F4IOZOlivier · radio amateur · JN18FS

Decode the telemetry the CubeSat talks

A practice CubeSat's frames: voltage, panel currents, charge, temperatures. Find the fault, or spot the false alarm. All games

A frame is coming in

Six frames from EX-1, an imaginary CubeSat. Tap the rows that look wrong, then choose the diagnosis: a fault, or “all normal”.

Badges

All-rounderFinish a game of each game.
First frameA first right diagnosis.
At a glanceA right diagnosis in under 10 seconds.
Don't panicRecognise 5 false alarms.
Battery doctorFind the three battery faults: gauge, cold charging, overheating.
FlawlessSix right diagnoses out of six.
Thermal engineer4,500 points or more at the Thermal level.
Telemetry expertSix out of six at the Diagnosis level.
Always listeningPlay ten games.

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Reading a frame

A CubeSat sends its telemetry in its beacon: voltages, currents, temperatures, the equipment's state. The ground stations decode it and the operators look in it for what is wrong — without ever seeing the satellite.

The panels: each face gives a current proportional to the cosine of the Sun's angle. The lit faces' currents are thus the components of the Sun's direction: the sum of their squares, relative to the full-Sun current, is 1. Two opposite faces are never lit together.
The balance: what the panels give, less what the equipment draws, goes into the battery (or out of it). In the shadow, everything comes from the battery.
The lithium-ion battery: its voltage follows its charge; it is never charged below 0 °C and must not go above 45 °C; a heater keeps it above zero.
False alarms: the eclipse, cold panels, survival mode, a commanded restart look frightening and are normal. A sensor saying −273 °C is lying.

The game's numbers EX-1 is imaginary: a 1U with six faces of two 28% cells (430 mA each at 4.7 V, full Sun), a 2S 2.6 Ah battery (19 Wh), 0.85 W of base load, a frame every 5 minutes on a 92-minute orbit, 35 of them in the shadow.