Syzdekistan

Back in September, I wrote about the unusual meteor impact in Peru. My comments got picked up by a New York Times science blog and, more recently, I was interviewed by a reporter from the Brown Daily Herald. His story ran today and here are some excerpts:

The handful of shepherds who happened to lead their Alpaca herds near the arroyo that day may have been the first humans ever to witness an explosive meteor impact. But the rest of the world quickly got its chance, if vicariously, through a flurry of activity in the blogosphere.

Hundreds of scientists, journalists and captivated amateurs weighed in on the bizarre events as they unfolded, offering scores of pet theories and radically revising them as more information streamed in from Peru.

Pravda, a Russian online newspaper born out of a print version run by the country’s former Communist Party, ran the headline “American spy satellite downed in Peru as U.S. nuclear attack on Iran thwarted” five days after the impact. The story attributes the villagers’ illness to radiation poisoning from the satellite’s plutonium power generator.

Other proposed explanations were less sensational. Nevadan wildlife biologist and amateur geologist David Syzdek wrote a Sept. 18 blog post titled “Meteorite strike in Peru gassing villagers? Maybe not.” In it, he proposed that a mud volcano producing toxic gases was responsible for both the illness and the crater.

“The Andes are very active geologically so I think there is a good possibility that this crater was caused by an outburst of geothermal activity,” he wrote.

As for the blinding light shooting across the sky, Syzdek chalked it up to coincidence.

“Fireballs are quite common,” he wrote. “One possible scenario is that the people who saw the fireball just happened on a recently formed mud volcano while they were out looking for the fireball impact site.”

Though Pravda and Syzdek drew radically different conclusions from the reports, what they shared with each other, many bloggers and even some scientists was a healthy skepticism about reports coming out of Peru. Pravda and Syzdek both pointed out in their posts that an explosion powerful enough to create such a large crater would be equivalent to 1,000 tons of TNT, or a tactical nuclear strike.

“When I first saw the news reports, they just didn’t seem right,” Syzdek later said in an interview. “Explosive impacts like this just don’t happen.”

OK, so I was wrong. Very wrong. I even admitted it later. On the ground, scientists determined it was a meteor — the geological equivalent of finding the body. Still, it was an unusual impact. I postulated further that it was a very high speed impact. This time I was right. The meteor wasn’t slowed down much by the atmosphere. A professor of geology, Peter Schultz, at Brown University thinks he knows why a meteor wouldn’t be slowed down by the atmosphere:

Back home in Providence, Schultz was now faced with the task of fitting the puzzle pieces together into a cohesive theory. And to do it, he looked to Earth’s closest planetary neighbor, Venus.

“Our models make predictions about what kind of objects can make it to the surface at what velocity, and the Carancas meteor isn’t usually one of them,” Schultz said. “But Venus has a much denser atmosphere and we still find craters on its surface. How did they get there? I think it might be the same thing here.”

To explain the alternative theory he developed, Schultz compared a typical meteor’s descent to a waterskier behind a boat.

“Normally when you’re on the outside of the wake, you’re pushed out further,” Schultz said. “From my experience looking at Venus, I realized that there was a certain condition where the waterskier will stay inside the wake, and actually get pushed inward.”

At last month’s Lunar and Planetary Science Conference, Schultz proposed that the meteor did break up into pieces, but shock waves created by the speeding mass may have kept them close together. And since the meteor descended as a clump of fragments instead of one large piece, it reshaped itself along the way to become more aerodynamic, like a football or a javelin cutting through the air instead of a poorly shaped hunk of rock.

“It’s like having a Volkswagen turn into a Ford Taurus,” Schultz said, adding that this sort of reshaping is well known to geologists who study islands and land-water interaction. “If you put a big pile of dirt in a stream, that mound will eventually turn into a teardrop shape. It’s trying to minimize the friction.”