At the Thales Alenia Space cleanroom in Cannes, France, European engineers successfully tested the deployment of one of the antennas of Lunar Link, ESA’s telecommunications element for the lunar Gateway station.

In orbit around the Moon, Lunar Link will provide vital communications between the Gateway and astronauts and infrastructures on the Moon.

Each of the two antennas measures 1.25 m in diameter and is mounted on a 1 m boom that will unfold in space. However, testing this on Earth is not straightforward: the boom and antenna actuators are designed to deploy and operate in zero gravity, while here on Earth the antenna’s mass of almost 20 kg makes it much heavier.

To overcome this challenge and avoid damaging the deployment boom, engineers attached a four-metre-wide helium balloon – proudly displaying ESA’s Lunar Link logo – to the antenna. The balloon lifted the antenna slightly, reducing its apparent weight and simulating the weightlessness conditions in orbit. With this setup, the team was able to verify that the boom deployed smoothly and reliably.

Lunar Link is being built by companies across Europe, with its two dish antennas have been built by the Spanish aerospace company SENER. In the same cleanroom where the balloon test took place, engineers are finalising the integration of Lunar Link's central section, known as the baybox. Positioned between the two antennas, the baybox houses critical components, including the flight computer – the “brain” that controls Lunar Link's operations.

The baybox and antennas will continue to be tested independently, before being integrated together early next year, forming ESA’s complete Lunar Link. Once fully assembled, the element will be sent to Northrop Grumman's facilities in the United States for assembly on top of NASA’s habitation module and then launched towards the Moon.