BC physicist aids NASA research

Historic OSIRIS-REx mission will shed light on asteroids, planet formation, and how life might have emerged on Earth

Associate Professor of Physics Cyril P. Opeil, S.J., is among a select few scientists taking part in an international research effort to shed light on the nature of asteroids, how the planets formed, and how life might have emerged on Earth.

Fr. Opeil is one of the rare researchers with experience studying the low-temperature thermo-physical properties of meteorites and asteroid formation. As part of NASA’s historic OSIRIS-REx mission, he has been tasked with conducting experiments on specific heat capacity and determining how a material from the asteroid 101955 Bennu expands and contracts at low temperatures. 

He expects to receive the sample, carefully curated by a NASA team, this spring and begin his experiments.

Cyril Opeil, SJ newly appointed Rector of the Jesuit community at BC. And newly appointed to the BC Board of Trustees. Photographed on the St. Mary's Hall premises.

Cyril Opeil, S.J., is one of the rare researchers with experience studying the low-temperature thermo-physical properties of meteorites and asteroid formation. (Lee Pellegrini)

“For me, it’s a wonderful moment,” said Fr. Opeil. “I think it is a tremendous time for a Boston College physicist, a Jesuit, to be asked to participate in this space mission. This is the first NASA program, similar in scope to the lunar Apollo missions of the 1970s, where an American spacecraft has traveled to a near-Earth asteroid to retrieve sample material.  So, it’s a historic moment.”

Launched on September 8, 2016, the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft traveled more than one billion miles to Bennu, classified as a near-Earth asteroid, and collected about 120 grams of rock and dust from its surface on October 20, 2020. The spacecraft spent more than two years on its return journey before it jettisoned a trapezoid–shaped capsule containing the samples that landed in the Utah desert on September 24, 2023.  From there the spacecraft continued on to its second mission, called OSIRIS-APEX, during which it will visit and scan the asteroid 99942 Apophis in 2029.

In fall 2023, while on sabbatical at the Vatican Observatory in Tucson, Ariz., Fr. Opeil was invited by some of his OSIRIS-REx colleagues to join in the official “watch party” at the University of Arizona as the capsule glided to Earth with the help of two parachutes.

“I would compare it to that moment watching TV when Neil Armstrong first stepped onto the moon,” said Fr. Opeil. “There was a crowd of scientists watching the big screens and they all cheered as the capsule landed. It was an awesome moment. Some of those researchers had spent the past six to seven years of their lives on this project, hoping the sample capsule would arrive safely. It was a picture-perfect landing.  This is the first NASA asteroid sample retrieval and a complete success.”

Fr. Opeil’s involvement in the analysis stems from his earlier work studying meteorites, specifically, those classified as carbonaceous chondrites—formed billions of years ago from a mix of space dust and stony materials, coming together under gravity. As a physicist, he studies meteorites as materials, exploring their thermal and physical properties.

To do that work, his BC lab includes a dilatometer, an instrument used to measure how a material expands as its temperature rises from near absolute zero. He first gained experience using a dilatometer while analyzing uranium compounds and magnetic shape-memory alloys at the Los Alamos National Laboratory in New Mexico as a post-doc of James L. Smith.

In 2020, Fr. Opeil published a paper about his experiments on a group of CM2 chondrite meteorite samples that revealed a surprising result: These materials did not expand and contract uniformly at low temperatures, exhibiting a rare phenomenon called negative thermal expansion. It was the first time negative thermal expansion had been observed in any extraterrestrial material. These findings attracted the attention of astronomers who were awaiting the samples from Bennu. Essentially, Fr. Opeil introduced a measurement technique that complemented the existing set used for chondrite analysis.

To better understand the findings, Fr. Opeil measured a kaolinite, a type of clay found on Earth. Kaolinite experiences a negative thermal expansion—similar to that used to make fine china—at exactly the same temperature as the CM2 meteorites. This type of clay can form on the Earth or Mars if, and only if, certain minerals and liquid water are present on the planet for a long period of time.

“I am one of the few people who specializes in measuring the low-temperature properties of meteorites. So, NASA wanted me to take part of the sample from Bennu and measure it in my laboratory on campus,” said Fr. Opeil.

In 2023 the International Astronomical Union named the asteroid 10692 Opeil for his contribution to astronomy. The main belt asteroid 10692 Opeil has a diameter of 3.126 km and a period of 3.543 years.

He’s been reviewing the scientific literature about Bennu and the models and measurements from earlier studies. “All of this indicates that Bennu may be made out of a similar material as a CM2 chondrite meteorite; I will be trying to confirm it has these characteristics,” he said. “If that doesn’t happen, it will be a surprise.”

Fr. Opeil acknowledged his collaborators at the University of Central Florida, including Dan Britt; noted astronomer/theorist Marco Delbo of the Observatoire de la Cote d’Azur in France; Jesuit brothers Guy Consolmagno, S.J., and Bob Macke, S.J., at the Vatican Observatory; and Alan Hildebrand of the University of Calgary.

Measuring a group of CM2 carbonaceous chondrites given by Br. Consolmagno, the Vatican Observatory director, led to identifying negative thermal expansion of this group of materials. Fr. Opeil’s paper confirmed an obscure meteoritic phenomenon of negative thermal expansion at the exact time samples of the same type were traveling back to Earth from Bennu.

Fr. Opeil will work with Britt and group leader Andrew Ryan of the University of Arizona to publish the findings in scientific journals. Fr. Opeil is currently working on another NASA-funded project involving Martian meteorites with colleagues from the Vatican Observatory in Rome, where he is spending the spring semester.

“I realize how important this is to be one of the few scientists, a Jesuit, who has been asked to participate in this mission. I think it stems in part from my association with the Vatican Observatory and my collaborators working with the meteorite samples,” Fr. Opeil said.

Prior to his characterization of meteorites, Fr. Opeil spent a decade working in the field of thermoelectrics, an alternative form of energy production where heat differentials produce electrical power. Collaborations with his BC colleagues, as well as the late MIT physicist Mildred Dresselhaus, sparked a deeper dive into materials coupled with an interdisciplinary approach to solid-state physics.

In 2023 the International Astronomical Union named the asteroid 10692 Opeil for his contribution to astronomy. The main belt asteroid 10692 Opeil has a diameter of 3.126 km and a period of 3.543 years.

“I feel very privileged that I have been supported by BC and that I have the laboratory to do this type of work,” Fr. Opeil said. “And it’s fun. You get to share with people your experience and discovery about things falling from the heavens.”