Mapping carbon dioxide from space

From New York City, at the National Meeting of the American Chemical Society

NASA is gearing up to make the first measurements of atmospheric carbon dioxide from space. Researchers at the agency’s Jet Propulsion Laboratory in Pasadena, Calif., are developing a spacecraft dubbed the Orbiting Carbon Observatory that will collect information on the greenhouse gas for 2 years.

This wealth of new data will not only generate the most detailed map ever of atmospheric carbon dioxide, but it will also enable researchers to dramatically improve their predictions of future climate changes. Scheduled to launch in the summer of 2007, the observatory will cover Earth every 16 days and collect 25 million CO2 measurements during each of these periods, says Charles Miller, the project’s deputy principal investigator.

The measurements are based on sunlight reflecting from Earth back to space. As the sunlight is reflected, molecules of CO2 absorb specific wavelengths of the light, creating a unique optical signature. A spectrometer on the spacecraft will detect that signature and beam the optical data back to Earth. Computers at the Jet Propulsion Laboratory will convert the data into values for the concentration of CO2 in various parts of the atmosphere.

About half the CO2 produced by industry and vehicles remains in the atmosphere, but just where the rest goes has long puzzled scientists. A global map showing variations in CO2 concentrations should identify which forests and oceans sequester huge amounts of the gas.

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