NASA climate observatory will monitor atmospheric carbon dioxide
A United Launch Alliance Delta II rocket lifted off from Vandenberg Air Force Base, Calif., July 2, carrying a state-of-the-art NASA climate observation satellite.
Scientists will use the Orbiting Carbon Observatory, called OCO-2, to study natural and man-made carbon dioxide emission and absorption to assess how the greenhouse gas contributes to global warming. OCO-2 is the second spacecraft designed for this purpose but only the first to successfully reach orbit, replacing OCO-1, which was lost during a failed launch attempt in 2009.
NASA’s Jet Propulsion Laboratory in Pasadena, Calif., is responsible for overall project management.
Orbital Sciences Corporation designed, built and tested the satellite at its manufacturing facility in Gilbert, Ariz. Both the spacecraft and launch vehicle performed flawlessly during prelaunch preparations but liftoff had to be postponed 24 hours due to a stuck water valve at the launch pad. OCO-2 joins a constellation of five other Earth-observation satellites of varied nationality, collectively known as the “A-train,” that are spaced a few minutes apart in sun-synchronous orbits. Each gathers information on particular aspects of Earth’s environment but OCO-2 is the first to collect data on the planet’s carbon dioxide cycles.
Carbon dioxide levels fluctuate seasonally and are affected by both natural conditions and human activities. Although some of this gas is absorbed by plants and by the oceans, the rest remains in the atmosphere where it traps the sun’s heat.
“Understanding the processes controlling carbon dioxide in our atmosphere will help us predict how fast it will build up in the future,” said Michael Gunson, OCO-2 project scientist at JPL. “Data from this mission will help scientists reduce uncertainties in forecasts of how much carbon dioxide will be in the atmosphere and improve the accuracy of global climate change predictions.”
Data from OCO-2 will also be used to quantify carbon dioxide “sinks”— places in the ocean and land that naturally absorb and store carbon dioxide from Earth’s atmosphere.
“Knowing what parts of Earth are helping remove carbon from our atmosphere will help us understand whether they will keep doing so in the future,” Gunson said.
From an altitude of 438 miles above Earth’s surface OCO-2 will circle the globe every 100 minutes and scan the entire planet from pole to pole once every 16 days. The spacecraft is equipped with a three-channel, high-resolution spectrometer to measure carbon dioxide and molecular oxygen absorption of sunlight reflected off the Earth’s surface.
“Carbon dioxide in the atmosphere plays a critical role in our planet’s energy balance and is a key factor in understanding how our climate is changing,” said Michael Freilich, director of NASA’s Earth Science Division in Washington, D.C.
Measurements from OCO-2 will be combined with data from ground stations, aircraft, and other satellites to help answer key questions about carbon dioxide and climate change.
“With the OCO-2 mission, NASA will be making an important new contribution to the scientific challenge of better understanding our Earth and its future,” Freilich said.
Success of the OCO-2 launch comes as a relief to NASA officials still stinging from the loss of the first OCO satellite five years ago. The launch vehicle for that attempt was a Taurus XL built by Orbital Sciences. Failure of the payload shroud to separate prevented the spacecraft from reaching its planned orbit. Instead, the $209 million mission ended abruptly with a fiery shower of debris over the Pacific Ocean near Antarctica. It was a serious blow to NASA’s climate scientists.
There was some good news, however, when in December 2009 the Congressional Conference committee directed NASA to allocate no less than $50 million for initial costs associated with an OCO replacement. The Fiscal-Year 2010 budget provided adequate funding to support the launch of an OCO re-flight mission (now known as OCO-2) but the mission cost ultimately rose to $468 million, mainly due to the decision to use a more expensive launch vehicle. The cost was considered justified because the Delta II is one of the most reliable rockets ever flown with more than 100 successful launches.
Design of the OCO-2 spacecraft was based on the original Orbiting Carbon Observatory mission to minimize cost, schedule and performance impacts, though engineers did have to swap out some obsolete components. While OCO-2 is designed for a nominal two-year mission, the spacecraft’s service life could be extended. NASA scientists hope to begin making data collected by the observatory available to anyone who wants it, free of charge, as early as the beginning of next year.
This mission’s importance was highlighted by a personal visit from NASA Administrator Charlie Bolden on Monday. In a brief statement to media in front of the Vandenberg launch pad Bolden said, “We’re constantly trying to expand our knowledge of our environment, of this planet, and OCO-2 … gives us an opportunity to learn more about the planet than we’ve ever known before.”