About 21 years ago, team members started building and testing the Sounding of the Atmosphere using Broadband Emission Radiometry, or SABER instrument. Back then, they dreamed of how great two years of data from an unexplored region of the upper atmosphere would be.

Now, 15 years later, SABER aboard the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics, or TIMED, spacecraft has more than delivered on that dream as it continues to provide a wealth of fundamental knowledge about the radiation budget, chemistry and dynamics of the upper atmosphere. On Jan. 31, 2017, SABER team members gathered at NASA's Langley Research Center to acknowledge and celebrate 15 years of atmospheric discovery.

"SABER, which marked 15 years of on-orbit operation on Jan. 22, 2017, has provided a never-before-seen view of the atmosphere and paved the way for new avenues of scientific study," said NASA Langley's Deputy Director Clayton Turner. "Fifteen years of SABER data has deepened our knowledge of the planet's radiation budget - the balance between Earth's incoming and outgoing energy. That's an important achievement."

Earth's heat engine does more than simply move heat from one part of the surface to another; it also moves heat from Earth's surface and lower atmosphere back to space. This flow of incoming and outgoing energy is Earth's energy budget.

Built by Utah State University Space Dynamics Laboratory and managed by NASA Langley and Hampton University in Hampton, Virginia, SABER is one of four instruments on the TIMED spacecraft.

"SABER has scanned the horizon more than 8 million times since launch," said Joann Haysbert, Chancellor and Provost of Hampton University. "And without that good home (TIMED) to carry SABER, we would not be where we are today."

As Dave Grant, TIMED Project Manager from Johns Hopkins University - Applied Physics Laboratory, explained, TIMED was given a two-year baseline plan. "No one was thinking 15 years," he said. "But here we are with more than 15,000 contacts with the spacecraft and 98 percent of all SABER data recovered."

A Series of Scientific "Firsts"
The Earth's atmospheric limb known as the MLTI region - Mesosphere and Lower Thermosphere/Ionosphere - is home to the International Space Station and hundreds of satellites in Low Earth Orbit. It is also where the sun's energy first impacts Earth's atmosphere. Although it is the first shield from the sun's ultraviolet radiation and contains important gases such as ozone, water vapor and carbon dioxide, very little was known about this thin, outer layer between 10 and 110 miles in altitude.

Fifteen years ago, the MLTI was considered one of the least explored regions of Earth. But thanks to SABER on TIMED there is a new wealth of comprehensive global measurements of the MLTI.

The SABER dataset is the first global, long-term, and continuous record of thermosphere, or upper atmospheric, emissions of nitric oxide and carbon dioxide (- molecules that, in this region of the atmosphere, serve as atmospheric thermostats that send upper atmospheric heat back into space.

One well-documented occurrence of this transfer of heat was in 2012 when over just three days, solar storms dumped enough energy in Earth's upper atmosphere to power every residence in New York City for two years. SABER data revealed that the nitric oxide and carbon dioxide in the thermosphere re-radiated 95 percent of that energy back into space.

Data from that event, as well as other more recent solar events, continue to be analyzed to determine the effect on Earth's upper atmosphere.

As Marty Mlynczak, SABER associate principal investigator and senior research scientist at NASA Langley explained, in order to understand Earth's atmosphere, we must understand all of its layers.

"This climate record of the upper atmosphere is our first chance to have the other side of the equation," Mlynczak said.

James Russell III, SABER principal investigator and co-director of the Center for Atmospheric Sciences at Hampton University adds, "We broke new ground on the coupling of high and low atmosphere, and on the long-term change in carbon dioxide, water and other gases."

The usefulness of SABER's unprecedented data is evident by the more than 1,350 journal articles in peer-reviewed literature that use SABER data.

SABER continues to exceed expectations and find new purpose. The SABER data are now also being considered as a guide in the search for life on exoplanets. As Mlynczak explained, SABER detects elements through radiative signals from Earth's atmosphere. Similar signals can be sought from Earth-like planets residing in habitable zones around sun-like stars. This knowledge can be utilized by NASA's James Webb Telescope in the search for new planets that may harbor life.

"In the '90s when we were building SABER, it had a specific focus," Turner said. "But today, it has an even greater focus to understand Earth and other planets by leveraging the knowledge and expertise of the SABER instrument and team."

SABER's atmospheric scanning has marked a series of "firsts" for the scientific community, and with no end in sight, that series continues.

According to the Deputy Director of NASA's Heliophysics Division Peg Luce, SABER's advancement in our understanding of the waves and dynamics that shape our upper atmosphere and ionosphere come into increased focus as NASA prepares for the launch of the Ionospheric Connection, or ICON, explorer and The Global-scale Observations of the Limb and Disk, or GOLD, missions later this year, and anticipates significant collaboration potential between the three missions.

"The SABER story is not over yet," Grant said. "We have a long way to go."