Mars Rover Finds Evidence of Ancient Streambed

An ankle- or hip-deep stream once flowed with force across the surface of Mars in the very spot where NASA's Curiosity rover is currently exploring. The finding, announced by members of the project's science team today at the Jet Propulsion Laboratory (JPL), provides new information about a once wet environment in Gale Crater, the ancient impact crater where the rover touched down in early August.

Using Curiosity's mast camera to analyze two rock outcrops known as Hottah and Link, the team has identified a tilted block of an ancient streambed—a layer of conglomerate rock, which is made up of stones of different sizes and shapes cemented together.

"Curiosity's discovery of an ancient streambed at Gale Crater provides confirmation of the decades-old hypothesis that Mars once had rivers that flowed across its surface," says John Grotzinger, the mission's project scientist and the Fletcher Jones Professor of Geology at Caltech. "This is the starting point for our mission to explore ancient, potentially habitable environments, and to decode the early environmental history of Mars."

The sizes of the gravels in the conglomerate rock suggest that the stream once flowed at a rate of about a meter per second. The discovery marks the first time scientists have identified gravel that was once transported by water on Mars.

In coming weeks and months, the team plans to use all of Curiosity's analytical instruments to study these types of rocks. And Grotzinger points out, "Finding geological evidence for past water is a prerequisite to beginning geochemical measurements that inform analysis of ancient potentially habitable environments. Curiosity has the most sophisticated and comprehensive suite of geochemical instruments ever flown to Mars."

For more about the finding, read the full JPL release.

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Kimm Fesenmaier
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Two Caltech Researchers Receive NIH Director's Awards

Two members of the California Institute of Technology (Caltech) faculty have been given National Institutes of Health (NIH) Director's Awards. The awards are administered through the NIH's Common Fund, which provides support for research deemed to be both innovative and risky.

"The Common Fund High Risk–High Reward program provides opportunities for innovative investigators in any area of health research to take risks when the potential impact in biomedical and behavioral science is high," said NIH Director Francis S. Collins in a press release.

There are three types of NIH Director's Awards: the Pioneer Award, the New Innovator Award, and the Transformative Research Award. This year, biologist Doris Ying Tsao was given one of 10 Pioneer Awards, and geobiologist Dianne K. Newman was among the 20 scientists to receive Transformative Research Awards.

The Pioneer Award, established in 2004, "challenges investigators at all career levels to develop highly innovative approaches that have the potential to produce a high impact on a broad area of biomedical or behavioral research," according to the NIH. Tsao, an assistant professor of biology, will explore the question of how objects that we see are initially processed in the brain. 

"The retina essentially transmits an array of unconnected pixels to the brain. These are first processed locally, through various local filters for color, motion, etc., and the image does not yet contain objects, or bound units," says Tsao. "But after this, there is a mysterious operation that puts all these local pieces together for the first time—and that is what I am studying. I want to know how the brain dynamically links all these pixels over space and time, based on surface contiguity, to form bound units."

For example, as a truck makes a U-turn, the pixels defining the truck can change completely, yet we have no trouble tracking those pixels and seeing they belong to a single invariant object, she explains. 

"I am incredibly excited to have the chance, with the NIH Pioneer Award, to hunt for the circuits implementing these computations within the brain," says Tsao. "We just have to open our eyes to know the circuits exist, but understanding them is going to be an immense challenge that will require huge resources, and to now suddenly have these resources is unbelievable to me." 

The Transformative Research Award program, established in 2009, "promotes cross-cutting, interdisciplinary approaches" for research that "has the potential to create or overturn fundamental paradigms," according to the NIH. Newman, professor of biology and geobiology, will use the award to apply geobiological approaches to understanding the progression of pulmonary infections. 

Due to the challenges of working in situ, or in the body, most studies of infectious disease agents are conventionally performed with representative isolates and imperfect disease models in the laboratory, says Newman. Very few direct measurements of the physiological state of drug-tolerant populations in the host exist, and little is known about which metabolic pathways are actually in play, much less how they change over time in response to coevolving conditions within the lung, she explains. 

"We will tackle this critical knowledge gap using an approach inspired by geobiology," says Newman, who is also an investigator with the Howard Hughes Medical Institute. "Geobiologists are experienced in studying the growth and metabolism of microbial populations in poorly accessible natural habitats by combining molecular biology and stable isotope geochemistry; we will apply these tools to the lung." 

The goal of this project, she says, is to lay a foundation for novel therapeutics to modify and control infectious disease agents. 

"I am honored to have received this award because it will take our research in a meaningful new direction," says Newman. "The opportunity to collaborate with an outstanding group of colleagues at Caltech and at USC and Johns Hopkins hospitals is very exciting. I'm grateful that the NIH took a chance on our idea, and I hope it fulfills its promise."

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Katie Neith
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Researchers Receive NIH Director's Awards
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Martian Clay Minerals Might Have Much Hotter Origin

Ancient Mars, like Earth today, was a diverse planet shaped by many different geologic processes. So when scientists, using rovers or orbiting spacecraft, detect a particular mineral there, they must often consider several possible ways it could have been made.

Several such hypotheses have been proposed for the formation of clay minerals, which have been detected from orbit and are sometimes considered indicators that the surface has, in the past, been altered by liquid water. Now, publishing in the journal Nature Geoscience, a team of French and American scientists led by Alain Meunier of the Université de Poitiers and including Caltech's Bethany Ehlmann, has suggested a new, very different possibility.

Previously, planetary scientists considered two hypotheses—both offering the potential for once-habitable environments on Mars—that explain clay mineral formation. One holds that over long enough periods, contact with liquid water can alter igneous rock, such as basalt, producing clays; the other proposes that waters flowing through the martian subsurface can produce clays through a hydrothermal process.

In the new paper, the authors suggest that the clay minerals instead might have precipitated directly from scalding hot magmas.

"This new hypothesis is less exciting for astrobiology because life could not survive in those types of conditions," says Ehlmann, an assistant professor of planetary science at Caltech and a research scientist at the Jet Propulsion Laboratory. "But all three hypotheses need to be on the table as we consider a given clay-bearing deposit. Each hypothesis has a different implication for the history and habitability of ancient Mars."

Ehlmann says that scientists hope to use the Curiosity rover and its suite of instruments to study the clays found in sediments at Gale Crater—the impact crater that the robotic geologist was sent to explore. However, she notes, clays are typically found in even older igneous bedrock on Mars. Future rover missions would need to study clay formation in that ancient crust to rigorously test the various clay formation hypotheses. "There's more exploration that needs to be done before we understand all the mysteries of Mars," she says.

The Los Angeles Times recently spoke to Ehlmann about the new paper and its implications.

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Kimm Fesenmaier
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Hotter Origin Possible for Martian Clays
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Geologists in the Field

Field geologists at Caltech come face to face with bears and wolverines, climb steep cliffs and mountains, and endure scorching sunlight and frigid temperatures. Sometimes risking life and limb, they travel to some of the most remote corners of the globe—all in the name of science. A feature-length story in the Summer 2012 issue of E&S magazine describes some of their adventures in the quest to understand our planet. 

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Marcus Woo
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Anchors Aweigh

At Caltech, hydrophilic researchers in the Division of Geological and Planetary Sciences take to the salty seas to gather data, explore the deep, and get a firsthand view of the beasts at the bottom. The briny treasures they collect along the way are helping them learn more about past, present, and future environmental conditions and hazards. Read about their ocean adventures in a feature-length story in the Summer 2012 issue of E&S magazine.

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Katie Neith
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Ocean-based Researchers Take to the Sea
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Countdown to Mars: Caltech goes to the Red Planet

On Sunday, August 5, the Mars Science Laboratory (MSL) rover, known as Curiosity, will make its dramatic descent onto Mars's surface. Once it lands, the rover will check its instruments to make sure everything's functioning properly—and then it will get right to work.

In fact, on just the second day of its Martian excursion, Curiosity is scheduled to turn on some of its key scientific instruments, taking pictures and making measurements of its immediate environment. About a week later, the rover will spin its six wheels and start exploring. Curiosity will ramp up its science mission over the following weeks, deploying its suite of instruments to scoop, drill, zap, examine, and analyze. And through it all, a couple of Caltech researchers will be among the 300 scientists working here on Earth, taking the information Curiosity sends home and trying to figure out what it all means.

Back in February, Caltech's Ken Farley and Bethany Ehlmann were named as participating scientists on the mission; each will be directing their own Martian science projects. Ehlmann, an assistant professor of planetary science and a JPL research scientist, has been analyzing rocks and minerals on Earth to help MSL's science team choose which Martian rocks to study in detail. Farley, the W. M. Keck Foundation Professor of Geochemistry and chair of the Division of Geological and Planetary Sciences, will measure the presence of noble gases in Martian rocks to determine their ages. Here are some excerpts from Kimm Fesenmaier's story about how these two scientists intend to make their mark on Mars.

Examining the capabilities of one of Curiosity's science instruments, Sample Analysis at Mars (SAM), which was designed to look for organic matter, Farley realized that it might be possible to detect the isotope helium-3 with SAM's spectrometer. Since helium-3 is produced by the bombardment of surface materials by incoming cosmic rays, measurements of the isotope can be used to determine how long rocks or other geologic features have been exposed on the surface of a planet. This could help scientists date features on Mars such as impact craters, but it could also come in handy in terms of target selection.

Imagine, for example, that the science team locates an impact site on Mars that seems to have been created within the last few million years. The rocks around that site would be ideal targets for closer study because any organic matter they contain would have been protected from cosmic rays until they were thrown out onto the surface. "The trouble is, it's easy to say that an impact happened a million years ago, but how would you ever really know?" Farley says. "The technique that I have is a way to say, 'Yes, this is, in fact, a very young surface.'"

Farley says his involvement with MSL is a major departure from his previous work, as he has not been heavily involved in the study of the geology of Mars. "Most of what I do is technique development," he says. "So it's interesting for me to see potential application of one of those techniques in another very different setting."

In contrast, space missions are Ehlmann's bread and butter. She got her first taste of rover operations while an undergraduate student working on the Mars Exploration Rovers mission. Then as a graduate student, she was a collaborator on the Mars Reconnaissance Orbiter mission and used data from multiple orbiters to locate hydrated minerals on the surface of the red planet.

For MSL, Ehlmann proposed to help improve the team's ability to select rocks from a distance for more extensive study. Curiosity is equipped with a laser and a telescope known collectively as ChemCam, mounted on its mast. From a distance of about seven meters, the laser can zap a rock to create a plasma, which can be analyzed with the ChemCam spectrometer to get a sense of the chemical elements present. The science team needs to be able to use those results and their knowledge of mineralogy to quickly decide whether to spend more time and energy on a particular target or to keep Curiosity moving.

To give them a leg up, Ehlmann is analyzing rocks from places such as Iceland as well as synthetic mixtures of minerals in the lab that are similar to the materials observed from Mars orbit at the Gale Crater landing site. The rocks can be well characterized in Earth laboratories to understand their mineralogy, the elements they are made of, and how they would appear from orbit. She is studying how they have been changed by different types of interaction with water. She plans to take the samples to Los Alamos National Laboratory, which partnered with the French national space agency to build the ChemCam, in order to test her samples with a ChemCam-like instrument.

"It's very helpful to have this beforehand understanding of what you might see or what kinds of analyses you need to run," Ehlmann says. "If you understand the processes enough that you develop quick-look algorithms for detecting different styles of alteration, it will help in the tactical timescale when you only have a few hours to come up with a plan for the rover for the next day."

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Marcus Woo
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An Earthquake in a Maze

Caltech researchers provide highest-resolution observations yet of the complex 2012 Sumatra earthquake

PASADENA, Calif.—The powerful magnitude-8.6 earthquake that shook Sumatra on April 11, 2012, was a seismic standout for many reasons, not the least of which is that it was larger than scientists thought an earthquake of its type—an intraplate strike-slip quake—could ever be. Now, as Caltech researchers report on their findings from the first high-resolution observations of the underwater temblor, they point out that the earthquake was also unusually complex—rupturing along multiple faults that lie at nearly right angles to one another, as though racing through a maze.

The new details provide fresh insights into the possibility of ruptures involving multiple faults occurring elsewhere—something that could be important for earthquake-hazard assessment along California's San Andreas fault, which itself is made up of many different segments and is intersected by a number of other faults at right angles.

"Our results indicate that the earthquake rupture followed an exceptionally tortuous path, breaking multiple segments of a previously unrecognized network of perpendicular faults," says Jean-Paul Ampuero, an assistant professor of seismology at Caltech and one of the authors of the report, which appears online today in Science Express. "This earthquake provided a rare opportunity to investigate the physics of such extreme events and to probe the mechanical properties of Earth's materials deep beneath the oceans."

Most mega-earthquakes occur at the boundaries between tectonic plates, as one plate sinks beneath another. The 2012 Sumatra earthquake is the largest earthquake ever documented that occurred away from such a boundary—a so-called intraplate quake. It is also the largest that has taken place on a strike-slip fault—the type of fault where the land on either side is pushing horizontally past the other.

The earthquake happened far offshore, beneath the Indian Ocean, where there are no geophysical monitoring sensors in place. Therefore, the researchers used ground-motion recordings gathered by networks of sensors in Europe and Japan, and an advanced source-imaging technique developed in Caltech's Seismological Laboratory as well as the Tectonics Observatory to piece together a picture of the earthquake's rupture process. 

Lingsen Meng, the paper's lead author and a graduate student in Ampuero's group, explains that technique by comparing it with how, when standing in a room with your eyes closed, you can often still sense when someone speaking is walking across the room. "That's because your ears measure the delays between arriving sounds," Meng says. "Our technique uses a similar idea. We measure the delays between different seismic sensors that are recording the seismic movements at set locations." Researchers can then use that information to determine the location of a rupture at different times during an earthquake. Recent developments of the method are akin to tracking multiple moving speakers in a cocktail party.

Using this technique, the researchers determined that the three-minute-long Sumatra earthquake involved at least three different fault planes, with a rupture propagating in both directions, jumping to a perpendicular fault plane, and then branching to another.

"Based on our previous understanding, you wouldn't predict that the rupture would take these bends, which were almost right angles," says Victor Tsai, an assistant professor of geophysics at Caltech and a coauthor on the new paper. 

The team also determined that the rupture reached unusual depths for this type of earthquake—diving as deep as 60 kilometers in places and delving beneath the Earth's crust into the upper mantle. This is surprising given that, at such depths, pressure and temperature increase, making the rock more ductile and less apt to fail. It has therefore been thought that if a stress were applied to such rocks, they would not react as abruptly as more brittle materials in the crust would. However, given the maze-like rupture pattern of the earthquake, the researchers believe another mechanism might be in play.

"One possible explanation for the complicated rupture is there might have been reduced friction as a result of interactions between water and the deep oceanic rocks," says Tsai. "And," he says, "if there wasn't much friction on these faults, then it's possible that they would slip this way under certain stress conditions."

Adding to the list of the quake's surprising qualities, the researchers pinpointed the rupture to a region of the seafloor where seismologists had previously considered such large earthquakes unlikely based on the geometry of identified faults. When they compared the location they had determined using source-imaging with high-resolution sonar data of the topography of the seafloor, the team found that the earthquake did not involve what they call "the usual suspect faults."

"This part of the oceanic plate has fracture zones and other structures inherited from when the seafloor formed here, over 50 million years ago," says Joann Stock, professor of geology at Caltech and another coauthor on the paper. "However, surprisingly, this earthquake just ruptured across these features, as if the older structure didn't matter at all."

Meng emphasizes that it is important to learn such details from previous earthquakes in order to improve earthquake-hazard assessment. After all, he says, "If other earthquake ruptures are able to go this deep or to connect as many fault segments as this earthquake did, they might also be very large and cause significant damage."

Along with Meng, Ampuero, Tsai, and Stock, additional Caltech coauthors on the paper, "An earthquake in a maze: compressional rupture branching during the April 11 2012 M8.6 Sumatra earthquake," are postdoctoral scholar Zacharie Duputel and graduate student Yingdi Luo. The work was supported by the National Science Foundation, the Gordon and Betty Moore Foundation, and the Southern California Earthquake Center, which is funded by the National Science Foundation and the United States Geological Survey.

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Kimm Fesenmaier
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Geological Society of America Awards Eiler

John Eiler, Robert P. Sharp Professor of Geology and professor of geochemistry at Caltech, has been awarded the 2012 Arthur L. Day Medal by the Geological Society of America (GSA).

Arthur Louis Day established the award in 1948 for "outstanding distinction in contributing to geologic knowledge through the application of physics and chemistry to the solution of geologic problems."

Eiler will receive the medal at the GSA's annual meeting, which will be held November 4–9 in Charlotte, North Carolina.

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Allison Benter
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Caltech Scientists Find New Primitive Mineral in Meteorite

PASADENA, Calif.—In 1969, an exploding fireball tore through the sky over Mexico, scattering thousands of pieces of meteorite across the state of Chihuahua. More than 40 years later, the Allende meteorite is still serving the scientific community as a rich source of information about the early stages of our solar system's evolution. Recently, scientists from the California Institute of Technology (Caltech) discovered a new mineral embedded in the space rock—one they believe to be among the oldest minerals formed in the solar system.

Dubbed panguite, the new titanium oxide is named after Pan Gu, the giant from ancient Chinese mythology who established the world by separating yin from yang to create the earth and the sky. The mineral and the mineral name have been approved by the International Mineralogical Association's Commission on New Minerals, Nomenclature and Classification. A paper outlining the discovery and the properties of this new mineral will be published in the July issue of the journal American Mineralogist, and is available online now.

"Panguite is an especially exciting discovery since it is not only a new mineral, but also a material previously unknown to science," says Chi Ma, a senior scientist and director of the Geological and Planetary Sciences division's Analytical Facility at Caltech and corresponding author on the paper.

The Allende meteorite is the largest carbonaceous chondrite—a diverse class of primitive meteorites—ever found on our planet and is considered by many the best-studied meteorite in history. As a result of an ongoing nanomineralogy investigation of primitive meteorites—which Ma has been leading since 2007—nine new minerals, including panguite, have been found in the Allende meteorite. Some of those new finds include the minerals allendeite, hexamolybdenum, tistarite, and kangite. Nanomineralogy looks at tiny particles of minerals and the minuscule features within those minerals.

"The intensive studies of objects in this meteorite have had a tremendous influence on current thinking about processes, timing, and chemistry in the primitive solar nebula and small planetary bodies," says coauthor George Rossman, the Eleanor and John R. McMillan Professor of Mineralogy at Caltech.

Panguite was observed first under a scanning electron microscope in an ultra-refractory inclusion embedded in the meteorite. Refractory inclusions are among the first solid objects formed in our solar system, dating back to before the formation of Earth and the other planets. "Refractory" refers to the fact that these inclusions contain minerals that are stable at high temperatures and in extreme environments, which attests to their likely formation as primitive, high-temperature liquids produced by the solar nebula.

According to Ma, studies of panguite and other newly discovered refractory minerals are continuing in an effort to learn more about the conditions under which they formed and subsequently evolved. "Such investigations are essential to understand the origins of our solar system," he says.

Additional authors on the American Mineralogist paper, "Panguite, (Ti4+,Sc,Al,Mg,Zr,Ca)1.8O3, a new ultra-refractory titania mineral from the Allende meteorite: Synchrotron micro-diffraction and EBSD," are John R. Beckett, senior research scientist at Caltech; Oliver Tschauner from the University of Nevada–Las Vegas; and Wenjun Liu from the Argonne National Laboratory. The study was supported through grants from the National Science Foundation, the U.S. Department of Energy, and NASA's Office of Space Science.  

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Katie Neith
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Notes from the Back Row: "The Isotope Time Machine"

Were dinosaurs slow and stupid, as used to be the prevailing wisdom, or nimble and smart enough to eat an attorney, as in the 1993 film Jurassic Park? The answer depends largely on whether the T. Rex in question is cold blooded, like an alligator—although gators, in a shocking lack of professional courtesy, are fully capable of chowing down on counsel—or warm blooded, like a bird. This is because creatures capable of maintaining a constant body temperature, regardless of their environment, generally also have the energy to move fast and think quickly. There's only one sure way to settle the debate, but taking the temperature of an animal that's been extinct for 150 million years poses certain obvious problems.

Fortunately, John Eiler, the Robert P. Sharp Professor of Geology and professor of geochemistry, has mastered the art of time travel without leaving the lab. His time machine is a mass spectrometer, a device that separates atoms of different weights in a process he likens to the workings of "a good, old-fashioned television set from the days when TV sets were the size of smart cars." Atoms of a given element that have different weights are called isotopes, and in his Watson Lecture on February 29, 2012, Eiler shows how isotope analysis can not only take a dinosaur's temperature, but perhaps tell us why they died. It's CSI: Jurassic Park.

"The Isotope Time Machine" is available for download in HD from Caltech on iTunesU. (Episode 9)

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Doug Smith
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