ESA’s Ground Laser Transmitter shooting lasers at NASA’s Psyche (sped up 1000 times)

Over the summer 2025, ESA’s Ground Laser Transmitter, installed at the Kryoneri Observatory in Greece, has been the half of a optical communication demonstration campaign between Earth and NASA’s Psyche mission.

The Ground Laser Transmitter integrates five high-power lasers with ultra-precise steering controllers into a special 20-foot-long container with a lifting platform. This allowed to protect the sensitive equipment from sunlight during the day and lift it into the open after sunset.

This timelapse sped 1000 times shows the final test of the campaign, effectuated after the fourth and final pass, when the four lasers used in the experiment, as well as the fifth one, were activated.

“For the fourth link, we continued to use the limited available time to characterise the behaviour of each of the 1kW beams that together form the Ground Laser Transmitter beacon in the far-field, aiming to optimise the pointing” says Andrea Di Mira, project manager for the ESA Ground Laser Transmitter at the Kryoneri Observatory.