Evrim Yazgin
Cosmos science journalist
Data gathered more than 30 years ago by NASA’s Magellan deep space probe has been reanalysed and it might show evidence of tectonic activity on the planet Venus.
Magellan was launched in 1989 to image the entire surface of Venus, the hottest planet in the solar system. It used radar to peer through the planet’s thick atmosphere to study the topography of Venus’s mountains and plains.
The mission ended when Magellan was commanded to plunge into the Venusian atmosphere in 1994.
More than 30 years on, Magellan’s data is still yielding new information about Venus.
The new study, published in the journal Science Advances, looks at measurements related to oval-shaped features called corona on the planet’s surface, spotted by Magellan.
Corona on Venus range from 10s to 100s of kilometres across. Scientists don’t know what coronae are, but believe these are locations where a plume of hot, buoyant material from the planet’s mantle rises, pushing against the crust and uppermost mantle layers.
“Coronae are not found on Earth today; however, they may have existed when our planet was young and before plate tectonics had been established,” says lead author Gael Cascioli from the University of Maryland, US and NASA’s Goddard Space Flight Center.
“By combining gravity and topography data, this research has provided a new and important insight into the possible subsurface processes currently shaping the surface of Venus.”
“Coronae are abundant on Venus,” says co-author Anna Gülcher from the University of Bern in Switzerland. “They are very large features, and people have proposed different theories over the years as to how they formed.”
Sophisticated 3D models allowed the researchers to test different potential causes behind the formation of coronae on Venus. Of the 75 coronae studied, 52 appear to have buoyant mantle material underneath which is driving tectonic processes.
“The most exciting thing for our study is that we can now say there are most likely various and ongoing active processes driving their formation. We believe these same processes may have occurred early in Earth’s history.”
A key process is subduction.
On Earth, this refers to the sliding of one tectonic plate underneath another. Friction between these plates can cause earthquakes.
Venusian subduction is a little different – thought to occur at the edges of some coronae. There could also be other unique geological processes on Venus around the coronae, including “lithospheric dripping” where relatively cool material can accumulate and sink into the hot mantle.
Scientists are hopeful that future missions will continue to help us understand Venus – sometimes thought of as Earth’s “evil twin” – a planet very like ours, but the victim of a runaway greenhouse effect.
One such mission is VERITAS (Venus Emissivity, Radio science, InSAR, Topography, and Spectroscopy), due to launch after 2031.
“The VERITAS gravity maps of Venus will boost the resolution by at least a factor of 2 to 4, depending on location – a level of detail that could revolutionise our understanding of Venus’s geology and implications for early Earth,” says Suzanne Smrekar, principal investigator for VERITAS.
