MICHELE NORRIS, Host:
Authorities had to decide whether to ground planes and inconvenience tens of thousands of travelers or let the planes fly and risk an accident. They decided to ground the planes, and as NPR's Joe Palca reports, it now appears that was a good call.
JOE PALCA: The Icelandic eruption was a pain in the neck for a lot of people. One of them was Susan Stipp. She's a professor of nanotechnology at the University of Copenhagen. She had colleagues that needed to get home to Denmark and others who were waiting to leave.
SUSAN STIPP: And I had some samples that needed to come from Scotland and get processed in Denmark.
PALCA: Stipp wondered if officials had made the right decision to close the airspace over Europe, and since she studies tiny particles like the ones in volcanic ash, she was in a position to find out.
STIPP: So I phoned up my friend and colleague Siggy Gislason in Iceland, and we agreed to get some ash and see if we could do something.
PALCA: Gislason and some of his colleagues drove from Reykjavik to the foot of the volcano, collected some ash, and when planes started flying again, they sent the samples to Stipp in Denmark, where she analyzed them. One thing became clear to once.
STIPP: They made exactly the right decision.
PALCA: To close the airspace, that is. Stipp says her analysis showed there were several reasons the ash particles from the Iceland volcano were so dangerous. First, they were particularly fine-grained.
STIPP: And those fine particles are extremely sharp compared to typical ash, which is usually somewhat more rounded.
PALCA: They were also extremely hard.
STIPP: And the sharpness and the hardness makes them abrasive for airplane wings and bodies and windows.
PALCA: The abrasion can make it impossible to see out the cockpit window. Finally, the fact they were small posed a particular threat to jet engines.
STIPP: If they're tiny particles, then they can melt quickly, and then they condense on the cooler engine parts and cause them to fail.
PALCA: Joe Palca, NPR News.
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