to develop tools and techniques for studying the solar system. Among other advances, Clair Patterson, professor of geochemistry, determined the age of the earth as 4.55 billion years, while Gerald Wasserburg, John D. MacArthur Professor of Geology and Geophysics, built a mass spectrometer for making high-precision measurements of lunar samples obtained by the Apollo missions.

The division’s rich planetary science tradition has been carried on by its current leadership in NASA’s exploration of Mars. Grotzinger served as project scientist for the Mars Science Laboratory Curiosity rover mission from 2007 to 2015, and Kenneth A. Farley, the W. M. Keck Foundation Professor of Geochemistry, is project scientist on the upcoming Mars 2020 mission. Caltech planetary scientists are also reshaping our understanding of the solar system itself. In 2005, GPS’s Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy, made headlines with the discovery of the dwarf planet Eris, which ultimately led to Pluto being downgraded from a planet to a dwarf planet. In 2016, he and colleague Konstantin Batygin, assistant professor of planetary science, followed up that discovery with the announcement that an actual (but as-yet unobserved) ninth planet exists, touching off a worldwide race among astronomers to locate the planet.

In recent years, the division has expanded its program in environmental science with key hires in the field of climate science. It also established the Ronald and Maxine Linde Center for Global Environmental Science in 2008. The center, with an $ 18 million endowment from Ronald Linde (MS ’62, PhD ’64) and his wife, Maxine, is working to develop solutions to environmental issues like air pollution and climate change. The division has also established a nation-leading program in geobiology, the study of the interface between the biosphere and the earth. This new field explores how the earth’s history has shaped life and how life has shaped the earth’s history. In September, Caltech geobiologists Dianne Newman and Victoria Orphan earned national recognition when both were awarded MacArthur Fellowships.

“Some of the most difficult problems of our time relate to interactions within the Earth system and other planetary systems,” Grotzinger says. “In the future, GPS will be well positioned to participate in elucidating the fundamental physics of earthquakes and how this enables their prediction; the processes that regulate climate and how this impacts local and global change; and address the inevitable questions of where do we come from and are we alone.”  

Members of the Caltech community interested in attending the GPS 90th anniversary celebration are asked to register for the event online.

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Introducing Caltech Magazine

Caltech rolls out a new Institute magazine, in print and online

Magazine cover

Our new Institute magazine features a wide array of stories about Caltech's people, research, and impact.

This month, we launch Caltech magazine, a new publication for the community featuring a range of stories about the Institute, its people, and its impact on the world.

Caltech magazine replaces E&S magazine, which shared the Institute’s transformative research for eight decades. E&S magazine began life in June 1937 as a means for disseminating news to and about Caltech alumni, then morphed a few years later into Engineering and Science Monthly. By the time the magazine carried the E&S logo for the first time in 1967, its focus had broadened to include both alumni and general Institute research.

Over the years, generations of Caltech graduates came to rely on E&S as one of the primary ways to stay connected with their alma mater. Caltech magazine is the next step in its evolution. After months of audience research, discussions with a broad variety of the magazine’s readers, and conceptual design work, we have reimagined our publication to become a truly Caltech magazine, one that both embodies the entire Institute and serves all its stakeholders.

In each issue, readers will find a wide variety of stories, targeted toward the many different audiences such a magazine serves. Complementary material, including videos, will be available throughout the year on the magazine’s website,

We look forward to your thoughts and comments on how we can make Caltech magazine as useful and compelling as possible for you; you can reach us at

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‘Detergent’ Molecules May Be Driving Fluctuations in Atmospheric Methane Concentrations

New study suggests hydroxyl radicals may be behind unexplained recent increase in methane levels
News Writer: 
Robert Perkins


An illustration of hydroxyl and methane atoms

During the early 2000s, environmental scientists studying methane emissions noticed something unexpected: the global concentrations of atmospheric methane (CH4)—which had increased for decades, driven by methane emissions from fossil fuels and agriculture—inexplicably leveled off.

The methane levels remained stable for a few years, then started rising again in 2007. Previous studies have suggested a variety of potential culprits behind the renewed rise: increasing emissions from high-latitude wetlands, increasing fossil fuel emissions, or the growth of agriculture in Asia.

However, new modeling by researchers at Caltech and Harvard University suggests that methane emissions might not have increased dramatically in 2007 after all. Instead, the most likely explanation has less to do with methane emissions and more to do with changes in the availability of the hydroxyl (OH) radical, which breaks down methane in the atmosphere. As such, the amount of hydroxyl in the atmosphere governs the amount of methane. If global levels of hydroxyl decrease, global methane concentrations will increase—even if methane emissions remain constant, the researchers say.

Methane is the second most prevalent greenhouse gas, after carbon dioxide. However, the colorless, odorless gas can be difficult to track and derives from a wide range of sources, from decomposing biological material to leaks in natural gas pipelines.

John Eiler, the Robert P. Sharp Professor of Geology and Professor of Geochemistry, answers five critical questions about methane in our atmosphere.

When atmospheric concentrations of methane increase, it may not be correct to chalk it up solely to an increase in methane emissions, says Caltech’s Christian Frankenberg, co-corresponding author of a study on the decadal trends of methane concentrations that was published the week of April 17 in the early online edition of the Proceedings of the National Academy of Sciences.

Frankenberg is an associate professor of environmental science and engineering at Caltech and a research scientist at the Jet Propulsion Laboratory, which is administered by Caltech for NASA. His collaborators on the paper are Paul Wennberg, the R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering at Caltech, and Alexander Turner and Daniel Jacob of Harvard.

“Think of the atmosphere like a kitchen sink with the faucet running,” Frankenberg explains. “When the water level inside the sink rises, that can mean that you’ve opened up the faucet more. Or it can mean that the drain is blocking up. You have to look at both.”

In this analogy, hydroxyl represents part of the draining mechanism in the sink. Hydroxyl is the neutral form of the negatively charged hydroxide molecule (OH). It is described as a “radical” because it is highly reactive and, as such, acts like a detergent in the atmosphere, breaking down methane into oxygen and water vapor. 

Tracking decadal trends in both methane and hydroxyl, Frankenberg and his colleagues noted that fluctuations in hydroxyl concentrations correlated strongly with fluctuations in methane.

However, the authors do not yet have a mechanistic explanation for the last decade’s global changes in hydroxyl concentrations. Future studies are needed to investigate this further, Frankenberg says. The researchers also would like to see the trends they detected verified with a more detailed study of both methane sources and sinks.

“The tropics are the tricky part,” Frankenberg says. “They’re very complex in terms of methane emissions and destruction.” Methane has the shortest lifetime in the tropics due to the large amounts of water vapor and radiation there. But because tropical areas are often remote and cloud-covered (thwarting satellite observation), they remain understudied, Frankenberg says.

The PNAS study is titled “Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl.” Alexander Turner, graduate student at Harvard University, is the lead author. The co-authors are Christian Frankenberg and Paul Wennberg from Caltech, and Daniel Jacob from Harvard. This research was funded by the Department of Energy and a NASA Carbon Monitoring System grant.

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Caltech Students and Alumni Receive 2017 NSF Graduate Research Fellowships

Twenty current students and eight alumni have been selected to receive funding for graduate studies.
News Writer: 
Lori Dajose

The logo of the National Science Foundation.

This year, the National Science Foundation (NSF) has selected 20 current Caltech students and eight alumni to receive its Graduate Research Fellowships. The awards support three years of graduate study within a five-year fellowship period in research-based master’s or doctoral programs in science or engineering.

The NSF notes that the Graduate Research Fellowship Program (GRFP) “is a critical program in NSF’s overall strategy to develop the globally-engaged workforce necessary to ensure the nation’s leadership in advancing science and engineering research and innovation.” The selection criteria used to identify NSF fellows reflect the potential of the applicant to advance knowledge and benefit society.

Caltech’s awardees for 2017 are seniors Alexander Anferov, Daniil Lukin, Stephanie Moon, Anjali Premkumar, Gerri Roberts, and Sasha Zemsky; and graduate students Mary Arrastia, Stephanie Breunig, Ivanna Escala, Riley Galton, Phillip Helms, Kari Hernandez, Celeste Labedz, Ethan Pickering, William Poole, Alexander Sorum, Alvita Tran, Krystal Vasquez, Zachary Wu, and Lealia Xiong. The graduate student awardees join 135 current NSF fellows enrolled at Caltech.

Caltech alumni in the 2017 class of Graduate Fellows are: Oliver Chen, Linda Chio, Anne Davis, Connie Hsueh, Anna Liu, Aleena Patel, Madeleine Youngs, and Leonardo Zornberg.

In total this year, the NSF selected 2,000 GRFP recipients from a pool of more than 13,000 applicants. Caltech’s Fellowships Advising and Study Abroad office works with current students and recent Caltech graduates interested in applying for an NSF fellowship; sponsoring a panel discussion of previous winners each fall and offering one-on-one advising.

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