SCOTT SIMON, Host:
Astronomers are lining up to use a powerful new NASA telescope called SOFIA. Unlike most of the space agency's telescopes, SOFIA isn't actually in space - it flies around mounted in a 747 with a large door cut out one of the sides so the telescope can see out. NASA asked NPR's science correspondence Joe Palca to join astronomers on a trip aboard the new flying observatory, and here's his report.
JOE PALCA: Who could resist a ride in a 747 with a large hole cut in the side? When NASA called I said, sign me up. But I was unclear about something. Putting telescopes in space makes sense. There's no pesky atmosphere to make stars twinkle. But why put a telescope on an airplane? Actually, there are several reasons.
ALYCIA WEINBERG: One is that it lands every day.
PALCA: Alycia Weinberg is an astronomer at the Carnegie Institution for Science. She says because SOFIA lands every day you can fix things or upgrade the instruments. Can't do that with a space telescope anymore. And then there's the advantage of a flying telescope for doing what's called infrared astronomy. And what you ask is infrared astronomy? Well, just as there are sounds that are too low or too high for our ears to hear, there are wavelengths of light that the human eyeball can't see, but they're there. You can't do infrared astronomy on the ground. The water vapor of the atmosphere gets in the way. But at 45,000 feet, you're above most of the moisture in the atmosphere.
Weinberg says there are really interesting things you can only see with an infrared telescope. For example...
WEINBERG: The cocoons of dusts that old stars give off as they go through their final stages of life.
PALCA: Those cocoons of dust are where new stars come from. On my flight, an astronomer named David Neufeld will be looking at the infrared light from an interstellar gas cloud. I decided to toodle up to his office in Baltimore before the flight to talk about his plans, because A, it was going to be noisy on the airplane, and B, he would be busy during the flight. He explained he was looking for a specific molecule in the gas cloud.
DAVID NEUFELD: I'm looking for a small molecule composed of one sulfur atom and one hydrogen atom. It's called mercapto, or mercapto radicals, and it's never been seen before in the interstellar gas.
PALCA: The reason Neufeld is interested in mercapto radicals is they only form at certain temperatures.
NEUFELD: So if we see it, what it will tell us is that the clouds of interstellar gas that we're looking at, which are traditionally thought to be very, very cold, may have parts of them where it's been heated up to much higher temperatures.
PALCA: Stars are forming the material in these interstellar gas clouds. Finding this sulfur-hydrogen molecule will help explain how get from a gas cloud to a star. This is one of those rare times in science when there might actually be a eureka moment. Neufeld says if it's there, the molecule show up as a specific line in a read-out from one of the instruments attached to the SOFIA telescope.
NEUFELD: We may see nothing, the instrument may not work, but hopefully we'll see, you know, pretty quickly we'll see a hint of the line. So hopefully it will seem like a eureka moment, anyway.
(SOUNDBITE OF LAUGHTER)
PALCA: I've always wanted to be present at the moment of discovery so I was looking forward to our upcoming flight. The plan was to meet up again at Andrews Air Force Base just outside of Washington. SOFIA was stopping there on its ways back from an air show in Germany. The telescope is a joint project with the German space agency. SOFIA would observe Neufeld's gas cloud on its way from Andrews back to its home base in Palmdale, California. But, the night before the flight, I got a call. It was the NASA press office. The trip was cancelled. What? Despite the fact it was pouring down with rain, I went out to Andrews and demanded an explanation.
Well, actually, the NASA press office invited me out to Andrews for a tour of the plane as a consolation prize. So, why weren't we flying?
JOHN GAGOSIAN: There were really two reasons. The first reason is there's a cooling fan for the telescope that malfunctioned.
PALCA: John Gagosian is the program executive for SOFIA at NASA headquarters.
GAGOSIAN: The second reason is the weather.
PALCA: Flight rules say SOFIA can't take off in a rainstorm, because water might get into the telescope's sensitive equipment. So no scientific observations on the way back to Palmdale, and no passengers. A few days later, the fan was fixed and last Tuesday night, SOFIA got to observe Neufeld's interstellar gas cloud- without Neufeld. He couldn't make the rescheduled flight, and if I was bummed, imagine how he felt. He had to wait for an email with the results. It came right after the plane landed.
NEUFELD: It was immediately obvious that we had an absolutely clear detection of the mercapto radicals, so I was really delighted.
PALCA: A sort of a virtual eureka moment. Joe Palca, NPR News.
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