GMV's Celeste IOD-1 satellite successfully transmits first navigation signal

At 10:38 CET on April 8, the Celeste IOD-1 satellite, developed by GMV and Alén Space under the European Space Agency’s (ESA) Celeste In-Orbit Demonstrator (IOD) program, successfully transmitted its navigation signal for the first time.

The reception of the signal from the Celeste IOD-1 satellite, confirmed by ESA teams at ESTEC, marks a key milestone for the program as it confirms the satellite’s successful commissioning in orbit. The signal was also received at GMV’s monitoring station in Lisbon.

The first two IOD satellites of the Celeste program—built by GMV and Thales Alenia Space, respectively—were launched on March 28 at 10:14 CET from Rocket Lab’s Launch Complex 1 in Mahia, New Zealand. Separation from the launch vehicle took place approximately one hour later, marking the start of the initial operations phase (LEOP) and commissioning, carried out by GMV for the IOD-1 satellite from the mission control center in Tres Cantos.

Celeste is ESA’s strategic program to demonstrate the benefits of an additional low Earth orbit (LEO) navigation layer that complements Galileo and EGNOS, with the goal of improving the accuracy, resilience, and security of positioning, navigation, and timing (PNT) services in Europe. The in-orbit demonstrator (IOD) represents the program’s first phase and will validate key LEO-PNT technologies in flight ahead of potential future operational deployment.

The Celeste IOD phase is being carried out in parallel by two European consortia and will include a total of eleven satellites plus one in-orbit spare. As one of the prime contractors, GMV is responsible for the end-to-end mission for six of the demonstrator satellites, including system definition and design, the space and ground segments, the user segment, and operations.

Next-generation LEO navigation

The Celeste program began with two demonstrator satellites, IOD-1 and IOD-2, aimed at securing registered frequency allocations and testing representative navigation signals through the end of the year. The mission will demonstrate precise autonomous orbit determination without relying on ground infrastructure, as well as stronger radionavigation signals in the L- and S-bands from low Earth orbit.

By demonstrating the advantages of integrating LEO capabilities into a multi-orbit architecture alongside Galileo (MEO), Celeste aims to improve resilience to interference and expand advanced navigation services. Operating at altitudes between 500 and 560 km, the Celeste demonstrators will assess how a complementary LEO layer can enhance Europe’s Galileo system in medium Earth orbit. Eight additional, larger satellites are currently under development to extend the capabilities of the initial demonstrators. These will form part of the full fleet (eleven operational spacecraft and one spare) and will pave the way for subsequent launches starting in 2027.

GMV was selected in 2024 by the European Space Agency (ESA) to lead one of the parallel contracts for the development of Celeste. The first satellite in the constellation, a 12U CubeSat named Celeste IOD-1, was jointly developed by GMV and Alén Space. In recent months, Celeste IOD-1 has undergone a complex assembly and integration process, as well as rigorous environmental and system testing. The results of these tests, carried out at GMV’s facilities, confirmed that the satellite was ready for launch, as well as for initial LEOP (Launch and Early Orbit Phase) operations and in-orbit experimentation activities.