February 1, 2013
New Rocket Project Aims To Study Auroral Wind Of Northern Lights
Lawrence LeBlond for redOrbit.com - Your Universe Online
For many in the extreme upper latitudes of the Northern Hemisphere, the Aurora borealis (better known as the Northern Lights) offer breathtaking displays of color and lights, dancing effortlessly across the night sky. These lights, which are caused by solar winds bouncing off the Earth´s upper atmosphere, are typically visible only around the Polar ℠auroral zone´ due to the strong magnetic forces around this region. However, these lights can sometimes be seen in the lower latitudes of North America when geomagnetic storms occur.
While most people admire these night lights for the dazzling beauty of their displays, a team of scientists from NASA´s Goddard Space Flight Center (Greenbelt, Maryland) and The Aerospace Corporation (El Segundo, California) are enjoying them for an inherently different reason.
The team is positioned in Poker Flat, Alaska and is awaiting the perfect conditions to launch a sounding rocket up through the night sky into the Aurora borealis, hopefully as early as Feb. 2. However, with a two-week window of opportunity, the team said they have plenty of time to find the perfect launch conditions to launch the projectile.
The rocket is armed with a series of instruments developed specifically for the “VISualizing Ion Outflow via Neutral atom imaging during a Substorm” (VISIONS) mission. The rocket should soar high into the Arctic sky to study the auroral wind, a strong but intermittent stream of oxygen atoms arising from the Earth´s atmosphere into outer space.
The rocket should collect plenty of data during its brief flight before splashing down in the Arctic Ocean 15 minutes after lift-off. The information it gathers “will provide answers to some long-standing questions,” Doug Rowland, principal investigator for the VISIONS project at Goddard, said in a statement.
The rocket will study how oxygen atoms leave the atmosphere under the influence of the aurora. While most of the atmosphere is bound by Earth´s strong gravity, a small portion gets heated enough by the aurora to break free of Earth´s constant pull, and escapes outward into near-Earth space. The team explains that the atoms that form this wind are traveling initially at speeds of about 300 mph–only one percent of the speed required to break free of Earth´s gravity and escape into the edge of night.
“This oxygen would normally never gain enough energy to leave the atmosphere,” said 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.”
Rowland and his colleagues know that in order to capture the data from such a phenomenon, they have to wait until the right moment to press the launch button. The active phase of an aurora generally lasts only 20 to 30 minutes, which can be observed when a dramatic increase in energy input occurs in the upper atmosphere. This is the time when the researchers will need to be ready to launch their rocket.
If all goes as planned--and to be sure, the team only gets one shot at this--the rocket should be able to make the journey through the upper atmosphere to study the escaping oxygen, and collect invaluable data on “what gives the oxygen the energy it needs to escape from Earth.”
“The VISIONS mission will highlight the advantages of using a sounding rocket instead of a satellite to gather the new information. In addition to being smaller and less expensive, sounding rockets provide vertical profiles of the auroral environment, on both the upleg and downleg portions of their parabolic trajectory, with speeds much less than those of orbiting satellites. Further, rockets can be launched from the right place at just the right time to study the aurora — unlike a satellite that can only encounter an aurora when it flies through it by chance,” wrote Claire De Saravia of Goddard.
To solve the mystery behind the auroral wind, the team will implement four unique instruments on the sounding rocket. The main instrument, Goddard´s MIniaturized Low-energy Energetic Neutral Atom imager (MILENA), will directly observe the oxygen flowing out of the atmosphere. Previously, the up-flowing of oxygen into space was only able to be studied on much smaller scales.
MILENA contains twin imagers that can observe the oxygen further along its journey than any previous instrument implemented. Once the instrument captures an electron from a neutral gas atom, it can follow the oxygen that broke free from this magnetic prison as it travels up along its journey into space. By mapping the oxygen, the instrument “acts as a type of camera that builds a picture of the auroral wind using oxygen atoms instead of light.”
Although MILENA is relatively new, the technology behind it has had some success. It was modeled after a similar imager known as the Miniature Imager for Neutral Ionospheric Atoms and Magnetospheric Electrons (MINI-ME). That instrument flew on the NASA FASTSAT mission.
Other instruments on the VISIONS rocket include the Rocket-borne Auroral Imager (RAI), the Fields and Thermal Plasma (FTP) instrument, and the Energetic Electron Analyzer/Energetic Ion Analyzer (EEA/EIA). These instruments should complement the MILENA instrument well.
MILENA and the FTP are provided by Goddard, while The Aerospace Corporation provided the RAI and EEA/EIA instruments. The rocket and payload support system is provided by NASA´s Wallops Flight Facility in Virginia. The Poker Flat launch range is operated by the University of Alaska, Fairbanks, under contract to NASA.
While the VISIONS mission will last less than 20 minutes, the information gathered will be crucial to science, said Michael Collier, a planetary scientist at Goddard and lead operator of the MILENA instrument.
“What we´re doing is launching into a specific period of intense geomagnetic activity. With VISIONS, it may be the case we´re not getting a whole lot of data, but we get the data we want,” he said.