Fans of ozone data, rejoice. US science agencies announced on 11 April that they will restore an axed ozone sensor to a satellite that is due to launch in 2009.

The sensor was scrapped last June, when the National Polar-orbiting Operational Environmental Satellite System (NPOESS) was brutally restructured. The system is meant to merge and replace the US military and civilian weather-prediction satellites, but it is over budget and behind schedule. At least three climate sensors were axed at the time.

Now, the instrument known as the Ozone Mapping and Profiler Suite Limb will get to fly aboard the initial satellite in the system, according to NASA and the National Oceanic and Atmospheric Administration (NOAA). The sensor will measure the distribution of ozone concentrations from the ground to the top of the atmosphere, and can be used to monitor the ozone layer and the slow recovery of the ozone hole.

Earth scientists at NASA, along with ozone scientists, pushed hard for the sensor to be reinstated. Pawan Bhartia, senior staff scientist at the Goddard Space Flight Center in Greenbelt, Maryland, who helped to develop the instrument, says that the sensor will be there to collect ozone data when the current satellites Aura and Envisat stop operating, perhaps in the next couple of years. “Right now, the missions we have cost a billion dollars each,” he says. “But once you understand the science, you can keep on monitoring it on a long-term basis, but not spend so much money on it.”

Andrew Carson, an executive for the project at NASA headquarters in Washington DC, says that the change of heart was influenced in part by a January 2007 National Academy of Sciences report that called for stronger Earth-monitoring efforts from space. But he says there were moves to restore the sensor even before the report came out.

The money will come from outside the main NPOESS budget, and will be split equally between NOAA and NASA. None of the other sensors cut last year are slated to be restored.