Venus May Be Hot with Active Volcanoes
We already know Venus is hot from its suffocatingly dense atmosphere, but additional heat could be coming from underground. Results from the European Space Agency’s Venus Express orbiter suggest that volcanoes have erupted any time between now and 2.5 million years ago, a “geologically recent” time compared to the assumed age of the planet (4.5 billion years). The evidence consists of compositional differences on three lava flows that suggest they have not been exposed to weathering as long as others.
PhysOrg and Space.com are among the news outlets reporting the findings. All are mentioning the old conundrum about Venus’s young-looking surface. “The geological history of Venus has long been a mystery,” Sue Smrekar at JPL remarked. That’s because the paucity of large craters, and their apparent closeness in age, suggests that the whole planet was resurfaced relatively recently in the last 10% of its history.
That scenario was challenged this month in a paper in Geology, however.1 Hansen and Lopez believe that a rich and complex history is revealed in features named ribbon tesserae terrain (RTT). They believe the RTT are old and predate the global resurfacing (see summary on this GSA press release). Since this idea runs contrary to what other geoscientists have been claiming about Venus since the days of the Magellan mission (1990-1993), we will have to wait and see whether their claim can withstand critical analysis. On first glance it appears to be vulnerable to charges of special pleading that the oldest terrain somehow escaped catastrophic processes that admittedly smothered at least 80% of the surface. The authors argue that the RTT formed during a distinct ancient epoch on Venus but that individual units, some covering millions of square kilometers, display temporal evolution that “records a rich and prolonged history that awaits discovery.”
1. Hansen and Lopez, “Venus records a rich early history,” Geology, April 2010; v. 38; no. 4; p. 311-314; DOI: 10.1130/G30587.1.
There are numerous problems with standard explanations of Venus, and these add to the problems. The fact that our “sister planet” is so different from Earth is the main one. No plate tectonics, an extremely slow spin, a choking poisonous atmosphere, no large moon – the list was aggravated when Magellan led scientists to conclude that 90% of the planet’s history had been erased. Hansen and Lopez are trying to rescue some of that history, but still need to explain what kind of mechanism would smother 80% of a globe the size of earth in what looks like a single event so late in its history. Imagine something like that happening on Earth. The energy required to support that kind of catastrophe is phenomenal. Why did it slow down to a near stop, such that evidence for continuing activity has been difficult to detect? For a planet smothered in lava it would be surprising not to find activity going on now. Whatever the history, it is anything but uniformitarian. There are many questions that deserve a fresh look by clear-thinking scientists not beholden to the moyboy* club.
*(millions of years, billions of years).