Following a one-day delay to fix a balky water valve on its launch pad, the Delta II launch vehicle returned to service early Wednesday morning with a fiery nighttime ascent from California on a mission to deploy NASA’s first spacecraft dedicated to studying atmospheric carbon dioxide. The Orbiting Carbon Observatory 2 (OCO-2) will join a fleet of environment and climate monitoring spacecraft orbiting Earth as part of NASA’s mission to study the planet’s environment and long-term climate change.
The original launch date of July 1 was set two years ago when the OCO-2 mission was approved. However, the failure of a valve in the launch pad water deluge system forced a scrub yesterday at T-46 seconds. The failed hardware was replaced and the system thoroughly checked out overnight and the count restarted for a second launch attempt today.
The Delta II launch vehicle blasted off right on time at 2:56 a.m. PDT (5:56 a.m. EDT) from Space Launch Complex 2 at Vandenberg AFB on the west coast of California. Powered by a single liquid-fueled main engine and three solid rocket boosters, the rocket raced through a thick layer of ground fog and lit up the night sky as it arced southward on a trajectory to place OCO-2 into polar orbit.
The mission was required to launch south from Vandenberg in order to reach a polar orbit, a path that passes over the Earth’s poles and means that OCO-2 will be able to observe the entire planet every day.
“The only way to accomplish a polar orbit from U.S. soil is to launch from Vandenberg,” said Tim Dunn, NASA’s launch manager for the flight.
Approximately 56 minutes after the launch, the observatory separated from the rocket’s second stage into an initial 429-mile orbit. The spacecraft then performed a series of activation procedures, established communications with ground controllers and unfurled its twin sets of solar arrays. Initial telemetry shows the spacecraft is in excellent condition.
OCO-2 soon will begin a minimum two-year mission to locate Earth’s sources of and storage places for atmospheric carbon dioxide, the leading human-produced greenhouse gas responsible for warming our world and a critical component of the planet’s carbon cycle.
OCO-2 is a replacement for the original OCO spacecraft that was lost shortly after launch in February 2009 when its Taurus launch vehicle’s payload faring failed to separate. OCO-2 is NASA’s first spacecraft designed to directly measure carbon dioxide in the planet’s atmosphere and its sources, such as fossil fuel burning power plants, and “sinks”, like the shrinking Amazon rain forest, that remove CO2. To carry out its mission, the spacecraft carries one instrument to watch from space as the Earth “breathes” to see what becomes of the gas.
The instrument is precise enough that researchers will be able to count the number of carbon dioxide molecules in the layers of the atmosphere and use the data to draw conclusions about how the increasing amount of gas will affect things like the global temperature. OCO-2’s mission is to last at least two years.
“Climate change is the challenge of our generation,” said NASA Administrator Charles Bolden. “With OCO-2 and our existing fleet of satellites, NASA is uniquely qualified to take on the challenge of documenting and understanding these changes, predicting the ramifications, and sharing information about these changes for the benefit of society.”
While ground stations have been monitoring carbon dioxide concentrations, OCO-2 will be the first spacecraft to conduct a global-scale reading over several seasons. The spacecraft is expected to produce detailed readings to provide regional sources of carbon dioxide as well as sinks for the greenhouse gas.
“There’s quite a lot of urgency to see what we can get from a satellite like OCO-2,” said David Crisp, the science team lead for the mission.
OCO-2 will take NASA’s studies of carbon dioxide and the global carbon cycle to new heights. The mission will produce the most detailed picture to date of natural sources of carbon dioxide, as well as their “sinks” – places on Earth’s surface where carbon dioxide is removed from the atmosphere. The observatory will study how these sources and sinks are distributed around the globe and how they change over time.
“This challenging mission is both timely and important,” said Michael Freilich, director of the Earth Science Division of NASA’s Science Mission Directorate in Washington. “OCO-2 will produce exquisitely precise measurements of atmospheric carbon dioxide concentrations near Earth’s surface, laying the foundation for informed policy decisions on how to adapt to and reduce future climate change.”
Carbon dioxide sinks are at the heart of a longstanding scientific puzzle that has made it difficult for scientists to accurately predict how carbon dioxide levels will change in the future and how those changing concentrations will affect Earth’s climate.
“Scientists currently don’t know exactly where and how Earth’s oceans and plants have absorbed more than half the carbon dioxide that human activities have emitted into our atmosphere since the beginning of the industrial era,” said David Crisp, OCO-2 science team leader at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “Because of this we cannot predict precisely how these processes will operate in the future as climate changes. For society to better manage carbon dioxide levels in our atmosphere, we need to be able to measure the natural source and sink processes.”
Precise measurements of the concentration of atmospheric carbon dioxide are needed because background levels vary by less than two percent on regional to continental scales. Typical changes can be as small as one-third of one percent. OCO-2 measurements are designed to measure these small changes clearly.
During the next 10 days, the spacecraft will go through a checkout process and then begin three weeks of maneuvers that will place it in its final 438-mile (705-kilometer), near-polar operational orbit at the head of the international Afternoon Constellation, or “A-Train,” of Earth-observing satellites. The A-Train, the first multi-satellite, formation flying “super observatory” to record the health of Earth’s atmosphere and surface environment, collects an unprecedented quantity of nearly simultaneous climate and weather measurements.
“The A-Train constellation is an ideal measurement system for us,” Crisp.
OCO-2 will fly along the same path as NASA satellites CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) and CloudSat, which monitor minute particles in the atmosphere called aerosols, and clouds, respectively. “We’ve lined up the ground tracks of OCO-2, CALIPSO and CloudSat almost perfectly, and we’re hoping to keep them well aligned for as long as possible during the missions, so we can do the science we want with measurements from all three satellites,” Crisp said.
OCO-2 science operations will begin about 45 days after launch. Scientists expect to begin archiving calibrated mission data in about six months and plan to release their first initial estimates of atmospheric carbon dioxide concentrations in early 2015.
The observatory will uniformly sample the atmosphere above Earth’s land and waters, collecting more than 100,000 precise individual measurements of carbon dioxide over Earth’s entire sunlit hemisphere every day. Scientists will use these data in computer models to generate maps of carbon dioxide emission and uptake at Earth’s surface on scales comparable in size to the state of Colorado. These regional-scale maps will provide new tools for locating and identifying carbon dioxide sources and sinks.
OCO-2 also will measure a phenomenon called solar-induced fluorescence, an indicator of plant growth and health. As plants photosynthesize and take up carbon dioxide, they fluoresce and give off a tiny amount of light that is invisible to the naked eye. Because more photosynthesis translates into more fluorescence, fluorescence data from OCO-2 will help shed new light on the uptake of carbon dioxide by plants.
NASA’s Launch Services Program, based at Kennedy Space Center in Florida, managed the launch preparation and flight into orbit. The OCO-2 mission is handled by the Jet Propulsion Laboratory in California.
The OCO-2 mission marks the first launch of the venerable Delta II rocket since late 2011. Already rendered obsolete on the commercial market, NASA decided to shift its missions to the arguably more cost-effective Delta IV and Atlas V launch vehicles which can carry heavier payloads. Delta II traces its heritage to the original Thor IRBM first launched in the 1950’s. Since entering service in 1989, the Delta II racked up more than 150 launches.
After the launch of the GRAIL spacecraft from Cape Canaveral in September 2011 and a weather satellite from Vandenberg in October, Delta II manufacturer United Launch Alliance retired the rocket to focus on the newer vehicles and reduce operating costs. The twin Delta II launch pads at Cape Canaveral have already been deactivated and undergoing demolition. The two gantry towers at SLC-17A and B are scheduled for demolition later this year.
Seeing a continuing need for lighter-lift capability, NASA purchased launch services on the remaining inventory of Delta II rockets with the OCO-2 mission being the first.
“We’ve been preparing for the OCO-2 mission for almost two years now,” Dunn said before launch. “The biggest challenge has been in bringing the Delta II launch vehicle out of retirement. The last time we launched on a Delta II was October 2011, a weather satellite.”
The final Delta II is expected to fly sometime in 2017 or 2018.
OCO-2 is a NASA Earth System Science Pathfinder Program mission managed by JPL for NASA’s Science Mission Directorate in Washington. Orbital Sciences Corporation in Dulles, Virginia, built the spacecraft bus and provides mission operations under JPL’s leadership. The science instrument was built by JPL, based on the instrument design co-developed for the original OCO mission by Hamilton Sundstrand in Pomona, California. NASA’s Launch Services Program at NASA’s Kennedy Space Center in Florida is responsible for launch management. Communications during all phases of the mission are provided by NASA’s Near Earth Network, with contingency support from the Space Network. Both are divisions of the Space Communications and Navigation program at NASA Headquarters. JPL is managed for NASA by the California Institute of Technology in Pasadena.
For more information about OCO-2, visit: http://www.nasa.gov/oco2