Aura Around Earth

Ozone hole over Antarctica.
Image Credit: NASA

This week, NASA is set to launch Aura, a satellite designed to monitor the Earth’s atmosphere.

The envelope of gases surrounding the Earth is necessary for life as we know it. The atmosphere helps Earth regulate temperatures and maintain a climate, and the ozone layer protects life from the harmful ultraviolet (UV) radiation of the sun.

"The atmosphere is one of the most important and limited resources that we have," says Phil DeCola, Aura program scientist at NASA Headquarters in Washington D.C. "The kind of global coverage that we’re going to get on almost a daily basis from all these instruments (on Aura) is unprecedented."

Aura has four instruments to measure ozone and trace atmospheric gases: the Microwave Limb Sounder (MLS), the High Resolution Dynamics Limb Sounder (HIRDLS), the Tropospheric Emission Spectrometer (TES), and the Ozone Monitoring Instrument (OMI).

These instruments will track climate change, and also monitor the ozone layer. The "ozone hole" is actually a thinning of the ozone layer over Antarctica. Pollutants such as Chlorofluorocarbons (CFCs) deplete the ozone layer, although international agreements like the Montreal Protocol have banned such chemicals. Aura will determine if the treaties are effective by detecting global levels of CFCs and their byproducts, chlorine and bromine, that destroy the ozone layer.

Ozone formation from manmade and natural ultraviolet causes Image Credit: EPA Australia

Aura also will track regional and global air quality, detecting gases that create smog and ozone. When ozone exists in the lower atmosphere, the troposphere, it acts as an air pollutant.

"We live in one atmosphere," says Mark Schoeberl, Aura project scientist at NASA’s Goddard Space Flight Center in Maryland. "That one atmosphere contains pollutants which are pushed into the atmosphere by industrialized nations, by biomass burning in the tropics, by agricultural activity. Those pollutants float downstream, and you and I are breathing someone else’s exhaust gases."

Environmental monitoring by Aura satellite from orbit Image: JPL

Aura will work in cooperation with other satellites, which will all fly in formation to get a more comprehensive view of the planet. Dubbed the "A-train," the Aqua satellite, which monitors water quality, will lead the pack. Aqua will be followed by Calypso, due to be launched next year. Cloudsat and the French satellite Parasol will follow Calypso, and Aura will head up the rear.

Schoeberl says that using the new technologies of Aura to study the Earth could lead to technologies that will study other planetary atmospheres. Earth is the only planet that we know of that has life, and Aura could help us better understand the close relationship life has with a planetary atmosphere. Life on Earth is not only dependent on the planet’s atmosphere, it interacts with it and can even change it over time.

"Bacteria started probably 2 billion years ago making oxygen in an atmosphere that had none. We’re altering it even further," says Schoeberl. "So in the exploration of the universe, developing the technologies and precise instruments to look at the atmosphere is going to help. (Aura) is a technological stepping stone for the exploration of the solar system."