NASA made a literal last minute decision to delay the launch of the Orbiting Carbon Observatory-2 earlier today, leaving just 46 seconds up on the countdown clock, reports Kenneth Chang for The New York Times. Something was wrong with the system that sprays water beneath the rocket during liftoff, and with the seconds ticking off mission control decided it didn’t have enough time to diagnose the problem. NASA may try again tomorrow.

Orbiting Carbon Observatory-2 NASA

NASA is trying to identify carbon sinks

It’s not that hard to spot where carbon dioxide is coming from; major sources (eg coal-firing power plants, for instance) can be identified by looking for spots where carbon dioxide is most concentrated. Figuring out where all of the carbon ends up is a different story. When carbon emissions leave a power plant, or any other source, they drift in the atmosphere before about half of it falls back to earth. Most of that gets absorbed back into the oceans, but that still leaves roughly a quarter of all atmospheric carbon unaccounted for.

“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. “Wouldn’t it be nice to know where?”

Of course NASA is well aware that plants use up carbon dioxide, but they are looking for a much more detailed picture of what’s happening with carbon flows into and out of the atmosphere. To put that picture together, the Orbiting Carbon Observatory-2 will stay up for two years (once it finally gets into space), taking a million measurements per day and hitting the same spot every 16 days. Once all the data is collected, NASA hopes to determine the most important land-based carbon sinks.

NASA is hoping that the third time’s a charm

If you’re wondering why the Orbiting Carbon Observatory-1 didn’t get the job done, it’s because it never made good on the first part of its name. It failed to separate from the rocket back in 2009 and never made it into orbit, reports Brid-Aine Parnell for The Register. Then in 2011 the Glory satellite did a repeat performance, failing to separate from its booster rocket and falling into the sea.

Considering the track record so far, it’s understandable that NASA would rather wait another day and make sure everything is in good working order instead of explaining how they struck out with carbon-measuring satellites.