News and Updates


For the first time, more than 22,000 Arizonans will participate in the Great ShakeOut, an annual earthquake drill held on Oct. 18 at 10:18 a.m.

The ShakeOut began in 2008 in California as a way to educate the public about earthquake preparedness. Since then it has grown into an international event with nearly 17 million participants.

Although not traditionally thought of as a frequent epicenter for earthquakes, Arizona is not free from earthquake hazard. The USArray component of EarthScope, an earth science program that researches the structure and evolution of the North American continent, detected over 1,000 earthquakes in Arizona during the past two years.

“Earthquake risk in Arizona is low, but that doesn’t mean it is nonexistent,” said Wendy Bohon, an Arizona State University graduate student majoring in geological sciences and EarthScope social media coordinator. “It can almost be worse in places where there are smaller earthquakes, because people don’t know what to do.”

The EarthScope National Office (ESNO), based at ASU for the next three years, signed up to participate in the ShakeOut this year to encourage hazard awareness, Bohon said.

On Oct. 17 EarthScope will host a free public lecture series from 7-9 p.m. on the science behind earthquakes, earthquakes in Arizona, and ways to be prepared. The lecture will be held in the Interdisciplinary Science and Technology Building 4 in the Marston Exploration Theater.

The drill will take place the next morning.

ESNO director and speaker Ramon Arrowsmith said taking a few minutes to think about what to do in the event of an earthquake can only help.

“When you’re panicked, you can’t think, so it’s important to plan ahead and pay attention to what looks strong and what could fall on top of you,” said Arrowsmith, who is also a professor in the School of Earth and Space Exploration (SESE).

“It is also valuable to think about communications with your family and friends in the case of a natural or human-caused disaster,” he said.

SESE professors Steve Semken and Ed Garnero, along with SESE graduate student Jeff Lockridge, will also be speaking.

Sarah Robinson, education and outreach coordinator for EarthScope, said that although Arizona is relatively stable, faults in California and Mexico are close enough to cause significant shaking.

“A lot of people don’t realize that we have earthquake hazards here, but plates are moving all around us,” Robinson said. “There will be tectonic activity all the time because the ground is not totally solid.”

Robinson said the day of the drill the EarthScope office and anyone who wants to participate will be “dropping, covering and holding on” to simulate what they would do in the event of an earthquake.

Bohon said the drill might seem absurd, but earthquakes don’t stop at state boundaries and can happen anywhere.

“It’s my job as a scientist to tell people about earthquakes and to help prepare them for the possibility of earthquakes in their area,” she said.

Arrowsmith said it is important for people in areas that are not earthquake-prone to be aware of the dangers and consequences especially if they travel.

“We need to think globally and act locally,” he said. “We now live in a connected world where we might not feel the earthquake physically, but it will hit us economically or in some other way.”

(Kristen Hwang)


What meteorites on Mars tell us about its climate history will be the topic of a talk given by James Ashley, a postdoctoral research fellow in the School of Space and Earth Exploration, at 7 p.m., Oct. 12, in the Marston Exploration Theater, in the new Interdisciplinary Science and Technology Building 4 (ISTB 4), ASU Tempe campus.

The free lecture is sponsored by SESE. After the lecture, students will be scattered throughout the interactive exhibits in ISTB4 to explain the displays and answer questions.

“The pursuit of an answer to the time-honored question ‘Are we alone in the universe?’ leads scientists down many paths that cross a multitude of disciplines," says Ashley. “In the planetary sciences, the quest can result in the careful engineering of robotic spacecraft designed to answer specific questions about the habitability of planets they are sent to explore.

“Mars is a world that is both easily accessible at reasonable costs and potentially habitable. We are interested in the role that water may have played in Mars' geologic history because of its importance to astrobiology.

“Each of the Mars Exploration Rover (MER) spacecraft was designed to last for 90 days on Mars in 2004. One of the two rovers (Opportunity) continues exploring today, almost nine years later.

“Among the many discoveries made during this mission are several large, iron meteorites that show dramatic signs of water interaction near the martian equator. We will take a close look at these rocks and discuss their significance to climate on the Red Planet.”

The next astronomy event open to the public is an Open House scheduled from 8 to 10 p.m., Oct. 26, on the roof of the Bateman Physical Sciences Building H-Wing, Tempe campus. For more information,


(Judith Smith)


Researchers connect spike in ancient oceanic oxygen levels to earliest animal biodiversity

An international team of scientists has uncovered new evidence linking early animal evolution to extreme climate change.

A dramatic rise in atmospheric oxygen levels has long been speculated as the trigger for early animal evolution. In the Sept. 27 issue of the journal Nature, researchers for the first time offer evidence of a causal link between trends in early biological diversity and shifts in Earth system processes.

The fossil record shows a marked increase in animal and algae fossils roughly 635 million years ago. Researchers believe that oceanic oxygen levels spiked suddenly at this time, in the wake of a severe glaciation, reaching the level necessary to allow animals to flourish. The new evidence pre-dates previous estimates of a life-sustaining oxygenation event by more than 50 million years.

“For more than three quarters of the Earth’s history, the oxygen level in the atmosphere and ocean was insufficient to support animal life,” said Swapan Sahoo, lead author and University of Nevada Las Vegas (UNLV) Ph.D. student. “Our findings support a link between glaciation, oxygenation of surface environments and the diversification of animals. Knowing the environment where the first animals lived is critical for understanding the evolutionary stress of ecosystems.”

Sahoo visited Arizona State University to carry out trace metal analyses in Professor Ariel Anbar’s lab, under the supervision of Brian Kendall, who was a faculty research associate at ASU and is now a professor at Waterloo. Both are co-authors on the paper.

An analysis of iron and trace metal concentrations in organic-rich rocks collected from the Doushantuo Formation in South China revealed spikes in metals that denote higher levels of seawater oxygen. These elevated levels of molybdenum, vanadium and uranium slightly predated the earliest oxygen-demanding animal fossils, supporting the link between ocean oxygenation and animal evolution.

“This is the latest study using changes in the amount of the rare element molybdenum in ancient rocks to learn how Earth’s atmosphere has changed with time – and how those changes may have shaped the evolution of our distant ancestors,” says Anbar, a professor in ASU’s School of Earth and Space Exploration and Department of Chemistry and Biochemistry.

High element concentrations found in the South China rocks are comparable to modern ocean sediments and point to a substantial oxygen increase in the ocean-atmosphere system. Researchers say the oxygen rise is likely due to increased organic carbon burial. Nutrient supplies tend to go up because of weathering during glacial retreat, which leads to a positive feedback between organic carbon burial and oxygen release.

“Photosynthesis is the most efficient process to generate oxygen,” said UNLV’s Ganqing Jiang, principal investigator of the study. “Fast burial of a large quantity of photosynthetic organic carbon in sediments would leave free oxygen in the ocean-atmosphere system, leading to significant oxygen rise.”

The large variability of iron content and trace metal concentrations in the South China rocks may cause scientists to rethink existing geological interpretations about ancient oceans and could lead to accompanying investigations of similar-aged rocks in other continents.

The joint research was supported by grants from the National Science Foundation, the NASA Exobiology Program and National Natural Science Foundation of China.



For the second time, new students to ASU’s School of Earth and Space Exploration (SESE) traveled to the Retreat at Tontozona for Camp SESE Sept. 7-9 as part of the school’s growing effort to build an open network among new students and upperclassmen and faculty.

The Retreat at Tontozona, formerly known as Camp Tontozona, is located in the Tonto National forest near Payson, Ariz. Camp SESE became part of the Exploring SESE (SES 191) course this year that new students are required to take. The camp included a schedule of events designed to be fun and informative and to begin establishing connections between the 50 campers and 28 mentors and faculty who accompanied them.

Arjun Heimsath, SESE professor and this year’s camp director, said that the opportunity Camp SESE offers the students cannot be replaced by classroom learning.

“It’s all about engagement of the students. Camp SESE broadens horizons by getting people off of campus and into a real environment,” Heimsath said. “Students have fun and realize that we love what we do.”

Staying 5,600 feet above sea level under towering Ponderosa Pines, the campers explored SESE’s three main areas of research – geology, engineering and astronomy / astrophysics – through a variety of team-building activities.

Campers went on hikes to learn about geological features and the environment, practiced orienteering skills through a scavenger hunt, viewed the night sky and constellations, and interacted with rovers and remote-controlled helicopters.

Benjamin Stinnett, a systems design sophomore and camp mentor, was a camper last year and said he decided to come back as a mentor because of the positive way his own camp mentors impacted his experience with SESE.

“The most important thing about camp is the ability to make connections with leaders of student organizations and researchers,” Stinnett said. “I want to be the catalyst.”

Stinnett added that as a first-semester sophomore he now has a research position and is president of the ASU Robotics Club, opportunities that would not have come up without Camp SESE.

Another mentor, Andrew Bochko, is a geology sophomore who designed the camp’s t-shirts.

“Without Camp SESE, students are not put into an environment where they can meet people with the same major and have fun,” Bochko said, adding that his own mentors and peers are people whom he is still good friends with.

Chloe Antilla, a freshman earth and environmental studies major, was a camper this year. She said that being able to talk with professors and to see them outside of the classroom in the field gave her an appreciation for what they do.

“They care about what we learn, and when we asked questions they would get excited,” she said. “Their passion reinforces what I want to do.”

The experience for the campers, mentors and faculty was rewarding, Heimsath said.

“It’s fundamental to build a community. Nothing is more important than giving new students a sense of SESE, their peers, mentors and face time with faculty,” Heimsath said. “Many of the potential barriers to their academic career are dramatically lowered.”

(Kristen Hwang)

The giant asteroid Vesta, it turns out, has its own version of ring around the collar. Two new papers based on observations from the low-altitude mapping orbit of NASA’s Dawn mission reveal that volatile materials have colored Vesta’s surface in a broad swath around its equator. Pothole-like features mark some of Vesta’s surface when the volatiles, likely water, released from hydrated minerals boiled off. The findings were released today in the journal Science.
Dawn did not find actual water ice at Vesta, but signs of hydrated minerals delivered by meteorites and dust are evident in the giant asteroid’s chemistry and geology. One paper, led by Thomas Prettyman, the lead scientist for Dawn’s gamma ray and neutron detector (GRaND) at the Planetary Science Institute in Tucson, Ariz., describes how the instrument found signatures of hydrogen, likely in the form of hydroxyl or water bound to minerals in Vesta’s surface. A complementary paper, led by Brett Denevi, a Dawn participating scientist based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., describes the presence of pitted terrain created by the outgassing of volatiles.
David A. Williams, an associate research professor in ASU’s School of Earth and Space Exploration, is a participating scientist on the Dawn mission and contributed to the Denevi study.
Upon finding signs of hydrated minerals, the scientists set out to find out where the hydrogen within Vesta’s surface came from. It turns out that hydrated minerals appear to be delivered by carbon-rich space rocks that collided with Vesta at speeds slow enough to preserve their volatile content.
Scientists thought it might be possible for water ice to survive near the surface around the giant asteroid’s poles. But, unlike the Moon, Vesta has no permanently shadowed polar regions where ice might survive. And the strongest signature for hydrogen in the latest data came from regions near the equator, where water ice is not stable.
In some cases, other space rocks crashed into these deposits later at high speed. The heat from the collisions converted the hydrogen bound to the minerals to water, which evaporated. The holes that were left as the water escaped stretch as much as 0.6 miles (1 kilometer) across and go down as deep as 700 feet (200 meters). Seen in images from Dawn’s framing camera, this pitted terrain is the most spectacularly preserved in sections of Marcia crater.
“When we first saw the pitted terrain in Dawn images, many on the science team thought immediately that this was evidence for the release of volatiles from the surface,” said Denevi. “The pits look just like features seen on Mars, but while water [was] common on Mars, it was totally unexpected on Vesta in these high abundances. The results provide evidence that not only were hydrated materials present, they played an important role in shaping the asteroid’s geology and the surface we see today.”
“I am tasked with the geologic mapping of Marcia crater region, and I was amazed when we saw these pitted terrains on the crater floor,” said Williams. “When you place images of this terrain side by side with images of similar terrain on Mars, it is clear why we think release of volatiles, perhaps water ice, could explain this unusual vestan terrain.”
Williams worked with Denevi and others on the Dawn team to analyze the pitted terrain on Vesta, and compare it with similar features recently identified in high resolution images of Mars. After exploring various hypotheses that might explain the terrain, the leading hypothesis became the release of volatiles during the formation of the Marcia crater.
“The key unresolved question, was the volatile material, presumably water ice, in Vesta’s crust itself when the impact occurred, or was brought in by the impactor that formed Marcia crater? Further research may resolve this question,” said Williams.
Vesta is the second most massive member of the main asteroid belt. The orbit at which these data were obtained averaged about 130 miles (210 kilometers) above the surface.
GRaND’s data are the first direct measurements describing the elemental composition of Vesta’s surface. Dawn’s elemental investigation by the instrument determined the ratios of iron to oxygen and iron to silicon in the surface materials. These findings solidly confirm the connection between Vesta and a class of meteorites found on Earth called the Howardite, Eucrite and Diogenite (HED) meteorites, which have the same ratios for these elements. In addition, more volatile-rich fragments of other objects have been identified in HED meteorites, which supports the interpretation that the materials were deposited externally on Vesta.
“Working on the Dawn mission at Vesta has been very exciting,” said Williams. “Vesta is more than just a space rock; it is a protoplanet and shows evidence of geologic processes we see on the larger planets of the Solar System.”
Dawn left Vesta on Sept. 4, 2012 PDT (Sept. 5, 2012 EDT) and is now on its way to its second target, the dwarf planet Ceres.

Image: This perspective view of Marcia crater on the giant asteroid Vesta shows the most spectacularly preserved example of "pitted terrain," an unexpected discovery in data returned by NASA's Dawn mission. This view is a mosaic of images from Dawn's framing camera, overlain on a digital terrain model with five times vertical exaggeration. At right is a close-up of the floor of Marcia, which contains the largest concentration of pits on Vesta. Marcia is one of the youngest craters on Vesta, with a diameter of about 40 miles (70 kilometers). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/JHUAPL



ASU’s newest science building – the Interdisciplinary Science and Technology Building IV (ISTB 4), on the Tempe campus – is designed to advance research and discovery, and to encourage children to explore their futures as scientists and engineers. The building will do this through a mixture of high-tech labs, interactive environments and open spaces that will allow the public to witness research and technology advancement as it happens.

A formal opening of ISTB 4 will take place at 8 a.m., today.

The seven-story, 293,000-square-foot building is designed to provide flexible laboratories for ASU’s School of Earth and Space Exploration (SESE), ASU’s Security and Defense Systems Initiative, and research laboratories and centers of the Ira A. Fulton Schools of Engineering.

The building provides ample laboratory space –166 lab modules with wet and dry labs and a rooftop laboratory – and an inviting public space, in addition to offices, collaboration spaces and meeting rooms for faculty and staff.

“This new facility will not only offer state-of-the-art equipment and infrastructure, but will provide a unique collaborative environment that is designed to foster large, team-driven projects in areas such as earth and space exploration, security and defense systems research and renewable energy,” said Sethuraman Panchanathan, senior vice president with ASU’s Office of Knowledge Enterprise Development (OKED). The office advances research, innovation, entrepreneurship and economic development activities for ASU.

ISTB 4’s design embodies the transdisciplinary spirit of ASU, accommodating research programs from science and engineering, and continuously encouraging interaction of both worlds.

“The SESE faculty and research staff are well known for their scientific research, but many in the ASU and Phoenix communities are less aware of their well-deserved international reputation for engineering, particularly designing and deploying advanced instruments to enable scientific exploration of Earth and other worlds,” said Kip Hodges, director of SESE, part of ASU’s College of Liberal Arts and Sciences. “Sophisticated laboratories for instrument development in ISTB 4 will further increase ASU’s leadership, and we have designed several of these laboratories so that the public can watch technologies being created.”

“We encourage multiple faculty with compatible research agendas to use the major laboratories in a collaborative way, reinforcing the transdisciplinary spirit of ASU,” added Hodges.

One of the first engineering challenges for SESE in ISTB 4 is OSIRIS-REx Thermal Emission Spectrometer (OTES), which will be the first major scientific instrument completely designed and built at ASU for a NASA space mission. Viewing windows will allow visitors to see into the environmentally controlled facilities where the OTES instrument is being built.

For ASU engineering, ISTB 4 will help with facing today’s challenges and building a better society for tomorrow.

“This signature facility reflects our core research themes of energy, health, security, sustainability and education through the five main engineering centers housed in the building,” said Paul Johnson, dean of the Ira A. Fulton Schools of Engineering. “The interdisciplinary environment fosters close collaboration among SESE and Fulton Engineering researchers as we pursue complementary efforts to advance the technology of tomorrow and provide practical solutions to real-world challenges today.”

In addition to complex labs, the new building boasts a five-story, naturally lit atrium (starting at the third floor) offering a series of “living rooms in the sky” for scientists and engineers to meet. It also has world-class conference facilities and first and second floor public outreach spaces designed to communicate the excitement of scientific research and the technologies that enable it.

First floor facilities feature digital media, public lectures, visible laboratories and interactive displays. A focal point of the building is the Marston Exploration Theater.

“We all wonder what future scientific innovation will bring and are fortunate to now have a center that invites the public to witness and be participants in science and discovery happening on our own doorsteps,” said Robert Page, vice provost and dean of ASU’s College of Liberal Arts and Sciences. “A special gift from Carolyn ‘Susie’ Marston in memory of her husband Barret is the 238-seat theater for high-definition documentaries, 3-D planetarium-style shows and media-rich space for teaching undergraduates. It will touch people of all ages.”

Another highlight is the 4,300-square-foot “Gallery of Scientific Exploration,” outfitted with kiosk-style interactive exhibits and large-format, high-definition monitors that display video from Earth-observing satellites and robotic probes of other worlds.

On the second floor is ASU’s Center for Meteorite Studies, relocated and expanded for greater public access, which features interactive displays, touchable specimens and a video display of most of the collection’s specimens. Also on this floor are a variety of learning spaces designed to stimulate discovery and exploration of Earth and space science that will be used specifically for outreach to pre-college students.

“Research is vital to the health of our economy and our society, so it’s very important that we not only advance it, but we do it in such a way as to generate excitement for future generations of scientists and engineers,” said Panchanathan. “This facility is poised to advance new technologies, explore our world and encourage our children to be participants in this exciting endeavor.”

Sundt Construction Inc., served as the construction manager at risk for the ISTB 4 project working with the design teams of HDR and Ehrlich Architects.

(Nikki Cassis)



The NASA Space Grant Robotics team at Arizona State University sent 10 team members to Orlando, Fla. in June to compete in the Marine Advanced Technology Education (MATE) international robotics competition.

Armed with Koi, a robot capable of functioning 30 feet underwater, the ASU team challenged 22 teams from across the country and across the globe, ranking 11th overall.

Matthew Plank, a computer systems engineering junior and NASA Space Grant intern, is the team’s president and has been competing in robotics competitions since high school.

“Robots allow you to go places humans typically can’t,” explains Plank, who helped design Koi’s electronics. “They allow for exploration and study of deep sea and space.”

The MATE competition, which ASU has competed in since 2009, focuses on ocean-related occupations and real-world industry problems. Each team is judged on their ability to “sell” a design that could solve a real-world crisis or fill an exploratory need.

For past competitions, teams designed robots that could deal with issues surrounding the 2010 Gulf Oil Spill or could explore underwater volcanoes. This year’s mission revolved around a sunken World War II vessel and its potential impact on the environment. The robots removed fluid from the fuel tank and surveyed and mapped the surrounding area.

“Each team is treated like a pseudo company,” said Michael Przeslica, electrical team lead and material science and engineering junior. “We are judged and scored based on a professional engineering presentation, a twenty page technical report detailing every aspect of our robot, a poster presentation, and carrying out a physical mission with our robot.”

During the physical mission each team had 15 minutes to complete approximately 20 underwater tasks.

The six months of work that the team put in culminated in the Martin Klein MATE Mariner Award for the team’s practical application of their knowledge and skills and for the desire to improve. This award included a $1,000 grant to support next year’s team.

The team came home with a second award. Emily McBryan, a senior aerospace engineering major, received the Engineering Evaluation Most Valuable Player individual award.

“I have been a member of this robotics team for four years now and this year the greatest lesson I have learned is how a team can come together and combine its talents in order to fulfill a mission. Koi is a great representation of not just our engineering skills but our teamwork skills and leadership ability,” says McBryan, who served as the robotics’ team president for the past two years.

The ASU/NASA Space Grant Robotics team does more than build award-winning robots, however.

“This is an opportunity to learn hands-on skills and to demonstrate leadership in the field,” and anyone who is willing to learn can join, Plank said.

About 20 active members with majors ranging from materials engineering and Earth and space exploration to computer science participate on the team. The team meets officially two days a week for two hours each, but Plank said that members are welcome to work as long as they are willing.

“We’re big on getting our hands dirty,” Przeslica said.

Phil Christensen, Regents’ Professor of Geological Sciences in ASU’s School of Earth and Space Exploration, provides lab space for the team in the Mars Space Flight Facility in the Moeur building.

“We like to surround ourselves with the spirit of exploration,” Przeslica said, adding that the research that is conducted around them is an inspiration for the team.

The team also competes in the National Underwater Robotics Challenge competition and will be adding the Association for Unmanned Vehicle Systems International competition, which focuses on fully autonomous robots, to its schedule this year.

In addition to learning real-world skills, Anthony Hallas, a computational mathematical sciences senior, said that his experience on the robotics team has had a practical application to his classwork.

The group is mentored by Shea Ferring, propulsion engineering manager for Orbital Sciences Corporation and Space Grant alumnus, and ASU graduate student Robert Wagner.

Although the group has mentors, Plank said that the team is student-run and members learn from each other more than anything else.

He added that the “hands-off” dynamic has encouraged members to learn to work with other engineers and learn something completely different from their respective majors.

“You can never downplay how important actually doing engineering and learning from other members is,” Plank said.

The team relies on NASA Space Grant support, donations and awards for material costs and travel to competitions. Unfunded travel costs are paid by students determined to see their project from beginning to end. Their current robot, Koi, is valued at approximately $6,900. For this year’s competition, they plan to design and build new systems with upgraded capabilities.

Photo: Team picture with the Koi robot and MATE officials

By Kristen Hwang



Philip R. Christensen, Regents' Professor of Geological Sciences in ASU's School of Earth and Space Exploration, is among the engineers and scientists being honored by the 2012 Haley Space Flight Award from the American Institute of Aeronautics and Astronautics (AIAA). The award is going to the entire mission team for NASA's long-lived Mars Exploration Rovers, Spirit and Opportunity.

Christensen, director of the Mars Space Flight Facility on the Tempe campus, is the designer and principal investigator for the Miniature Thermal Emission Spectrometer (Mini-TES), an instrument carried by both Spirit and Opportunity. Working at heat-sensing wavelengths, Mini-TES was built to operate as a mineral-scouting device.

"Mini-TES played a critical role in identifying targets of interest which the rover then studied in detail with the instruments on its robotic arm," says Christensen. "For example, it identified more than a dozen different rock types on Mars, nearly all of them previously unknown."

He adds, "The instrument also led to several key discoveries. In the Columbia Hills in Gusev Crater, it spotted opaline silica deposits, which are evidence of hot springs. Mini-TES data also led ASU research scientist Steve Ruff to discover carbonate rocks there. Both findings clinched the case for significant water in Gusev."

Mars Exploration Rover (MER) project manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena, is accepting the Haley Award for the team at the AIAA's annual meeting, Sept. 12, 2012. The AIAA is the world's largest technical society for the aerospace profession, with more than 35,000 individual members worldwide.

Although partly upstaged by the Aug. 6 landing of Curiosity, NASA's new Mars Science Laboratory rover, both Spirit and Opportunity have set outstanding space exploration benchmarks. Landing in January 2004, each far exceeded its three-month design lifetime. Spirit operated more than six years in Gusev Crater. Its twin, Opportunity remains on the job today in Endeavour Crater on Meridiani Planum.

During the past two months, Opportunity has driven about a third of a mile, extending its total overland travel to 22 miles. The rover is surveying outcrops of layered rock in search of clay minerals to gain new insights into ancient wet environments.

"The MER rovers proved that medium-size rovers can play major role in Mars exploration," says Christensen. "Curiosity is a magnificent machine, but follow-on rovers are more likely to resemble Spirit and Opportunity. In the future, I expect we'll see a number of modest-sized rovers sent to different locations. Each of these would be equipped to find and cache potential samples for return to Earth."

Photo: ASU Mars scientist Philip Christensen is among those being honored by the American Institute of Aeronautics and Astronautics. Credit: Tom Story

(Robert Burnham)


A star’s internal chemistry can doom a planet’s life long before the star itself dies

The search for potentially habitable planets involves discussion of what is sometimes referred to as the Goldilocks Zone, the relatively thin band in a solar system in which conditions on a planet can support life. Astrobiologists and planetary scientists agree that a planet’s distance from its parent star is of paramount importance for creating those optimum conditions – like Goldilocks’s porridge, it has to be just right. A new study by Arizona State University researchers suggests that the host star’s chemical makeup can also impact conditions of habitability of planets that orbit them.
The team’s paper, published in the August issue of The Astrophysical Journal Letters, demonstrates that subtle differences in a star’s internal chemistry can have huge effects on a planet’s chances of long-term habitability.
“We have identified changes in the ratios of different elements as particularly important for a given solar system’s habitability,” says Patrick Young, an assistant professor in ASU’s School of Earth and Space Exploration and lead author on the paper. “The more abundant elements carbon, oxygen, silicon, magnesium, and sodium are particularly important. The greater the abundances of these four elements in a star, the slower it, and the location of its Goldilocks Zone, will evolve.”
As a star evolves, it becomes brighter, causing the habitable zone to move outwards through its solar system. The team’s study indicates that a greater abundance of oxygen, carbon, sodium, magnesium, and silicon should be a plus for an inner solar system’s long-term habitability because the abundance of these elements make the star cooler and cause it to evolve more slowly, thereby giving planets in its habitable zone more time to develop life as we know it.
To explore whether stellar internal chemistry causes significant changes in the evolution of stars and therefore their habitable zones, Young and his colleagues, graduate students Mike Pagano and Kelley Liebst, did simulations of stars that are like our sun.
“We used spectra from 145 broadly sun-like stars targeted by planet to estimate the amount of variation in the abundance ratios of elements. For each model we varied the amount of one element to the extremes of variation we estimated from our analysis of the observations,” explains Pagano, who is a graduate student in the School of Earth and Space Exploration astrophysics program. 
The largest changes, unsurprisingly, arise from variation in oxygen.
“Oxygen is the most abundant element in the universe besides hydrogen and helium, so a change in the oxygen abundance results in a significant change in the total amount of heavy elements in the star. Oxygen turns out to be highly variable in abundance.  The effect of increased heavy element abundance on a star is to make it harder for the energy produced by nuclear fusion to escape the star. This means less energy needs to be produced to support the star, and it can live longer.”
The stellar abundance of oxygen seems crucial in determining how long planets stay in the habitable zone around their host star. If there had been less oxygen in the Sun’s chemical makeup, for example, Earth likely would have been pushed out of the Sun’s habitable zone about a billion years ago, well before complex organisms evolved. Considering the first complex multicellular organisms only arose about 650 million years ago, such a move would have likely destroyed any chance of complex life taking hold on Earth. Planets we are searching for signs of life may be about to leave their habitable zones or only have just entered them.
“Habitability is very difficult to quantify because it depends on a huge number of variables, some of which we have yet to identify,” says Young. “It also depends on the definition of habitable that we choose to use. We chose to use a relatively simple model that predicts whether a planet can sustain liquid water on its surface with reasonable assumptions about planetary atmospheres.”  

(Nikki Cassis)


Arizona State University is unstoppable. We believe if you empower students and faculty with entrepreneurial thinking and encourage them to explore at the edge of learning, great things will happen. SESE Professor Ed Stump is featured in the new The Unstoppable commercial, which got its first airing during the Pac 12 Network's coverage of the August 30th Sun Devils football game with NAU.

The associated webpage is now live at with bios and a separate video with each of the people in the commercial.