Scientists have created a new map of 85,000 volcanoes on Venus.
โThis paper provides the most comprehensive map of all volcanic edifices on Venus ever compiled,โ says Paul Byrne, an associate professor of earth and planetary sciences at Washington University in St. Louis.
โIt provides researchers with an enormously valuable database for understanding volcanism on that planetโa key planetary process, but for Venus is something about which we know very little, even though itโs a world about the same size as our own.โ
Byrne and Rebecca Hahn, a graduate student in earth and planetary sciences, used radar imagery from NASAโs Magellan mission to Venus to catalog volcanoes across the planet at a global scale. Their resulting database contains 85,000 volcanoes, about 99% of which are less than 3 miles (5 km) in diameter.
โSince NASAโs Magellan mission in the 1990s, weโve had numerous major questions about Venusโ geology, including its volcanic characteristics,โ Byrne says. โBut with the recent discovery of active volcanism on Venus, understanding just where volcanoes are concentrated on the planet, how many there are, how big they are, etc., becomes all the more importantโespecially since weโll have new data for Venus in the coming years.โ
โWe came up with this idea of putting together a global catalog because no oneโs done it at this scale before,โ says Hahn, first author of the paper in JGR Planets. โIt was tedious, but I had experience using ArcGIS software, which is what I used to build the map. That tool wasnโt available when these data first became available back in the โ90s. People back then were manually hand-drawing circles around the volcanoes, when I can just do it on my computer.โ
โThis new database will enable scientists to think about where else to search for evidence of recent geological activity,โ says Byrne, who is a faculty fellow of the universityโs McDonnell Center for the Space Sciences. โWe can do it either by trawling through the decades-old Magellan data (as the new Science paper did) or by analyzing future data and comparing it with Magellan data.โ
The new study includes detailed analyses of where volcanoes are, where and how theyโre clustered, and how their spatial distributions compare with geophysical properties of the planet such as crustal thickness.
Taken together, the work provides the most comprehensive understanding of Venusโ volcanic propertiesโand perhaps of any worldโs volcanism so far.
Thatโs because, although we know a great deal about the volcanoes on Earth that are on land, there are still likely a great many yet to be discovered under the oceans. Lacking oceans of its own, Venusโ entire surface can be viewed with Magellan radar imagery.
Although there are volcanoes across almost the entire surface of Venus, the scientists found relatively fewer volcanoes in the 20-100 km diameter range, which may be a function of magma availability and eruption rate, they surmise.
Byrne and Hahn also wanted to take a closer look at smaller volcanoes on Venus, those less than 3 miles across that have been overlooked by previous volcano hunters.
โTheyโre the most common volcanic feature on the planet: they represent about 99% of my dataset,โ Hahn says. โWe looked at their distribution using different spatial statistics to figure out whether the volcanoes are clustered around other structures on Venus, or if theyโre grouped in certain areas.โ
The new volcanoes dataset is publicly available for other scientists to use.
โWeโve already heard from colleagues that theyโve downloaded the data and are starting to analyze itโwhich is exactly what we want,โ Byrne says. โOther people will come up with questions we havenโt, about volcano shape, size, distribution, timing of activity in different parts of the planet, you name it. Iโm excited to see what they can figure out with the new database!โ
And if 85,000 volcanoes on Venus seems like a large number, Hahn says itโs actually conservative. She believes there are hundreds of thousands of additional geologic features that have some volcanic properties lurking on the surface of Venus. Theyโre just too small to get picked up.
โA volcano 1 kilometer in diameter in the Magellan data would be 7 pixels across, which is really hard to see,โ Hahn says. โBut with improved resolution, we could be able to resolve those structures.โ
And itโs exactly that kind of data that future missions to Venus will acquire in the 2030s.
โNASA and ESA (the European Space Agency) are each sending a mission to Venus in the early 2030s to take high-resolution radar images of the surface,โ Byrne says. โWith those images, weโll be able to search for those smaller volcanoes we predict are there.
โThis is one of the most exciting discoveries weโve made for Venusโwith data that are decades old!โ Byrne says. โBut there are still a huge number of questions we have for Venus that we canโt answer, for which we have to get into the clouds and onto the surface.
โWeโre just getting started,โ he says.
Source: Washington University in St. Louis
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