NASA will launch a replacement for the Orbiting Carbon Observatory, a $278 million satellite that was lost during launch last year, the White House announced on Monday. The replacement, which should be able to measure man-made carbon dioxide emissions from cities and power plants, could pave the way for space probes designed to enforce future climate treaties.
The Orbiting Carbon Observatory was lost in February 2009 when a protective fairing atop the probe鈥檚 Taurus XL rocket failed to separate during launch, and the satellite fell into the Pacific Ocean.
The loss was seen as a setback by climate scientists, who hoped the probe鈥檚 unprecedented spatial resolution and sensitivity would help reveal how the Earth absorbs and emits carbon dioxide. Less than half of the carbon released since the dawn of the Industrial Revolution has ended up in the atmosphere, but the carbon 鈥渟inks鈥� that have absorbed the remainder are not well understood.
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The satellite would have had the added bonus of testing whether space probes could be used to measure carbon dioxide emissions from cities and power plants, the US National Research Council said in a to NASA administrator Charles Bolden last year.
Now, the White House has given the green light for a carbon copy to be flown, providing $170 million towards the effort in its proposed 2011 budget (). 鈥淭he good news in this budget is the president has decided that this is an important mission for both science and understanding our climate,鈥� NASA science chief Edward Weiler said in a briefing with reporters on Tuesday. The replacement, called OCO-2, could fly as early as February 2013.
Sharp resolution
闯补辫补苍鈥檚 satellite, which launched in January 2009, is currently the only satellite in orbit dedicated to measuring carbon dioxide levels.
But GOSAT can only measure carbon dioxide emissions in swathes of the atmosphere spanning 87 square kilometres. That is not sharp enough to resolve manmade sources, which can disperse within tens of kilometres.
The OCO boasted a resolution of 3 square kilometres and could sense carbon dioxide levels down to 1 part per million (ppm). That means it could have pointed its instruments at cities or power plants, which typically increase local levels of atmospheric CO2 by 1 to 10 ppm, the National Research Council committee said.
Technology testbed
Still, definitively tracing emissions to manmade sources won鈥檛 be easy. Natural sources of carbon and winds can confuse signals, committee member of NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California, said in an interview last year. The ratio of different isotopes of carbon, a measurement often used on the ground to measure how much carbon is produced by fossil fuels, is too subtle to be detected by the satellite.
But the satellite would nonetheless be the best measurement tool available, he said. 鈥淭here isn鈥檛 anything else planned that we think comes close to producing the level of information or data that OCO would provide,鈥� he told New Scientist.
OCO-2 will fly in a near-polar orbit and will make measurements of the atmosphere in thin strips below its flight path, covering just 7 per cent or so of the Earth鈥檚 surface every month. But it could serve as a technology 鈥減athfinder鈥� for follow-on satellites dedicated to policing future climate treaties.
鈥淔uture greenhouse gas monitoring satellite networks will need sensitivities and spatial resolutions similar to those provided by OCO, but much better spatial coverage, so that they can map the entire Earth at regular intervals,鈥� says OCO-2 lead scientist David Crisp of JPL.
Such satellites could verify that countries are complying with any international agreements that cap greenhouse gas emissions, or even that individual power plants are releasing as much greenhouse gases as they claim.
Issue of trust
That could provide a valuable cross-check for existing information on carbon emissions, which is largely self-reported. 鈥淩ight now, countries turn in reports, and those reports get reviewed by an executive committee, but there鈥檚 no independent verification,鈥� , who studies Earth鈥檚 carbon cycle at Purdue University in West Lafayette, Indiana, told New Scientist.
Rob Bradley, director of international climate policy at the World Resources Institute in Washington, DC, agrees. 鈥淪omething that鈥檚 missing from the international climate policy world is trust,鈥� he told New Scientist.
The uncertainty over self-reports could become a stumbling block in efforts to agree on more stringent carbon-reduction targets and to build confidence in a cap-and-trade market. 鈥淲hen things start getting tough and targets start getting tight and carbon starts costing money, there鈥檚 a strong incentive to fudge the books,鈥� Gurney said.
Overall, NASA鈥檚 Earth science budget got a boost of $1.8 billion, spread over four years, above previous forecasts. The extra funding is slated to go to the OCO鈥檚 replacement, the development of new satellites, and enhanced climate modeling capabilities, among other projects.
