1.06.2025

Credit: ClearSpace

On 26 May, the French space agency CNES issued a call for proposals for the development of an in-orbit demonstration of the storage and refuelling of cryogenic propellants.

The CRYOSTARS (CRYOgenic Storage and Transfer for Advanced Rocket Systems) initiative is being managed under the Space Transportation Solutions vertical of CNES’s Priority Innovation Vectors programme. Introduced in 2023, the programme aims to focus the agency’s innovation efforts on a defined set of strategic priorities. The Space Transportation Solutions vertical is focused on advancing technology that will ensure the country’s sovereign and independent access to space, including reusable launch systems, in-orbit refuelling, and satellite servicing capabilities.

According to the published consultation file, the initiative will first focus on examining potential use cases for the technology, including possible dual uses in terrestrial sectors such as naval and aeronautical applications. Additionally, while the call does not mandate the pursuit of specific applications, it highlights several potential avenues for consideration, including the long-term storage of liquid hydrogen for nuclear thermal propulsion, cryogenic refuelling of upper stages or orbital vehicles, cryogenic fluid storage and refuelling for electric propulsion systems, and the development of cryogenic orbital propellant depots.

The findings from this initial stage of the initiative will then inform the development of a demonstration mission. While the demonstration may take the form of a scaled-down version of the technology, any such prototype must still achieve Technology Readiness Level 6 (TRL 6), which requires testing a representative model or system in the intended operational environment. Additionally, while it allows for a minimum development level of TRL 6, it recommends pursuing a development level of TRL 9, which is a full-scale demonstration of the technology.

In February 2025, the European Space Agency announced its own initiative to develop in-orbit refuelling capabilities. Through the “In-Orbit Test of Prototype Refuelling Technologies for Green Propellants” programme, the agency aims to fund the demonstration of a prototype refuelling system that uses green, self-pressurising propellants. According to the call for proposals, the initiative is particularly targeted at supporting multi-orbit satellite communication constellations. As such, it may ultimately focus on equipping the European Commission’s IRIS2 satellites with in-orbit refuelling capabilities.

Quelle: European Spaceflight LTD