F4IOZOlivier · radio amateur · JN18FS

Run your CubeSat from the workshop to re-entry

A satellite 10 cm a side: build it, test it, then keep it alive in orbit — the power, the passes, the failures, down to re-entry. Each mission won fills your album of cards. All games

Your CubeSat is waiting

Start in the workshop: choose the size, put the boards in the cube, check the mass, the volume and the power. Then launch it!

Album

Every mission won gives cards: more stars, more cards. Tap a card to turn it over.

Badges

First cubePass a CubeSat's build and tests.
FeatherweightA 1U under 0.8 kg with two payloads.
Through the shadowFinish « Power » without ever going into survival.
PhotographerDownload 6 pictures in « Operations ».
Hear me10 beacon reception reports in a game.
By the bookTransmit nothing before 45 minutes after ejection.
RescueSolve every failure of « Anomalies ».
To the very endRun a whole mission down to re-entry.
Fifteen starsThree stars in all five missions.
Full albumEvery card of the album.
All-rounderFinish a game of each game.

My games

No game yet.

Your games, records and badges are kept in this browser only: nothing is sent to the site.

A satellite in one litre

The CubeSat was born in 1999 at Cal Poly (San Luis Obispo) and Stanford, with Jordi Puig-Suari and Bob Twiggs: a standard size, so that students could build a satellite in a few years and launch it beside the big ones. The unit, 1U, is a 10 cm cube (11.35 cm with its rails); the specification (rev. 14.1) allows up to 2.00 kg per unit — the older one (rev. 13) said 1.33 kg. They stack: 1.5U, 2U, 3U; 6U and 12U are put together. The PocketQube is 5 cm.

A 1U CubeSat: a cube 10 cm a side. © Zen4Telematik · CC BY-SA 4.0

What is inside

Power (EPS): solar cells on the faces (sometimes deployable panels), a lithium-ion battery, a board that regulates. A tumbling 1U draws about 1 to 2 W from the Sun on average: every watt counts.
On-board computer (OBC): the timers, the telemetry, the memory; a watchdog restarts it when it freezes.
Radio (COM): on amateur bands (145.800–146.000 MHz, 435–438 MHz), frequencies coordinated by the IARU; a telemetry beacon anyone can receive.
Attitude (ADCS): once ejected, the satellite tumbles. Magnetorquers brake it by pushing on the Earth's field (B-dot); a magnet and hysteresis rods do it with no power, slowly; reaction wheels point it.
Payload: a camera (SSTV pictures), an FM repeater, a linear transponder, an APRS digipeater, an experiment.

ArduSat exploded: frame, power, UHF radio, computer, Arduino boards. © Peter Platzer · CC BY-SA 3.0

The power budget

At 400 km an orbit lasts about 92 minutes, up to 36 of them in the Earth's shadow. What the cells give in the Sun must pay for the whole orbit: the night is spent on the battery. Tumbling, a convex body shows the Sun a quarter of its surface on average. Below the survival threshold, the computer cuts the payload and keeps only the essentials. And a lithium-ion battery is not charged below 0 °C: it must be warmed.

From the workshop to re-entry

Tests: random vibration on a shaker, thermal-vacuum bakeout.
Integration into a deployer (Cal Poly's P-POD, the ISS's): pressed switches keep everything off, plus a « remove before flight » pin.
Ejection: antennas and panels wait at least 30 minutes, transmitters 45 minutes (CubeSat specification).
LEOP (the first days): first signal, deployments, stopping the tumble, checking each subsystem. Then operations, pass after pass.
Re-entry: the air brakes the satellite; ejected off the ISS near 400 km, a CubeSat lives a few months to about a year, then burns up entirely.

Kits and programmes that exist

AMSAT's CubeSatSim (Alan Johnston, KU2Y): a 3D-printed demonstration 1U, with panels, battery and real UHF telemetry.
ArduSat: a 1U of Arduino boards funded on Kickstarter in 2012, ejected off the ISS in November 2013.
Fly Your Satellite! (ESA Academy): university teams and their 1U to 3U CubeSat, since 2013.
CubeSat Launch Initiative (NASA): since 2010, more than 150 CubeSats of schools and non-profits launched.

The sources

The game's numbers The parts' masses, volumes and power draws are orders of magnitude of a small CubeSat, not a maker's datasheet. The model: Kepler's circular orbit, the Earth's cylindrical shadow, 1,361 W/m² on 28% cells, free-space loss, an exponential atmosphere (Vallado) for re-entry.

The photos

The game's other pictures are drawn.