REPAVE THE PLANET
About 600 million years ago, something reset the goo-clock on Venus's surface, and nobody knows why or how.
Impact craters are by far the most common landform in the
Solar System, but Venus has less than a thousand of them.
Given the rate at which new impacts occur, this means that the planet lias somehow erased
all traces of the first 85 percent ot its history. There are various theories to explain this.
Venus may have a thin, soft crust that cannot preserve ancient terrain. Or episodes of plate tectonics might have erased old features, but these periods alternate with times (like now) when it is quiescent. Or maybe Venus has spasms of volcanism. Or perhaps we are seeing Venus soon after its geo-engine shut down. Or some combination of the above. The fact is, scientists do not yet know.
Some scientists think that Venus is still volcanically active. The amount ofsulfur dioxide—a common volcanic gas—in the atmosphere has changed over the last 15 years, perhaps indicating a recent eruption followed by a settling-out of the gas. Also, the tallest mountains are too high to be held up by Venus's crust alone, so either they are recently built or they are supported by hot rock still rising from below.