News and Updates


Nearly 460 kilometers wide, Greeley Crater on Mars has been named in honor of a pioneering planetary science researcher at Arizona State University.

Throughout his career Ronald Greeley was passionate about exploring Mars, so it’s fitting that the late Arizona State University professor’s name will grace maps of the Red Planet.

A large, ancient crater – nearly as wide as Arizona – now carries the name of Greeley Crater, in honor of the Mars science pioneer and longtime professor of planetary science.

Greeley was involved in almost every major solar system robotic mission flown since the late 1960s and advanced the study of planetary science at ASU.

The crater, which spans 457 kilometers (284 miles), lies in Noachis Terra, the geologically oldest terrain on Mars. Although the crater's exact age is not known, the smaller impact craters superimposed on it plus its preservation state all suggest an age of at least 3.8 billion years.

It is centered just east of Mars' "Greenwich meridian" and is 37 degrees south of its equator.

Kenneth Tanaka, a planetary geologist at the U.S. Geological Survey's Astrogeology Science Center in Flagstaff and longtime colleague of Greeley, proposed the name, noting that it was the oldest, relatively well-preserved impact crater on Mars that remained still unnamed.

Tanaka will announce the crater’s naming in his keynote talk at the 24th annual Arizona/NASA Undergraduate Research Symposium on April 17 in Tempe.  

The International Astronomical Union, the world's authority for feature names on extraterrestrial bodies, formally approved the name on April 11. IAU rules require that a person must be deceased for at least three years before any commemoration can be made; Greeley died in October 2011.

Planetary science pioneer

During his career, Ronald Greeley was involved in almost every major solar system robotic mission flown since the late 1960s. These include the Magellan mission to Venus, Galileo mission to Jupiter, Voyager 2 mission to Uranus and Neptune, and shuttle imaging radar studies of Earth.

Passionate about exploring Mars, he contributed to numerous Red Planet missions, including Mariners 6, 7 and 9; Viking; Mars Pathfinder; Mars Global Surveyor; and the Mars Exploration Rovers. He was a co-investigator for the High Resolution Stereo Camera on the European Mars Express mission.

Joining the ASU faculty in 1977, Greeley was a pioneer in planetary science experiments. For example, he created a vertical gun to study impact cratering processes. Another instance was the use of wind tunnels to study the behavior of wind-blown sand particles and dunes, which are important features on the surfaces of Earth, Mars, Venus, and Saturn's largest moon Titan.

To study sand movement on Venus, where the atmosphere is nearly 100 times denser than on Earth, he built a special high-pressure wind tunnel. This same tunnel was recently reconfigured for Titan's surface conditions, and researchers discovered that to move Titan's sands, winds have to be much stronger than scientists had thought.

At the time of his death, Greeley was Regents' Professor of planetary geology in the School of Earth and Space Exploration (SESE), an interdisciplinary school combining science and engineering studies. Greeley had a key role in creating it and he served as interim director at its inception.

First image: Almost 300 miles wide, Greeley Crater lies in the heavily impacted and ancient southern highlands of Mars. It honors Ronald Greeley, longtime ASU planetary scientist who died in 2011. (NASA)

Second image: A spacecraft view of Greeley Crater shows a heavily modified surface. After Greeley Crater formed billions of years ago by the impact of a small asteroid, later impacts and lava flows on its floor have altered and partly obliterated its appearance. This THEMIS daytime infrared mosaic uses images from an ASU-designed visible and infrared camera on NASA's Mars Odyssey orbiter. (NASA/JPL-Caltech/Arizona State University)

Written by Robert Burnham


Like something out of “CSI” or “Bones,” researchers at Arizona State University are working to solve the mysteries of unidentified human remains – and just as on those TV shows, science plays a key role.

Gwyneth Gordon, an associate research scientist in ASU’s School of Earth and Space Exploration, will soon be making a trip to academia’s most distinctive research facility: the University of Tennessee’s Anthropological Research Facility, the original “Body Farm.”

At the facility’s open-air crime labs, decomposing corpses are left out in the elements, some on the ground and others in shallow graves. Gordon will collect samples from the cadavers and samples of soil and groundwater; in May, she’ll do the same thing at Texas State University in San Marcos.

With funding from the Department of Justice’s National Institute of Justice, Gordon and professors Kelly Knudson and Ariel Anbar will study how various isotopes in the human body behave during decomposition in different environments. These techniques have long been used in the anthropologic study of migration and lifestyle of ancient peoples, but only recently have begun to be used in modern cases of homicide, mass graves and unidentified migrants.

With some 10,000 open cases of unidentified human remains in the U.S. today, the research’s results will have real-life implications for law enforcement, medical examiners and families looking for answers.

“Can our technique unravel a human story that was previously lost to history? That’s what we’re trying to find out,” Gordon says. “The donor histories provide premortem travel and geographic life histories, and we’ll see if our analyses match their life histories.”

Unlocking clues hidden in bones

Every molecule in our bodies is made up not just of different elements, but of different ratios of stable isotopes of those elements. They leave an isotopic signature that can speak for the dead, revealing diet, birthplace and travel history.

Samples collected at the body farms – including hair, tooth enamel and skeletal elements – will be analyzed at ASU for oxygen and hydrogen isotopes to determine latitude; carbon and nitrogen to obtain dietary history; and strontium and lead isotopes and trace elements to establish the type of bedrock where the deceased was born or lived.

Sample preparation will occur both in the School of Earth and Space Exploration and in collaboration with the Archaeological Chemistry Laboratory under the supervision of archaeological chemist Kelly Knudson, associate professor in ASU’s School of Human Evolution and Social Change and affiliated with the Center for Bioarchaeological Research.

Knudson uses biogeochemistry and bioarchaeology to answer anthropological research questions. She is a world expert on the application of isotopes to archaeological sites and individuals.

“As an archaeologist, I am more used to working with people who died hundreds or thousands of years ago. Applying my knowledge to forensics applications and, eventually, to helping to solve modern cases is one of the things that really appeals to me about our research project,” Knudson says.

Finding migrants’ birthplace

The sites of the two body farms have very different climates and soil types. Tennessee – very wet – is similar to significant portions of the United States, while the dry Texas site is similar to the U.S.-Mexico border.

“We chose that site explicitly because of the large number of undocumented immigrants who die in the desert while trying to get to the U.S. These individuals often have no identification on them, and their families never know what happened to them,” Gordon says. “There’s also commonly no DNA to match them to. If we can get a better idea where they were from using isotopes, the search for their families would be significantly easier.”

According to Knudson, archaeologists have been using isotopic data to figure out people’s diets for more than 30 years, while using that data to determine someone’s birthplace has been common only in the past 15 years.

“These techniques haven’t been used quite as much in forensic anthropology, despite what you may see on ‘CSI’ or ‘Bones,’ ” she says.

While stable isotopes have proven themselves useful, they aren’t staples of forensic science – yet. However, a number of case studies have demonstrated that these types of information can narrow the search and help discover a person’s identification.

“What I think is great about this research is that we are doing the kinds of baseline research into how these isotopes act during decomposition so that the forensics community can use them,” Knudson says.

Image: Armed with a high-tech, chemistry-driven approach, ASU researchers will study how different isotopes in the human body behave during decomposition in different environments. The results will have real-life implications for law enforcement, medical examiners, the military and countless families looking for answers about loved ones.
Photo by: Andy DeLisle

Written by Nikki Cassis


Two Arizona museums will soon add an astronaut as a docent – a digital docent called “Dr. U.”

The Arizona Science Center and the Arizona Museum of Natural History are partnering with Arizona State University to offer visitors an app to complement their exhibits. Dr. Universe, a mobile app, encourages museum visitors to ask questions and the astronaut responds back from its database.

Dr. Universe is a project spearheaded by students and faculty in the School of Earth and Space Exploration and the School of Computing, Informatics and Decision Systems Engineering. A team of engineering students worked on programming as earth and space exploration and biology students created content – a student from the Herberger Institute from Design and the Arts designed the visuals.

The project is run by Judd Bowman, associate professor at the School of Earth and Space Exploration, Brian Nelson, associate professor at the School of Computing, Informatics, and Decisions Systems Engineering, and Cassie Bowman, associate research professor at the School of Earth and Space Exploration. During Cassie Bowman’s graduate school career, she researched whether it’s possible to have a mentor relationship with a computer in an educational environment. Within the last three years, Judd Bowman said he and his colleagues considered how museum staff need help in evaluating visitors’ experiences.

“It seemed like a natural fit to take this idea of a ‘computerized scientist’ and let people have it within the museums and let people ask questions with it,” Bowman said.

Bowman said museum exhibits tend to have a long lifetime, but they aren’t always updated as quickly as science advances. The app, funded by the National Science Foundation, currently covers more than 12,000 questions on various topics from astronomy to geology. Bowman said he and the team collected many of the questions three years before the development of Dr. Universe. Museum staff will also have access to a dashboard that aggregates the popular topics and questions being asked on the app.

“The idea is it’s a trusted database of information,” Bowman said. “It’s been screened through us, through our students. You know it’s going to be safe for kids, safe for your family members to use it. It’s not just whatever Google happens to bring up.”

Kyle Rogers, a geological science senior, said he goes to the two museums and figures out what content to develop based on the open exhibits. He also talks with the docents to see what questions are commonly asked. In addition to information provided by the museum, Rogers also utilizes textbooks, government websites and peer reviewed articles.

Rogers said he’s worked on approximately 2,500 questions in the past four months. With the previous database and his work, Rogers said currently the database houses around 12,000 Q&As in English. He works about 10 hours a week.

“It’s a great project because it’s furthering someone’s education,” Rogers said.

Ivan Fernandez, biological sciences junior, translates the questions, and Itxier Meziani, earth and space exploration senior, works on translating the answers. Meziani said she spends about 10 hours a week translating the answers.

Meziani said she conducts a lot of research to find the right word because certain words don’t translate exactly into Spanish. Meziani said she’s translated 4,000 answers so far in Spanish. She also helped Fernandez translate questions, and she said it takes her about one hour to translate 200 questions.

Dheeraj Yennam, a computer science senior, said his group chose the project because of the flexibility it provided. The engineering students meet up weekly with the professors to talk about their progress and best next steps.

“They’re asking us for our opinion instead of telling us their opinion and to do it,” Yennam said. “We appreciate that as programmers.”
He said their group has enjoyed working on the project that they use some of their own time to put in extra hours.

The Dr. Universe team had their first testing of the app earlier in the semester at the Arizona Museum of Natural History. Bowman said it was a good testing experience because they had the real museum environment. It helped the whole team see if the speech detection worked in a loud environment or if its design for the iPad mini provided a good feel.

Meziani said that the trial run at the museum went well for the Spanish portion. However, there still needs to be work done for the microphone to catch Spanish accents.

“I was really surprised how much people have done on this application,” Meziani said. “We were able to talk back, and I even had my kids try it, and they loved it.”

The next trial run will incorporate another feature involving iBeacons placed throughout the exhibits that will track when a user is nearby. Bowman said in one exhibit they noticed how photographs' descriptions were in English but not Spanish. If the beacon recognizes the app, it could do something like pull up the Spanish descriptions.

Yennam said they have the bluetooth beacons ready to be tested. He said the beacons have been tested in smaller rooms, but he isn’t sure how it will work in a larger environment.

He said the team is excited that there is potential for the app to expand to other museums. Yennam said the museum staff seem impressed that a user could speak into it and there wouldn’t be spelling errors.

The project is set to last for three years, but Bowman said he hopes it develops into a product that many museums use and tailor to their content.
“This project is a really cool example of ASU getting into the community, students getting involved with the museums and seeing how the things they’re learning and the work they’re doing here applies in that context,” Bowman said.


Image: Dheeraj Yennam (left) and Jared Korinko, a student and faculty member from the School of Computing, Informatics, and Decision Systems Engineering, test the Dr. Universe app at the Arizona Museum of Natural History in Mesa.
Photo by: Judd Bowman

Written by Alicia Canales



Congratulations to Associate Professor Steve Semken for winning the 2014-2015 Zebulon Pearce Distinguished Teaching Award in the Natural Sciences!

The Zebulon Pearce Distinguished Teaching Award was established in memory of Zebulon Pearce, who graduated from Territorial Normal School at Tempe (now Arizona State University) with teacher’s credentials in 1899. Professors in the humanities, natural sciences and social sciences departments received this award.

Semken has worked at ASU since 2007 but he joined the School of Earth and Space Exploration in 2009. He also works as deputy director for education and outreach at the National Science Foundation EarthScope Project National Office. He teaches classes ranging from introductory courses to graduate. For Semken, context plays a huge role in his teaching philosophy.

"I will continue to draw on my education research program to inform and enhance my teaching, and I intend always to teach with unflagging, contagious enthusiasm for my discipline, and with sincere respect for all of my students,” he said.

“He is among our most dedicated faculty who passionately delivers on the fundamental values of place-based education, both in the classroom and nationally. We are very fortunate to have his leadership and high profile,” said Linda Elkins-Tanton, director of the School of Earth and Space Exploration.

“I feel so honored to have had, and continue to have, the opportunity to learn from Dr. Semken. Students remember the professors that touched them the most, through their inspirational teaching as well as their guidance and mentorship, for the rest of their lives. Dr. Semken is one of those very, very few professors for me,” said doctoral candidate Mary Schultz.

The Zebulon Pearce Distinguished Teaching Awards were established in memory of Zebulon Pearce, who graduated from Territorial Normal School at Tempe (now ASU) with teacher's credentials in 1899. These awards recognize teaching excellence in the College of Liberal Arts and Sciences. Last year, SESE Professor Phil Christensen received the honor.

Steve will be seated on the stage and recognized at the CLAS convocation ceremonies.



It doesn’t take a sky-high budget to conduct aerospace research, thanks to weather balloons and a little ingenuity.

Teams of students from across Arizona, including a team from Arizona State University, launched their unmanned research balloons as part of the Arizona Space Grant Consortium’s ASCEND program, short for Aerospace Scholarships to Challenge and Educate New Discoverers. The launch took place March 27 in Pinal County West Park in Maricopa. 

Every semester student teams design and build payloads for launch on high-altitude weather balloons. About 10 feet in diameter when inflated, these hardy balloons can reach altitudes of more than 100,000 feet – higher than a passenger plane – yet can be built on a shoe-string budget.

This semester, a team of 12 ASU students put together a research payload to collect panoramic video and thermal imaging data. Instead of rockets, boosters and expensive control systems, they filled a weather balloon with hydrogen and hung a carbon fiber box underneath to carry the cameras and sensing equipment.

The balloon and camera made it up high enough to see the black sky curling around our blue planet, a staggering 94,687 feet. The flight was approximately three hours. When the balloon burst, the payload took about 45 minutes to come back to Earth, landing about 5.7 miles from the launch site.

ASU/NASA Space Grant provides funding to the ASU ASCEND team for payload materials and travel expenses. The payload cost roughly $1,000. The Arizona Near Space Research provides the balloons for the launch. Launch costs typically run around $5,000, including the “extras,” such as GPS beacons.

“As the team leader, I was required to manage the logistics of a complex project, making sure all systems work together in the final product. Having done this before, I have the opportunity to pass on the lessons I’ve learned to others on the team,” said Jack Lightholder, a paid ASU/NASA Space Grant intern and veteran balloon launcher.

Part of the Arizona Space Grant Consortium Workforce Development program, ASCEND is designed to engage undergraduate students in the full “design-build-fly-operate-analyze” cycle of a space mission.

“This program gives students the experience of developing an experimental question, developing a payload design to test it, building said payload and analyzing the data. The dataset will also be used for some baseline testing of other instruments within SESE labs,” Lightholder said. This was his seventh launch.

The ASCEND team is led by Tom Sharp, a professor in ASU’s School of Earth and Space Exploration and the Arizona Space Grant Consortium’s associate director. This year’s members include: Jack Lightholder, SG intern/team lead, computer science; Mason Denney, SG intern/team lead, computer systems engineering; Tyler McKinney, aerospace engineering; Ines Weber, physics; Clelia Tommi, astrobiology; Trevor Van Engelhoven, astrophysics; Vishal Ghorband, electrical engineering; Jefferson Fleing, aerospace engineering; Claeren Mapili, aerospace engineering; Zach Burnham, electrical engineering; John Gehrke, aerospace engineering; Mateo Orama, mechanical engineering.

Team meetings are once a week. Please contact Jack Lightholder if interested in joining. No prior experience or specific skill sets required.

In addition, ASU/NASA Space Grant Undergraduate Fellowship applications are available for the 2015-2016 academic year at: Space Grant usually funds one or two team members per year.

Image courtesy of Jack Lightholder.

(Nikki Cassis)


The first space instrument to be built at Arizona State University has just received the electronics it will use in flight. This starts the final laboratory tests leading to its launch next year on a NASA rocket.

The last major subsystem for the OSIRIS-REx Thermal Emission Spectrometer — its electronics — has arrived in a cleanroom at Arizona State University's School of Earth and Space Exploration (SESE). The electronics are the third of three subsystems making up the spectrometer, called OTES for short. The other two are the spectrometer's optical and mechanical systems.

On March 31, 2015, NASA gave a green light for the OSIRIS-REx mission to transition from development to bringing instruments and their components together. This will be followed in the months ahead by integrating and testing the spacecraft's combined systems.

The OSIRIS-REx mission will launch in September 2016 and fly to an asteroid, 101995 Bennu. There it will collect a sample of its rocks and dirt and bring them back to Earth in 2023. (OSIRIS-REx is short for Origins Spectral Interpretation Resource Identification Security Regolith Explorer; the University of Arizona in Tucson leads the mission.)

OTES plays a key part in the mission to Bennu. Its task is to use long-wavelength infrared light to map the asteroid's minerals, which will help mission scientists select where to collect samples. Designed at ASU, OTES is the first space-qualified instrument to be built at the university. ASU is one of only a handful of universities in the United States capable of building NASA-certified space instruments.

"We have already built the spectrometer part of OTES, and attached it to the telescope that collects light so it can work," says Philip Christensen, OTES' designer and principal investigator. Christensen is a Regents' professor of geological sciences in SESE. "The final element is the electronics that will control the instrument. OTES has now received its brain and nervous system."

Next come tests as engineers working in a cleanroom in Interdisciplinary Science and Technology Building 4 on the Tempe campus work to integrate the electronics with the optical and mechanical parts of OTES.

Testing will include placing OTES in a chamber where it is subjected to the same conditions it will experience during the mission. Aerospace engineers call this process "shake and bake" because it reproduces the vibrations of a rocket launch as well as the extremes of heat and cold that OTES must survive to do its job.  

"NASA's rules for testing flight instruments and other space hardware are detailed and thorough," Christensen says. "They need to be. Once the spacecraft leaves Earth, there are no repair calls. Everything has to work perfectly."

Primitive target

Scientists chose asteroid Bennu as the target for the OSIRIS-REx mission because it has undergone relatively little change since it formed early in the solar system's history. Thus samples from Bennu may give us a better look at how the solar system formed.
With an orbit that brings it inside Earth's orbit, Bennu is the most accessible asteroid rich in organic materials. It is about 575 meters (1,900 feet) wide, roughly spherical, and spins once every 4.3 hours. Reflecting only three percent of the sunlight falling on it, Bennu is about as dark as a charcoal briquette.

The flight plan calls for the OSIRIS-REx spacecraft to launch in September 2016 and rendezvous with Bennu in November 2019. It will spend up to 15 months surveying Bennu's mineralogy with OTES and another spectrometer working at shorter visible and infrared wavelengths. A suite of three visible-light cameras and a laser altimeter will draw a complete picture of the asteroid.

Mission scientists will then select a target area. The spacecraft will approach Bennu, touch it briefly, and collect at least 60 grams (2 ounces) of dust, soil, and rubble from its surface. Then OSIRIS-REx will cruise back to Earth and deliver the encapsulated sample to a landing site in Utah in September 2023. After dropping off the sample as it flies past Earth, the spacecraft may go on to survey other asteroids, although it will not be able to collect samples from them.

Christensen says, "As we put all its flight parts together and start on this final series of testing, it's very exciting to see OTES come to life in our hands."

The School of Earth and Space Exploration is an academic unit of the College of Liberal Arts and Sciences.


Combining his love for 3-D animation, space and engineering, Sean Amidan has turned a hobby into a career opportunity.

Amidan, a senior earth and space exploration major with a concentration in systems design, is the lead visualization specialist at the Space and Terrestrial Robotic Exploration Laboratory (SpaceTREx) at Arizona State University.

He spends his days creating and designing 3-D models of CubeSats (miniature satellites) for the Asteroid Origins Satellite (AOSAT) project, designing logos for the School of Earth and Space Exploration outreach programs and developing 3-D visualization software.

“The professor I work for (Jekan Thanga) is in charge of the whole lab, and I know he has done a few things [with] the International Space Station, so that’s cool,” Amidan said. “Some of the professors I’ve had in my classes have worked on Hubble, the space telescope … and now I’m working with [them].”

Amidan discovered his skill for 3-D animation in high school when he took two years of 3-D animation classes, but never envisioned it carrying through into college. He started off at ASU on the pre-med track, then decided to try out engineering before he finally settled in at School of Earth and Space Exploration after accepting a job in the SpaceTREx lab.

“It was more kind of a hobby so I started to do different stuff in college but then I got lucky and found this job working for the lab,” Amidan said.

Along with his 3-D animation work in the lab, Amidan also gets to explore the software, programming and robotics elements of the space program in his classes, which, in turn, often informs his work in the lab.

“My degree really helps in the lab because I can really understand why [something is] being built this way, or what it’s being built for,” Amidan said. “It would be really hard to do the 3-D modeling without my degree and that knowledge.”

Amidan’s favorite project so far has been the AOSAT CubeSats. A CubeSat is a small, modular satellite, about the size of a loaf of bread. Amidan is designing the artistic renderings for the project, helping to bring the concept to life, with the guidance of his professor and NASA experts.

Currently in his last semester at ASU, Amidan is looking toward the future and has already started to apply for jobs after graduation. If he had to pick his dream job, the monthly magazine Popular Science would be at the top of his list.

“I joke around with people saying that I want to work at Popular Science and do all their artwork and science models. I think that would be pretty fun,” Amidan said.

Back at the lab, Amidan is continuing to create artist renderings of the CubeSat, and will continue to make tweaks as the project grows.

The ASU CubeSat is expected to be flight-ready by May 2016.

Written by Samantha Pell, ASU News

Photo: ASU student Sean Amidan created this concept art for a small highly energy efficient robot. The earth and space exploration senior is the lead visualization specialist at the Space and Terrestrial Robotic Exploration Laboratory at Arizona State University.
Photo by: Sean Amidan


An article assistant professor Christy Till wrote with a colleague was just posted on the American Geophysical Union, Volcanology, Geochemistry and Petrology (VGP) website and can be found here:

Amongst the discussion of exciting research topics, the article features descriptions and pictures of Till's laboratory and research group in SESE, which focuses on the study magma and how and why it forms in the lab under simulated high pressures and temperatures, and what that tells us about planetary differentiation. A more detailed explanation can be found on her lab website:



Come learn about the huge diversity of life as we know it, life as we think it might be, and how we're trying to discover it on other worlds at the next Earth and Space Open House, March 27.

Is there alien life beyond planet Earth? We don't yet know, and the job of astrobiologists — those who study life in space — is to find out.

One place to start the search is within our own solar system, where hunting for life is like looking for a good restaurant. There are three kinds of places: the chain franchises (decent, but so predictable), the up-and-coming areas (the next big thing), and the hidden gems (hit or miss, but could be amazing). Come find out about the must-go places in the Yelp of astrobiologists.

Those who wish to learn more about extraterrestrial life are invited to attend a free public lecture at the next Earth and Space Open House, from 7 to 10 p.m., March 27, at the Interdisciplinary Science and Technology Building IV (ISTB 4) on ASU’s Tempe campus.

The talk, "Hunting for Life in the Solar System," will be given by the School of Earth and Space Exploration's Marc Niveu, graduate student in astrophysics.

In addition to the public talk, there will be two 3-D planetarium shows in the Marston Exploration Theater, at 7:15 and 8:45 p.m. All seating is on a first-come basis.

At 8 p.m., attendees can "Create Your Own Planet" in the Marston Exploration Theater. (Participants must sign up at the welcome table beforehand.)

As usual, there will be telescope sky viewing outdoors next to the James Turrell Skyscape art installation from 8 to 10 p.m. (weather permitting). There will also be several exciting demonstrations and activities in the state-of-the-art ISTB4 Gallery of Scientific Exploration by experts in astrobiology, geology, cosmology and planetary science – as well as a free poster.

The open house can be accessed through the main entrance of ISTB 4, located on the building’s north side.

The monthly open house is sponsored by the School of Earth and Space Exploration, GeoClub, AstroDevils: ASU Astronomy Club, Icarus Rocketry, Students for the Exploration and Development of Space (SEDS), the Center for Meteorite Studies (CMS) and many others.

For more information, visit or visit the school's Facebook event page. The final open house of the spring semester will be held on April 24 (on the 25th anniversary of the Hubble Space Telescope).

The School of Earth and Space Exploration is an academic unit of the College of Liberal Arts and Sciences.


The moon is pelted with cosmic debris all the time, but the largest explosion on its surface that we’ve actually recorded occurred two years ago today. On March 17, 2013, an object the size of a small boulder hit the surface in Mare Imbrium and exploded in a flash of light nearly 10 times as bright as anything ever recorded before.

Images acquired of the surface before and after the impact by NASA’s Lunar Reconnaissance Orbiter Camera (LROC), overseen by a team at Arizona State University, reveal intricate details of the resulting impact crater and help calibrate models of crater formation.

Since 2005, astronomers have monitored the moon for signs of explosions caused by meteoroids hitting its surface. When a meteoroid strikes the moon, a large portion of the impact energy goes into heat and excavating a crater; however, a small fraction goes into generating visible light, which results in a brilliant flash at the point of impact.

The brightest flash recorded by researchers at NASA’s Marshall Space Flight Center occurred on March 17, 2013 with coordinates 20.6°N, 336.1°E. The team predicted the crater’s size based on the energy, and they eagerly awaited LROC’s next pass over the location to confirm their calculations.

Being able to get observations before, during and after the impact is a valuable opportunity to understand impact events better. Comparing the actual size of the crater to the brightness of the flash helps validate impact models.

The hunt for the March 17 crater

LROC’s first set of post-impact flash images acquired on May 21, 2013 by the Narrow Angle Camera were targeted on the Marshall-reported coordinates and numerous small surface disturbances (“splotches”) were detected by comparing the pre- and post-flash images, but no new crater was found.

A second set of Narrow Angle Camera images was acquired on July 1, 2013, showing three faint ray-like features and several chains of splotches and asymmetric splotches that generally pointed to a common area west of the Marshall coordinates. A Narrow Angle Camera pair was targeted on that convergence point for July 28, 2013; comparison of this third set of images with preexisting coverage revealed a new crater.

The crater itself is small, measuring 18.8 meters (61.7 feet) in diameter, but its influence large; debris excavated by the sudden release of energy flew for hundreds of meters. More than 200 related surficial changes up to 30 kilometers (19 miles) away were noted.

Not only did the LROC images reveal intricate details of ejecta distribution, but they also offered a valuable opportunity to study the structure of the top meter of the regolith. Regolith is a term that refers to a soil that is lacking organic material.

The soil on the Moon is formed slowly over time as micrometeorites impact the surface and slowly grind rocks into a fine powder. As the fresh soil grains sit on the surface they are exposed to radiation and slowly become darker and redder (mostly due to reduction of iron in minerals to iron metal – reverse of rusting that happens on Earth). This slow change in reflectance and color is generally referred to as space weathering; fresh soil is referred to as immature, and weathered soil is mature. The longer a soil sits on the surface the more mature it becomes.

Several surprises were revealed in the before and after image pairs around the new crater. Conventional thought predicted that the new crater should be surrounded by a high reflectance ejecta blanket out to about a crater diameter with some patchy ejecta spreading out two or three diameters.

“The high reflectance was there, but three other zones were discovered. At the edge of the high reflectance ejecta was a low reflectance zone, then beyond that another high reflectance zone and beyond that another low reflectance zone,” reports Mark Robinson, a professor in ASU’s School of Earth and Space Exploration and LROC’s principal investigator.

The results are published are in the Jan. 31 edition of the journal Icarus.

Finding new impact craters

It’s not easy to find new impact craters because most of them are very small. The only way to really do this is to have a before image and an after image to compare.

LROC began systematically mapping the Moon in the summer of 2009. Now, the team is going back to images taken in the first year or two and comparing them to recent images. Called temporal pairs, these before/after images enable the search for a range of surface changes, including new impact craters, formed between the time the first and second image were acquired.

As of Jan. 1, 2015, LROC has acquired about 10,000 before and after image pairs. Manual scanning of all these pairs is impractical so Robinson’s team developed a computer program that automatically identifies suspected changes from each temporal pair.

With the help of the automated tool, the team has identified 225 new impact craters ranging in size from 1.5 meters to 43 meters (4.9 feet to 140 feet) and over 25,000 small changes known as “splotches” (likely unresolved primary and secondary craters).

Image: Four different NAC images of crater (18 meter diameter) formed on the moon, March 17 2013, each scene is 560 meters wide, north is up.
Photo by: NASA/GSFC/Arizona State University

(Nikki Cassis)