Aura, Monitoring global air quality

Monitoring global air quality

• NASA mission
• Launched 15 July 2004
• Operational

Aura monitors global air quality on a daily basis. It measures the chemical composition of the Earth’s atmosphere including greenhouse gases such as carbon dioxide and ozone depleting gases such as nitrogen dioxide and CFCs (Chloro-Fluoro-Carbons). The spacecraft is designed to find out if the ozone layer is recovering, if air quality is deteriorating and how the Earth’s climate is changing.

Ozone plays many different roles in climate change. It absorbs ultraviolet radiation from the Sun and absorbs infrared radiation from the Earth’s surface. Man made CFCs, although now banned under an international treaty, persist in the atmosphere and deplete the ozone layer. Other pollutants such as bromine compounds and nitrous oxide also destroy ozone.

Aura’s scientific instruments allow scientists to make a complete assessment of the chemical processes controlling ozone.

For more information, see NASA’s Aura homepage.

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Mission facts

• Aura is part of the Earth Observing System – a series of satellites that monitor and study the Earth’s changing environment.
  
  
• Aura takes approximately 100 minutes to orbit the Earth.
  
  
• The spacecraft provides atmospheric measurements over most points on Earth.

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Technology

HIRDLS (High Resolution Dynamics Limb Sounder) is one of the main instruments on board Aura. It was designed to measure atmospheric temperatures and composition, including ozone. Unfortunately, during the launch the instrument’s optical beam had become obscured by a piece of protective plastic film, reducing its visibility to just 20 per cent.

Scientists at the University of Oxford and University of Colorado have since been developing new mathematical formulas to maximise the data from HIRDLS. As a result the team can retrieve data from nearly the entire world in 24 hours.

MLS (Microwave Limb Sounder) uses microwaves to measure temperatures in the stratosphere and chemicals in the upper troposphere.

OMI (Ozone Monitoring Instrument) measures cloud pressure and coverage. It provides data relating to ozone chemistry and levels. OMI can identify different aerosol types.

TES (Tropospheric Emission Spectrometer) produces infrared images and can assess targets such as volcanoes.

UK involvement

UK scientists helped develop HIRDLS. The University of Oxford, which provided some the flight hardware and calibrated the instrument, led the science team.

STFC Rutherford Appleton Laboratory designed and built a power supply for the instrument and was responsible for the optical design of the telescope. The University of Reading developed the infrared filters.

Astrium Limited built the main structure, sun shield mechanism and thermal subsystem. BAE Systems supplied gyroscope units.

Data from Aura is being distributed in the UK through the British Atmospheric Data Centre at the Natural Environment Research Council (NERC), a BNSC partner.