White House Puts Spotlight on Earthquake Early-Warning System

Since the late 1970s, Caltech seismologist Tom Heaton, professor of engineering seismology, has been working to develop earthquake early-warning (EEW) systems—networks of ground-based sensors that can send data to users when the earth begins to tremble nearby, giving them seconds to potentially minutes to prepare before the shaking reaches them. In fact, Heaton wrote the first paper published on the concept in 1985. EEW systems have been implemented in countries like Japan, Mexico, and Turkey. However, the Unites States has been slow to regard EEW systems as a priority for the West Coast.

But on February 2, 2016, the White House held the Earthquake Resilience Summit, signaling a new focus on earthquake safety and EEW systems. There, stakeholders—including Caltech's Heaton and Egill Hauksson, research professor in geophysics; and U.S. Geological Survey (USGS) seismologist Lucy Jones, a visiting associate in geophysics at Caltech and seismic risk advisor to the mayor of Los Angeles—discussed the need for earthquake early warning and explored steps that can be taken to make such systems a reality. 

At the summit, the Gordon and Betty Moore Foundation announced $3.6 million in grants to advance a West Coast EEW system called ShakeAlert, which received an initial $6 million in funding from foundation in 2011. The new grants will go to researchers working on the system at Caltech, the USGS, UC Berkeley, and the University of Washington.

"We have been successfully operating a demonstration system for several years, and we know that it works for the events that have happened in the test period," says Heaton. "However, there is still significant development that is required to ensure that the system will work reliably in very large earthquakes similar to the great 1906 San Francisco earthquake. This new funding allows us to accelerate the rate at which we develop this critical system."

In addition, the Obama Administration outlined new federal commitments to support greater earthquake safety including an executive order to ensure that new construction of federal buildings is up to code and that federal assets are available for recovery efforts after a large earthquake.

The commitments follow a December announcement from Congressman Adam Schiff (D-Burbank) that Congress has included $8.2 million in the fiscal year 2016 funding bill specifically designated for a West Coast earthquake early warning system.

"By increasing the funding for the West Coast earthquake early-warning system, Congress is sending a message to the Western states that it supports this life-saving system. But the federal government cannot do it alone and will need local stakeholders, both public and private, to get behind the effort with their own resources," said Schiff, in a press release. "The early warning system will give us critical time for trains to be slowed and surgeries to be stopped before shaking hits—saving lives and protecting infrastructure. This early warning system is an investment we need to make now, not after the 'big one' hits."

ShakeAlert utilizes a network of seismometers—instruments that measure ground motion—widely scattered across the Western states. In California, that network of sensors is called the California Integrated Seismic Network (CISN) and is made up of computerized seismometers that send ground-motion data back to research centers like the Seismological Laboratory at Caltech.

Here's how the current ShakeAlert works: a user display opens in a pop-up window on a recipient's computer as soon as a significant earthquake occurs in California. The screen lists the quake's estimated location and magnitude based on the sensor data received to that point, along with an estimate of how much time will pass before the shaking reaches the user's location. The program also gives an approximation of how intense that shaking will be. Since ShakeAlert uses information from a seismic event in progress, people living near the epicenter do not get much—if any—warning, but those farther away could have seconds or even tens of seconds' notice.

The goal is an improved version of ShakeAlert that will eventually give schools, utilities, industries, and the general public a heads-up in the event of a major temblor.

Read more about how ShakeAlert works and about Caltech's development of EEW systems in a feature that ran in the Summer 2013 issue of E&S magazine called Can We Predict Earthquakes?

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White House Spotlights Quake Warning System
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On February 2, 2016, the White House held the Earthquake Resilience Summit, signaling a new focus on earthquake safety and EEW systems.

A New Power Source for Earth's Dynamo

The earth's global magnetic field plays a vital role in our everyday lives, shielding us from harmful solar radiation. The magnetic field, which has existed for billions of years, is caused by a dynamo—or generator—within the mostly molten iron in the earth's interior; this liquid iron churns in a process called convection. But convection does not happen on its own. It needs a driving force—a power source. Now, graduate student Joseph O'Rourke and David Stevenson, Caltech's Marvin L. Goldberger Professor of Planetary Science, have proposed a new mechanism that can power this convection in the earth's interior for all of the earth's history.

A paper detailing the findings appears in the January 21 issue of Nature.

Convection can be seen in such everyday phenomena as a pot of boiling water. Heat at the bottom of the pot causes pockets of fluid to become less dense than the surrounding fluid, and thus to rise. When they reach the surface, the pockets of fluid cool and sink again. This same process occurs in the 1,400-mile-thick layer of molten metal that makes up the outer core.

The earth consists mostly of the mantle (solid material made of oxides and silicate in which magnesium is prominent) and the core (mainly iron). These two regions are usually thought of as completely separated; that is, the mantle materials do not dissolve in the core materials. They do not mix at the atomic level, much as water does not usually mix with oil. The core has a solid inner part that has been slowly growing throughout the earth's history, as liquid iron in the planet's interior solidifies. The outer, liquid part of the core is a layer of molten iron mixed with other elements, including silicon, oxygen, nickel, and a small amount of magnesium. Stevenson and O'Rourke propose that the transfer of the element magnesium in the form of mantle minerals from the outer core to the base of the mantle is the mechanism that powers convection.

Magneisum is a major element in the mantle, but it has low solubility in the iron core except at very high temperatures—above 7,200 degrees Fahrenheit. As the earth's core cools, magnesium oxides and magnesium silicates crystallize from the metallic, liquid outer core, much as sugar that has been dissolved in hot water will precipitate as sugar crystals when the water cools. Because these crystals are less dense than iron, they rise to the base of the mantle. The heavier liquid metal left behind then sinks, and this motion, Stevenson argues, may be the mechanism that has sustained convection for over three billion years—the mechanism that in turn powers the global magnetic field.

"Precipitation of magnesium-bearing minerals from the outer core is 10 times more effective at driving convection than growth of the inner core," O'Rourke says. "Such minerals are very buoyant and the resulting fluid motions can transport heat effectively. The core only needs to precipitate upwards a layer of magnesium minerals 10 kilometers thick—which seems like a lot, but it's not much on the scale of the inner and outer cores—in order to drive the outer core's convection."

Previous models assumed that the steady cooling of iron in the inner core would release heat that could power convection. But most measurements and theory in the past few years for the thermal conductivity of iron—the property that determines how efficiently heat can flow through a metal—indicates that the metal can easily transfer heat without undergoing motion. "Heating up iron at the bottom of the outer core will not cause it to rise up buoyantly—it's just going to dissipate the heat to its surroundings," O'Rourke says.

"Dave had the idea of a magnesium-powered dynamo for a while, but there was supposed to be no magnesium in Earth's core," O'Rourke says. "Now, models of planetary formation in the early solar system are showing that Earth underwent frequent impacts with giant planetary bodies. If these violent, energetic events occurred, Earth would have been experiencing much higher temperatures during its formation than previously thought—temperatures that would have been high enough to allow some magnesium to mix into liquid metallic iron."

These models made it possible to pursue the idea that the dynamo may be powered by the precipitation of magnesium-bearing minerals. O'Rourke calculated that the amounts of magnesium that would have dissolved in the core during Earth's hot early stages would have caused other changes in the composition of the mantle that are consistent with other models and measurements. He also calculated that the precipitation of these magnesium minerals would have enough energy to power the dynamo for four billion years.

Experimental verification of the amount of magnesium that can go into the core is still sparse, O'Rourke and Stevenson say. "Further applications of our proposed mechanism include Venus—where there is no magnetic field—and the abundant exoplanets that are more massive than the Earth but may have similar chemical compositions," Stevenson says.

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Caltech Researchers Find Evidence of a Real Ninth Planet

Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.

The researchers, Konstantin Batygin and Mike Brown, discovered the planet's existence through mathematical modeling and computer simulations but have not yet observed the object directly.

"This would be a real ninth planet," says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy. "There have only been two true planets discovered since ancient times, and this would be a third. It's a pretty substantial chunk of our solar system that's still out there to be found, which is pretty exciting."

Brown notes that the putative ninth planet—at 5,000 times the mass of Pluto—is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighborhood of the solar system. In fact, it dominates a region larger than any of the other known planets—a fact that Brown says makes it "the most planet-y of the planets in the whole solar system."

Batygin and Brown describe their work in the current issue of the Astronomical Journal and show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt.

"Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there," says Batygin, an assistant professor of planetary science. "For the first time in over 150 years, there is solid evidence that the solar system's planetary census is incomplete."

The road to the theoretical discovery was not straightforward. In 2014, a former postdoc of Brown's, Chad Trujillo, and his colleague Scott Sheppard published a paper noting that 13 of the most distant objects in the Kuiper Belt are similar with respect to an obscure orbital feature. To explain that similarity, they suggested the possible presence of a small planet. Brown thought the planet solution was unlikely, but his interest was piqued.

He took the problem down the hall to Batygin, and the two started what became a year-and-a-half-long collaboration to investigate the distant objects. As an observer and a theorist, respectively, the researchers approached the work from very different perspectives—Brown as someone who looks at the sky and tries to anchor everything in the context of what can be seen, and Batygin as someone who puts himself within the context of dynamics, considering how things might work from a physics standpoint. Those differences allowed the researchers to challenge each other's ideas and to consider new possibilities. "I would bring in some of these observational aspects; he would come back with arguments from theory, and we would push each other. I don't think the discovery would have happened without that back and forth," says Brown. " It was perhaps the most fun year of working on a problem in the solar system that I've ever had."

Fairly quickly Batygin and Brown realized that the six most distant objects from Trujillo and Sheppard's original collection all follow elliptical orbits that point in the same direction in physical space. That is particularly surprising because the outermost points of their orbits move around the solar system, and they travel at different rates.

"It's almost like having six hands on a clock all moving at different rates, and when you happen to look up, they're all in exactly the same place," says Brown. The odds of having that happen are something like 1 in 100, he says. But on top of that, the orbits of the six objects are also all tilted in the same way—pointing about 30 degrees downward in the same direction relative to the plane of the eight known planets. The probability of that happening is about 0.007 percent. "Basically it shouldn't happen randomly," Brown says. "So we thought something else must be shaping these orbits."

The first possibility they investigated was that perhaps there are enough distant Kuiper Belt objects—some of which have not yet been discovered—to exert the gravity needed to keep that subpopulation clustered together. The researchers quickly ruled this out when it turned out that such a scenario would require the Kuiper Belt to have about 100 times the mass it has today.

That left them with the idea of a planet. Their first instinct was to run simulations involving a planet in a distant orbit that encircled the orbits of the six Kuiper Belt objects, acting like a giant lasso to wrangle them into their alignment. Batygin says that almost works but does not provide the observed eccentricities precisely. "Close, but no cigar," he says.

Then, effectively by accident, Batygin and Brown noticed that if they ran their simulations with a massive planet in an anti-aligned orbit—an orbit in which the planet's closest approach to the sun, or perihelion, is 180 degrees across from the perihelion of all the other objects and known planets—the distant Kuiper Belt objects in the simulation assumed the alignment that is actually observed.

"Your natural response is 'This orbital geometry can't be right. This can't be stable over the long term because, after all, this would cause the planet and these objects to meet and eventually collide,'" says Batygin. But through a mechanism known as mean-motion resonance, the anti-aligned orbit of the ninth planet actually prevents the Kuiper Belt objects from colliding with it and keeps them aligned. As orbiting objects approach each other they exchange energy. So, for example, for every four orbits Planet Nine makes, a distant Kuiper Belt object might complete nine orbits. They never collide. Instead, like a parent maintaining the arc of a child on a swing with periodic pushes, Planet Nine nudges the orbits of distant Kuiper Belt objects such that their configuration with relation to the planet is preserved.

"Still, I was very skeptical," says Batygin. "I had never seen anything like this in celestial mechanics."

But little by little, as the researchers investigated additional features and consequences of the model, they became persuaded. "A good theory should not only explain things that you set out to explain. It should hopefully explain things that you didn't set out to explain and make predictions that are testable," says Batygin.

And indeed Planet Nine's existence helps explain more than just the alignment of the distant Kuiper Belt objects. It also provides an explanation for the mysterious orbits that two of them trace. The first of those objects, dubbed Sedna, was discovered by Brown in 2003. Unlike standard-variety Kuiper Belt objects, which get gravitationally "kicked out" by Neptune and then return back to it, Sedna never gets very close to Neptune. A second object like Sedna, known as 2012 VP113, was announced by Trujillo and Sheppard in 2014. Batygin and Brown found that the presence of Planet Nine in its proposed orbit naturally produces Sedna-like objects by taking a standard Kuiper Belt object and slowly pulling it away into an orbit less connected to Neptune.


A predicted consequence of Planet Nine is that a second set of confined objects should also exist. These objects are forced into positions at right angles to Planet Nine and into orbits that are perpendicular to the plane of the solar system. Five known objects (blue) fit this prediction precisely.
Credit: Caltech/R. Hurt (IPAC) [Diagram was created using WorldWide Telescope.]

But the real kicker for the researchers was the fact that their simulations also predicted that there would be objects in the Kuiper Belt on orbits inclined perpendicularly to the plane of the planets. Batygin kept finding evidence for these in his simulations and took them to Brown. "Suddenly I realized there are objects like that," recalls Brown. In the last three years, observers have identified four objects tracing orbits roughly along one perpendicular line from Neptune and one object along another. "We plotted up the positions of those objects and their orbits, and they matched the simulations exactly," says Brown. "When we found that, my jaw sort of hit the floor."

"When the simulation aligned the distant Kuiper Belt objects and created objects like Sedna, we thought this is kind of awesome—you kill two birds with one stone," says Batygin. "But with the existence of the planet also explaining these perpendicular orbits, not only do you kill two birds, you also take down a bird that you didn't realize was sitting in a nearby tree."

Where did Planet Nine come from and how did it end up in the outer solar system? Scientists have long believed that the early solar system began with four planetary cores that went on to grab all of the gas around them, forming the four gas planets—Jupiter, Saturn, Uranus, and Neptune. Over time, collisions and ejections shaped them and moved them out to their present locations. "But there is no reason that there could not have been five cores, rather than four," says Brown. Planet Nine could represent that fifth core, and if it got too close to Jupiter or Saturn, it could have been ejected into its distant, eccentric orbit.

Batygin and Brown continue to refine their simulations and learn more about the planet's orbit and its influence on the distant solar system. Meanwhile, Brown and other colleagues have begun searching the skies for Planet Nine. Only the planet's rough orbit is known, not the precise location of the planet on that elliptical path. If the planet happens to be close to its perihelion, Brown says, astronomers should be able to spot it in images captured by previous surveys. If it is in the most distant part of its orbit, the world's largest telescopes—such as the twin 10-meter telescopes at the W. M. Keck Observatory and the Subaru Telescope, all on Mauna Kea in Hawaii—will be needed to see it. If, however, Planet Nine is now located anywhere in between, many telescopes have a shot at finding it.

"I would love to find it," says Brown. "But I'd also be perfectly happy if someone else found it. That is why we're publishing this paper. We hope that other people are going to get inspired and start searching."

In terms of understanding more about the solar system's context in the rest of the universe, Batygin says that in a couple of ways, this ninth planet that seems like such an oddball to us would actually make our solar system more similar to the other planetary systems that astronomers are finding around other stars. First, most of the planets around other sunlike stars have no single orbital range—that is, some orbit extremely close to their host stars while others follow exceptionally distant orbits. Second, the most common planets around other stars range between 1 and 10 Earth-masses.

"One of the most startling discoveries about other planetary systems has been that the most common type of planet out there has a mass between that of Earth and that of Neptune," says Batygin. "Until now, we've thought that the solar system was lacking in this most common type of planet. Maybe we're more normal after all."

Brown, well known for the significant role he played in the demotion of Pluto from a planet to a dwarf planet adds, "All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found," he says. "Now we can go and find this planet and make the solar system have nine planets once again."

The paper is titled "Evidence for a Distant Giant Planet in the Solar System."

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The giant planet, nicknamed Planet Nine, traces a bizarre, highly elongated orbit in the outer solar system.

15 for 2015: The Year in Research News at Caltech

The year 2015 proved to be another groundbreaking year for research at Caltech. From seeing quantum motion, to reconfiguring jellyfish limbs, to measuring stellar magnetic fields, researchers continued to ask and answer the deepest scientific questions.

In case you missed any of them, here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.

 

 

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Here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.

Developing a Picture of the Earth's Mantle

Deep inside the earth, seismic observations reveal that three distinct structures make up the boundary between the earth's metallic core and overlying silicate mantle at a depth of about 2,900 kilometers—an area whose composition is key to understanding the evolution and dynamics of our planet. These structures include remnants of subducted plates that originated near the earth's surface, ultralow-velocity zones believed to be enriched in iron, and large dense provinces of unknown composition and mineralogy. A team led by Caltech's Jennifer Jackson, professor of mineral physics has new evidence for the origin of these features that occur at the core-mantle boundary.

"We have discovered that bridgmanite, the most abundant mineral on our planet, is a reasonable candidate for the material that makes up these dense provinces that occupy about 20 percent of the core-mantle boundary surface, and rise up to a depth of about 1,500 kilometers. Integrated by volume that's about the size of our moon!" says Jackson, coauthor of a study that outlines these findings and appears online in the Journal of Geophysical Research: Solid Earth. "This finding represents a breakthrough because although bridgmanite is the earth's most abundant mineral, we only recently have had the ability to precisely measure samples of it in an environment similar to what we think the materials are experiencing inside the earth."

Previously, says Jackson, it was not clear whether bridgmanite, a perovskite structured form of (Mg,Fe)SiO3, could explain seismic observations and geodynamic modeling efforts of these large dense provinces. She and her team show that indeed they do, but these structures need to be propped up by external forces, such as the pinching action provided by cold and dense subducted slabs at the base of the mantle.

Jackson, along with then Caltech graduate student Aaron Wolf (PhD '13), now a research scientist at the University of Michigan at Ann Arbor, and researchers from Argonne National Laboratory, came to these conclusions by taking precise X-ray measurements of synthetic bridgmanite samples compressed by diamond anvil cells to over 1 million times the earth's atmospheric pressure and heated to thousands of degrees Celsius.

The measurements were done utilizing two different beamlines at the Advanced Photon Source of Argonne National Laboratory in Illinois, where the team used powerful X-rays to measure the state of bridgmanite under the physical conditions of the earth's lower mantle to learn more about its stiffness and density under such conditions. The density controls the buoyancy—whether or not these bridgmanite provinces will lie flat on the core-mantle boundary or rise up. This information allowed the researchers to compare the results to seismic observations of the core-mantle boundary region.

"With these new measurements of bridgmanite at deep-mantle conditions, we show that these provinces are very likely to be dense and iron-rich, helping them to remain stable over geologic time," says Wolf.

Using a technique known as synchrotron Mössbauer spectroscopy, the team also measured the behavior of iron in the crystal structure of bridgmanite, and found that iron-bearing bridgmanite remained stable at extreme temperatures (more than 2,000 degrees Celsius) and pressure (up to 130 gigapascals). There had been some reports that iron-bearing bridgmanite breaks down under extreme conditions, but the team found no evidence for any breakdown or reactions.

"This is the first study to combine high-accuracy density and stiffness measurements with Mössbauer spectroscopy, allowing us to pinpoint iron's behavior within bridgmanite," says Wolf. "Our results also show that these provinces cannot possibly contain a large complement of radiogenic elements, placing strong constraints on their origin. If present, these radiogenic elements would have rapidly heated and destabilized the piles, contradicting many previous simulations that indicate that they are likely hundreds of millions of years old."

In addition, the experiments suggest that the rest of the lower mantle is not 100 percent bridgmanite as had been previously suggested. "We've shown that other phases, or minerals, must be present in the mantle to satisfy average geophysical observations," says Jackson. "Until we made these measurements, the thermal properties were not known with enough precision and accuracy to uniquely constrain the mineralogy."

"There is still a lot of work to be done, such as identifying the dynamics of subducting slabs, which we believe plays a role in providing an external force to shape these large bridgmanite provinces," she says. "We know that the earth did not start out this way. The provinces had to evolve within the global system, and we think these findings may help large-scale geodynamic modeling that involves tectonic plate reconstructions."

The results of the study were published in a paper titled "The thermal equation of state of (Mg,Fe)SiO3bridgmanite (perovskite) and implications for lower mantle structures." In addition to Jackson and Wolf, other authors on the study are Przemeslaw Dera and Vitali B. Prakapenka from the Center for Advanced Radiation Sources at Argonne National Laboratory. Support for this research was provided by the National Science Foundation, the Turner Postdoctoral Fellowship at the University of Michigan, and the California Institute of Technology.

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A team led by Caltech's Jennifer Jackson, professor of mineral physics has new evidence for the origin of features that occur at the core-mantle boundary.

15 for 2015: The Year in Research News at Caltech

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15 for 2015: The Year in Research News at Caltech
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Credit: K.Batygin/Caltech

New Research Suggests Solar System May Have Once Harbored Super-Earths

Thanks to recent surveys of exoplanets—planets in solar systems other than our own—we know that most planetary systems typically have one or more super-Earths (planets that are substantially more massive than Earth but less massive than Neptune) orbiting closer to their suns than Mercury does. In March, researchers showed that our own solar system may have once had these super-Earths, but they were destroyed by Jupiter's inward and outward migration through the solar system. This migration would have gravitationally flung small planetesimals through the solar system, setting off chains of collisions that would push any interior planets into the sun.
Credit: Lance Hayashida/Caltech and the Hoelz Laboratory/Caltech

Caltech Biochemists Shed Light on Cellular Mystery

The nuclear pore complex (NPC) is an intricate portal linking the cytoplasm of a cell to its nucleus. It is made up of many copies of about 34 different proteins. Around 2,000 NPCs are embedded in the nuclear envelope of a single human cell and each NPC shuttles hundreds of macromolecules of different shapes and sizes between the cytoplasm and nucleus. In February, Caltech biochemists determined the structure of a significant portion of the NPC called the outer rings; in August, the same group solved the structure of the pore's inner ring. Understanding the structure of the NPC could lead to new classes of cancer drugs as well as antiviral medicines.
Credit: iStockphoto

Research Suggests Brain's Melatonin May Trigger Sleep

For decades, supplemental melatonin has been sold over the counter as a sleep aid despite the absence of scientific evidence proving its effectiveness. Few studies have investigated melatonin produced naturally in the human body. This March, Caltech researchers studying zebrafish—animals that, like humans, are awake during the day and asleep at night—determined that the melatonin hormone does help the body fall asleep and stay asleep. Specifically, they found that zebrafish larvae that could not produce melatonin slept for only half as long as normal larvae.
Credit: Gregg Hallinan/Caltech

Advances in Radio Astronomy

In May, a new radio telescope array called the Owens Valley Long Wavelength Array (OV-LWA) saw its first light. Developed by a consortium led by Caltech, the OV-LWA has the ability to image simultaneously the entire sky at radio wavelengths with unmatched speed, helping astronomers to search for objects and phenomena that pulse, flicker, flare, or explode.

In July, Caltech researchers used both radio and optical telescopes to observe a brown dwarf located 20 light-years away and found that these so-called failed stars host powerful auroras near their magnetic poles.
Credit: Michael Abrams and Ty Basinger

Injured Jellyfish Seek to Regain Symmetry

Some kinds of animals can regrow lost limbs and body parts, but moon jellyfish have a different strategy. In June, Caltech researchers reported that the star-shaped eight-armed moon jellyfish rearranges itself when injured to maintain symmetry. It is hypothesized that the rearrangement helps to preserve the jellyfish's propulsion mechanism.
Credit: NASA/JPL-Caltech

Geologists Characterize Nepal Earthquake

In April, a magnitude 7.8 earthquake rocked Nepal. While the damage was extensive, it was not as severe as many geologists predicted. This year, a Caltech team of geologists used satellite radar imaging data and measurements from seismic instruments in Nepal to create models of fault rupture and ground movement. They found that the quake ruptured only a small fraction of the "locked" tectonic plate and that there is still the potential for the locked portion to produce a large earthquake.
Credit: Caltech/JPL

New Polymer Creates Safer Fuels

Plane crashes cause devastating damage, but this damage is often exacerbated by the highly explosive nature of jet fuel. This October, researchers at Caltech and JPL discovered a polymeric fuel additive that can reduce the intensity of postimpact explosions that occur during accidents and crashes. Preliminary results show that the additive can provide this benefit without adversely affecting fuel performance. The polymer works by inhibiting "misting"—the process that causes fuel to rapidly disperse and easily catch fire—under crash conditions.
Credit: Spencer Kellis/Caltech

Controlling a Robotic Arm with a Patient's Intentions

When you reach for a glass of water, you do not consciously think about moving your arm muscles or grasping with your fingers—you think about the goal of the movement. This May, by implanting neural prosthetic devices into the posterior parietal cortex (PCC)—the region of the brain that governs intentions for movement—rather than the motor cortex, which controls movement, Caltech researchers enabled a paralyzed patient to more smoothly and naturally control a prosthetic limb. In November, the researchers showed that there are individual neurons in the PPC that encode for entire hand shapes, such as those used for grasping or gesturing.

 

Caltech Scientists Develop Cool Process to Make Better Graphene

Graphene is an ultrastrong and conductive material made of a single layer of carbon atoms. While it is a promising material for scientific and engineering advances, manufacturing it on an industrially relevant scale has proven to be impractical, requiring temperatures of around 1,800 degrees Fahrenheit and long periods of time. A new technique invented at Caltech allows the speedy production of graphene—in just a few minutes—at room temperatures. The technique also produces graphene that is stronger, smoother, and more electrically conductive than normally produced synthetic graphene.
Credit: Rafael A. García (SAp CEA), Kyle Augustson (HAO), Jim Fuller (Caltech) & Gabriel Pérez (SMM, IAC), Photograph from AIA/SDO

Astronomers Peer Inside Stars, Finding Giant Magnets

Before this October, astronomers have only been able to study the magnetic fields of stars on the stellar surfaces. Now, using a technique called asteroseismology, scientists were able to probe the fusion-powered hearts of dozens of red giants (stars that are evolved versions of our sun) to calculate the magnetic field strengths inside those stars. They found that the internal magnetic fields of the red giants were as much as 10 million times stronger than Earth's magnetic field. Magnetic fields play a key role in the interior rotation rate of stars, which has a dramatic effect on how the stars evolve.
Credit: Chan Lei and Keith Schwab/Caltech

Seeing Quantum Motion

To the casual observer, an object at rest is just that—at rest, motionless. But on the subatomic scale, the object is most certainly in motion—quantum mechanical motion. Quantum motion, or noise, is ever-present in nature, and in August, Caltech researchers discovered how to observe and manipulate that motion in a small device. By creating what they called a "quantum squeezed state," they were able to periodically reduce the quantum fluctuations of the device. The ability to control quantum noise could one day be used to improve the precision of very sensitive measurements.
Credit: Ali Hajimiri/Caltech

New Camera Chip Provides Superfine 3-D Resolution

3-D printing can produce a wide array of objects in relatively little time, but first the printer needs to have a blueprint of what to print. The blueprints are provided by 3-D cameras, which scan objects and create models for the printer. Caltech researchers have now developed a 3-D camera that produces the highest depth-measurement accuracy of any similar device, allowing it to deliver replicas of an object to be 3-D printed within microns of similarity to the original object. In addition, the camera, known as a nanophotonic coherent imager, is inexpensive and small.
Credit: Image provided courtesy of Joint Center for Artificial Photosynthesis; artwork by Darius Siwek.

One Step Closer to Artificial Photosynthesis and 'Solar Fuels'

Plants are masters of photosynthesis—the process of turning carbon dioxide, sunlight, and water into oxygen and sugar. Inspired by this natural and energy-efficient process, Caltech researchers have created an "artificial leaf" that takes in CO2, sunlight, and water to produce hydrogen fuels. This solar-powered system, one researcher says, shatters all of the combined safety, performance, and stability records for artificial leaf technology by factors of 5 to 10 or more.
Credit: Santiago Lombeyda and Robin Betz

Potassium Salt Outperforms Precious Metals As a Catalyst

Rare precious metals have been the standard catalyst for the formation of carbon-silicon bonds, a process crucial to the synthesis of a host of products from new medicines to advanced materials. However, they are expensive, inefficient, and produce toxic waste byproducts. This February, Caltech researchers discovered a much more sustainable catalyst in the form of a simple potassium salt that is one of the most abundant metals on Earth and thousands of times less expensive than other commonly used catalysts. In addition, the potassium salt is much more effective at running challenging chemical reactions than state-of-the-art precious metal complexes.
Credit: Qi Zhao/National University of Singapore

Probing the Mysterious Perceptual World of Autism

The way in which people with autism spectrum disorder (ASD) perceive the world is unique. It has been a long-standing belief that people with ASD often miss facial cues, contributing to impaired social interaction. In a study published in October, Caltech researchers showed 700 images to 39 subjects and found that people with ASD pay closer attention to simple edges and patterns in images than to the faces of people. The study also found that subjects were strongly attracted to the center of images—regardless of what was placed there—and to differences in color and contrast rather than facial features. These findings may help doctors diagnose and more effectively treat the different forms of autism.
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The year 2015 proved to be another groundbreaking year for research at Caltech. From seeing quantum motion, to reconfiguring jellyfish limbs, to measuring stellar magnetic fields, researchers continued to ask and answer the deepest scientific questions.

In case you missed any of them, here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.

Written by Lori Dajose

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The Interface of Earth and Atmosphere: An Interview with Christian Frankenberg

Plants are an important mediator between the earth and the atmosphere. In order to grow, they breathe in carbon dioxide—one of the major greenhouse gases. Caltech associate professor Christian Frankenberg is interested in this relationship and how the biosphere reacts to climate change.

A native of Germany, Frankenberg earned a Diploma degree at the University of Bayreuth and a PhD at Ruprecht-Karls-University in Heidelberg. He spent the past five years as a research scientist at JPL and joined the Caltech faculty this fall. We recently spoke with Frankenberg about remote sensing, the biosphere, and life in Pasadena.

What do you do?

I use remote sensing tools—based on spectrometers in space and the air—to gain a deeper understanding of the carbon cycle. This means making measurements of atmospheric greenhouse gases like carbon dioxide and methane as well as measuring plant activity by sensing solar-induced chlorophyll fluorescence from space. Chlorophyll fluorescence happens when plants take in sunlight. A tiny fraction of that sunlight gets emitted at a slightly longer wavelength. We can see this glow from space, and it is a good proxy of the photosynthetic uptake of CO2 by plants.

One of my goals is to combine the atmospheric measurements and the fluorescence measurements to gain a deeper understanding of when, where, and why the carbon cycle changes. I work with the Orbiting Carbon Observatory 2 (OCO-2) at JPL, and also with a Japanese project called the Greenhouse Gases Observing Satellite (GOSAT).

Why is it important to understand the carbon cycle?

Many people are familiar with the famous Keeling Curve—a ground-based measurement of atmospheric carbon dioxide that has been ongoing since 1958. This curve shows a continual increase in CO2 abundances from year to year, but it also shows a strong seasonal cycle—abundances go up in winter and down in summer. This is because in the Northern Hemisphere summer, plants are growing and removing CO2 from the atmosphere; in winter, plants are releasing CO2.

If we count all the barrels of oil and everything else that we burn to release CO2, only about one-half of it remains in the atmosphere. One-fourth goes into the oceans, and the rest is taken up by vegetation. The biosphere is doing us a big favor in taking up a lot of what we're emitting, but we don't know exactly where on Earth that vegetation is absorbing the most or if will it persist in the future.

What can we do to improve our relationship with the biosphere?

There's always talk about reducing CO2 emissions, which is great, but often actions are pound-foolish and penny-wise. I think energy efficiency is a big factor in improving our relationship with the biosphere. This means probably not having single-pane windows, and it definitely means not running the air conditioning and the heater at the same time, which I've seen (too often)! I do see a great opportunity for clean solar power in California—there's so much sun!

How did you get interested in biogeosciences?

At school I liked natural sciences, like math and chemistry, but I didn't want to focus on just one of them. During my undergraduate education, I studied geoecology, which gives a broad background of all the natural sciences. But I found out pretty quickly that I liked the more quantitative stuff, so I focused on the physics, math, and chemistry aspects, and did my PhD in environmental physics. That's where I started working on remote sensing. I really liked it; the combination of working with the biosphere but also doing more technical work suited me. Now it seems I'm making a full turn again with my plant-based research. It's like going back to my geoecology roots.

What brought you to Caltech?

I've always been interested in Caltech, but after a postdoc in the Netherlands, I got a job offer from JPL—five and a half years ago. I knew that in the long term, I wanted to be in academia doing more basic research and having academic freedom.

How does your job as a professor differ from your previous appointment as a research scientist?

I still retain the title of research scientist at JPL, and I spend one day a week there. For me, it's an ideal situation to be at Caltech but still have the relationship with JPL, where so many things are happening in my field.

But now that I am on the Caltech faculty, I'll be expanding from pure remote sensing to ground-based and laboratory measurements of fluorescence and carbon exchange. We are studying the part of plants that are more relevant for the global carbon cycle, connecting the leaf scale to the global scale. Additionally, I will start teaching courses in the next academic year, which will probably be the biggest change.

What do you like about being in Southern California?

I like the mountains a lot. Pasadena is a nice combination of having a small-town feeling next to the foothills but also having a big city nearby if you want it. It's a sweet spot. What I miss most from Europe is the ability to just bike everywhere you need to go. There is no way to get around without a car here in the L.A. area.

What do you do outside of work?

I try to let the weekend be a weekend and not let it be too busy. I like getting outdoors, hiking and running, playing some soccer or squash. And, of course, spending time with my family and son is also a full-time sort of job.

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The Interface of Earth and Atmosphere
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An interview with Christian Frankenberg, an atmospheric and biogeoscientist and one of the most recent additions to the Caltech faculty.

Tracking Down the "Missing" Carbon From the Martian Atmosphere

Caltech and JPL scientists suggest the fingerprints of early photochemistry provide a solution to the long-standing mystery

Mars is blanketed by a thin, mostly carbon dioxide atmosphere—one that is far too thin to prevent large amounts of water on the surface of the planet from subliming or evaporating. But many researchers have suggested that the planet was once shrouded in an atmosphere many times thicker than Earth's. For decades that left the question, "Where did all the carbon go?"

Now a team of scientists from Caltech and JPL thinks they have a possible answer. The researchers suggest that 3.8 billion years ago, Mars might have had only a moderately dense atmosphere. They have identified a photochemical process that could have helped such an early atmosphere evolve into the current thin one without creating the problem of "missing" carbon and in a way that is consistent with existing carbon isotopic measurements.

The scientists describe their findings in a paper that appears in the November 24 issue of the journal Nature Communications.

"With this new mechanism, everything that we know about the martian atmosphere can now be pieced together into a consistent picture of its evolution," says Renyu Hu, a postdoctoral scholar at JPL, a visitor in planetary science at Caltech, and lead author on the paper.

When considering how the early martian atmosphere might have transitioned to its current state, there are two possible mechanisms for the removal of excess carbon dioxide (CO2). Either the CO2 was incorporated into minerals in rocks called carbonates or it was lost to space.

A separate recent study coauthored by Bethany Ehlmann, assistant professor of planetary science and a research scientist at JPL, used data from several Mars-orbiting satellites to inventory carbonate rocks, showing that there are not enough carbonates in the upper kilometer of crust to contain the missing carbon from a very thick early atmosphere that might have existed about 3.8 billion years ago.

To study the escape-to-space scenario, scientists examine the ratio of carbon-12 and carbon-13, two stable isotopes of the element carbon that have the same number of protons in their nuclei but different numbers of neutrons, and thus different masses. Because various processes can change the relative amounts of those two isotopes in the atmosphere, "we can use these measurements of the ratio at different points in time as a fingerprint to infer exactly what happened to the martian atmosphere in the past," says Hu.

To establish a starting point, the researchers used measurements of the carbon isotope ratio in martian meteorites that contain gases that originated deep in the planet's mantle. Because atmospheres are produced by outgassing of the mantle through volcanic activity, these measurements provide insight into the isotopic ratio of the original martian atmosphere.

The scientists then compared those values to isotopic measurements of the current martian atmosphere recently collected by NASA's Curiosity rover. Those measurements show the atmosphere to be unusually enriched in carbon-13.

Previously, researchers thought the main way that martian carbon would be ejected into space was through a process called sputtering, which involves interactions between the solar wind and the upper atmosphere. Sputtering causes some particles—slightly more of the lighter carbon-12 than the heavier carbon-13—to escape entirely from Mars, but this effect is small. So there had to be some other process at work.

That is where the new mechanism comes in. In the study, the researchers describe a process that begins with a particle of ultraviolet light from the sun striking a molecule of CO2 in the upper atmosphere. That molecule absorbs the photon's energy and divides into carbon monoxide (CO) and oxygen. Then another ultraviolet particle hits the CO, causing it to dissociate into atomic carbon (C) and oxygen. Some carbon atoms produced in this way have enough energy to escape the atmosphere, and the new study shows that carbon-12 is far more likely to escape than carbon-13.

Modeling the long-term effects of this ultraviolet photodissociation mechanism coupled with volcanic gas release, loss via sputtering, and loss to carbonate rock formation, the researchers found that it was very efficient in terms of enriching carbon-13 in the atmosphere. Using the isotopic constraints, they were then able to calculate that the atmosphere 3.8 billion years ago might have had the pressure of Earth's or less under most scenarios.

"The efficiency of this new mechanism shows that there is in fact no discrepancy between Curiosity's measurements of the modern enriched value for carbon in the atmosphere and the amount of carbonate rock found on the surface of Mars," says Ehlmann, also a coauthor on the new study. "With this mechanism, we can describe an evolutionary scenario for Mars that makes sense of the apparent carbon budget, with no missing processes or reservoirs."

The authors conclude their work by pointing out several tests and refinements for the model. For example, future data from the ongoing Mars Atmosphere and Volatile EvolutioN (MAVEN) mission could provide the isotope fractionation of presently ongoing atmospheric loss to space and improve the extrapolation to early Mars.

Hu emphasizes that the work is an excellent example of multidisciplinary effort. On the one hand, he says, the team looked at the atmospheric chemistry—the isotopic signature, the escape processes, and the enrichment mechanism. On the other, they used geological evidence and remote sensing of the martian surface. "By putting these together, we were able to come up with a summary of evolutionary scenarios," says Hu. "I feel that Caltech/JPL is a unique place where we have the multidisciplinary capability and experience to make this happen."

Additional authors on the paper, "Tracing the Fate of Carbon and the Atmospheric Evolution of Mars," are Yuk Yung, the Smits Family Professor of Planetary Science at Caltech and a senior research scientist at JPL, and David Kass, a research scientist at JPL. The work was supported by funding from NASA.

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The Atmospheric Evolution of Mars
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Caltech and JPL researchers identify a process that helps explain how a moderately dense early martian atmosphere could have evolved into the current thin one.

New Jenkins Leadership Chair Is a Tribute to Exploration

Ted (BS '65, MS '66) and Ginger Jenkins—longtime Caltech supporters and early employees in the semiconductor industry—have established a leadership chair for the Division of Geological and Planetary Sciences (GPS). The new leadership chair is one of a set of discretionary endowments being established for Caltech's president, provost, and the leaders of each academic division.

"This new endowment will support some of the most exploratory work in the division and help secure our future," says John Grotzinger, the Fletcher Jones Professor of Geology and inaugural holder of the Ted and Ginger Jenkins Leadership Chair. "The completely flexible funding it provides—a rarity in geological and planetary sciences—will give me and future division chairs greater freedom to support highly creative and timely projects. By its nature our science involves complex interdisciplinary work for which flexible funding is ideal."

Ted Jenkins feels confident that this type of agility will give Caltech a competitive edge. "Possibilities come up that are not sufficiently well known or forecastable to pass the hurdles for a grant," he explains. "On the other hand, they could be worth a little bit of exploratory money. By applying extra resources to things that look exciting but uncertain, Caltech has come up with more than its fair share of interesting discoveries.

"These kinds of endowments for division chairs allow the whole Institute to go out and do this aggressive science. This, together with the other resources we have, puts us way, way ahead."

The story of the Jenkins gift can be traced back half a century to a moment of curiosity—and, admittedly, some jealousy—during Ted Jenkins's days as an engineering student at Caltech.

"The geology students were always going camping and taking field trips," he says. "They had great stories." So he jumped at the chance to take Ge 1, a class taught by the late Robert Sharp, whom he describes as an iconic geologist and leader.

Ted Jenkins's memory of that course inspired him and Ginger to sign up for a geology-focused Caltech Alumni Association (CAA) program in Alaska in 1997. Soon after, the couple's retirement freed them to travel often with the CAA and the Caltech Associates.

The more they learned about what was happening at Caltech, the more Ted and Ginger Jenkins got involved. Ted served as president of both the CAA and the Associates, and he became a Caltech trustee in 2006. He was also a founding member and chairman of the GPS chair's council, a volunteer leadership board.

"Ted and Ginger Jenkins have seen and supported Caltech from many angles," says Caltech President Thomas F. Rosenbaum, holder of the Sonja and William Davidow Presidential Chair and professor of physics. "The Institute has benefited enormously from their decades of thoughtful counsel and generosity. Their extraordinary new commitment goes even farther to position us as the destination of choice for the most imaginative scholars."

With past gifts to Caltech, the couple has endowed a professorship in information science and technology, and supported diverse initiatives across campus: two astrophysical observatories, the Community Seismic Network project, schizophrenia research, a graduate fellowship and travel funds for GPS students, an annual staff prize, improvements to the Athenaeum, and the Carver Mead New Adventures Fund, which provides early support for novel projects in information science and technology.

Ted and Ginger Jenkins see giving as a way to do their part—both for the world, through the discoveries and educational experiences they enable, and for Caltech itself.

Ted Jenkins's career, and even his marriage, hinged on a single conversation that took place in a Caltech conference room. In 1966, Gordon Moore (PhD '54) paid a visit to Jenkins's adviser Carver Mead, now Caltech's Gordon and Betty Moore Professor of Engineering and Applied Science, Emeritus. Mead introduced Moore to his students, and Moore recruited Jenkins to Fairchild Semiconductor International during that same visit. During his time at Fairchild, Ted Jenkins met the woman who would become his wife. Two years later, Moore hired him again, this time as employee number 22 at the start-up that would become Intel¾where Ted Jenkins built a three-decade career and rose to the rank of vice president.

"My Caltech experience and connections have been a huge part of the means that I was able to assemble," Ted Jenkins says. "Giving back so that the activity continues is really what I like to do."

In addition to the Jenkins chair, Caltech has received funding for the Sonja and William Davidow Presidential Chair, the Carl and Shirley Larson Provostial Chair, the William K. Bowes Jr. Leadership Chair in the Division of Biology and Biological Engineering, the Otis Booth Leadership Chair in the Division of Engineering and Applied Science, and the Kent and Joyce Kresa Leadership Chair in the Division of Physics, Mathematics and Astronomy.

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New Leadership Chair Is a Tribute to Exploration
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Ted (BS ’65, MS ’66) and Ginger Jenkins have established a leadership chair for the Division of Geological and Planetary Sciences.

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