What GreenCube was
GreenCube, later designated Italy-OSCAR 117 (IO-117), was a 3U CubeSat from Sapienza University of Rome’s S5Lab, launched in July 2022 on Vega-C. Its primary mission was a closed-cycle hydroponic experiment; for radio amateurs the headline payload was a 70 cm digipeater in Medium Earth Orbit (MEO), around 5,800 km up.
That orbit gave an enormous footprint (roughly 13,000 km across), so a single pass could stitch continents together in a way LEO FM birds never could. The digipeater came up on 29 October 2022 and quickly became one of the busiest amateur satellite channels in living memory: DXCC, WAS, WAJA and rare entities (including DXpeditions such as TX5S Clipperton) were worked through the digi in volume that had not really been possible since AO-40 went quiet.
MEO is a harsh radiation environment. After a mission that already outlasted many companions from the same launch, the onboard radio is widely believed to have failed; by autumn 2024 the bird was no longer responding usefully to the community. There is no successor digipeater planned for a similar orbit in the near term.
What used to be at /greencube
While the digipeater was alive, OscarWatch ran a live “GreenCube Reporter” map at this URL. Packet clients (notably GreenCube Terminal by OZ9AAR) could forward hearing statistics to oscarwatch.org so operators worldwide could see which stations were active on the current pass: a rough real-time view of who was on frequency, without exposing who was working whom.
That map was a pass-planning and situational-awareness tool for a uniquely congested digipeater. Once GreenCube went QRT and the surrounding stack moved on, the old map code was removed. The path is kept so bookmarks and old links still land somewhere honest.
How GreenCube started UHM
Popularity was the problem. Between telemetry bursts you might only see one or two digipeats make it through. Without feedback, operators did the rational-but-destructive thing: call again, and again, until something happened. Fifty stations doing that on one pass meant hundreds of needless transmissions fighting for a tiny airtime budget.
UHM (You Heard Me) grew directly out of that mess. GreenCube Terminal began reporting decoded frames to OscarWatch; the server answered a simple question in near real time: did the station I just called actually decode my packet? A checkmark meant stop repeating; a stop sign meant wait rather than pile on. All real QSO traffic stayed on RF. The internet only carried the confirmation.
In other words, the crowded IO-117 digipeater is why OscarWatch’s UHM service exists. The idea was never “chat over the web”; it was fewer blind retransmissions so more genuine satellite contacts could get through. That same confirmation loop still works today on other packet digipeaters (for example the ISS), even though GreenCube itself is silent.
UHM also outgrew a shared hobby host. When the service needed rock-solid uptime during busy passes, the amateur community dug into its pockets so OscarWatch could run on its own dedicated server. That generosity kept the confirmation API reliable for GreenCube Terminal and every client that followed. Thank you to everyone who donated.
A community that fought to keep it on
In January 2024 the GreenCube team announced planned passivation: the digipeater was to be switched off for good on 5 February 2024. For many operators that felt like the end of the first true MEO amateur digipeater, and of the rare DX that only that orbit made routine.
The amateur satellite community pushed back hard. Peter Goodhall, MM9SQL, started a Change.org petition, Save the GreenCube Satellite Digipeater, asking decision-makers to keep IO-117’s digipeater available to radio amateurs after the scientific mission. Within days it had thousands of signatures, and AMSAT organisations publicly offered support to keep the bird in service.
Passivation did not go ahead as first announced. AMSAT Italia later took ownership so amateur operations could continue. The digipeater kept serving the community for months longer, which is why so many of us still type /greencube out of habit, even now that the radio side has gone QRT.
Where to go from here
- UHM (You Heard Me) guide: how the confirmation service works on packet digipeaters that are still active
- OscarWatch Tracker: pass prediction, Doppler and station tools for the birds we still have
- GreenCube Terminal (OZ9AAR): the client that first put UHM on the air with OscarWatch
- UHM in GreenCube Terminal (PDF): OZ9AAR’s operator notes on symbols, busy-pass etiquette and why UHM was written
73, and thanks to everyone who made those MEO passes memorable.