NASA grant allows Purdue researchers to study and recreate the surface of Mercury
An exploration mission comprised of two spacecraft and named BepiColombo launched in 2018 and embarked on a first-of-its-kind seven-year journey. At the end of the mission in 2025 when the spacecrafts are eventually sucked into the gravity of the Sun, these crafts will have endured temperatures exceeding 350 degrees Celsius and gathered data from one of the least explored planets in our solar system: Mercury. Mercury is so close to the Sun that it is difficult to get a spacecraft near the planet without it melting or exploding. Much like Icarus, these crafts will need to navigate the delicate balance of melting into the Sun and grazing Mercury to gather data scientists can use to evaluate the scorched planet.
This mission will take a robust team of scientists from around the world to help make its pursuit a success. The mission itself is a joint venture between JAXA and ESA, but due to the collaborative nature of the international space programs, scientists from all over the world will be using the data collected from Mercury. Dr. Michelle Thompson, Associate Professor of Purdue Earth, Atmospheric, and Planetary Sciences (EAPS), and Dr. Nicolas Bott, Postdoctoral Research Associate, have been awarded a $1.4 million research grant by NASA to study the surface of Mercury based on data returned from BepiColombo.
The team from Purdue was awarded the grant support as part of the 3 Solar System Workings (SSW) program. The proposal submitted by Thompson and Bott was titled, “An Experimental Investigation of Space Weather Processes on the Surface of Mercury.” Thompson is the lead for this proposal and her team will have multiple subcontracting partners on the award, including scientists from the University of Virginia, the University of Northern Arizona University, the University of Hawaii, and NASA Johnson Space Center. Leadership for the proposal will be coordinated from Purdue University in West Lafayette.
According to Thompson, it is known that Mercury is especially enriched in chemicals like sulfur and is depleted in chemicals like iron compared to other planets in our solar system. There are also pockets that are enriched in carbon in the form of graphite, like the graphite in your pencil, on the surface of Mercury.
“Mercury doesn't have a robust atmosphere like we have here on Earth,” says Thompson. “It is constantly being hit with ions from the Sun. It is also constantly bombarded with hypervelocity dust impacts. There is a really high dust flux in the inner solar system and since it is so close to the Sun, Mercury experiences an extreme environment for these processes going on at the surface of the planet. The processes we are studying in this project are focused on how the surfaces of these bodies are altered in the solar system because of their exposure to interplanetary space.”
In addition to using data from BepiColombo, the team will use data collected from the original mission to Mercury, NASA’s Mariner 10 (1973), and NASA’s MESSENGER (2004-2015) and compare it to data collected from BepiColombo to gain a much more robust understanding of the chemical makeup of the planet’s surface. The team will also be using this data to synthesize samples that are analogs to what they think are on Mercury’s surface to help them study the chemical makeup up close and in person.
“We will prepare our analogs using terrestrial materials poor in iron and mix them with other chemicals that are enriched on the surface of Mercury, like graphite or sulfur,” explains Bott. “This way, we recreate a chemical composition close to the one observed by MESSENGER, on which we can simulate the harsh environment of Mercury."
Thompson’s LEAPS Lab at Purdue University uses a combination of sample analysis and laboratory experiments to study the evolution of airless planetary bodies like the Moon, Mercury, and asteroids using state-of-the art analytical techniques. Due to the highly specialized nature of the work performed in this lab, it made the ideal place to create an analog, or functioning model, of Mercury’s surface.
“We don't have samples from Mercury, so we have to make analog materials that are unlike things that we see here on Earth because they have this weird chemistry,” says Thompson. “We simulate solar ion radiation, we simulate the dust impacts and then we characterize the structure and the chemistry of the samples. Then we measure their optical properties. There are spectral properties that we can observe with a remote sensing spacecraft. We don't understand how this unique composition affects the types of minerals that we can detect on the surface… chemistry that we can measure with spacecraft. So the project’s aim is to simulate these surface processes in the lab.”
Long after the two spacecraft from BepiColombo have been suctioned into the Sun and die in a fiery explosion, the data collected from the mission will allow planetary scientists around the world to closely analyze the surface of Mercury. Comparing the data from this mission and others will allow a more pinpoint precision on the chemical makeup of the planet.
“The MESSENGER mission was actually able to measure surface chemistry,” says Thompson. “This is how we know it's really enriched in sulfur, depleted in iron and enriched in carbon. But the types of instruments they had on that mission were not able to actually measure specific minerals, only able to measure elements. We cannot say it's definitively olivine or it's definitively pyroxene or whatever. So for the analog, we are using our best estimates for what the minerals are going to be. Doing these experiments will actually give us better constraints so we can tell what the mineralogy might be from the spectral data that we're getting with BepiColombo and how they might be altered on Mercury’s extreme surface environment.”
With this grant, Thompson said that persistence has paid off. This proposal was submitted three times. Each time, they returned with great feedback.
“It was a very clear that there was a good idea there. So, for the students, persistence is important. Mercury is a totally understudied planet, so it's time we went back.”
About the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University
The Department of Earth, Atmospheric, and Planetary Sciences (EAPS) combines four of Purdue’s most interdisciplinary programs: Geology & Geophysics, Environmental Sciences, Atmospheric Sciences, and Planetary Sciences. EAPS conducts world-class research, educates undergraduate and graduate students, and provides our college, university, state and country with the information necessary to understand the world and universe around us. Our research is globally recognized, our students are highly valued by graduate schools, employers, and our alumni continue to make significant contributions in academia, industry, and federal and state government.
Writer/photo: Cheryl Pierce, Communications Specialist
Contributors: Dr. Michelle Thompson, Associate Professor and Dr. Nicolas Bott, Postdoctoral Research Associate