On a cold February night in Poker Flat, Alaska, a team of scientists will wait patiently for the exotic red and green glow of an aurora to illuminate the sky. Instead of simply admiring the view, this group from NASA’s Goddard Space Flight Center of Greenbelt, Md., and The Aerospace Corporation of El Segundo, Calif. will launch a sounding rocket up through the Northern Lights. The rocket could launch as early as the night of Feb. 2, 2013, but the team has a two-week window in order to find the perfect launch conditions.
Image: Swirls of green and red appear in an aurora over Whitehorse, Yukon on the night of Sep. 3, 2012. NASA’s VISIONS sounding rocket will study what makes the aurora, and how it affects Earth’s atmosphere. Image Courtesy of David Cartier, Sr.
Armed with a series of instruments developed specifically for this mission, the VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) rocket will soar high through the arctic sky to study the auroral wind, which is a strong but intermittent stream of oxygen atoms from Earth’s atmosphere into outer space. Although the rocket will survive only fifteen minutes before splashing down in the Arctic Ocean, the information it obtains will provide answers to some long-standing questions, says Doug Rowland, who is the VISIONS principal investigator at Goddard.
VISIONS will study how oxygen atoms leave Earth’s atmosphere under the influence of the aurora. Most of the atmosphere is bound by Earth’s gravity, but a small portion of it gets heated enough by the aurora that it can break free, flowing outwards until it reaches near-Earth space. The atoms that form this wind initially travel at about 300 miles per hour — only one percent of the speed needed to overcome gravity and leave Earth’s atmosphere.
“This oxygen would normally never gain enough energy to leave the atmosphere,” says Rowland. “On the other hand, at very high altitudes, satellite experiments have measured oxygen atoms moving faster than 50 miles per second. These experiments have shown that if oxygen can reach these high altitudes, there are plenty of ways for it to gain even more energy, in which case the oxygen atoms can escape near-Earth space entirely. What we don’t know is how the oxygen gets enough energy to fight against gravity and reach the higher altitudes where these slingshots are active.”