The Trump Administration’s budget proposal for Fiscal Year 2026 would take an axe to NASA science. Two satellite missions on the chopping block have provided climate scientists, oil and gas companies, and farmers with critical atmospheric carbon data for years.

The Orbiting Carbon Observatories are a pair of instruments that map atmospheric carbon on a global scale. NASA launched the OCO-2 in 2014 and mounted the OCO-3 on the International Space Station in 2019. Trump’s budget proposal threatens both missions, but the standalone OCO-2 would be completely destroyed during its fiery descent through Earth’s atmosphere. Though the budget has yet to pass, NPR reports that NASA scientists working on the OCO missions are already making “Phase F” plans—essentially laying out options for termination.

David Crisp, a retired NASA scientist who designed the satellites and managed the missions until 2022, told NPR that the NASA employees making those plans have reached out to tap his expertise. “They were asking me very sharp questions,” Crisp said. “The only thing that would have motivated those questions was [that] somebody told them to come up with a termination plan.”

Three other academic scientists and two current NASA employees—all of whom requested anonymity—also confirmed to NPR that the agency is planning to terminate the missions. Congress has already funded both satellites through the end of fiscal year 2025, NPR reports. It could still choose to extend their funding through 2026, but it remains to be seen. In July, congressional Democrats did warn acting NASA administrator Sean Duffy not to terminate missions that Congress has funded—a sign that they may attempt to save the OCOs.

Decommissioning these satellites would mark a significant scientific loss. The OCO-2 and OCO-3 sniff out atmospheric carbon dioxide using spectrometers to detect wavelengths of light absorbed by CO2 molecules. NASA designed them to improve monitoring of human-driven carbon emissions and variations in the natural carbon cycle, and they’ve certainly done a good job of this.

OCO-2 data have helped scientists quantify how natural carbon sinks such as forests and oceans offset carbon dioxide emissions and how carbon sinks can become carbon emitters through drought, deforestation, or wildfires, according to NASA’s Jet Propulsion Laboratory. This instrument has also provided valuable insights into urban carbon dioxide emissions and contributed data that supported the Paris Agreement.

That’s not all. Shortly after launching the satellite, NASA realized it could also measure plant growth, according to JPL. It does this by detecting the “glow” plants emit during photosynthesis. When plants absorb sunlight to convert carbon dioxide and water into energy, their chlorophyll—a light-absorbing pigment—leaks some unused photons, JPL explains. This produces a faint glow called solar-induced fluorescence, and OCO-2 can spot it. This data helps farmers and agricultural scientists estimate crop productivity, monitor drought, and more.

If Trump’s budget passes, it will mean the end of the OCO-2, but there is hope for the OCO-3. NASA is seeking partnerships with institutions and companies willing to take over the cost of maintaining this ISS instrument. For now, like many of America’s climate and environmental science programs, the future of both Earth-observing satellites hangs in the balance.