The launching of NASA’s Orbiting Carbon Observatory-2 spacecraft was called off on Tuesday morning, with 46 seconds left in the countdown, when equipment on the launching pad malfunctioned.  The spacecraft, on top of a Delta 2 rocket, was scheduled to lift off from Vandenberg Air Force Base in California at 5:56 a.m. Eastern time.  The problem occurred in a system that sprays water beneath the rocket engines during liftoff to dampen the roar and protect the launching pad. With only a 30-second window for a liftoff that would get the spacecraft into the proper orbit, controllers did not have time to diagnose and repair the problem.  NASA may make another attempt on Wednesday at the same time.  When the spacecraft gets off the ground, mission controllers will spend six to seven weeks testing out it out while nudging it into its final orbit 438 miles up, passing over the North and South Poles. From that vantage, it is to make a million measurements a day of carbon dioxide in the earth’s atmosphere. Every 16 days, it will pass over the same stops as the planet rotates beneath.  These repeated measurements will allow scientists to observe the rise and fall of carbon dioxide with the seasons. They may also help determine how the balance changes with droughts or floods.  That should give scientists 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 to linger in the air.  The $467.5 million mission is planned to last at least two years.  On an average day, some 100 million tons of carbon dioxide is liberated from oil and coal by combustion and wafts 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 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. “Wouldn’t it be nice to know where?”  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.  The orbiting observatory carries a single instrument, to measure the colors of sunlight bouncing off the earth. The relative intensity of the colors will tell how much carbon dioxide the light beam passed through. Because of intervening clouds, only a tenth of the measurements — about 100,000 a day — will prove useful data.  An earlier version of this article misstated the scheduled liftoff time for the Orbiting Carbon Observatory-2. It was 5:56 a.m. Eastern time on Tuesday, not 6:56 a.m. Eastern time.
An equipment malfunction has pushed the liftoff of the spacecraft, which will measure carbon dioxide in the atmosphere, until at least Wednesday.