Taking Care of Our Rarified Air: Langley Scientists at Work

Taking Care of our Rarified Air

Langley Scientists at Work

By Edward Goldstein

As the seagull flies, it’s roughly 90 miles from the windswept dunes of Kitty Hawk, North Carolina, where the Wright brothers first flew in 1903, to Hampton, Virginia, where the Langley Research Center was founded 14 years later, in part to understand the effect the atmosphere has on the problems of flight.

Those early Langley National Advisory Committee for Aeronautics (NACA) researchers quickly determined that there was a lot more to learn about the atmosphere than just going outside and breathing in the humid mid-Atlantic air. And that’s why today, as part of a scientific enterprise that spans the globe and beyond, Langley scientists like Michael Obland can find themselves detailed to America’s most northern town, Barrow, Alaska, where the Arctic tern flies, while working on a campaign to fly over the vast icy expanses of the North Pole in search of new insights about the composition of the thin layer of atmosphere that sustains us.

“We’d get all geared up, wander down the street, warm the instruments up, get the plane out, and go fly across the frozen north,” said Obland. “It was an amazing experience for me, coming from the continental U.S. I spent a lot of time looking out the window. There’s phenomenal topography out there with the mountains farther south near Anchorage and Juneau and you look out and you can see glaciers as far as you can see. Eventually, when you fly farther north, air traffic control in Anchorage gets on the line and says, ‘All right NASA, 529, we’re about to lose you. See you when you get back.’ That’s because they can’t see us on radar anymore. You are truly alone out there, and then there’s a tremendous feeling of isolation.”

What Obland and his The fellow Bell X-1 Langley – the type scientists of are aircraft seeking that in broke airborne the campaigns barrier like these in 1947. is much more sound than esoteric knowledge. In fact, we can thank the Langley team for helping to provide inconvertible evidence that rallied the nations of the planet to act decisively to avert an environmental catastrophe.

NASA Photo

Solving the Ozone Hole Problem

Back in the 1950s scientists first observed the phenomenon of ozone depletion in the upper atmosphere, and later linked the ozone loss to a chlorine buildup in the atmosphere. Eventually, with a big assist from Langley and other NASA scientists, it was determined that in polar regions, especially over the south pole where air temperatures drop below -78 degrees Celsius for five to six months, polar stratospheric clouds (PSCs) are formed in the polar ozone layer. Within these clouds, reactions on PSC particles cause the chlorine gas ClO to be formed, which destroys ozone, creating the dreaded “ozone hole.”

This dramatic finding led to the 1987 Montreal Protocol agreement, whereby the nations of the world agreed to phase out the use of ozone depleting chlorofluorocarbons (CFCs), most commonly used in refrigerants and aerosols. Due to the phase-out, which is allowing the ozone layer over Antarctica to heal, the World Meteorological Organization and the United Nations found that the Montreal Protocol will prevent about 2 million cases of skin cancer annually by 2030.

In Obland’s telling, Langley’s involvement in ozone studies beginning in the 1970s, came naturally: “The early days of science at Langley were focused on understanding the aircraft’s interaction with the atmosphere. As you went faster and faster, into supersonic and hypersonic flight, you had an interaction with the atmosphere that is a fundamental limitation on what you’re trying to do. You also have to start thinking about the waste particulates that come out of that engine and how that affects the atmosphere.”

The Stratospheric Aerosol and Gas Experiment II, which was central in our understanding of the hole in Earth’s ozone layer, was deployed on the Earth Radiation Budget Satellite from the Space Shuttle Challenger in 1984.

Photo Courtesy of NASA

“In the 1970s,” Obland continued, “it was shown theoretically that if you put certain chemicals into the atmosphere, those chemicals will thin the ozone layer. That was known theoretically, so the question was, ‘Is this true? Can we go and make measurements to show whether this is happening or not?’ And it was Langley that led some of the efforts for developing, testing, flying, and proving instrumentation that could make measurements from space to show the state of ozone and other gases and constituents in the atmosphere.

“One of the first of those was the Stratospheric Aerosol Measurement instrument – SAM – which flew in July 1975 on the Apollo-Soyuz Test Project Mission. Astronaut Deke Slayton operated it by hand. It was one of the first instruments that showed you can measure gases in the atmosphere and start to get a handle on what was going on with gases such as ozone at high altitude. That led to the further development of instruments – SAM-2, which flew in 1978, and the Stratospheric Aerosol and Gas Experiment, SAGE, of which there have been several. SAGE was put up in 1979 on the Applications Explorer Mission-B satellite and operated for several years. SAGE II flew on the Earth Radiation Budget Satellite (ERBS) from 1984 through 2005. This instrument was seminal in monitoring the ozone layer, and helped contribute to our understanding of the ozone hole issues, and subsequently the policies that led to the Montreal Protocol in 1987 that banned CFCs. The latest iteration, SAGE III, launched in February and is now on the International Space Station.”

The purpose of SAGE III, noted David Young, Director of Langley’s Science Directorate, “is to now show the recovery is in full swing.”

From Earth to the Troposphere

Langley’s ozone work began at a time when environmental consciousness was growing in our country, and the center was taking a leadership role throughout the agency in determining how satellite assets could be used to get a better understanding of Earth as a planet. Langley senior scientist and historian Ellis Remsberg wrote that in August 1971, NASA Headquarters directed Langley to convene a working group on the topic of the Remote Measurement of Pollution (RMOP):

“The three primary RMOP panels and their chairmen were focused on gaseous air pollution (Will Kellogg), particle air pollution (Verner Suomi) and water pollution (Gifford Ewing). Two additional panels reviewed and reported on the principles of remote sensing and the associated instrument techniques. The historical evidence indicates that the findings of the SCEP report (a separate international study group assessing the potential human impact on the global environment) and the RMOP Workshop Report represent the genesis of and blueprint for the satellite Earth-sensing programs within NASA for the following two decades.” Young said from the start of this work, Langley has benefitted from a sense of focus. “We concentrate on the areas where we feel we have worldwide intellectual leadership. And it’s in four key areas. The first is understanding the energy budget of the Earth; it’s the parameter you need to set the boundary conditions for understanding the present and future climate. The second is measuring the atmospheric composition of the upper atmosphere, understanding ozone and how it’s changing the chemistry of the stratosphere and mesosphere. Also, measuring things like volcanic ash and aerosols in the atmosphere and their impact on climate. The third area is atmospheric chemistry, specifically tropospheric chemistry and air pollution – making key measurements on air quality and the impacts on public health. And the fourth area where we are taking the lead is the use of active remote sensing in the form of LIDAR [light detection and ranging] for measuring the constituents of the atmosphere. Where we add value is we’ve been making these measurements for more than 40 years and we’ve been constructing long-term, highly accurate climate records in each of these areas. This knowledge is essential for our understanding the Earth system in its present state and how it could be changing in the future.”

The Space Shuttle Discovery launches on Mission STS-64 with the Lidar In-Space Technology Experiment (LITE) on board.

NASA Photos

Langley’s accomplishments with LIDAR have been particularly impressive, beginning with the flying on the Space Shuttle Discovery in 1994 of the Lidar In-Space Technology Experiment (LITE), which demonstrated a new active remote sensing technique to provide information on the vertical profile of the atmosphere. “When we started the LIDAR work in the late 1960s, no one was sure that you would have the necessary power to be able to make measurements at great distances,” said Young. “The other big challenge was making sure it was safe. As we worry about people pointing laser pens at airplanes, we had to demonstrate that if we were going to fly these systems in space, we weren’t going to put people at risk. Finally, to take this level of power and some of the complexities with the instrument itself, there were some real challenges in terms on demonstrating that you could do that in the vacuum of space, with the radiation environment etc. So our successes were multiple. We were at the forefront in showing you could make these measurements from aircraft and ensure people’s safety and return the science we needed. When we put the LIDAR on the LITE experiment, that showed we could overcome all these challenges and have a successful mission. That led to the CALIPSO [Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation] mission, which is wildly successful. We’re now into our 11th year of getting a record of thin clouds and aerosols, from what was originally planned to be a three-year mission to provide key insights into the vertical distribution of clouds and aerosols and the role they play in regulating Earth’s weather, climate, and air quality.”

The CALIPSO satellite, a research partnership between NASA Langley and the French Space Agency Centre National d’Etudes Spatiales, has been on orbit collecting data on clouds and aerosols for more than 11 years.

NASA Photo

But that’s not the only “first” Langley scientists are credited with. Among the center’s greatest hits are the following:

• A 1974 photochemical model that provided the first detailed timetable for the origin and evolution of ozone in Earth’s atmosphere.

• The 1981 Measurement of Air Pollution from Space (MAPS) Instrument, the space shuttle’s first science payload, which demonstrated that trace gases in the troposphere are measurable from space. Subsequent flights in 1984 and two in 1994 developed a near-global database of carbon monoxide levels.

• Langley pioneered the use of aircraft to understand the composition and chemistry of the troposphere during the CITE (Chemical Instrumentation Test and Evaluation) studies in the 1980s.

On Sept. 23, 2015, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite acquired this view of a plankton bloom in the North Atlantic. The image was composed with data from the red, green, and blue bands from VIIRS, in addition to chlorophyll data. A series of processing steps were then applied to highlight color differences and bring out the bloom’s more subtle features. (The process also accentuates striping artifacts from the detectors that can be seen throughout the image.) Six weeks after this image was acquired, researchers were in this area with NASA’s North Atlantic Aerosols and Marine Ecosystems Study (NAAMES), which aims to make ship- and aircraftbased measurements that, when combined with satellite and ocean sensor data, will help clarify the annual cycles of ocean plankton and their relationship with atmospheric aerosols.

NASA Image By Norman Kuring, Using Viirs Data from the Suomi National, Polar Orbiting Partnership

• The launch of the Earth Radiation Budget Satellite (ERBS) on the Space Shuttle Challenger in 1984 included the first ERBE instrument to measure the planet’s energy budget.

• Langley’s Global Tropospheric Experiment (GTE) series of airborne field studies from the late 1980s through the early 2000s provided observations across the remote atmosphere to benchmark atmospheric composition. GTE observations continue to be the only information available for certain remote portions of the globe.

• The Halogen Occultation Experiment (HALOE) is the first atmospheric science instrument built in-house, launched, and operated by Langley. HALOE launched aboard the Space Shuttle Discovery/Upper Atmosphere Research Mission in 1991. HALOE data were among the most highly cited data sets about ozone in the 1990s.

• In 1993, Langley established an Atmospheric Science Data Center (ASDC) to archive and distribute Earth science data related to radiation budget, clouds, aerosols, and tropospheric chemistry. The ASDC archive holdings have surpassed four petabytes of atmospheric science data, including 300 data products supporting more than 44 science projects in 150 countries.

• The Clouds and the Earth’s Radiant Energy System (CERES) instrument on the TRMM satellite was launched in 1997 to learn how clouds affect Earth’s energy balance. A total of five subsequent CERES flight models are now in orbit on the Terra, Aqua, and Suomi NPP spacecraft, and a sixth is slated to launch this fall.

• Through 2020, Langley science teams are leading two Earth Venture airborne science missions: NAAMES (North Atlantic Aerosols and Marine Ecosystem Study) and ACT-America (Atmospheric Carbon and Transport-America).

NASA Langley’s ACT-America airborne science campaign is looking at the transport of carbon emissions around the eastern half of the United States.

NASA Photo

An important element of Langley’s science mission includes public engagement. Young noted that the education outreach component of the CERES Earth radiation budget measurement mission fostered the S’COOL project – Student’s Cloud Observations on Line.

“The idea was to get students involved in making cloud measurements directly at the time when a satellite passes overhead,” he said. “It led to us using data from students in kindergarten through college in scientifically peer-reviewed journal articles as part of causal statements made in conjunction with theory.” The student ground observations helped scientists by confirming the presence of clouds in areas and under conditions that are challenging for satellite instruments.

“We often hear about how NASA satellite data helps students, but there are also quite a few things the students do for us,” said Lin Chambers, the former S’COOL program lead. In 2017, S’COOL merged with GLOBE (Global Learning and Observations to Benefit the Environment), an international science and education community of teachers, students, scientists and citizen scientists who collect and analyze Earth systems data.

Also, through DEVELOP, part of NASA’s applied science program, said Young, “We have a science adviser who works with state and local governments to understand their needs and how they can potentially use Earth science projects for direct social benefit.”

Langley Research Center’s B200 King Air prepares for a dawn launch in the far north.

Photo Courtesy of NASA

An ongoing project advised by Langley’s Dr. Kenton Ross is helping biologists understand the impact of light pollution on the behavior of nocturnal wildlife in Grand Teton National Park. Another advised by Langley’s Joseph Spruce is helping the National Park Service monitor the impact of changing snow-cover patterns in southeastern Arizona’s biodiversity-rich Sky Islands. Young also noted DEVELOP brings in college students, young professionals, and active-duty military to develop a cadre of people who can do this work when they leave the program. “It’s a tremendous program, a great advertisement about the benefits of Earth science for the public.”

When asked to describe the ultimate value of Langley’s Earth and Atmospheric science program, Young summed it up this way: “A lot of people were inspired by the Earthrise picture from Apollo 8. That thin layer of atmosphere the astronauts saw makes life possible. And between that thin layer there’s not a lot there. That and the magnetic fields that protect us from the harmful radiation coming into the Earth and the ozone that protects us from ultraviolet radiation. You must be careful to understand how that can change in the future. Looking at Earth from space reminds us that we are on a really lonely outpost in a really cold universe, and it’s that atmosphere that’s keeping us warm and making it possible for you and your family to be alive.”