The already twice-delayed rocket was slated to lift off Monday, but had to be delayed after the discovery of a dysfunctional valve.

The high-profile mission aims to carry a French military satellite into orbit, as well as more broadly to establish independent European access to space, without reliance on either the United States or Russia.

It comes as Europe's commercial space industry struggles to remain competitive in the face of Elon Musk's SpaceX.

Initially planned for December, the Ariane 6 mission was pushed back until February 26 and then again to March 3 because of problems getting the satellite to the launchpad.

But minutes before Monday's blast off from Europe's spaceport in Kourou, French Guiana, the company found an "anomaly" in one of the refuelling pipes.

After further evaluating the ground equipment, Arianespace said it is now targeting a launch on "March 6, 2025 at 1:24 pm local time in Kourou" (1624 GMT).

"Ariane 6 and its passenger, the CSO-3 satellite, are in stable and safe conditions," the company said in a statement.

- Boosting autonomy -

The launch of the CSO-3 satellite into orbit will complete a network of three French military imaging satellites, with the first two carried into space on Russian Soyuz rockets in 2018 and 2020.

Europe has not been able to use Russia's Soyuz rockets since Moscow invaded Ukraine in 2022, while the workhorse Ariane 5 was retired in 2023.

European nations have been trying to boost their security autonomy, an effort that has taken on renewed urgency since the Trump administration's rapprochement with Russia.

The CSO-3 satellite is expected to strengthen France's intelligence capabilities, allowing the army to receive extremely high-resolution images.

Europe has only a handful of military satellites, compared to the hundreds sent into orbit by the United States and China.

Given the military role of the satellite, strict security precautions are being taken to limit access at the Kourou spaceport on the northern coast of South America, with three Rafale fighter jets deployed to patrol the surrounding skies.

Europe has struggled to find a way to independently launch its space missions.

The Vega-C launcher did not resume flights until December 2024 after being grounded for two years following an accident that resulted in the loss of two satellites.

Four years of delays to Ariane 6 compounded the issue.

However, the heavy-lift rocket underwent a successful test in July 2024 and is scheduled to carry out five launches this year.