• TEMPO satellite data estimated average NOx emissions of about 730kg an hour from the Southaven site after February 2026
  • SpaceXAI says local monitors have not shown a similar increase and plans to remove all 69 temporary turbines by July 2027

The fact

Researchers using NASA's TEMPO satellite have reported a sharp rise in nitrogen oxide emissions around SpaceXAI's gas-turbine site in Southaven, Mississippi, which supplies power to the Colossus 2 data centre across the state line in Tennessee. Their study was published as a preprint in August and has not yet been peer reviewed.

The researchers first detected emissions in December 2025 at an estimated 460kg an hour. From February 2026, the average rose to about 730kg an hour. The study said this was roughly 16 times the rate expected from the 41 permanent turbines covered by SpaceXAI's March air permit, which are designed to use stronger emissions controls.

SpaceXAI disputed the pollution picture. It provided New Scientist with a court filing from a third-party air-quality expert saying local monitoring stations had not recorded a notable increase since the temporary generators began operating. The company has agreed with Mississippi regulators to remove all 69 temporary turbines by July 2027 while building a permitted 1.2GW permanent power plant.

The assessment

Southaven now has two different ways of observing the same power site. Ground monitors measure pollution at particular locations, while TEMPO looks down from orbit and tracks changes in the atmospheric plume over a wider area. The two approaches are producing different pictures of what happened after the temporary turbines began operating.

That difference cannot be settled by satellite data alone. TEMPO estimates emissions from the plume rather than determining legal compliance at individual turbines, while ground readings depend on where monitors are placed and how pollution moves through the surrounding area. Operating hours and emissions data from the turbines would help connect the two sets of measurements.

For BTW readers, the Southaven transition now has an environmental record that can be followed as the temporary turbines leave and the permanent plant enters service. Comparing satellite observations, ground monitoring and turbine operating data during that change could provide much clearer evidence of how the new power system affects local emissions.

What to watch

Watch the removal of the 69 temporary turbines and commissioning of the permanent plant, alongside new TEMPO measurements and local monitoring results. Emissions data from the individual turbines would help explain any difference between the satellite estimates and readings collected on the ground.