Everyone remembers what they did in the long days spent in quarantine due to the pandemic. While some of us struggle to stay afloat between work and childcare, others like graduate student Rebecca Hahn (University of Washington in St. Louis) found the quiet time they needed to stay busy.

Hahn took the highest resolution image of the surface of Venus taken 30 years ago by NASA’s Magellan spacecraft and uploaded it to the mapping software used by engineers and urban planners on Earth. He then decided to manually map each volcano visible in the grainy black-and-white images.

“We knew these maps or catalogs had been made before, but no one really took the time, probably because no one had the time to get down to the level of detail that Rebecca did,” says thesis supervisor Hana Paul Byrne (University of Washington). Louis). Hahn and Byrne describe the study as follows: JGR Planets.

The result is the most detailed and complete map of volcanoes ever made on the surface of Venus, possibly surpassing that of any other planet, including Earth. The new catalog shows the size and location of 85,000 individual volcanoes, 50 times more than the previous most comprehensive catalogue. Khan’s efforts lasted more than two years.

“A complete dataset with platforms for all volcanoes and larger volcanoes will be extremely useful for both mission planning and future studies of Venus volcanism and its relationship to internal processes,” says Robert Herrick of the University of Alaska Fairbanks. Herrick recently found the first clear signs of active volcanism in the same Magellan images, but was not involved in the study.

Hahn explains that Magellan has mapped about 90 percent of Venus’ surface with radar, so these images aren’t really pictures. Magellan emitted radio signals to the surface of Venus as it passed through an elliptical orbit, meaning that the spacecraft’s angle and distance from the planet were not always the same. Surfaces with different slopes and material properties reflected these waves back to the spacecraft, which detected the returning radar and converted it into an image. This makes Magellan images extremely difficult for automated analysis such as image recognition software. Humans are still better at distinguishing shapes and patterns from complex images.

Magellan’s low resolution also made the task difficult. Structures of this size are difficult to distinguish, as a 1 kilometer object on the surface looks like 7 pixels in the image. Volcanoes less than 5 kilometers in diameter make up about 99% of the volcanoes on the map, but there are probably many more that are too small to count. “There are many small volcanoes on Earth as well as many kilometers in length, so there are definitely a lot of small volcanoes on Venus that we just missed,” Hahn says.

Researchers already know that Venus volcanoes are less than 5 kilometers in diameter or more than 100 kilometers in diameter, with little in between. Large volcanoes also seem to cluster towards the equator, with none at the south pole and relatively few near the north pole.