Introducing Celeste

Celeste will play a pioneering role in maintaining European leadership and state-of-the-art in satellite navigation. As ESA’s first initiative for satellite navigation in low earth orbit (LEO), the mission will be testing next-generation technologies and explore new frequency bands for satellite navigation.

Celeste will test and demonstrate how a complementary layer flying closer to Earth can enhance Europe’s current Galileo system in medium Earth orbit (MEO), boosting the overall resilience, enhancing its performance and opening opportunities for new service capabilities directly from LEO.

Celeste also contributes to one of the three core pillars of ESA’s new European Resilience from Space (ERS) initiative. ERS aims to address critical security and resilience needs for Member States while laying the groundwork for future European strategic space capabilities.

Celeste in‑orbit demonstration phase

To be launched starting 2026, the Celeste in-orbit demonstration (IOD) phase, composed of eleven small satellites of varying capabilities serve as a platform for rapid development and testing of LEO-based navigation technologies and services.

The first two spacecraft (IOD-1 and IOD-2) - developed by GMV and Thales Alenia Space respectively - are scheduled for launch with a window starting on 24 March 2026. From 2027 onward, they will be joined by nine additional satellites, forming a demonstration constellation.

This phase will:

• Demonstrate how LEO-based navigation can broadcast GNSS signals, improving accuracy, availability and robustness, particularly in environments where MEO‑based signals are obstructed or attenuated.
• Contribute to commitments towards regulatory requirements such as bring ITU frequency filings into use, and requirements towards space debris mitigation in preparation of future operational constellations.
• Introduce new frequency bands, that allow for new applications and show strong resilience against both intentional and naturally occurring interferences.
• Offer an in-orbit testbench for the demonstration of service capabilities for a broad range of satellite navigation applications, for autonomous vehicles, railway, maritime and aviation, critical infrastructure, wireless networks, emergency services, 5G applications and many others.

The IOD phase of Celeste was approved at ESA’s Council at Ministerial Level of 2022 and is supported by Austria, Belgium, Finland, France, Germany, Hungary, Italy, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom. Two parallel contracts to develop the fleet were awarded in 2024 to two consortia involving over 50 entities from 14 countries.

Celeste in‑orbit preparatory phase

Following the demonstration activities, the Celeste in-orbit preparatory (IOP) phase will prepare European industry to be ready to engage into the future development of an operational LEO‑based constellation layer supporting navigation services. Key objectives include:

• Maturing essential technology building blocks, such as integrated digital and RF modules, advanced antenna systems, and miniaturised clocks.
• Driving industrialisation across Europe, enabling scalable production, lower unit costs, and broad industrial participation.
• Validating technologies through in‑orbit experimentation, ensuring their readiness for a future operational programme.

The IOP phase of Celeste was approved at ESA’s Council at Ministerial Level of 2025, marking a major step toward eventually developing resilient European positioning and timing services from low Earth orbit. At this point, Czech Republic, Luxembourg and the Netherlands joined the programme.

Towards a future European LEO‑PNT constellation

In 2023, the European Commission identified low-Earth-orbit (LEO) satellite navigation constellations as pivotal to meeting the threat of malicious interference and ensure more robust, diverse, and interference-proof navigation systems.

The Celeste mission has been identified as “the right precursor to a future EU LEO-PNT system reinforcing Galileo”. The long‑term ambition of Celeste is to allow for a smooth transition towards the establishment of an operational LEO‑based navigation layer within the European Union’s current position, navigation and timing architecture, with Galileo remaining at its core.