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February 8, 2022

Most people know that cartographers create maps, but did you know that there’s a lot more to making maps than just drawing what you see? Before you can make a map, you need to define the coordinate system you’re going to use, and two experts from Astrogeology Science Center are helping to provide that foundation for planetary mapping.

Dr. Brent Archinal and Trent Hare gave virtual presentations at the 30th International Cartographic Conference on December 17, 2021, in Florence, Italy. About 30 people were in attendance.

Brent Archinal at USGS
Brent Archinal at USGS

 

Dr. Archinal is a Geodesist at ASC, and chairs a cartographic working group whose work underpins nearly all derived extraterrestrial maps of planetary bodies in our Solar System. 

Within the broader International Astronomical Union (IAU) are many working groups. Dr. Archinal chairs the IAU Working Group on Cartographic Coordinates and Rotational Elements.

In brief, the Working Group is charged with providing the recommended coordinate system and body size and shape information for the cartographic coordinates and rotational elements of all Solar System bodies other than the Earth.   

These accurate and precise coordinates provided by the IAU Working Group 

  • allow spacecraft missions to land on a target body precisely where intended,
  • allow for accurate and safe navigation of spacecraft near Solar System bodies, and
  • provide planetary science researchers assigned geographic position information to their data sets, so that their data can be registered and compared at known levels of accuracy and precision. 

At the conference, Dr. Archinal presented on an abstract called “International Coordination of Planetary Coordinate System Recommendations and the IAU Working Group on Cartographic Coordinates and Rotational Elements.” He summarized the working group’s efforts and activities in 2019-2021. He also covered near-future plans discussing the IAU’s upcoming recommendations.

Reports from the working group meetings are published tri-annually and are freely available to the public. They can be found here.

 

Trent Hare, Cartographer at USGS Astrogeology Science Center.
Trent Hare at USGS

 

Trent Hare is a cartographer and geographic information system (GIS) expert at ASC.  He specializes in supporting GIS-based analyses, data set interoperability, creation of geospatial tools, cartographic representations, and metadata.

At the conference, Trent presented on an abstract called “Standards Proposal for 2021 to Support Planetary Coordinate Reference Systems.”

Building on the IAU Working Group recommendations, Trent define planetary projection codes for web mapping applications to recognize pre-defined planetary coordinate reference systems.

More than 2,000 of these projection codes, across nearly 100 planetary bodies have now been implemented in an open-source library called PROJ by the Open Source Geospatial Foundation. Because PROJ is used across several mapping applications, the codes should also be available from within these applications improving capabilities in planetary science while also driving scientific and technological advancements. For example, the Geographic Information System application QGIS, which utilizes PROJ, has just released a version which now has access to these planetary projections. 

The implementation of the codes in Open Source is good news for those who want to overlay multiple data sets from different sources (e.g., images taken from NASA’s Mars Reconnaissance Orbiter Context and the High Resolution Imaging Science Experiment cameras) and achieve accurate measures and calculations for them.

The International Cartographic Association Commission on Planetary Cartography welcomes new members who have interests in the fields of cartographic communication, mapping techniques, map projections, and reference systems, as well as topics covering analytical and algorithm-oriented cartography. Please contact Trent Hare for more information (thare@usgs.gov).