Greek CubeSat ERMIS-3 Establishes Ground-to-Space Optical Laser Communications Link

ERMIS-3, an 8U CubeSat built by the National and Kapodistrian University of Athens, has successfully established a 1-gigabit-per-second optical laser link with a ground station in northern Greece. The milestone marks the country's first optical connection with a satellite in low Earth orbit.[1][5][6]

The system relies on the ATLAS-1 laser terminal, manufactured by Lithuanian startup Astrolight. It beams an invisible infrared laser to the Holomondas Optical Ground Station, a facility developed and operated by the Aristotle University of Thessaloniki.[4][5][6]

The achievement validates a compact commercial laser terminal that bypasses congested radio frequencies to deliver secure, high-speed data. It represents a major step forward for Europe's commercial space communications sector and university-led space infrastructure.[1][4]

"The successful optical targeting between a CubeSat and a national observatory demonstrates how Greek universities and technology companies can jointly use new infrastructure," said Greek Minister of Digital Governance Dimitris Papastergiou. He added that the project opens pathways for the satellite communications of tomorrow.[5]

Beaming data from orbit

Establishing a laser link from space requires extreme precision, as the satellite travels at several kilometers per second. The ATLAS-1 terminal must acquire the ground station's signal and continuously track it during a brief communication window.[1][6]

Unlike geostationary satellites that appear fixed in the sky, a low Earth orbit spacecraft crosses from horizon to horizon in just minutes. Both the satellite and the ground telescope must continuously adjust their orientation to keep the laser perfectly centered.[1]

According to Astrolight, the satellite and ground equipment were operating automatically by their third active pass. The engineering team controlled the systems remotely from Lithuania to complete the initial calibration and synchronize the tracking hardware.[6]

The system currently transmits data at a verified rate of 1 gigabit per second. However, researchers calculate that the link budget could eventually support speeds up to 10 gigabits per second, though that higher rate has not yet been demonstrated in orbit.[5][6]

Following calibration, link availability exceeded 85 percent of the available time during passes where the satellite was more than 15 degrees above the horizon. The equipment even received signals at elevation angles below 10 degrees, proving robust against atmospheric interference.[5][6]

The satellite now conducts two scheduled optical links per day, transitioning from an experimental demonstration to routine operations. Initial results show that the system transmits data reliably during both daytime and nighttime passes, even when clouds intermittently obstruct the optical path.[4][5]

Bypassing radio congestion

Traditional satellite communications rely on radio frequencies, which face severe bandwidth limitations and strict international licensing requirements. As the number of satellites in low Earth orbit multiplies, radio spectrum scarcity has become a critical bottleneck for the industry.[1]

Optical links solve this capacity problem by shifting data transport to narrow beams of light. This approach offers vastly higher throughput, which is essential for downloading massive datasets like the hyperspectral imagery generated by modern Earth observation missions.[1][5]

The technology also provides inherent security advantages over standard radio transmissions. Because the laser beam is highly directional, intercepting or jamming the signal requires an adversary to physically intersect the line of sight between the satellite and the telescope.[5]

This anti-jamming capability is increasingly vital for European defense and security sectors. Terrestrial radio and GPS signals in regions like the Baltics have faced escalating interference, making secure optical downlinks a strategic priority for national infrastructure.[5]

A European collaborative effort

ERMIS-3 launched on March 30, 2026, aboard a SpaceX Falcon 9 rocket as part of the Transporter-16 rideshare mission. It flew alongside two smaller Greek satellites, ERMIS-1 and ERMIS-2, which are currently testing 5G connectivity for the Internet of Things.[1][6]

The mission is a core component of the Greek Connectivity Programme, managed by the European Space Agency. Funding comes from the European Union's Recovery and Resilience Facility, aiming to build European technological sovereignty and establish Greece as a data relay center.[6]

Frederic Rouesnel, head of ESA's Resilience Initiatives Implementation Management Office, noted the achievement's collaborative nature. He stated that the project demonstrated Europe's ability to deliver world-class innovation through close cooperation between industry, academia, and public institutions.[5]

The Holomondas Optical Ground Station represents the transition of a historic astronomical observatory into a high-capacity communications hub. Astrolight equipped the site with a proprietary optical core and an 808-nanometer laser beacon to ensure precise beam alignment.[4][5]

By vertically integrating both the orbital terminal and the ground receiver, the engineering team streamlined the complex tracking process. This end-to-end configuration significantly reduces the physical size, complexity, and cost of the required ground hardware.[4]

Scaling the infrastructure

The ground equipment is also slated to support a separate Greek CubeSat project known as PeakSat. That upcoming mission will further test laser communications between small satellites and optical stations across the country, expanding the national network.[6]

While the ERMIS-3 link is currently operating reliably, atmospheric conditions remain a persistent challenge for optical communications. Heavy cloud cover can block infrared lasers entirely, and atmospheric turbulence can severely degrade signal quality during a pass.[1][5]

To build a truly global broadband network based on laser links, operators will need a distributed network of ground stations in diverse weather zones. If one station is clouded over, the satellite can simply beam its data to an alternative receiver in a clear location.[1]

The successful deployment of the ATLAS-1 terminal proves that miniaturized, low-power hardware can handle these complex optical handshakes. It validates the concept that small, cost-effective CubeSats can participate in high-bandwidth optical networks previously reserved for massive telecommunications satellites.[1][4]

Engineers will continue to monitor the system's performance as ERMIS-3 completes its orbital lifespan. The data gathered from these daily connections will inform the design of future optical terminals, pushing the theoretical 10-gigabit limit closer to reality.[5][6]