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Europeans map the geology of Mercury

April 18, 2016

The BepiColombo team is preparing a geological map of Mercury in several quadrangles in Italy and the UK, involving PhD students, postdocs and one undergraduate student.

While USGS is now publishing the MESSENGER team’s global geologic map of Mercury, in 1:15M scale, last year, employing three mappers, one for each quadrangle, the BepiColombo team have completed the 1:3M mapping of a little more than one-fifth of the surface of Mercury in three sheets.

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Work in progress: The boundary between the H03 and H04 quadrangles has yet to be checked.

We spoke to Valentina Galluzzi and asked her to give us an insight into the mapping process. Galluzzi told us that they are working thanks to the BepiColombo mission related funds. Beside the active mappers, the PI, Co-PI, Co-I and associates of the SIMBIO-SYS team and the BepiColombo Surface and Composition Working Group also support the project. “We need a full synergy of geologists, astrophysicists and engineers in order to have a complete grasp of the data that we are using” – Galluzzi says.

The beginnings

“The mapping process began in the middle of my PhD in 2013 but we were not considering of a global project at that time. When the map was finished (even though it still needed a lot of refinements) by the end of 2014, my supervisors started thinking to a broader project and we decided to contact other Mercury geologists to make this project real. It was a slow start, but as of today, the three finished maps are encouraging people to go on”.

There are students involved in the project, what is their reaction to this kind of job?

“When I started mapping the Victoria Quadrangle I was a [PhD] student myself, it was my first planetary geologic map, I was enthusiastic. When I realized that I had to map 5 million square km at an average mapping scale of 1:400.000 I became a bit scared. I couldn’t guess how long it would have taken to finish it because I was the first in the group to do that kind of work. Now, I can see the same kind of enthusiasm/concern in the eyes of other students/starters, but at least now they have someone who can tell them “hey, I know how you feel!”. The more we go on, the more support we can give to the new mappers.

What were the best moments in the mapping?
“The best moment is when you realize that your map is finished. However, when Laura and I stitched our finished quadrangles for the first time, we suddenly realized how much work was done. I could feel that also the other people working with us strengthened their confidence in the project and that everything was taking shape”.

Worst moments?
“When you realize that each time that you look at your map you want to change the contacts you drew the day before. However, eventually, you understand that the process of drawing-deleting-redrawing is what is needed to obtain a reliable product.”

Any major discovery so far?
“During my PhD I started mapping the structural features of the quadrangle and in the mean time, I was studying craters cross-cut by faults. Many authors use faulted craters to qualitatively assess fault kinematics or quantitatively calculate the strain field. I realized that thanks to some craters I could quantitatively assess the hidden fault geometry (e.g. fault true dip) and kinematics (e.g. slip trend, displacement). Although there are still many uncertainties for these quantitative results (mostly due to the lack of high-resolution topography on Mercury), we were able to publish this innovative (and simple) method (Galluzzi et al., 2015, Geol. Soc. Lon., Spec. Pub. 401), while currently we are working on the dating of fault systems through buffered crater counting.

How will the BepiColombo mission benefit from the maps?
“The “exploration” of Mercury, in a strict sense, was already done by Mariner 10 and MESSENGER. By exploiting the available data to map Mercury, we started knowing its surface like the back of our hand. Now, BepiColombo has to deepen our grasp of the planet by answering open questions and focusing on specific targets. An exhaustive geologic map can help individuating those scientific targets and prioritize the areas that need a different coverage (e.g. higher resolution or different illumination angles).”

New maps after the mission?
“For sure! After and during the mission higher resolution images will be available, it will be exciting to uncover new features and update the existing maps by producing advanced products.”

Williams et al 2014 describe Lessons Learned during their Vesta mapping. Any lessons learned during your mapping?
“Every scientist wants his/her own freedom when interpreting morphological features and finding an agreement is often difficult, especially if the mappers work in different institutes far away from each other. The greatest lesson learned is to start with the right tools right away: like, for example, a ready-to-use geodatabase with defined symbologies (as USGS also recommends). ”

 

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Valentina Galluzzi at LPSC 2016, with the poster showing the three merged quadrangles. 

The mappers: Valentina Galluzzi, Laura Guzzetta (both post-docs at the Italian National Institute of Astrophysics); Paolo Mancinelli (post-doc at the University of Perugia), Jack Wright, PhD student at the Open University in Milton Keynes, UK, whose supervisor, David A. Rothery helps coordinate the project. In addition, Lorenza Giacomini (University of Padova), and one undergraduate student (Alessandro Mosca, University of Naples) who partially mapped a quadrangle for his MS thesis, are also part of the team.

Without any ESA organization for planetary mapping, the final results of the group will be published in the Journal of Maps, as separate quadrangle sheets.

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