News and Updates

07/17/2014

Asteroids named for two ASU faculty members

Two Arizona State University professors can add an unusual honor to the long list of accolades they have received: An asteroid has been named after each of them. This ‘out-of-this-world’ honor has been conferred on professors Phil Christensen and Dave Williams. The two planetary geologists, both faculty members in ASU’s School of Earth and Space Exploration, now have even more reason to be gazing at the night sky.

You know the names of our solar system’s planets, but you might not have realized that thousands of asteroids and minor planets revolving around the sun also have names.

Asteroid (10461) Dawilliams was discovered on December 6, 1978, by E. Bowell and A. Warnock at Palomar Observatory. It orbits about 2.42 astronomical units from the Earth in the Main Belt, the vast asteroid belt located between the orbits of Mars and Jupiter.

Despite Hollywood’s love of Earth-smashing asteroid blockbusters, Williams has no worries that “his” asteroid will make doomsday headlines.

“It’s very unlikely that it will hit Earth, as it is in a stable orbit in the Main Belt,” explains Williams.
Also honored with an asteroid named for his work is Christensen, the instrument scientist for the OSIRIS-Rex Thermal Emission Spectrometer, a mineral-scouting instrument on the OSIRIS-REx mission to asteroid Bennu. He was also the principal investigator for the infrared spectrometers and imagers on NASA’s Mars Global Surveyor, Mars Odyssey, and Mars Exploration Rovers.

The asteroid is named (90388) Philchristensen and like Williams’ it too is a Main Belt asteroid that is relatively small – approximately 4.6 kilometers (2.8 miles) across. It was discovered November 24, 2003 by the Catalina Sky Survey. It also poses no risk of collision with Earth.

“My research has long focused on Mars,” says Christensen. “But my broader interests involve all solar system bodies, and I’ve spent the last several years working on an asteroid mission. I really appreciate this honor.”

What’s in a name?
Having a namesake in the sky is no small honor. Unlike the selling of star names over the Internet, the naming of asteroids is serious business, presided over by the International Astronomical Union, an organization of professional astronomers.

Upon its discovery, an asteroid is assigned a provisional designation by the Minor Planet Center of the IAU that involves the year of discovery, two letters and, if need be, further digits. When its orbit can be reliably predicted, the asteroid receives a permanent number and becomes eligible for naming. Proposed names must be approved by the IAU’s Committee on Small Body Nomenclature.

Although many objects end up being named after astronomers and other scientists, some discoverers have named the object after celebrities. All four Beatles have their names on asteroids, for example, and there is even one named after James Bond – Asteroid (9007) James Bond.

“I was very surprised to receive this honor from the astronomical community. Only a select few of the Dawn at Vesta participating scientists, who did exemplary work during the mission, were so honored,” said Williams, whose expertise in mapping of volcanic surfaces has been key to developing geologic maps of planetary bodies that include Mars, Io and Vesta.

Christensen and Williams share this honor with several colleagues in the School of Earth and Space Exploration. The following all have namesakes in the sky:

  • Professor Erik Asphaug - Asteroid (7939) Asphaug
  • Professor Jim Bell - Asteroid (8146) Jimbell
  • Foundation Professor and SESE Director Lindy Elkins-Tanton - Asteroid (8252) Elkins-Tanton
  • Professor Emeritus Ronald Greeley - Asteroid (30785) Greeley, and Greeley’s Haven (on Mars)
  • Regents Professor Emeritus Carleton Moore - Asteroid (5046) Carletonmoore
  • Regents’ Professor Sumner Starrfield - Asteroid (19208) Starrfield
  • Professor Meenakshi Wadhwa - Asteroid (8356) Wadhwa

Image credit: NASA/JPL-Caltech

(Nikki Cassis)

07/17/2014

Researchers discover natural clay deposits with antibacterial properties

Superbugs, they're called: Pathogens, or disease-causing microorganisms, resistant to multiple antibiotics.

Such antibiotic resistance is now a major public health concern.

"This serious threat is no longer a prediction for the future," states a 2014 World Health Organization report, "it's happening right now in every region of the world and has the potential to affect anyone, of any age, in any country."

Could the answer to this threat be hidden in clays formed in minerals deep in the Earth?

Biomedicine meets geochemistry

"As antibiotic-resistant bacterial strains emerge and pose increasing health risks," says Lynda Williams, a biogeochemist at Arizona State University (ASU), "new antibacterial agents are urgently needed."

To find answers, Williams and colleague Keith Morrison of ASU set out to identify naturally-occurring antibacterial clays effective at killing antibiotic-resistant bacteria.

The scientists headed to the field--the rock field. In a volcanic deposit near Crater Lake, Oregon, they hit pay dirt.

Back in the lab, the researchers incubated the pathogens Escherichia coli and Staphylococcus epidermidis, which breeds skin infections, with clays from different zones of the Oregon deposit.

They found that the clays' rapid uptake of iron impaired bacterial metabolism. Cells were flooded with excess iron, which overwhelmed iron storage proteins and killed the bacteria.

"The ability of antibacterial clays to buffer pH also appears key to their healing potential and viability as alternatives to conventional antibiotics," state the scientists in a paper recently published in the journal Environmental Geochemistry and Health.

"Minerals have long had a role in non-traditional medicine," says Enriqueta Barrera, a program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

"Yet there is often no understanding of the reaction between the minerals and the human body or agents that cause illness. This research explains the mechanism by which clay minerals interfere with the functioning of pathogenic bacteria. The results have the potential to lead to the wide use of clays in the pharmaceutical industry."

Ancient remedies new again

Clay minerals, says Williams, have been sought for medicinal purposes for millennia.

Studies of French clays--green clays historically used in France in mineral baths--show that the clays have antibacterial properties. French green clays have been used to treat Mycobacterium ulcerans, the pathogen that causes Buruli ulcers.

Common in Africa, Buruli ulcers start as painful skin swellings. Then infection leads to the destruction of skin and large, open ulcers on arms or legs.

Delayed treatment--or treatment that doesn't work--may cause irreversible deformities, restriction of joint movement, widespread skin lesions, and sometimes life-threatening secondary infections.

Treatment with daily applications of green clay poultices healed the infections. "These clays," says Williams, "demonstrated a unique ability to kill bacteria while promoting skin cell growth."

Unfortunately, the original French green clays were depleted. Later testing of newer samples didn't show the same results.

Research on French green clays, however, spurred testing of other clays with likely antibacterial properties.

"To date," says Williams, "the most effective antibacterial clays are those from the Oregon deposit."

Samples from an area mined by Oregon Mineral Technologies (OMT) proved active against a broad spectrum of bacteria, including methicillin-resistant S. aureus (MRSA) and extended-spectrum beta-lactamase-resistant E. coli (ESBL).

What's in those rocks?

Understanding the geologic environment that produces antibacterial minerals is important for identifying other promising locations, says Williams, "and for evaluating specific deposits with bactericidal activity."

The OMT deposit was formed near volcanoes active over tens to hundreds of thousands of years. The Crater Lake region is blanketed with ash deposits from such volcanoes.

OMT clays may be 20 to 30 million years old. They were "born" eons before deposits from volcanoes such as Mt. Mazama, which erupted 7,700 years ago to form the Crater Lake caldera.

Volcanic eruptions over the past 70,000 or so years produced silica-rich magmas and hydrothermal waters that may have contributed to the Oregon deposit's antibacterial properties.

To find out, Williams and Morrison took samples from the main OMT open pit. Four types of rocks were collected: two blue clays, and one white and one red "alteration zone" rock from the upper part of the deposit.

Blue clay to the rescue

The OMT blue samples were strongly bactericidal against E. coli and S. epidermidis. The OMT white sample reduced the population of E. coli and S. epidermidis by 56 percent and 29 percent, respectively, but the red sample didn't show an antibacterial effect.

"We can use this information to propose the medicinal application of certain natural clays, especially in wound healing," says Williams.

Chronic, non-healing wounds, adds Morrison, are usually more alkaline (vs. acidic) than healthy skin. The pH of normal skin is slightly acidic, which keeps numbers of bacteria low.

"Antibacterial clays can buffer wounds to a low [more acidic] pH," says Williams, like other accepted chronic wound treatments, such as acidified nitrate. "The clays may shift the wound environment to a pH range that favors healing, while killing invading bacteria."

The Oregon clays could lead to the discovery of new antibacterial mechanisms, she says, "which would benefit the health care industry and people in developing nations. A low-cost topical antibacterial agent is quickly needed."

Answers to Buruli ulcers, MRSA and other antibiotic-resistant infections may lie not in a high-tech lab, but in ancient rocks forged in a hot zone: Oregon's once--and perhaps future--volcanoes.

Image: Are the best medicines hidden in the Earth? French green clays are used for healing Buruli ulcers. Credit: Thierry Brunet de Courssou

(Written by Cheryl Dybas, NSF)

07/15/2014

Follow the adventures of Prof. Youngbull in the Alvin submersible

Our very own intrepid explorer Cody Youngbull is about to go where no one has gone before: 1.5 km below the ocean surface in the Alvin submersible to explore an underwater volcano!

You can follow his journey on SESE’s Explorers Blog at: http://asuexplorers.wordpress.com

Cody just posted his first entry this weekend as he and fellow SESE explorers Amanda and Greg arrived in Portland to begin their scientific cruise.

Stay tuned to the blog for more updates!

 

 

07/15/2014

A heat-sensing camera designed at Arizona State University has provided data to create the most detailed global map yet made of Martian surface properties.

The map uses data from the Thermal Emission Imaging System (THEMIS), a nine-band visual and infrared camera on NASA’s Mars Odyssey orbiter. A version of the map optimized for scientific researchers is available at the U.S. Geological Survey (USGS).

The new Mars map was developed by the Geological Survey's Robin Fergason at the USGS Astrogeology Science Center in Flagstaff, Arizona, in collaboration with researchers at ASU's Mars Space Flight Facility. The work reflects the close ties between space exploration efforts at Arizona universities and the U.S. Geological Survey.

"We used more than 20,000 THEMIS nighttime temperature images to generate the highest resolution surface property map of Mars ever created," says Fergason, who earned her doctorate at ASU in 2006. "Now these data are freely available to researchers and the public alike."

Surface properties tell geologists about the physical nature of a planet or moon's surface. Is a particular area coated with dust, and if so, how thick is it likely to be? Where are the outcrops of bedrock? How loose are the sediments that fill this crater or that valley? A map of surface properties lets scientists begin to answer questions such as these.

Darker means cooler and dustier

The new map uses nighttime temperature images to derive the "thermal inertia" for areas of Mars, each the size of a football field. Thermal inertia is a calculated value that represents how fast a surface heats up and cools off. As day and night alternate on Mars, loose, fine-grain materials such as sand and dust change temperature quickly and thus have low values of thermal inertia. Bedrock represents the other end of the thermal inertia range: because it cools off slowly at night and warms up slowly by day, it has a high thermal inertia.

"Darker areas in the map are cooler at night, have a lower thermal inertia and likely contain fine particles, such as dust, silt or fine sand," Ferguson says. The brighter regions are warmer, she explains, and have surfaces with higher thermal inertia. These consist perhaps of coarser sand, surface crusts, rock fragments, bedrock or combinations of these materials.

The designer and principal investigator for the THEMIS camera is Philip Christensen, Regents' Professor of Geological Sciences in the School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences on the Tempe campus. (Four years ago, Christensen and ASU researchers used daytime THEMIS images to create a global Mars map depicting the planet's landforms, such as craters, volcanoes, outflow channels, landslides, lava flows and other features.)

"A tremendous amount of effort has gone into this great global product, which will serve engineers, scientists and the public for many years to come," Christensen says. "This map provides data not previously available, and it will enable regional and global studies of surface properties. I'm eager to use it to discover new insights into the recent surface history of Mars."

As Fergason notes, the map has an important practical side. "NASA used THEMIS images to find safe landing sites for the Mars Exploration Rovers in 2004, and for Curiosity, the Mars Science Laboratory rover, in 2012," she says. "THEMIS images are now helping NASA select a landing site for its next Mars rover in 2020."

Image: A small impact crater on Mars named Gratteri, 4.3 miles (6.9 km) wide, lies at the center of large dark streaks. Unlike an ordinary daytime photo, this nighttime image shows how warm various surface areas are. Brighter tones mean warmer temperatures, which indicate areas with rockier surface materials. Darker areas indicate cooler and dustier terrain. For example, the bright narrow rings scattered across the image show where rocks are exposed on the uplifted rims of impact craters. Broad, bright areas show expanses of bare rock and durable crust. Fine-grain materials, such as dust and sand, show up as dark areas, most notably in the streaky rays made of fine material flung away in the aftermath of the meteorite's impact. Photo by: NASA/JPL-Caltech/Arizona State University

(Robert Burnham)

07/15/2014

The Marston Exploration Theater at the School of Earth and Space Exploration is currently presenting two science-themed programs: To the Edge of the Universe and The Search: Discovering Unknown Worlds. These shows alternate each Wednesday evening at 7:30 p.m. and each Saturday at 1:00 p.m. and 3:30 p.m.

Between now through August 16th we are offering a ‘Buy Three - Staff is Free’ discount. Bring three guests (family or friends), and receive one staff admission for free. Tickets are $7.50 for general admission and $5.50 for students of any age. This promotion is only available at the door (no online reservations for this offer); the box office is open 45 minutes before show time.

The Marston Exploration Theater is located in ISTB 4 at Terrace Mall and McAllister Ave.

Marston presentations are live-narrated, 3-D immersive experiences designed for all audiences. For presentation descriptions and a calendar of show times visit: http://sese.asu.edu/marston

 

07/07/2014

SESE undergrad researcher Linda Kuenzi is featured in a video from ASU news. She is a pole vaulter and aerospace engineering student researcher at Arizona State University. When she's not competing with ASU's track and field team, she's working in the lab with Christopher Groppi, a professor in the School of Earth and Space Exploration. Their research focuses on building better cameras to capture images of the cosmos. In addition to receiving an "Outstanding Honors Thesis" award from ASU's School for the Engineering of Matter, Transport, and Energy, Kuenzi made the 2013 and 2014 lists for the Pac-12's All Academic Track and Field Team. Her honors thesis, designing and building an automated test system for terahertz receivers, won a best honors thesis award from SEMTE. She is a member of the Barrett Honors College and graduated summa cum laude with a degree in aerospace engineering this spring. Congratulations, Linda!

Produced by Alexander D. Chapin

 

07/06/2014

New simulations show that Mercury and other unusually metal-rich objects in the Solar System may be relics left behind by hit and run collisions in the early Solar System

Planet Mercury’s unusual metal-rich composition has been a longstanding puzzle in planetary science. According to a study published online in Nature Geoscience July 6, Mercury and other unusually metal-rich objects in the Solar System may be relics left behind by collisions in the early Solar System that built the other planets.

The origin of planet Mercury has been a difficult question in planetary science, because its composition is very different from that of the other terrestrial planets and the Moon. This small innermost planet has more than twice the fraction of metallic iron of any other terrestrial planet. Its iron core makes up about 65 percent of Mercury’s total mass; Earth’s core, by comparison, is just 32 percent of its mass.

How do we get Venus, Earth and Mars to be mostly ‘chondritic’ (having a more-or-less Earth-like bulk composition) while Mercury is such an anomaly? For Arizona State University Professor Erik Asphaug, understanding how such a planet accumulated from the dust, ice, and gas in the early solar nebula is a key science question.

There have been a number of failed hypotheses for Mercury’s formation. None of them until now has been able to explain how Mercury lost its mantle, while retaining significant levels of volatiles (that is, easily vaporized elements or compounds, such as water, lead, and sulfur). Mercury has substantially more volatiles than the Moon does, leading scientists to think its formation could have had nothing to do with a giant impact ripping off the mantle, which has been a common popular explanation.

To explain the mystery of Mercury’s metal-rich composition, ASU’s Asphaug and Andreas Reufer of the University of Bern have developed a new hypothesis involving hit and run collisions, where proto-Mercury loses half its mantle in a grazing blow into a larger planet (proto-Venus or proto-Earth). One or more hit and run collisions could have potentially stripped away proto-Mercury’s mantle without an intense shock, leaving behind a mostly-iron body and satisfying a number of the major puzzles of planetary formation, including the retention of volatiles, in a process that also can explain the absence of shock features in many of the mantle-stripped meteorites.

Asphaug and Reufer have developed a statistical scenario for how planets merge and grow, based on the common notion that Mars and Mercury are the last two relics of an original population of maybe 20 bodies that mostly accreted to form Venus and Earth. These last two planets lucked out.

“How did they luck out? Mars, by missing out on most of the action – not colliding into any larger body since its formation, and Mercury, by hitting the larger planets in a glancing blow each time, failing to accrete,” explains Asphaug, who is a professor in ASU’s School of Earth and Space Exploration. “It’s like landing heads two or three times in a row – lucky, but not crazy lucky. In fact, about 1 in 10 lucky.”

By and large, dynamical modelers have rejected the notion that hit and run survivors can be important because they will eventually be accreted by the same larger body they originally ran into. Their argument is that it is very unlikely for a hit and run relic to survive this final accretion onto the target body.

“The surprising result we have shown, is that hit and run relics not only can exist in rare cases, but that survivors of repeated hit and run incidents can dominate the surviving population. That is, the average unaccreted body will have been subject to more than one hit and run collision,” explains Asphaug. “We propose one or two of these hit-and-run collisions can explain Mercury’s massive metallic core and very thin rocky mantle.”

According to Reufer, who performed the computer modeling for the study, “Giant collisions put the final touches on our planets. Only recently have we started to understand, on how profound and deep those final touches can be.”

“The implication of the dynamical scenario explains, at long last, where the ‘missing mantle’ of Mercury is – it’s on Venus or the Earth, the hit and run targets that won the sweep-up,” says Asphaug.

Disrupted formation
The duo’s modelling has revealed a fundamental problem with an idea implicit to modern theories of planet formation: that protoplanets grow efficiently into ever larger bodies, merging whenever they collide.

Instead, disruption occurs even while the protoplanets are growing.

“Protoplanets do merge and grow, overall, because otherwise there would not be planets,” says Asphaug. “But planet formation is actually a very messy, very lossy process, and when you take that into account, it’s not at all surprising that the ‘scraps’ like Mercury and Mars, and the asteroids, are so diverse.”

These simulations are of great relevance to meteoritics, which just like Mercury’s missing mantle, faces questions such as: Where’s all the stripped mantle rock that got removed from these early core-forming planetesimals? Where are the olivine meteorites that correspond to the dozens or hundreds of iron meteorite parent bodies?

“It’s not missing – it inside the mantles of the planets ultimately,” explains Asphaug. “It got gobbled up by the larger growing planetary bodies in every hit and run series of encounters.”

Image credit: NASA

(Nikki Cassis)

 

06/30/2014

Ariel Anbar among 15 top scientist-educators selected nationwide

Biogeochemist Ariel Anbar has been selected as Arizona State University’s first Howard Hughes Medical Institute (HHMI) Professor. This distinguished honor recognizes Anbar’s pioneering research and teaching.

He is one of 15 professors from 13 universities whose appointments were announced by the Maryland-based biomedical research institute on June 30. The appointment includes a five-year $1 million grant to support Anbar’s research and educational activities.

Since the inception of the HHMI Professor program in 2002, and including the new group of 2014 professors, only 55 scientists have been appointed HHMI professors. These professors are accomplished research scientists who are working to change undergraduate science education in the United States.

“Exceptional teachers have a lasting impact on students,” said HHMI President Robert Tjian. “These scientists are at the top of their respective fields and they bring the same creativity and rigor to science education that they bring to their research.”

Anbar, a professor in ASU’s School of Earth and Space Exploration and the Department of Chemistry and Biochemistry in the College of Liberal Art and Sciences, as well as a Distinguished Sustainability Scientist in the Global Institute of Sustainability, was named an ASU President’s Professor in 2013 in recognition of his pioneering online education efforts. He is deeply involved in using the medium to its fullest to help educate and encourage a generation that has grown up with the Internet.

A leading geoscientist with more than 100 peer-reviewed papers to his name, Anbar’s research focuses on Earth’s past and future as a habitable planet. This expertise feeds directly into his teaching in the highly successful class Habitable Worlds, developed through ASU Online. In Habitable Worlds, Anbar and course designer Lev Horodyskyj combine the power of the Internet, game-inspired elements, and the sensibilities of a tech savvy generation to teach what makes planets habitable and engage students in a simulated hunt for other habitable worlds in the cosmos. This innovative online course kindles student interest and learning. Beginning in fall 2014, it will be available outside of ASU as HabWorlds Beyond (www.habworlds.org), via a partnership with education technology company Smart Sparrow. Habitable Worlds has been taken by more than 1,500 ASU students and consistently receives outstanding student reviews.

The HHMI grant will enable Anbar to develop a suite of online virtual field trips (VFTs) that teach the story of Earth’s evolution as an inhabited world. The virtual field trips will be based on nearly 4 billion years of Earth’s geological record. These immersive, interactive VFTs will take students to locations that teach key insights into Earth’s evolution, fundamental principles of geology, and practices of scientific inquiry.

Anbar helped lead a multi-institutional team that developed a number of such VFTs for use in Habitable Worlds and elsewhere (vft.asu.edu), supported by the NASA Astrobiology Institute and the National Science Foundation. Now, working with ASU education technologist and doctoral student Geoffrey Bruce, ASU professor and geoscience education specialist Steven Semken, and partners at other institutions, Anbar will build virtual field trips covering the sweep of Earth history. He and his team will take students to some of the most important places on Earth to explore how the planet came to be what it is today.

“The goal is to develop powerful and engaging new tools to teach about Earth’s evolution,” explains Anbar. “In the near term, we will create VFT-based lessons that can be incorporated into existing introductory geoscience courses. Right away, that can impact the roughly 2,000 majors and non-majors who take such courses each year at ASU, as well as thousands of students elsewhere. In the long run we aim to create a fully online course like Habitable Worlds – I’m calling it Evolving World for now - that covers the content of one of the most important introductory geoscience courses, historical geology.”

Anbar’s plan could re-invigorate instruction in historical geology, which is taught in nearly every geoscience program. In addition to being fundamental to the field of geology, it provides vital context for the search for life beyond Earth, and for the changes that humans are causing to the planet. However, historical geology is best taught through field experiences, which are logistically challenging at large universities. Even when they are possible, it is impossible to expose students to all the most scientifically important sites because they are scattered around the globe. While VFTs cannot rival physical field trips, they are a big advance over teaching this material only through lectures.

“Most science classes teach science as facts and answers,” says Anbar. “With VFTs, as with Habitable Worlds, we are trying to teach that science is really a process – a process of exploration that helps us first organize our ignorance about questions to which we don’t have answers, and then helps us narrow the uncertainties so that we can replace ignorance with understanding.”
 

Photo by Nathaniel Anbar

(Nikki Cassis)

06/26/2014

Soil moisture measurements are needed to improve our understanding of water availability in rural and urban areas. Adam Schreiner-McGraw, an Arizona State University graduate student studying hydrology, has installed a new type of soil moisture sensor in four different ecosystems in the southwestern U.S. and northwest Mexico. Currently in the second year of measurements, these probes have tracked remarkably well the moderate drought conditions in Arizona and the aid provided by the wetter-than-average conditions during last summer’s monsoon.

Many parts of the hydrologic cycle are difficult to measure (such as groundwater movement or evapotranspiration) so mathematical models are used to help estimate these fluxes and understand how the hydrologic cycle might be changing. Schreiner-McGraw hopes that the data obtained by these soil moisture sensors can be used to improve watershed hydrology models used commonly for assessing impacts of land cover or climate change.

About the size of a person and shaped like a space shuttle, these novel probes are called cosmic-ray soil moisture sensors. They are affiliated with the COSMOS (cosmic-ray soil moisture observing system) project, an NSF-supported project to measure soil moisture based upon cosmic-ray neutrons. An off-the-shelf device, these solar-powered sensors have remote data capture and can be installed in two days with a single field calibration.

The technology uses ‘fast neutrons’ generated when cosmic-rays hit the atmosphere, cascade onto the land surface and are captured by hydrogen atoms. Intermediate scale measurements are possible meaning that soil moisture is averaged over several hundred square meters. This allows observations that are in between traditional soil sensors and satellite estimates, the two most common ways to measure soil moisture. The sensor itself measures the density of fast neutrons above the soil surface. This density is inversely proportional to the amount of hydrogen bound in water within and above the soil surface. The higher number of neutrons measured by the sensor, the drier the soil is, providing a means to track water availability in rural or urban areas.

“We are currently obtaining real-time soil moisture data at three rural sites – southern Arizona, southern New Mexico, and Sonora, Mexico – that have each been affected by human-induced land cover change,” explains Schreiner-McGraw, who is pursuing a doctorate in ecohydrology within the School of Earth and Space Exploration, under the supervision of ASU Associate Professor Enrique R. Vivoni.

The two rural sites in the United States are undergoing woody plant encroachment, a process in which woody shrubs have occupied historical desert grasslands, while the site in Mexico had woody trees cleared away for the establishment of a pasture for cattle grazing. Both of these land cover changes are widespread throughout the world in arid and semiarid regions. Schreiner-McGraw is investigating the effects of these land cover changes on the water cycle and the implications on ecosystem functioning, runoff generation and soil erosion.

“Recently, I installed another sensor in west Phoenix within the Maryvale community. To my knowledge, this is the first time one of these sensors has been installed in an urban setting. It is difficult to obtain an accurate measurement for soil moisture in urban settings because these sensors measure all sources of water in the footprint, so if somebody fills up their bathtub it will likely affect the measurement,” says Schreiner-McGraw. “What we have found so far is that the neutron count rate in an urban setting is much lower and more stable than in the various rural areas that we are sampling. This indicates that soil moisture is likely higher and less variable in our urban setting, probably due to the large amount of urban irrigation occurring in Phoenix.”

According to Schreiner-McGraw, these sensors are useful because they provide a single value for soil moisture over a large region that is being sampled, thus averaging the amount of water available at scales relevant for management purposes. A network of such sensors in a metropolitan area, such as Phoenix, could aid in quantifying outdoor water use at an intermediate scale, a highly elusive measurement due to the large variations among individual homeowners.

“Hopefully, integrating this type of soil moisture data into hydrologic models of rural and urban areas will improve our ability to predict the changing hydrologic cycle,” says Schreiner-McGraw, who after graduation would like to continue doing research, perhaps with the USGS, USDA, or at a university as a professor.

Photo: 72-foot meteorological flux tower in the west Phoenix neighborhood of Maryvale with COSMOS sensor installed at the base of the tower.

(Nikki Cassis)

06/18/2014

Steven Semken and David Williams, professors in ASU’s School of Earth and Space Exploration, join an elite group of Earth scientists, having been elected this spring as Fellows of the Geological Society of America (GSA).

Semken is an ethnogeologist and geoscience education researcher whose research focuses on ways that place, culture, and affect influence modes of inquiry, teaching, and learning in the Earth system sciences. His research is directed toward enhancing public Earth science literacy and diversity in the geoscience profession, and it is predominantly based in the geologically, ecologically, and culturally diverse American Southwest. He is deputy director of the EarthScope National Office and a Senior Sustainability Scientist in the Julie Ann Wrigley Global Institute of Sustainability, both at ASU.

Williams’ research focuses on volcanology and planetary geology, with an emphasis on understanding the emplacement styles and compositions of extrusive volcanic products on the terrestrial planets and outer planet satellites. He is the director of the Ronald Greeley Center for Planetary Studies, the NASA Regional Planetary Image Facility at ASU. He is also the director of the NASA Planetary Aeolian Laboratory, which operates wind tunnels at ASU and at the Ames Research Center in California.

Semken and Williams join a distinguished line of GSA Fellows at Arizona State University. SESE faculty elected as Fellows also include: Ariel Anbar, Ramon Arrowsmith, Peter Buseck, Don Burt, Phil Christensen, Kip Hodges, Steve Reynolds, Kelin Whipple, Lynda Williams, and Stan Williams.

The Geological Society of America (GSA) is a global professional society with a growing membership of more than 25,000 individuals in 107 countries. Its mission is to advance geoscience research and discovery, service to society, stewardship of Earth, and the geosciences profession.