Previous studies of Ovda Fluctus had been done by eyeball and had concluded that its flow pattern looked like that from a water-rich granitic lava. They tend to make much more complicated edges.” Rhyolite and other granitic lavas, he adds, are “thick, really viscous,” oozing and spreading more-or-less evenly, “like bread dough”.īasaltic lavas are runnier, “sort of like heavy motor oil. “The fractal dimensions for basalt are different from rhyolite.” “The margins of lava flows look like fractal curves,” Treiman says. In particular, it can map its edges, allowing scientists to see how the lava moved in the last meters before it solidified. Radar mapping can’t tell directly what type of rock a lava flow is made of, but it can show details of the flow’s shape. Magellan Radar mosaic of Venus the Ovda Fluctus lava flow at the arrow’s point. But re-examination of it suggests that Ovda Fluctus isn’t made up of granitic lava, as was previously believed, but is instead made of basalt. “That’s the best data we have,” Treiman says. It was discovered by NASA’s Magellan spacecraft, which orbited Venus from 1990 to 1994 and used radar to map the cloud-covered planet’s surface to a resolution of up to 75 metres. The flow, called Ovda Fluctus, sprawls across several thousand square kilometres near the Venusian equator. But it does mean that this lava flow, once believed to be evidence for water, is not, says Allan Treiman, a geologist at the Lunar and Planetary Institute in Houston, Texas. Not that this means there wasn’t water on the early Venus. ‘Goldilocks’ planets might not be so niceĪ lava flow on Venus once believed to have been formed under wet conditions early in the planet’s history was actually formed under dry conditions, scientists say.ET ‘habitable zone’ much smaller than thought.
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