November 2026 Mission Telemetry Review: NKUA/ESA’s 8U ERMIS-3 Closes a 100 Mbps LEO-to-Ground Laser Link as ESA’s Hera Arrives at Didymos with 6U CubeSats Milani & Juventas
November 2026 nadir lab. engineering analysis examining two European nanosatellite milestones reported by ESA in early November 2026: closed-loop 100 Mbps optical LEO-to-ground laser communications on Greece’s 8U ERMIS-3 CubeSat and Hera’s rendezvous with binary asteroid Didymos–Dimorphos carrying the 6U XL CubeSats Milani and Juventas.
Two ESA mission bulletins published in the first week of November 2026 highlight how multi-unit CubeSats now operate across regimes once reserved for 200+ kg spacecraft: sub-milliradian free-space optical (FSO) downlinks from Low Earth Orbit and multi-payload geophysical characterization at near-Earth asteroids.
On 3 November 2026, ESA Connectivity and Secure Communications reported that ERMIS-3—an 8U CubeSat developed under the National and Kapodistrian University of Athens (NKUA) within the ESA Greek CubeSat In-Orbit Validation programme and launched on SpaceX Transporter-16 (30 March 2026)—established a bidirectional acquisition and 100 Mbps optical downlink between its onboard Astrolight ATLAS-1 laser terminal and Aristotle University of Thessaloniki’s HolOGS-1 optical ground station in northern Greece. Unlike UHF or S-band links whose 10°–60° beamwidths forgive degree-level ADCS pointing errors, near-infrared 1550 nm optical downlinks require arcminute-class body pointing supplemented by fine-steering mirrors and closed-loop upward beacon tracking through atmospheric scintillation.
Two days later, on 5 November 2026, ESA Space Safety published Hera’s first close-up Asteroid Framing Camera imagery of (65803) Didymos and its moonlet Dimorphos from approximately 60 km range, marking arrival at the DART kinetic-impact target following launch on 7 October 2024. Stowed inside Hera’s Asteroid Deck Deep Space Deployers are two ~12 kg 6U XL CubeSats added to the nadir lab. mission database in this release: Milani (Tyvak International, carrying the ASPECT visible/near-IR hyperspectral imager and VISTA dust detector) and Juventas (GomSpace, carrying the JuRa 60 MHz monostatic radar and GRASS gravimeter).
Published Papers & Primary Proceedings (Open-Access / DOI)