Science

NASA Launching Satellite to Track Carbon

By KENNETH CHANGJUNE 29, 2014

An illustration of the Orbiting Carbon Observatory-2, ready to launch Tuesday to measure atmospheric carbon dioxide. Credit Image by JPL/NASA

On an average day, some 100 million tons of carbon dioxide is liberated from oil and coal by combustion, wafting into the air. The gas traps heat in the atmosphere, resulting in the gradual warming that has alarmed scientists and much of the public.

But only half of the carbon dioxide stays up there; the other half falls back to earth. While scientists know what happens to half of that half — it dissolves into the oceans — the rest is a continuing puzzle. It is taken up by growing plants, but nobody knows exactly where and how. “Somewhere on earth, on land, one-quarter of all our carbon emissions released through fossil fuel emissions is disappearing,” said David Crisp, a senior research scientist at NASA’s Jet Propulsion Laboratory. “We can’t identify the processes responsible for this. Wouldn’t it be nice to know where?”

Now NASA is launching a satellite to help solve the puzzle.

The satellite, the Orbiting Carbon Observatory-2, is scheduled to lift off Tuesday morning from Vandenberg Air Force Base in California. Passing over the North and South Poles at an altitude of 438 miles, it will observe the same spots every 16 days as the earth rotates beneath.

These repeated measurements will allow scientists to observe the rise and fall of carbon dioxide with the seasons. They may also figure out how the balance changes with droughts or floods.

That should give them a better idea of whether the oceans and land plants will continue to absorb half of the carbon dioxide emissions as in the past or whether any of these so-called carbon sinks are close to overflowing, leaving even more gas in the air.

In particular, scientists do not understand how plants have kept pace with fossil fuel emissions that have nearly tripled since 1960. “Have you seen a new rain forest spring out of nowhere that wasn’t there before?” asked Dr. Crisp, the leader of the science team for the mission. “No.”

The orbiting observatory carries a single instrument, to measure colors of sunlight bouncing off the earth. The relative intensity of the colors will tell how much carbon dioxide the light beam passed through, and the spacecraft will take a million measurements a day.

Because of intervening clouds, only a tenth of the measurements — about 100,000 a day — will prove useful data. Still, that will dwarf what 150 carbon dioxide measuring stations on the ground are able to provide. A Japanese satellite is making similar measurements, but with less precision.

An earlier Orbiting Carbon Observatory mission failed in 2009, when the clamshell nose cone surrounding the spacecraft did not open and the satellite splashed into the ocean a few minutes after liftoff — a $273 million loss. “That was a heartbreak, utter devastation,” said Ralph R. Basilio, the project manager for the current mission.

At the end of 2009, the Obama administration decided to build a nearly identical satellite scheduled for launch in February 2013. But those plans were disrupted when the same launch failure that had doomed the first mission occurred again, destroying another NASA satellite, the Glory mission, in 2011.

The space agency then decided to switch rockets, putting the new satellite on a Delta 2 rocket, which has long history of successful launches.

The switch delayed the launching date, and the bigger Delta 2 added to the cost — which totaled $467.5 million this time. The cost also includes an extra copy of the carbon dioxide measuring instrument, which was built to ensure against delays if problems arose during testing. That extra instrument may be flown to the International Space Station to provide another set of observations.

Levels of carbon dioxide in the air have jumped 40 percent since the start of the Industrial Revolution, but the amount is still tiny: Of every million molecules of air, just 400 are carbon dioxide. Over a power plant or a city where emissions are higher, that number rises by perhaps one molecule per million. A field of corn stalks at the height of growing season might reduce the number by a similar amount.

To detect such minute changes, Dr. Crisp said, the parts of the 300-pound instrument had to be aligned within the width of a human hair. The scientists think they may also be able to discern a faint infrared fluorescent glow emitted by plants as they photosynthesize, which could indicate their health.

The Orbiting Carbon Observatory-2 is part of a busy year for NASA’s earth sciences division — the second of five launches — reflecting increased financing for this segment of NASA even as other parts have been squeezed by tight budgets.

Michael Freilich, director of the earth sciences division, said, “There is no question that the Obama administration puts a very high priority on understanding the earth.”