Sciency Words: Global Resurfacing

Hello, friends!  Welcome back to Sciency Words, a special series here on Planet Pailly where we talk about those wild and crazy words scientists like to use.  Today on Sciency Words, we’re talking about:

GLOBAL RESURFACING

Venus is a mysterious planet.  Ever since the detection of phosphine in the Venusian atmosphere, the mystery du jour has been: does Venus support life?

We’ll circle back to Venus’s phosphine in a moment, but first I’d like to turn our attention to a different mystery concerning Venus: where did all of Venus’s craters go?

Impact craters are a common sight in the Solar System, especially here in the inner Solar System.  You’ll find plenty of craters on the Moon, of course.  You’ll find lots of them on Mercury, Earth, and Mars as well.  Some of those craters look fresh and new.  Others, due to weathering and erosion, look quite old—sometimes extremely old.

But the surface of Venus is relatively crater free, and the few craters we do find appear to be very, very recent.  In his book Venus Revealed, American planetary scientist David Grinspoon describes Venus’s craters thusly:

All the craters on Venus look unnaturally pristine.  Instead of blending into the volcanic plains that cover most of the planet, they seem planted on top as an afterthought, as though a crew had built a cheap movie-set planet and realized at the last minute that they had better throw in some craters.

Grinspoon goes on to explain how this might have happened:

Suppose that half a billion years ago something happened to Venus, wiping out all older craters.  Vast lava flows occurring simultaneously all over the planet would do the trick.  Then, if there has been relatively little surface activity since that time and Venus has been slowly collecting craters all along, things should look as they do.

This sudden event, when the whole surface of Venus got covered in fresh lava, is called “global resurfacing.” That’s a nice euphemism for an apocalyptic event, isn’t it?

Now this is important: Venus should have had little-to-no volcanic activity since her last global resurfacing event.  Otherwise, those younger, fresher, “unnaturally pristine”-looking craters would have gotten resurfaced too.  But in the last few years, circumstantial evidence has emerged suggesting that there are active volcanoes on Venus after all.

And now, finally, we circle back to the detection of phosphine in the Venusian atmosphere.  Some have suggested that that could be evidence of Venusian life.  But according to this preprint paper, that phosphine signature could also be interpreted as further evidence of volcanic activity.  Maybe global resurfacing was not a one-time event half a billion years ago.  Maybe resurfacing is an ongoing process that’s still happening today!

In a previous post, I said that Venus is about to teach us something we did not know: maybe it’ll be a biology lesson, or maybe it’ll be a chemistry lesson.  But now I think there’s a third possibility: maybe it’ll be a geology lesson.

P.S.: Special thanks to Mike Smith from Self Aware Patterns for sending that preprint paper my way.  At this point, it is just a preprint paper waiting to go through the peer review process, so don’t get too excited.  But the more I think about it, the more I feel like the authors of that paper are on the right track.