The wind was whipping at the General Aviation Terminal on Wednesday afternoon as a King Air B-200 landed for a pit stop.
“We’ve been bounced around all day,” said Greg Slover, one of the aircraft’s two pilots. Dressed in a beige NASA jumpsuit, he greeted a group of Penn State scientists as crews refueled the plane after a two-and-a-half-hour flight.
Also aboard the aircraft was Jim Plant, an instrument operator for NASA, who had to sit facing backward for a particularly bumpy ride.
The aircraft traveled over Centre County on the sunshiny day as part of the Atmospheric Carbon and Transport-America project, a study funded by NASA and led by Penn State.
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Selected as part of NASA’s Earth Venture program, it’s a five-year, $30 million mission to study greenhouse gas sources and sinks.
“We are trying to learn more about the breathing of the Earth’s biosphere. It is currently slowing down climate change by removing (carbon dioxide) from the atmosphere. But we don’t fully understand why that is happening, so it is difficult to predict how the biological system will change in the future,” said Ken Davis, the project’s principal investigator. “... Right now, the biosphere is buying us time by acting, globally, as a net sink of (carbon dioxide). If we want to predict climate change, we need to understand both human and ecosystem contributions to the carbon cycle.”
The B-200 was one of two aircraft in the sky for the project on Wednesday.
The project’s larger aircraft, a C-130, flew over the area from Mill Creek in Huntingdon County to Pennsylvania Furnace and Port Matilda at 20,000 feet above sea level at about 2 p.m., while the B-200 followed about an hour later at 1,000 feet, said Davis, professor of atmospheric and climate science at Penn State.
The purpose of the day’s flights was to compare carbon dioxide measurements collected by the aircraft to the Orbiting Carbon Observatory satellite, he said.
Satellite measurements are powerful but difficult to calibrate, Davis said. Scientists who want to use the satellite data need to know how accurate and precise it is.
The measurements from the aircraft and the satellite will never be exactly the same, he added.
Each aircraft collected data along the path of the satellite, flying a bit south of the bases and a bit north of Centre County, said Slover, who’s also a trained engineer.
The B-200, based at Langley Research Center; the C-130, based at Wallops Flight Facility; and the satellite were at the same point over the earth in northern Virginia, Davis said.
Slover said the B-200 had to do a spiral for about 30 minutes when it was lined up with the satellite.
It was continuously measuring carbon dioxide along the path, and flasks of air will also be sent to a lab in Colorado to be analyzed for different greenhouse gases, Davis said.
The larger aircraft has two laser-based sensors, Davis said, which fired laser beams at the ground and were reflected back up to a telescope on the plane to see how much light comes back.
That provides a column carbon dioxide measurement — how much of the gas is between the ground and the aircraft, he said.
Only two days remain of flights for the current campaign, Davis said. The first two weeks of the campaign were flown out of Shreveport, La., the next two out of Lincoln, Neb., with the final two out of Virginia, he said.
The planes returned to the NASA bases at different altitudes than they left — 15,000 feet above sea level for the B-200 and 9,000 feet for the C-130, Davis said.