NASA launches Aura spacecraft to study atmosphere

Nasa successfully launched a new satellite from California on Thursday that promises scientists their best gauge yet of how the tug of war between international treaties and industrial pollutants is being played out in Earth's atmosphere.

The bus-sized Aura spacecraft was launched aboard a Boeing Co. Delta 2 rocket from Vandenberg Air Force Base at 10.02pm NZT.

The US$785 million (NZ$1217 million) mission will use four instruments aboard the Aura to sweep and scan the atmosphere as it circles the planet in a polar orbit, studying the movement of pollutants and paying particular attention to the stratospheric ozone layer that buffers the Earth from potentially harmful solar radiation.

"Whether you're in Europe getting pollution from the United States or you're in the United States getting pollution from China, it's one atmosphere and we need to look at it from a global sense," said Mark Schoebert, a project scientist from Nasa's Goddard Space Flight Center in Greenbelt, Maryland.

Among its primary mission objectives, Aura will collect data on "holes" detected in the protective ozone layer at the poles. International treaties ban most uses of ozone-depleting chlorofluorocarbons, but Aura should show whether any earlier damage is being reversed.

The spacecraft will also track aerosols in the atmosphere, both industrial pollutants and those generated by fires.

"Aura is focused on trace gasses and aerosols that make up about one per cent of the atmosphere, but are almost as important as oxygen itself to life on Earth," said Phil DeCola, another mission scientist.

Aura will fall into an orbit trailing another of Nasa's Earth observation satellites, Aqua, which studies oceans and was launched in 2002.

Four more US and French satellites should be launched over the next several years and take their places between the Aqua and Aura, forming a flotilla of environmental monitors that Nasa has dubbed the A-Train.

Earth observation may lack some of the glamour of the Mars and Saturn missions that have grabbed headlines in recent months, but the trip is shorter.

While it took Nasa's Cassini spacecraft seven years to reach Saturn, Aura should be in its proper orbit, all its systems tested and fully operational in 90 days, Nasa said.

Scientists said they expect their first findings to be made public in December.

- REUTERS