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May 21, 2007

NASA robot Zacaton sinkhole metrics... or footage?

The El Zacaton (or Xacatun) sinkhole near the coast of northeastern Mexico may well be the world's deepest sinkhole. It's where Sheck Exley lost his life in 1994. His partner Jim Bowden returned from around 900 feet. Neither had found the bottom, which had been plumbed at about 1080 feet.

Now comes interesting news. None other than NASA is using a robot named DEPTHX (which stands for Deep Phreatic Thermal Explorer) to explore El Zacaton, map the vast sinkhole and collect samples. The robot uses sonar for mapping and has an arm to grab things and bring them back to the surface. So far so good.

The whole project seems to be under the auspices of NASA's Ames Research Center, and the project is described in a March 12 article entitled "DEPTHX Robot Prepares to Explore Earths Deepest Sinkhole" on NASA's website at http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=10603. That is where it gets a bit dicey. The second paragraph of the article reads:

Zacaton is a forbidding place. It has never been fully explored, and no one knows exactly how deep it is, but estimates are that its floor lies more than 1,000 meters (well over half a mile) below the surface. A pair of SCUBA divers attempted to plumb its depths in 1994. After descending to 925 meters, one of the divers, Jim Bowden, was forced to turn back. At 925 feet, the water pressure is more than 90 times what it is at sea level. Bowdens partner, Scheck Exley, drowned in his attempt to reach the bottom.

Well. Yes, a forbidding place is certainly is, no doubt there. But that is where the accuracy ends. Does no one know how deep it is? Jim Bowden, Sheck Exley and Ann Kristovich did figure that out when they used a plumb line in April of 1993 and found a depth of over 300 meters. 329 meter or 1,080 feet, to be exact. That is over 1,000 feet, but the article on the NASA site then confuses that with 1,000 meters, which is indeed over half a mile, but also a good three times more than Zacaton actually is. Jim Bowden got down to 925 feet, not meters as stated in the article (Bowden'd be in every record book had he been to 925 METERS, and rather dead). In the next sentence it's correct: feet. But now the author claims the water pressure at 925 feet is more than 90 times that on the surface. He'd have failed PADI Open Water with that answer. Assuming Zacaton is sweetwater, the pressure at 925 feet would be more like 27 times that on the surface. And hey, Exley was not exactly unknown. Let's get his name right. It's Sheck, not Scheck.

Whew. What do we make of this? And of everyone else who simply copied the errors? Just the usual worldwide confusion over the imperial versus the metric system? Why did so many newspapers, websites, and magazines mindlessly reproduce the mistakes? Reuters goes: "El Zacaton, near the Gulf coast of northeastern Mexico, is about 100 metres (328 feet) wide and more than 1,000 metres (3,280 feet) deep. It could easily hold the Eiffel Tower" (http://www.reuters.com/article/scienceNews/idUSN1742917220070518), Six hours later, after someone must have brought it to their attention, a "corrected" version is issued, but it remains wrong: "El Zacaton, near the Gulf coast of northeastern Mexico, is about 100 metres (328 feet) wide and more than 1,000 metres (3,280 feet) deep. It could easily hold the Eiffel Tower." (http://uk.news.yahoo.com/rtrs/20070518/tsc-uk-space-jupiter-corrected-a337f0f.html). Obviously they thought they had the meters to feet conversion wrong when, in fact, they had simply copied the original error.

The Eiffel Tower should have been a dead giveaway; it is about 320 meters, and that would indeed neatly fit into Zacaton...

Most of the world's news media, including news.com, continued to have it wrong, and as of May 21, 2007, the NASA site still has it wrong also. A May 21 article by Ceci Connolly of the Washington Post has it right, and the guys at dailytech.com also caught the error, though they link to a source that includes the error.

Now I can't blame anyone in the news media for taking Reuter's word or NASA's, though a bit of fact checking never hurts. But on the NASA site itself, I really don't like to see this sort of error. I mean, in rocket science, the difference between feet and meters is pretty dramatic.

Note: Much to NASA's credit, a representative from the agency returned my email within hours, confirming the errors, and informing me that the article had been revised. The information is now correct.

Posted by conradb212 at May 21, 2007 11:13 PM

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