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Stories of Planetary Mapping      

Riccardo Pozzobon and Matteo Massironi (University of Padova, Italy) explains how Europlanet’s GMAP activity has created infrastructure to support geological mappers around the world.

Read article in the fully formatted PDF of the Europlanet Magazine.

Geological mapping is an exercise in storytelling; by creating a map, you can show the different ages of rocks present in a region, their composition, the timings and the processes of formation. Essentially, a geological map is like a book that brings all this information together to build up a complete story of a landscape.

Over the past 50 years, there have been multiple space missions that have explored objects in the Solar System and sent back detailed images of planetary surfaces. Most mapping of planetary bodies has used these images to create ‘morphostratigraphic’ maps. ‘Morphology’ is the study of the appearance and characteristics of different units of rocks, such as surface textures, roughness and albedo (the amount of light that they reflect). ‘Stratigraphy’ charts the relative timing of the emplacement of the units of different relative ages – i.e. the sequence in which they were laid down – and assigns a legend so that the oldest units are at the bottom of the chart and the most recent units are on top. Morpho-stratigraphic maps bring these elements together to build up a story of the characteristics, configuration and evolution of the different morphological units and planetary landscapes. 

However, these planetary maps are a long way from the comprehensive geological maps we have for the Earth, where the geomorphological, structural and stratigraphic characteristics are integrated with lithological information including mineralogical composition. 

Geologists don’t have the luxury when studying planetary bodies to go out into the field and see for themselves the texture of rocks, or dig to see what’s happening in the subsurface and take multiple samples back to the laboratory for analysis. However, there is a wealth of spectral data collected by remote sensing missions, which can reveal the composition of the rocks, as well as data like altimetry and digital elevation models that can show the topography and the processes that shape the terrain. Radar sounding techniques can probe the sub-surface and have allowed us to discover, for example, layered ice deposits in the polar caps of Mars. Techniques and software that are commonly used for oil and gas exploration on Earth can also be used to understand the subsurface of planetary objects. Craters are important too, because impacts excavate different types of rock units below the surface. This means planetary geologists can use craters in a similar way to how the mining exploration industry drills boreholes. 

The challenge is then to bring together all these elements to create planetary mapping products. 

Europlanet’s geological mapping activity, GMAP, builds on the success of another European Commission-funded project, called PLANMAP, which aimed to employ and develop innovative techniques for creating mapping products for planetary bodies. With PLANMAP’s results, we aimed to use the wider resources funded through the €10 million Europlanet 2024 Research Infrastructure (RI) project to provide services for newcomers to planetary mapping and enable the mapping community to produce planetary geological maps in a more structured way. Essentially, for the first time in Europe, GMAP provides an umbrella under which planetary maps can be created, with guidelines and insights on how to produce effective mapping products that are suitable for scientific exploitation, as well as information on how to display and archive results in a structured way. 

GMAP targets people, such as early career researchers, who are interested in learning how to build their own mapping products. However, we also aim to support scientists who want to learn how to incorporate other types of data analysis into a mapping product so that it becomes a summary of everything that is known about a region. 

The guidelines developed for GMAP cover a complete workflow that, starting with a data set from an orbital mission, shows mappers how to create a basemap that can be uploaded into a geographic information system, where it can be used to develop a mapping product. We have built bespoke plugins to apply mapping techniques more effectively and time efficiently, and a wiki that can be consulted on a range of topics (e.g. to find relevant literature), which is continually added to and improved. We have also provided an archive where users can store mapping products and a very comprehensive 90-page document about all the cartography products that exist and the approaches that can be used for all Solar System bodies. 

One of GMAP’s major successes has been the establishment of the annual Geology & Planetary Mapping Winter School. The original idea for the Winter School, back in 2019- 2020, was for an in-person event with around 20-30 participants, requiring funds for travel and accommodation and for people to devote a full week of their time. However, the Covid-19 pandemic forced us to switch to a virtual format. As soon as we opened the registrations, we were amazed to find we were getting 10-20 people signing up every day, ending up with more than 200 participants for the first Winter School, which took place from 1-5 February 2021.

The format for the virtual meeting mixes ‘synchronous’ lessons that people can watch live and ‘asynchronous’ content where people can follow recorded lessons and training resources in their own time. This has proved a very effective and successful format that enables people from different time zones, or with other commitments, to participate. The second edition had 300 participants, the third had more than 400 people and the most recent school, from 22-26 January 2024, had 609 registrants – far beyond our wildest expectations!

The training materials for the schools for the schools are all accessible and archived in Zenodo for long-term sustainability. Every year, the programme includes new mapping topics along with the core modules, so that all participants – whether new or repeat – have something fresh to learn, as well as an opportunity to practice and develop skills.

The first edition of the Winter School took place during the year of overlap and transition between the end of PLANMAP and the start of GMAP. The programme showcased PLANMAP products, like mapping techniques, and introduced the cartographic standards that we were developing for the GMAP community. The second year focused broadly on mapping of inner Solar System bodies, like Mercury, the Moon and Mars. The third year provided guidance and insights for mapping landing sites in preparation for crewed missions to the Moon and Mars, thinking about the characterisation, in terms of geology and safety, for how and where to land humans. In the most recent school, we focused on icy bodies and small bodies that are the targets of missions like Juice, Europa Clipper, OSIRIS-Rex and Dawn. Data from these bodies are very beautiful and sometimes overlooked, especially data from the icy satellites of Jupiter, so the school gave us an opportunity to showcase them using modern techniques. This year, we also looked at software and guidelines on how to approach full 3D mapping of small bodies, like comets, which can be challenging in that there is no fixed cartographic standard reference system of north, south, east and west. Every year we start from the basics, so that everyone can be in sync and those with expertise can refresh their knowledge. We try to pitch the level of the difficulty of the topics in order to be understandable to everybody.

In forcing us to have a comprehensive approach and be as inclusive as possible, Covid-19 also drove us to adopt open-source software. This turned out to be a game-changer; some of the software packages developed for terrestrial mapping meet industry standards and are very effective – at zero cost – and this has impacted the way we work more widely in the planetary mapping community. Thus, the Winter Schools have been opportunities not just to gain scientific knowledge, but also to share effectively the benefits of mapping techniques across the community.

There is a lot to oversee and it’s been a complex task to design the platform and tools to deliver the Winter School, edit the recorded lessons, and store the data. 

Preparation normally starts at least six months ahead of the event. The schools are a big challenge to organise, as they involve bringing together many people from different backgrounds and with different expectations. Initially, we had 30-40 people contributing to the schools, including the main lecturers, seminar leads, and a team to manage breakout rooms, which were overseen by a core instructor with other trainers helping out. Over time, the number has stabilised at around 20 people actively involved all the time, along with a core Scientific Organising Committee and volunteers who help out during the actual events. 

Over the four editions of the Winter School, we have had more than 1200 participants in total, with repeat participants as well as new people joining each year. Feedback from attendees has been extremely positive, with over 95% feeling that they had learned something related to content and/or skills and many reporting other outcomes such as confidence and increasing their networks. We now have an active community of over 1000 people that we keep in touch with and who request information about the future schools. 

The majority of participants are Master’s students and PhD candidates, but we also have registrations from amateur enthusiasts, and people from industry and space agencies that want to have a glimpse of what’s happening around the community, or are just curious. The specialised nature of our community attracts all kinds of people, ranging from civil engineers with a personal interest in new approaches, to regular geologists who are interested in planetary mapping. Because of data limitations, planetologists still have to think out-of-the-box sometimes, or may approach things differently because planetary surfaces can be different from those we see on Earth. This has many benefits and, with commercial sectors like space mining growing rapidly, planetary mapping can only become more relevant over the coming years. 

Early careers have been particularly important in developing GMAP and the Winter Schools. Many early careers started with helping in the organisation, managing the data, or with social events in the first year, then progressed to become coaches for breakout sessions and eventually instructors in later editions. We have examples of Bachelor’s students who joined the first edition and went on to take their degree and publish papers as Master’s students with maps they created. 

A major legacy and highlight from GMAP has been the establishment of a worldwide planetary mapping community. While most of the interaction is focused in the month before and after the Winter School, we have a permanent Discord channel and there are regular time slots every month, where people can join an open Zoom call and bring up mapping topics of interest to them. Many of the community have been very active in providing feedback and advice on how to improve Winter Schools, for example, showcasing the best maps and developing collaborative mapping exercises. 

A further heritage of GMAP will be a didactic atlas of around 20 mapping products contributed by the community about specific planetary bodies or specific topics. Themes covered will include how to map polar layer deposits, how to map landslides, how to do structural mapping on icy satellites, and how to map sedimentary environments on Mars. Each map will include a brief description of the approach, the techniques used, and tips on getting the best outcome for the topic covered. 

In summary, GMAP has built on PLANMAP to deliver lasting legacies, with the Winter School, the mapping community and the atlas, which will benefit the community for a long time to come. 

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Issue 7 of Europlanet Magazine

This article is featured in the Europlanet 2024 RI Special Issue of the Europlanet Magazine