A 1U CubeSat with two deployable solar wings and four deployable antenna elements, designed to schematic level with selected, orderable parts. No part has been bought, made or weighed. SQSO-MECH-CAD-001 status
Illustration drawn from the CAD dimensions: the wings in the plane 38.75 mm toward +Y, hinged at x = ±54.1 mm; the 2 m elements are shortened to fit. SQSO-MECH-CAD-001 §4.2
A bought 1U frame, 100 × 100 × 113.5 mm. Two solar wings on torsion-spring hinges, each held down by a line cut by two redundant burn resistors on their own current-limited drivers. Mass 1.52 kg current best estimate, 1.75 kg with growth, against a 2.00 kg limit.
16 triple-junction cells, two on each long body face and two on each side of the two wings. A 4S1P Li-ion 18650 pack of ≈ 50 Wh, charged only to 4.10 V per cell. End-of-life generation 3.84 W sun-pointed, 2.48 W tumbling.
An STM32L4R5ZI microcontroller running all the flight software, written in Rust on the Embassy executor with no RTOS. It enforces every hard limit itself, whatever the AI proposes.
An NVIDIA Jetson Orin Nano 8 GB module on a custom carrier in its 7 W mode, with no fan. Each power-on lasts at most 10 minutes including boot, then at least 100 minutes off, in sunlight only. The flight computer cuts its rail on its own current and temperature measurements.
A single-channel FM transponder (70 cm up, 2 m down) and the 1200 bps AX.25 beacon, 0.5 W nominal and 1 W maximum. Telecommand is authenticated (HMAC-SHA-256) and sent in the clear; TX-OFF removes the power amplifier's supply through a hardware switch.
An ISIS AntS unit on the −Z face with four tape monopoles: two for 2 m (≈ 0.5 m) along ±X and two for 70 cm (≈ 0.17 m) along ±Y. They deploy after the wings.
Magnetorquer rods, a magnetometer, the panel photodiodes as sun sensors and a MEMS gyro. B-dot detumble, then a spin of 8°/s that keeps the wings' side toward the Sun. No reaction wheels and no propulsion.
A duty-cycled GNSS receiver (SkyFox piNAV-NG/FM) gives the operator ephemeris the launch provider requires within 24 hours of first contact.
No fan or active cooling: a ≈ 207 Ω battery heater that switches on below +5 °C and off above +9 °C, and a heat spreader from the Jetson to the frame.
Hidden-line projections of the parametric CAD model (SQSO-MECH-CAD-001 version D),
generated by hardware/mechanical/model.py. They are layout drawings for review, not manufacturing
drawings. SQSO-MECH-CAD-001 §7
STEP models of both configurations are in hardware/mechanical.
Each board is captured as code (SKiDL) with selected parts, a netlist, a bill of materials with derating and an electrical rules check; the mechanical design is a CAD model with interference checks and a finite-element model. SQSO-REV-CDR-002 §5
| Item | Document | What exists | Key results |
|---|---|---|---|
| EPS and safety board | SQSO-EPS-BRD-001 G | 742 placements, ERC 0; trackers, battery management (BQ76952 with the BQ771806 backup protector and F3 on the battery sense board), current-limited rails, four independent burn lines, DS1–DS3 inhibits, one-shot end-of-life disconnect, recharge lockout, EPS controller | Burn 0.67 A nominal one resistor at a time; storage drain 7.8 µA typical, 13.8 µA worst; diverse pack fuses F0A/F0B/F0N (C-16); every timing worst case with the X7R cold change |
| OBC board | SQSO-OBC-BRD-001 E | 385 placements, ERC 0; STM32L4R5, window-watchdog supervisor (440 nF C0G), RTC, two FRAMs, gyros, sun-sensor ADC, magnetorquer drivers; magnetometer board A2; access-port board A3 | Every pin one function (SQSO-ICX-001 D); IWDG refreshed with the supervisor kick, IWDG first by 1.5 s; magnetometer at the +Z end |
| RF board | SQSO-RF-BRD-001 F | 330 parts (300 fitted), ERC 0; CC1200 receiver, TNC MCU, LMX2571 exciter with readback, PA, filters, nickel-silver shield, MMCX ports | Desense ≤ 0.44 dB; receive noise 552–603 K (L106 18 nH); carrier-detect and receiver-health lines; PA cold characterisation VI-RFB-14; CC1200 TX-OFF leakage VI-RFB-16 |
| Jetson carrier | SQSO-JET-BRD-001 E | 137 placements, ERC 0; 5 V buck and eFuse, sequencing, translated UART, NVMe | Module capped at 6.5 W (+6.5–10 % to 8 W); gyro window; 2.0 mm, 6 layers; module cold limits governed by the −15 °C power-on gate and V-THM-8 |
| Interconnect | SQSO-ICX-001 D | Master pin allocation and harness list | Every firmware pin change implemented (OBCB-02) |
| Harness | SQSO-HAR-001 2.0 | 210 conductors, 61 zones in the CAD frame, calculations script, wire list | Derating ≤ 60 % normal; gold terminals; four D-200-82 splices, 28 AWG leads on solder tabs; 85.6 g |
| Mechanical | SQSO-MECH-CAD-001 B | CAD (STEP), harness zones, splice and tab envelopes, interference checks (529 / 523 pairs); hinge model with the line spring; shell FE (eight cases) | First mode 170 / 162 Hz; lowest strength margin +0.97 (+0.86 MEV); board fatigue +0.42 to +0.72 (+0.14 MEV); inertia ratio 1.056 / 1.047 with the C-13 ballast; mass 1.755 kg MEV (+14.0 %) |
| Parts | SQSO-MFG-003 C, SQSO-MFG-002 G | Temperature-grade audit of all 443 flight BOM lines; every line orderable | Five parts below −40/+70 °C, each covered by design, qualification or a dated vendor action (P3T-02 to P3T-04, P3T-09) |
| Flight software | SRS 1.12; software/rust | Passivation, stored housekeeping, acknowledgements, receiver supervision, memory-upset handling (round 2); pin map and drivers, AntS temperature gate and transmitter hold, PTT watch, closure-panel fixes (round 3) | 622 Rust tests, 56 C suites; safety-critical gate 32 files at 100 % / 100 %; stack 5,812 / 8,192 B; full mission simulation 0 anomalies in 50 checks (SQSO-SIL-001 G §7) |
| Board firmware | SQSO-SRS-TNC-001 B, SQSO-SRS-EPSC-001 B | Requirements for the RF board TNC firmware (67) and the EPS controller firmware (62), hazards SW-HAZ-014 to -017, schedule tasks | Toolchains for PI ratification (DA-22): Rust no_std (TNC), C11 MISRA (EPS controller) |
What the design does not yet have: PCB layouts (SE-24, scheduled after the independent PDR), an engineering model, and the vendor-drawing confirmations listed as verification items (connector mated heights, gold part numbers, fuse ratings, outgassing data).
Margins on mass, power, structure, links and more: engineering.