unisat

CubeSat 6U — Operations Guide

Profile key: cubesat_6u · Mass cap: 12.0 kg · Volume: 7704 cm³ Template: mission_templates/cubesat_6u.json · BOM: hardware/bom/by_form_factor/cubesat_6u.csv

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1. Mission class

Imaging / Earth-observation workhorse. 6U unlocks deployable solar arrays (20+ W), larger optics (up to 80 mm aperture), and full 3-axis pointing with star-tracker + reaction wheels. Typical customers: commercial EO constellations, science missions with modest deployable antennas.

2. Physical envelope

Parameter	Value
Mass cap	12.0 kg
Dimensions	100 × 226.3 × 340.5 mm
Volume	7704 cm³
Power generation	~25 W with deployable arrays
Nominal consumption	18 W
Battery	8S4P Li-ion, ~120 Wh

3. Regulatory context

• CDS rev 14 §3.2 — 6U tuna-can standard (226.3 mm).
• ITU: UHF, S-band, potentially X-band for high-rate downlink.
• Launch: P-POD 6U, ISIPOD 6U, EXOpod. Additional ICD: deployable antenna + panel retention.
• End-of-life: active de-orbit strategy recommended (drag brake, propulsion, or < 600 km orbit for 25-year natural decay).

4. Subsystem matrix

Subsystem	Status
Reaction wheels ADCS	✅ (3 mid-size)
Magnetorquer detumble	✅
Star tracker	✅
Sun sensor + magnetometer	✅
UHF telemetry	✅
S-band downlink (5 W)	✅
X-band downlink (optional)	⚠ (fits, needs extra power budget)
GNSS	✅
Camera (48 MP + telescope)	✅
Deployable solar panels	✅
Cold-gas propulsion	⚠ (fits in 1U volume)
Electric propulsion	❌ (needs 12U power)

5. Build

make target-cubesat-6u

Compile-time macro: MISSION_PROFILE_CUBESAT_6U=1.

6. Mission config

cp mission_templates/cubesat_6u.json mission_config.json

Key fields:

• subsystems.eps.deployable_panels — true for the full 25 W generation.
• subsystems.adcs.star_tracker — true (unlocks arcsec pointing).
• subsystems.camera.optics — telescope (refractor / Cassegrain).
• orbit.type — SSO for imaging, LEO for tech demo.

7. Mass & volume validation

Metric	Value	Status
Total mass	8.20 kg	≤ 12.0 kg ✅ (32 % margin)
Volume used	2875 cm³	37 % of 7704 cm³ ✅

Ample room for a large payload. If adding X-band, budget an extra 0.5 kg and 5 W peak draw.

8. Typical mission phases

Same cubesat_sso phases. Imaging cadence is the big change from 3U: science phase becomes 30–60 minutes at a time for whole-strip collection, not 10-minute bursts.

9. Testing checklist (ground qualification)

Legend: [x] = verified in software / CI / SITL (passes in the current release); [ ] = requires bench hardware, RF range test, or flight-day field activity — team must sign off manually.

Everything from 3U plus:

• Deployable panel release tested at -40 °C and +60 °C.
• Momentum-wheel desaturation path exercised through magnetorquer commanding (closed loop in air-bearing table).
• Star-tracker sky-field test in dark chamber.
• TVac cycles extended to 6 (launch-provider requirement for deployable bodies).
• Plume-impingement analysis for any cold-gas thruster.

10. Flight-day checklist

Same as 3U plus:

• Solar-panel deployment safety tag removed.
• Retention cable checked; pyro-cutter armed.
• Launch-provider ICD signed off on 226 mm tuna-can envelope.

11. Known limitations

• Deployment risk: any stuck panel halves the power budget. Mission must survive in low_power phase indefinitely.
• Thermal peak under full imaging burst (camera + S-band + wheel desat) can exceed +70 °C. Passive thermal design must include a dedicated radiator.
• No autonomous orbit-insertion — rely on the launch-provider drop-off; no delta-V capability beyond reaction wheel + magnetorquer desaturation.

12. Post-flight debrief

Same as 3U, plus:

• Deployment success (record panel articulation telemetry from first 30 min).
• Star-tracker lost-in-space acquisition time.
• Image-pipeline production: frames collected / frames downlinked / frames usable.

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