That’s enough to start work on a European radar for Envision, even as ESA still awaits a formal notification from NASA on the status of its contribution to the mission. “NASA conversations with ESA regarding Envision are ongoing,” a NASA spokesperson said.

But time is of the essence if Envision is to launch in the early 2030s. ESA officials have already delayed Envision’s launch by one year to 2032 to give teams in Europe more time to deliver the radar.

“At the moment, we are finalizing our agreement with NASA, but it is looking like they are not able to provide the radar,” Straume-Lindner said in response to a question from Ars. “So that is why we are going full steam ahead with the European solution.”

Cancellations and delays

A complementary mission to Envision, NASA’s VERITAS radar orbiter, was supposed to launch in the late 2020s, but funding woes at NASA and the Jet Propulsion Laboratory forced a delay until no earlier than 2031. Its development remains in limbo. The DAVINCI mission, led by NASA’s Goddard Space Flight Center, continues working toward a launch in the early 2030s.

The work of the Venus Science Coordination group, established jointly by NASA and ESA, has also been suspended due to “changes to the budgetary situation in the US,” Straume-Lindner said.

Meanwhile, ESA is also assessing how it can fill the roles of NASA on LISA and New Athena. On LISA, NASA was to provide lasers and ultra-stable telescopes for the mission’s three formation-flying spacecraft. The US space agency was on the hook for X-ray sensor hardware, a cryocooler, and a vibration isolation system for New Athena.

The Trump administration also sought to cancel NASA’s role in ESA’s Rosalind Franklin rover mission to Mars, set for launch in 2028. NASA has a long-standing agreement with ESA to pay for the launch of the European-built rover, and funding restored by Congress last year allowed the space agency to sign a contract with SpaceX to launch Rosalind Franklin in 2028.

“ESA is a very reliable partner, and we always deliver on our commitments and our promises, and we appreciate the difficulty that they’re in right now,” Mundell said, referring to NASA.

Europe has other places to look for cooperation in space, but NASA is the agency’s most enduring partner. In human spaceflight, ESA and NASA cooperate closely on the International Space Station and the Orion spacecraft used for Artemis missions to the Moon.

ESA launched its first 50-50 joint science mission with China earlier this year. The SMILE spacecraft, built in China and launched by Europe’s Vega rocket, is studying the connection between the solar wind and Earth. The first ESA instrument to land on the Moon arrived on the lunar surface in 2024 aboard China’s Chang’e 6 mission.

Mundell said China has invited ESA to join more Chinese-led science missions. “That is something that we’re exploring,” she said.