CubeSat achieves challenging laser link to ground

Despite the complexity of the operation, ERMIS-3, an 8U CubeSat developed by the National and Kapodistrian University of Athens, has established a link with an optical ground station, marking an important step in validating optical communications on small satellites. The demonstration, supported by the European Space Agency (ESA) and achieved using optical terminals developed by Lithuanian company Astrolight, happened only weeks after the satellite’s commissioning.

This milestone represents Greece’s first optical link with a low Earth orbit (LEO) satellite.

Unlike conventional radio-frequency communications, optical links use narrow laser beams to transmit data. This enables high data rates, but it also makes establishing and maintaining a connection technically demanding. The beam must be directed precisely toward a receiver while the satellite moves through orbit at several kilometers per second. Both terminals must acquire the signal and continuously track one another during a limited communication window. Not only that: atmospheric conditions add more complexity as clouds can block the link entirely and turbulence can degrade signal quality.

The satellite connected with the Greece-based Holomondas Optical Ground Station (OGS), HolOGS-1, developed by the Aristotle University of Thessaloniki. The quickly established link demonstrated one of the mission’s main objectives: precise pointing, acquisition and tracking (PAT).

ERMIS-3 carries Astrolight’s ATLAS-1 optical terminal, paired with a terminal at the ground station.

Launched on March 30, 2026, alongside ERMIS-1 and ERMIS-2, ERMIS-3 is part of an in-orbit demonstration program testing communications technologies for small satellites. Optical links could help address the growing volume of data generated by missions such as Earth observation, where high-resolution and hyperspectral imagery must be transferred to the ground.

ESA contributed technical expertise to ERMIS-3, including through environmental testing and optical alignment at ESA’s European Space Research and Technology Center (ESTEC) in the Netherlands, supporting the successful demonstration of its optical communication link.

The mission is part of Greece’s National Space Program, implemented by ESA on behalf of the Greek government.

“This achievement demonstrates that Europe can deliver world-class innovation through close cooperation between industry, academia and institutions. For the first time, an 8U CubeSat developed by the University of Athens has established a laser communication link directly to Earth using a miniaturized optical terminal developed by Astrolight under the Greek National Space Program.

“ESA is proud to have provided program management, technical supervision and engineering support throughout this journey, helping transform an ambitious concept into a pioneering in-orbit resilient demonstration,” said Frederic Rouesnel, head of the Resilience Initiatives Implementation Management Office at ESA.

“The ERMIS-3 nanosatellite is among the most advanced CubeSats developed in Europe. Using ATLAS-1 as a laser communications terminal has led to a unique collaboration and the first operations of a laser optical link on the CubeSat. This achievement is opening new capabilities and opportunities for secure communications for small satellites within the European ecosystem,” said professor Vaios Lappas and Antonis Paschalis, principal investigators of ERMIS.

“This is an important milestone for AUTh and for optical communications in Greece, as it marks the first successful optical link with a low Earth orbit (LEO) satellite from Greece—and specifically from Holomondas. It is all the more significant that this link was established with a Greek space asset, ERMIS,” said professor Kleomenis Tsiganis, head of SSA and OGS activities at the Aristotle University of Thessaloniki.

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