Better there than here

Apparently it's the year of Tunguska. Was there some big announcement that we were all supposed to be gearing up for the centennial next year? Did I miss the memo?

In November, we had a report that Italian scientists thought they'd found the impact crater. Then, two days ago, an announcement that Sandia Labs believes the mystery object was smaller than anyone thought. The news today--which isn't exactly directly related to Tunguska, except as a reference point, is that there's a 1.3% chance that Mars is going to get walloped next month.

Which would actually be a good thing. Mars has been asking for it for more than a century, taunting us with its canals, space-princesses, and shape-shifting golden-eyed supermodels; not to mention the way it keeps eating our robots and spaceships. Take that, Mars! You bastard planet!

Naw, I'm just kidding. About Mars asking for it, not about it being a good thing if Mars got slammed by a 160'-wide brick. In 1908, when we got hit, nobody knew quite what happened: seismographs spiked, there were some lovely sunsets worldwide and a few accounts from local tribesmen made local newspapers. But scientists didn't get out to the scene until 1921, and a full expedition had to wait 'til 1927. As a result, you have a century's worth of explanations ranging from cometary impacts to a crashed alien spaceship. And "crashed alien spaceship" is one of the more conventional explanations that's seen daylight: the exotic proposals have included such improbable suggestions as a black hole fragment or a piece of string.

The leading explanation these days is the most prosaic--we got a rock. But there even remains debate about what kind of rock, with some scientists favoring a flying gravel pit (i.e. a smaller version of something like Itokawa) and others proposing a standard-issue solid chunk of space rock of the sort that occasionally puts a hole in someone's roof. With the data we have--the blast pattern of flattened trees photographed in '27, the eyewitness accounts, etc.--we can attempt to reconstruct the impact with computer simulations and physical modeling, but ultimately those reconstructions are only as good as the data that goes into them. Better data equals better models.

Mars is a bit like Earth--smaller, with a thinner atmosphere, but it's the same basic make. A crash test of a VW Beetle won't be 100% applicable to modeling SUV accidents, but it will tell you more about such impacts than merely going out onto a street corner after everything's been towed away and trying to assess accident risks by studying skid marks and pebbles of broken safety glass. So, here's to a collision with Mars in January, and to good viewing weather down here! We need the data, and better there than here.

UPDATE 12/31/2007: On December 28, NASA/JPL announced the chance of Mars getting creamed is up to 3.9%. Which is pretty whomping big as these things go. Hit! Hit! Hit!




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