This scientific instrument, called TEMPO, should make it possible to follow the spread of pollutants much more accurately than before, from where they are emitted and when they are spread by wind.
Its applications are multiple: improving alerts to the population in case of poor air quality, better determining where in the ground new detectors should be installed, or even helping research on the impact of air pollutants on health.
But they also measure pollution from fires, which are becoming more frequent due to global warming.
About 40% of Americans (about 137 million people) live in areas with poor air quality, according to the American Lung Association. The poorest regions are disproportionately affected.
Air pollution causes nearly 60,000 premature deaths annually in the United States. It also harms the economy, as it affects the productivity of workers and even crops.
“full time”
The satellites used so far to make this kind of assessment in the United States are located at an altitude of about 700 kilometers and fly around the Earth fifteen times a day.
“We’ll be able to take measurements every day over New York, say at 1:30 p.m.,” Carolyn Nolan, an atmospheric physicist at the Center for Astrophysics, explained in a news conference. But “There’s a lot going on in New York in one day. There are two hours of rush hour that can’t be measured.”
TEMPO, which weighs just under 140 kg, will attach to a satellite in geostationary orbit, at an altitude of more than 35,000 km. Therefore, it will revolve around the Earth at the same time as it revolves around itself, which will allow it to always remain over North America.
“For the first time, we’ll be able to take hour-by-hour measurements” in this part of the world, Nolan said.
Geostationary orbit is very common for communications satellites, and one of them has a TEMPO inserted: the Intelsat IS-40e satellite.
– Ozone and nitrogen dioxide –
The satellite lifted off Friday at 0030 local time (0430 GMT) aboard a SpaceX Falcon 9 rocket from Kennedy Space Center in Florida.
It will take about two weeks to reach the correct orbit, according to Jean-Luc Froelleger, vice president of Intelsat.
From that moment on, operations can begin.
TEMPO will work by analyzing light reflecting off cloud surfaces using a spectrometer.
Each gas absorbs light differently, Nolan explained, so “you can see what’s in the atmosphere by the colors or wavelengths of the light that’s being absorbed.”
Three main measurements will be made.
The first would be nitrogen dioxide from combustion, notably of gasoline or diesel cars but also from coal or gas power plants.
Then ozone is evaluated, which when high in the atmosphere protects against sunlight but is detrimental to health when on Earth.
Finally, formaldehyde will be measured, which can be used to infer the presence of volatile organic compounds, namely those elements “that make certain things smell, like paint or gasoline or markers,” Nolan said.
TEMPO, which will operate for at least two years but likely much more, joins NASA’s fleet of 25 Earth observation missions.
A similar instrument, called GEMS, is already in geostationary orbit to do the same task over Asia, since its takeoff in 2020. Another, Sentinel-4, should be operational from 2024 to cover Europe.
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