A key NASA instrument that can directly measure the impact of solar events on the Earth's upper atmosphere has weighed in on the huge flare that impacted Earth last week.

The flare was considered one of the largest solar events in years even though its impact on the power grid and communications was minimal due to the angle it hit Earth.

Its direct interaction with the upper atmosphere was measured by NASA's SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument orbiting on the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) satellite.

The upper atmosphere heated up, and huge spikes occurred in infrared emission from nitric oxide and carbon dioxide, said Marty Mlynczak, SABER's associate-principal investigator at NASA's Langley Research Center in Hampton, Va.

Sol 'waking up'
"It's been seven years since we've had a storm like that," he said. "This is the first major storm event since the deep solar minimum of 2008-2009. We are finally seeing the Sun 'wake up' as it proceeds to the next solar maximum."

A solar maximum is a period of increased activity on the Sun, and minimum-to-maximum-to-minimum cycles generally last 11 years each. Solar activity began to pick up in 2010, is steadily increasing and should peak in late 2014.

As the Sun becomes more active, Mlynczak said, it emits more ultraviolet radiation and produces more solar flares - coronal mass ejections (CMEs) - which are absorbed in the atmosphere. "More heating results, and the atmosphere gets warmer, and the infrared emission increases," he said.

"We don't know yet how these affect weather or climate - likely there is not any direct effect," he said, "but there may be, over time, influences on ozone that affect climate."

"These results are very timely," said James Russell, SABER's principal investigator at Hampton University in Hampton, Va. "SABER is cataloging the atmospheric response to solar forcing and is providing a solid baseline for examining long-term changes in the climatology of the upper atmosphere."

"The data set is a vital resource for study of atmospheric trends, for validating atmospheric models of the region, and for evaluating our understanding of solar/atmosphere coupling, he said.

Unique Record
SABER is one of four instruments on the TIMED spacecraft launched in December 2001. TIMED studies the Earth's mesosphere and lower thermosphere, the least explored and least understood region of our atmosphere.

"SABER has a unique, continuous record of over 3,700 days observation of the climate and energy balance of the Earth's upper and outer atmosphere," Mlynczak said.

"From this, we are learning with each event how sensitive this region of the Earth's atmosphere is to short- and long-term variability of the Sun," he said. "We have documented the decline of the prior solar cycle, the deep minimum and the 'ground state' of the atmosphere during that time, and are now seeing the uptick."

TIMED was designed to operate for two years but has operated flawlessly for more than 10 years. Another NASA review is planned in 2013 to determine if SABER will continue operating for at least three more years.

"This is well before the predicted solar maximum," Mlynczak said. There are no other measurements like it, and the entire SABER science team is working hard to make the scientific case to keep the mission operating."

Partners in the SABER mission include Hampton University in Hampton, Va.; Science Systems and Applications, Inc.; GATS Inc.; NASA's Goddard Spaceflight Center in Greenbelt, Md.; and Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Utah State University Space Dynamics Laboratory built SABER.