Aura studies atmospheric chemistry — the composition of the air rather than its motion. Its instruments measure ozone, nitrogen dioxide, sulphur dioxide, formaldehyde, methane and aerosols, tracking both the stratospheric ozone layer and the pollution in the air people actually breathe.
Its ozone monitoring instrument, built in the Netherlands, has produced the daily maps of the Antarctic ozone hole that document its slow recovery following the Montreal Protocol — one of the clearest examples of an environmental problem being measurably reversed by international agreement.
The same instrument turned out to be an excellent pollution monitor. Nitrogen dioxide is produced by combustion and lasts only hours, so its concentration maps show exactly where fuel is being burned — revealing declining pollution over Europe and North America, sharp rises and then falls over China, and the abrupt drop during the 2020 lockdowns.
That capability made satellite data directly relevant to public health and regulatory policy in a way that atmospheric science rarely is. Air quality agencies now use it routinely, and it has been used to identify unreported emission sources.
Aura completes the trio of large EOS observatories with Terra and Aqua, and like them has operated far beyond its design life. Its instruments have been progressively retired as the spacecraft ages, with its successors carrying more capable versions of the same measurements.
