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\t\t\t\t\t\t27\/08\/2025<\/span> Over the summer, the European Space Agency ran an optical communication demonstration campaign using two observatories on Earth and NASA\u2019s Psyche mission. All four optical links were successful.<\/p>\n<\/div>\n Four out of four! In a remarkable demonstration of precision, coordination, and cutting-edge technology, ESA successfully completed a series of four increasingly complex deep-space optical communication links with NASA\u2019s Deep Space Optical Communications (DSOC) experiment aboard the Psyche spacecraft – currently flying at over 300 million kilometres from Earth.<\/p>\n Each link demanded greater accuracy, longer distances, and more refined operations, culminating in a final transmission that pushed the boundaries of what\u2019s possible in interplanetary laser communications: receiving a cat video sent from across the solar system.<\/p>\n<\/p><\/div>\n “The lessons learned during this activity will certainly be useful as we prepare for the future. With the results achieved during ESA\u2019s links with NASA\u2019s DSOC, we have demonstrated that Europe is ready to support the future of high data rate, deep space optical communications,\u201d says Andrea Di Mira, project manager for the ESA Ground Laser Transmitter (GLT), deployed at the Kryoneri Observatory.<\/p>\n “Autonomous and resilient connectivity is key to sovereignty, not only on Earth, but also in space. This demonstration marks a critical step toward establishing European access to high-capacity optical communication networks for the Moon, Mars, and beyond. Optical links will be essential to handle the massive data volumes expected from future missions, both institutional and commercial, enabling higher-resolution science and richer exploration\u201d, says Mehran Sarkarati, ESA\u2019s Head of Ground Stations Engineering Division and Programme Manager for ASSIGN Programme.<\/p>\n \u201cIt lays the groundwork for ESA\u2019s proposed ASSIGN (Advancing Solar System Internet and GrouNd) programme, to be presented at the ESA Council Meeting at Ministerial Level (CM25) in November\u201d.<\/p>\n<\/p><\/div>\n The first link\u00a0was made on 7 July. In the evening, ESA\u2019s portable Ground Laser Transmitter, installed at the Kryoneri Observatory in Greece, shot a laser beam in the direction of NASA\u2019s Psyche spacecraft.<\/p>\n About fifteen minutes later, onboard the spacecraft, the DSOC experiment, led by NASA\u2019s Jet Propulsion Laboratory in Southern California, caught the signal and replied with another laser beam that was acquired by ESA\u2019s Ground Laser Receiver (GLR), installed about 37 kilometres away from the first observatory.<\/p>\n This 30-minute-roundtrip communication link marked European history for it was the first time a deep-space optical communications was made from a European ground segment. For the purpose of the campaign, the two observatories had to be temporarily converted into an optical transmitter and receiver duo.<\/p>\n<\/p><\/div>\n For the following two links, the ESA team thrived to maintain a continuous reception link with the spacecraft.<\/p>\n \u201cThese two attempts allowed us to provide the most stable ground laser beacon possible to the spacecraft, so it could reliably send data down to our ground laser receiver,\u201d says Clemens Heese, ESA\u2019s Head of Optical Technologies and ESA\u2019s DSOC demonstration project manager.<\/p>\n \u201cThis worked like a charm, and, by the third attempt, we were able to receive a data stream of 1.3 Mbps, coming from a distance around twice as far away as the Sun, and successfully decode the incoming data\u201d.<\/p>\n<\/p><\/div>\n This fourth and final link pushed the limits, with the GLR at the Helmos Observatory in Greece tracking the spacecraft low on the horizon, through a turbulent atmosphere, while catching individual photons on a detector cooled to just 1 Kelvin.<\/p>\n Unlike previous reception links, the communication link contained an unexpected and adorable surprise – a cat-chasing-a-laser video \u2013 sent at speeds of up to 1.8 Mbps.<\/p>\n<\/p><\/div>\n \u201cWith the fourth link, we have passed the distance threshold of two astronomical units. This required an especially complex operation that involved the organisation of parallel activities at the GLT,\u201d says Andrea Di Mira.<\/p>\n \u201cThis time, the round-trip time of about 34 minutes, leaving us much less time to adjust laser pointing angles and maximise irradiance. We carefully planned every single activity, prepared contingency actions and precisely calibrated each and every one of our systems to align our high-power beams at arcsecond level and keeping them stably locked in the right direction towards Psyche.\u201d<\/p>\n<\/p><\/div>\n For the four links, the Helmos Observatory was not only home to the Ground Laser Receiver. It also served as ESA\u2019s main operations hub. From there, the team coordinated every pass, including the interface between GLR, GLT and JPL\u2019s DSOC Flight Terminal team in Southern California.<\/p>\n “Every adjustment had to be anticipated and pre-coordinated. The flight terminal team at JPL continuously reported power metrics from the spacecraft back to us in Greece, while we executed a predefined decision tree to adapt scanning patterns and beam pointing,” says Sinda Mejri, project manager for ESA\u2019s Ground Laser Receiver.<\/p>\n \u201cIt was like conducting an orchestra: each cue had to be perfectly timed so that every decision brought us closer to the sweet spot of maximizing Psyche\u2019s tracking and downlink reception\u201d.<\/p>\n<\/p><\/div>\n After completing the links with Psyche, the collected data will undergo detailed analysis to evaluate the performance of each system.<\/p>\n The Helmos telescope, used for the GLR, is scheduled for an upgrade to enhance its capabilities, while the GLT is also being considered for future activities. Discussions are ongoing for a potential on-sky experiments in 2026.<\/p>\n \u201cOur journey with the GLR continues, we are exploring new uses for the current system, such as characterising sky background at Helmos to prepare for quantum key distribution applications. Looking ahead, a GLR-twin is now under development to be paired with larger telescopes, with a validation campaign planned in Chile in 2026- more results are coming,” says Sinda Mejri.<\/p>\n The demonstration campaign is key to the optical communication roadmap, carried out at ESA’s Space Operations Centre (ESOC) to develop the future of space communication. It is a joint success made possible through close collaboration with colleagues and partners across industry, academia (National Observatory of Athens), ESA\u2019s Directorate of Technology, and NASA\u2019s Jet Propulsion Laboratory.<\/p>\n Looking ahead, ESA is currently studying a Mars electric propulsive tug capability, called \u2018LightShip\u2019, which would transport passenger spacecraft to Mars. Following passenger drop off, LightShip would transfer to a service orbit where it would provide communications and navigation services through the\u00a0MARs COmmunication and Navigation Infrastructure\u00a0(MARCONI) payload, part of which will include an optical communications demonstrator as part of the roadmap towards supporting future human missions.<\/p>\n<\/p><\/div>\n
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\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\n
\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nA laser round-trip to mark European history<\/h2>\n
\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nMaintaining the connection<\/h2>\n
\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nCat-ching a needle in haystack<\/h2>\n
\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nConducting an optical orchestra<\/h2>\n
\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nNext steps<\/h2>\n
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