Postdoc Spotlight: Cosmochemist Jemma Davidson

Jemma Davidson
Wednesday, March 11, 2015 

The life of DTM NASA Associate Jemma Davidson revolves around old, lifeless rocks, thanks to her 9th grade geography teacher and a high school research paper.

Davidson had already resigned to become an accountant while sitting in her 9th grade geography class. But when her teacher accidentally dropped a volcanic rock he had collected during fieldwork, denting her wooden desk and releasing a sulfurous smell into the air, her aspirations changed. She was now determined to study geology.

As an undergraduate, while writing a research paper on a recent advancement in science, Davidson came across these foreign things called presolar grains, microscopic pieces of dust created by dying stars that are preserved by meteorites.  

Davidson with a meteorite from the Moon at the 45th Lunar and Planetary Science Conference held in Houston, Texas. March, 2014. Photo courtesy of Jemma Davidson. 

“They [presolar grains] are literally pieces of stars that can be studied in the lab and they’re older than the Solar System,” says Jemma Davidson about her first encounter with the interstellar grains. “That completely blew my mind.”

DTM Staff Scientist and cosmochemist Larry Nittler, who is now Davidson’s mentor at Carnegie, was involved in many of the developments in that field of presolar grain research at the time of her undergraduate discovery. Davidson says Nittler, unknowingly, had a huge influence on her career path even then.

After finishing her masters in geochemistry at Durham University in 2006, she completed her Ph.D. in cosmochemistry and planetary science in 2009 at The Open University.  While at The Open University, her supervisor, and recent DTM alum, Henner Busemann who had just finished his own fellowship with Nittler, gave Davidson the opportunity to work with presolar grains.

Flash-forward six years later, Davidson says she is now asking a lot of her own questions about our Solar System:

    • What was the nature of the material present during the earliest stages of Solar System formation?
    • What survived, what was destroyed, and how did this material evolve?
    • What material may have been delivered to early Earth by asteroids and comets?

Her research works to identify material that has not changed much, if at all, since it formed 4.5 billion years ago in the early Solar System. This ‘pristine’ material survives inside asteroids and comets, as well as meteorites and interplanetary dust particles. She uses a number of different analytical techniques, like microscopy, spectroscopy, and mass spectroscopy, all of which are at Davidson’s disposal at DTM.

NanoSIMS ion image showing the hydrogen isotopic composition of a microscopic piece of organic matter (orange-yellow colored region) in the chondritic meteorite MIL 07687. Image courtesy of Jemma Davidson.

“Determining how this material formed and evolved during asteroidal alteration is essential to understanding what material may have been delivered to the early Earth by meteorites,” says Davidson. The organic matter within these meteorites may reveal prebiotic molecules that were crucial for the origin of life on Earth.

Although Davidson came to DTM to work with Nittler and fellow DTM cosmochemist Conel Alexander on these measurements, she has also been forming a new working relationship with the Geophysical Laboratory’s Acting Director George Cody.

Davidson intended to make spectroscopic measurements of meteorites with Nittler and Alexander in order to determine which organic species are present in them. However to do this, she needed the Advanced Light Source synchrotron in Berkeley, California, an instrument Cody is a longtime-user of. 

“I have to say in my experience of introducing people to this instrument, I have never seen any new user understand the fundamental aspects of this instrumentation quicker than Jemma did.”

-George Cody 

During Davidson’s first trip to Berkeley in April 2014, the synchrotron broke, making it impossible to collect the data she needed for her research. After hearing about her dilemma, Cody offered to take her with him on his next visit to the synchrotron in September 2014. 

“He shared his beam time with me and taught me how to use the instrument to get the best possible data,” says Davidson about her second visit to Berkeley with Cody. “George is also an amazing resource because he’s an expert in the study of organic matter in meteorites.”

“I have to say in my experience of introducing people to this instrument, I have never seen any new user understand the fundamental aspects of this instrumentation quicker than Jemma did,” says Cody speaking about this experience teaching Davidson how to use the instrument.  

Cody says in subsequent email conversations with David Kilcoyne, the beam line scientist who built the instrument, his high estimations of her were confirmed when Kilcoyne wrote he had never had a user who learned the instrument faster nor got great data in the speed Davidson has.

In the future, Davidson hopes to study samples returned directly from carbon-rich asteroids by missions such as JAXA’s Hayabusa-2 and NASA’s OSIRIS-Rex.

Davidson was recently granted a NASA Astrobiology Early Career Collaboration Award to perform more analyses at the synchrotron. She will be presenting her work at the synchrotron at the 46th Lunar and Planetary Science Conference in Houston, Texas, this month.

Written by Robin A. Dienel11 March 2015