ASU scientist uses NASA MESSENGER mission data to measure chromium on Mercury

July 7, 2023

The origin of Mercury, the closest planet to the sun, is mysterious in many ways. It has a metallic core, like Earth, but its core makes up a much larger fraction of its volume – 85% compared to 15% for Earth. 

The NASA Discovery-class MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) mission, and first spacecraft to orbit Mercury, captured measurements revealing that the planet also strongly differs chemically from Earth. Mercury has relatively less oxygen, indicating that it formed from different building blocks in the early solar system. However, it has proven difficult to precisely pin down Mercury’s oxidation state from available data.  Color-coded chromium abundance map overlain on MESSENGER image of Mercury. Image courtesy Larry Nittler/ASU Download Full Image

In a new study led by Arizona State University scientist Larry Nittler, of the School of Earth and Space Exploration, data acquired during the MESSENGER mission were used to measure and map the abundance of the minor element chromium across Mercury’s surface. 

Chromium is commonly known for being extremely shiny and resistant to corrosion on metal work, and it gives color to rubies and emeralds. But it also can exist in a wide range of chemical states, so its abundance can provide information about the chemical conditions under which it was incorporated into rocks. 

Nittler and collaborators found that the amount of chromium varies across Mercury by a factor of about four. They calculated theoretical models of how much chromium would be expected to be present at Mercury’s surface as the planet separated into a crust, mantle and core under varying conditions. By comparing these models with the measured chromium abundance, the researchers found that Mercury must have chromium in its large metallic core, and they were able to put new limits on the overall oxidation state of the planet.

The work appears in the July issue of Journal of Geophysical Research Planets.  

“This is the first time that chromium has been directly detected and mapped across any planetary surface,” Nittler said. “Depending on the amount of available oxygen, it likes to be in oxide, sulfide, or metal minerals, and by combining the data with state-of-the-art modeling, we can glean unique insights into the origin and geological history of Mercury.” 

Co-author Asmaa Boujibar, of Western Washington University, who performed the modeling described in the paper, added: “Our model, based on laboratory experiments, confirms that the majority of chromium in Mercury is concentrated within its core. Due to the unique composition and formation conditions of Mercury, we cannot directly compare its surface composition with data obtained from terrestrial rocks. Therefore, it is essential to conduct experiments that simulate the specific oxygen-deficient environment in which the planet was formed, distinct from Earth or Mars.”

In the study, Nittler, Boujibar and their co-authors compiled data from laboratory experiments and analyzed the behavior of chromium under varying oxygen abundances in the system. They subsequently developed a model to investigate the distribution of chromium among the different layers of Mercury. 

The findings demonstrate that, similar to iron, a substantial portion of chromium is indeed sequestered within the core. The researchers also observed that as the planet becomes increasingly oxygen-deficient, a larger amount of chromium is concealed within its interior. This knowledge significantly enhances our understanding of the elemental composition and geological processes at play within Mercury. 

Media Relations and Marketing Manager, School of Earth and Space Exploration


Transfer student turns interest in electrical engineering into career with MyPath2ASU

Program helps plan term by term, minimizes loss of credit

July 7, 2023

Jared Gale said he always envisioned going to college and was growing concerned about the toll his job repairing heavy equipment in Arizona copper mines was taking on his health and well-being. 

Gale started his road to higher education at Central Arizona College before completing his degree at Arizona State University via the MyPath2ASU program. Transfer student Jared Gale Jared Gale (right) has an undergraduate degree in electrical engineering from ASU. He started his higher education journey at Central Arizona College and used the MyPath2ASU program to transfer. Download Full Image

Gale said he found the Central Arizona College professors approachable, with a passion for teaching and making difficult concepts easier to understand. 

His father was an electrical engineer, and Gale ultimately developed a strong interest in electrical engineering as well, making it his major.

Gale said he chose to transfer to ASU because of the innovative programs, experiential learning opportunities and support services that were especially helpful as a working parent. Gale met with his community college advisor and learned how the MyPath2ASU program would help to plan his transfer path term by term, saving him time and money while minimizing loss of credit.

Gale said he appreciated the MyPath2ASU pathway program for helping him successfully navigate the transfer process. 

“It was amazing, my advisor was able to lay out my entire program for me while at CAC. That also provided me with the resources I needed to do the same when I started at ASU, so the transition between the two was very smooth and there were very few surprises. When I actually started at ASU, I understood what to expect,” Gale said.

Gale graduated from ASU with his Bachelor of Science in engineering from the Ira A. Fulton Schools of Engineering in December 2021. 

He discusses more about his transfer journey below.

Question: Were you involved in any clubs or organizations at your community college?

Answer: I was involved with the honors group, Phi Theta Kappa, which included many research opportunities through the organization as well. I was also involved in helping a teacher with his astronomy class; he did a lot of community outreach with the younger elementary aged kids, and I helped him in the evenings with different stargazing activities using telescopes.

Q: Why did you choose ASU?

A: I chose ASU because I lived in Casa Grande and it was the closest university for us, as I didn't want to uproot my wife and little daughter. I also looked at the course load and the different classes that were offered under the engineering path and they seemed a lot more interesting than what the other universities offered. It seemed like ASU had more classes that were directed towards what I wanted to learn in the path I wanted to take.

Q: What did you enjoy most about your ASU experience?

A: One of the things I enjoyed most about My ASU experience was the flexibility I had with my professors. I had to bring my daughter with me to school many times and all my professors seemed to very much enjoy having her be a part of our class. My professors were also willing to work with me when dad duties came and I needed additional support.

The professors all around just understood that we are people and that we're not just machines here to master specific things. They were able to work with you a lot more than just during office hours, which was a great thing. Another thing I really enjoyed about ASU is the undergraduate teaching assistant program, which I participated in and worked as a TA for quite a few semesters. That was really cool to be a part of and give back to some of the students. The experience also solidified my foundation of the more basic concepts and skillset.

Q: What's one piece of advice that you would give to a new ASU transfer student?

A: Your success is going to be based on three factors. It's going to be about showing up, doing the work, and then following through to the end. And if you can do those three things, you're going to graduate with an amazing GPA and with amazing opportunities.

Q: How are you using your bachelor’s degree?

A: I'm currently working in environmental testing, testing components at a subassembly level to make sure they will survive the environment you design them to meet. So, you can definitely apply what you learned at ASU and from your engineering degree.

Q: Is there anything else you would like to share?

A: I think ASU has a lot of really good resources that are not very well known, especially for transfer students. When you have questions, don't be afraid to ask. And a lot of times people are willing to go further than you'd imagine just to help you. Don't ever be afraid to stand out and ask a question that may seem silly or stupid, as it really could be the key to your success.

Melanie Pshaenich

Coordinator senior, Office of the University Provost, Academic Alliances