Atmospheric Chemistry Experiment celebrates 20 year anniversary

2023 is the 20th year on orbit for the Canadian Space Agency’s Atmospheric Chemistry Experiment (ACE) satellite (, which stands as Canada’s most successful scientific space mission. ACE was launched by NASA in August 2003 and continues to make daily measurements of atmospheric composition.

Originally planned to have a two-year lifetime, ACE performs flawlessly 20 years on. This longevity allows measurement of long-term trends in the concentration of chlorine-containing molecules to monitor the success of the Montreal Protocol on Substances That Destroy the Ozone Layer. (The ozone layer protects humans from dangerous UV radiation.)

ACE uses Fourier transform infrared spectroscopy of sunlight during sunrise and sunset to determine the abundance of 46 atmospheric molecules associated with air pollution and climate change. In addition, ACE observes both sulfate aerosols from volcanic eruptions that cool the surface of the Earth, and smoke from large wildfires that alter the chemistry of the stratosphere.

All these mission data products are produced in the Chemistry Department at the University of Waterloo at the ACE Science Operations Centre (SOC). The SOC analyzes the ACE infrared spectra and distributes their data products to hundreds of users around the world.