Firing laser pulses between satellites is promising a step up in tracking greenhouse gases.
More renowned for their appeal as holiday destinations, the Spanish Canary Islands recently played host to an experiment that involved shooting laser beams from a peak on La Palma to Tenerife.
Over the course of two weeks, the night sky lit up with green pulses of light between the two islands – looking more like a scene from a Star Wars film than an experiment to help understand Earth’s atmosphere.
The experiment was devised to test the concept of using ‘infrared differential absorption spectroscopy’ as a way of making extremely accurate measurements of trace gases such as carbon dioxide and methane.
The approach links two satellites orbiting Earth: one acts as a transmitter and the other acts as a receiver, with the atmosphere being probed as the beam travels between them.
Radio occultation involves tracking signals from satellites as they rise or set behind Earth and is a well-established method of sensing the atmosphere using microwave signals.
This new concept, however, uses shortwave infrared laser pulses. At the right wavelength, the atmospheric molecules affect the beam.
This information can then be used to calculate concentrations of trace gases, and potentially wind.
Repeated at different altitudes, a vertical profile stretching from the lower stratosphere to the upper troposphere could be built up.
As an important part any new development, the theory has to be put to the test.
Read more: Esa Website portal
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