INTERACTIVE ENGINEERING CURRICULUM

Learn PocketQube & CubeSat Engineering

A 12-module self-paced engineering course covering both PocketQube (1P–3P) and CubeSat (1U–12U) platforms: from scaling laws and CDS/backplate standards to orbital mechanics, EPS/battery ageing, 3-axis ADCS, UHF/S/X-band link budgets, and AIT qualification.

Curriculum completion:0 / 12 (0%)

Interactive 1P PocketQube & 1U CubeSat Exploded Anatomy

Switch between 1P PocketQube and 1U CubeSat stacks and click any subsystem layer (L1–L5) to inspect its mass, power budget, and SatWiki specification.

1P PocketQube (50 × 50 × 50 mm · ~250 g · 42×42 mm Stack)
L1 — +Z SOLAR & ANTENNA CAPL2 — UHF / LORA TRANSCEIVER PCBL3 — OBC, FRAM & ADCS SENSORSL4 — EPS, MPPT & LI-ION PACKL5 — AL 7075-T6 BACKPLATE & KILL-SWITCH

L1 — +Z SOLAR & ANTENNA CAP

+Z Solar Panel & Tape-Spring Dipole Spool

Triple-junction GaInP/GaAs/Ge solar cells (30% eff.) + UHMWPE dyneema burn-wire spool holding two 172 mm 437 MHz tape-spring monopoles.

Mass: 26 g · Power: +380 mW (peak)SatWiki →

12-Module Core Curriculum & Verification Quizzes

MODULE 01·8 min

The Physics of Miniature Scaling (L, L², L³)

Why shrinking a satellite from 10 cm (1U) to 5 cm (1P) changes surface-to-mass ratio, thermal time constant, and rotational inertia by orders of magnitude.

  • Linear dimension scales as L (1:2), surface area as L² (1:4), and enclosed volume as L³ (1:8).
  • By Cauchy's theorem, the mean projected area of any convex tumbling body is A_proj = A_total / 4 (37.5 cm² for a 1P cube).
  • Principal moment of inertia scales as m·L² (~1.0×10⁻⁴ kg·m² for 1P vs. ~2.2×10⁻³ kg·m² for 1U), making 1P 20× more responsive to magnetic torques.

Engineering Check

According to Cauchy's theorem, what is the average projected area of a 50 × 50 × 50 mm 1P PocketQube tumbling randomly in orbit?

SatWiki Entry →Interactive Lab Tool →
MODULE 02·10 min

LEO Orbital Mechanics, Drag & The 5-Year Rule

Sun-synchronous orbits, eclipse fractions, atmospheric scale height, and why the FCC 5-year rule caps passive 1P missions at ~525 km.

  • At 525 km SSO (i ≈ 97.5°), orbital period is ~95.1 minutes with ~35.7 minutes of maximum Earth shadow eclipse.
  • Atmospheric drag deceleration is proportional to the ballistic parameter B = C_D·A / m.
  • Under moderate solar activity (F10.7 = 140 sfu), a 250 g 1P PocketQube passively deorbits within 5 years from altitudes up to ~530 km.

Engineering Check

What happens to orbital lifetime if spacecraft mass is halved while external geometry remains unchanged?

SatWiki Entry →Interactive Lab Tool →
MODULE 03·9 min

Solar Power Generation & Li-Ion Battery Ageing

Body-mounted GaAs solar cells, MPPT conversion losses, eclipse Depth-of-Discharge (DoD), and why derating charge voltage to 4.10 V doubles mission life.

  • A body-mounted 1P cube generates ~0.75–0.85 W in sunlight, yielding ~0.50–0.55 W orbit-average power after eclipse and MPPT efficiency.
  • Keeping eclipse Depth-of-Discharge (DoD) below 15–20% and charge cut-off at 4.10 V enables >15,000 LEO cycles (>3 years).
  • Li-ion cells must never be charged below 0 °C to prevent metallic lithium plating on the anode.

Engineering Check

Why do small-satellite EPS designs inhibit Li-ion battery charging when cell temperature drops below 0 °C?

SatWiki Entry →Interactive Lab Tool →
MODULE 04·8 min

Orbital Thermal Balance & Solder Fatigue

Solar absorptivity (α), IR emissivity (ε), why 1P thermal time constants are only ~7–10 minutes, and Engelmaier solder-joint fatigue.

  • Because thermal mass scales as L³ while radiating area scales as L², a 1P PocketQube has a thermal time constant τ ≈ 8 min (vs. ~25 min for 1U).
  • A 1P spacecraft closely approaches cold radiative equilibrium during every 35-minute eclipse, experiencing 5,500 thermal cycles per year.
  • Large ΔT swings across ceramic QFN/BGA packages on FR-4 boards drive low-cycle Engelmaier solder fatigue.

Engineering Check

Why does a 1P PocketQube experience a wider per-orbit temperature swing than a 3U CubeSat with identical surface coatings?

SatWiki Entry →Interactive Lab Tool →
MODULE 05·10 min

Disturbance Torques, PMAC & B-Dot Detumbling

Why residual magnetic dipoles dominate 1P disturbance torques, sizing hysteresis rods for PMAC, and active B-dot magnetorquer laws.

  • At 500–550 km, a 1.5×10⁻³ A·m² stray current loop produces ~6.5×10⁻⁸ N·m—exceeding gravity-gradient and solar torques on a 1P.
  • Passive Magnetic Attitude Control (PMAC) aligns one axis to the geomagnetic field using a permanent magnet and damps libration with permeable hysteresis rods.
  • Active B-dot control commands coil dipole m = −k · (dB/dt) to dissipate rotational kinetic energy within 1–2 orbits.

Engineering Check

Why is gravity-gradient boom-less stabilisation ineffective for a symmetric 1P PocketQube cube?

SatWiki Entry →Interactive Lab Tool →
MODULE 06·11 min

UHF / LoRa Link Budgets, Antennas & Doppler

Closing a 437 MHz downlink with +22 dBm RF power, tape-spring dipole deployment, Eb/N0 vs. LoRa chirp spread spectrum, and ±10 kHz Doppler tracking.

  • At 437 MHz (λ ≈ 68.6 cm), a half-wave dipole is ~34.3 cm tip-to-tip—nearly 7× the width of a 1P cube.
  • Free-space path loss at 525 km increases from ~140 dB at zenith (90° el.) to ~151 dB at 10° elevation.
  • LoRa SF10–SF12 demodulates signals 12–18 dB below the thermal noise floor, enabling reception on low-gain ground antennas.

Engineering Check

By approximately how many decibels does free-space path loss (FSPL) increase when slant range doubles?

SatWiki Entry →Interactive Lab Tool →
MODULE 07·9 min

On-Board Computing, Radiation SEU & Watchdogs

Single-Event Upsets (SEU) and Latch-ups (SEL) in the South Atlantic Anomaly, FRAM memory, and multi-tiered hardware watchdog recovery.

  • Commercial MCUs in LEO survive Total Ionising Dose (TID ~1–3 krad/yr behind 1.5 mm Al) but suffer Single-Event Upsets (SEUs) in the SAA.
  • Ferroelectric RAM (FRAM) resists radiation bit-flips and offers 10¹⁴ write cycles without Flash page-erase latency.
  • An external windowed hardware watchdog + EPS power-cycle timer ensures recovery even if the MCU clock or bus hangs.

Engineering Check

Why must a satellite's primary watchdog timer be an external hardware IC rather than an internal MCU peripheral timer?

SatWiki Entry →Interactive Lab Tool →
MODULE 08·9 min

Spacecraft Materials, Outgassing & Atomic Oxygen

Al 6061-T6 vs. 7075-T7351 stress-corrosion cracking, ECSS outgassing limits (TML < 1%, CVCM < 0.1%), and LEO atomic oxygen polymer erosion.

  • All polymers and adhesives must satisfy ECSS-Q-ST-70-02C / ASTM E595 screening: Total Mass Loss (TML) < 1.0% and CVCM < 0.10%.
  • Al 7075-T6 has low resistance to stress-corrosion cracking (SCC); over-aged 7075-T7351 or 6061-T6 belongs to ECSS Class 1.
  • Ram atomic oxygen (AO) impacts at 7.6 km/s (~4.5 eV) erode unprotected Kapton (~3.0×10⁻²⁴ cm³/atom), whereas SiOx coatings cut erosion by >98%.

Engineering Check

What are the standard ASTM E595 / ECSS-Q-ST-70-02C screening limits for spacecraft material outgassing?

SatWiki Entry →Interactive Lab Tool →
MODULE 09·8 min

AIT, Vibration Qualification & TVAC Testing

Test-as-you-fly philosophy, sine sweep modal searches (>200 Hz), 14.1 G_rms GEVS random vibration, and thermal-vacuum bakeout/cycling.

  • Low-level sine sweeps (0.25–0.5 g) before and after random vibration verify that the fundamental mode f₁ has not shifted by >5%.
  • A 1.6 mm Al 7075-T6 1P backplate exhibits f₁ > 400 Hz, providing large margin above launch vehicle 100–120 Hz floors.
  • TVAC testing verifies cold-start inhibit release, burn-wire antenna deployment in vacuum, and PA thermal conduction.

Engineering Check

Why is a low-level sine sweep performed both immediately before and immediately after a random vibration test?

SatWiki Entry →Interactive Lab Tool →
MODULE 10·9 min

IARU/ITU Spectrum Coordination, Deployers & Operations

AlbaPod deployer integration, 15–30 minute deployment timers, IARU/ITU API filings, NORAD TLE lottery identification, and SatNOGS ground networks.

  • Amateur-satellite band missions (435–438 MHz) require IARU frequency coordination and ITU API filing submitted 9–18 months before launch.
  • Deployer inhibit switches keep the satellite completely unpowered during launch; upon ejection, a 15–30 min timer delays antenna burn-wire firing and RF transmission.
  • Open SatNOGS ground stations combined with a dedicated primary command station resolve early rideshare TLE object identification.

Engineering Check

Why do launch providers require a 15–30 minute inhibit timer after deployer ejection before a PocketQube deploys its antennas or transmits RF?

SatWiki Entry →Interactive Lab Tool →
MODULE 11·12 min

CubeSat Design Specification (CDS Rev. 14.1) & PC/104 Bus Architecture

How 1U–16U CubeSats scale from 100×100×113.5 mm rails to 226.3×100×366 mm 6U dispensers, MIL-A-8625 Type III hard anodizing, separation switches, and the 90×96 mm PC/104 avionics stack.

  • Under CDS Rev. 14.1, a 1U CubeSat measures 100.0 × 100.0 × 113.5 mm (±0.1 mm) with up to 2.00 kg mass, riding on four 8.5 × 8.5 mm corner rails rather than a PocketQube sliding baseplate.
  • Corner rails must be Al 6061-T6 or 7075-T6 with MIL-A-8625 Type III hard anodizing (surface roughness Ra ≤ 1.6 µm) to prevent cold-welding inside P-POD, ISIPOD, or Exolaunch QuadPack deployers.
  • Legacy 1U–3U avionics stack 90.17 × 95.89 mm PC/104 boards through a 104-pin pass-through header (I²C, SPI, CAN, UART, 3.3V/5V/VBAT), while 6U/12U buses increasingly adopt modular CAN/RS-422/SpaceWire backplanes.

Engineering Check

Why does the CubeSat Design Specification (CDS) mandate MIL-A-8625 Type III hard anodizing on all four 8.5 × 8.5 mm aluminium corner rails?

SatWiki Entry →Interactive Lab Tool →
MODULE 12·13 min

3U/6U CubeSat 3-Axis Reaction Wheels, Star Trackers & S/X-Band Downlinks

Scaling from 1P magnetic detumbling to arcsecond star trackers, reaction wheel momentum desaturation, deployable 20–60 W solar wings, and 50–150 Mbps X-band Earth observation downlinks.

  • A 3-axis reaction wheel pyramid or orthogonal triad stores angular momentum H = I_w · ω_w (typically 2–30 mN·m·s), enabling <0.05° nadir or target-tracking slew profiles when paired with a miniature CMOS star tracker.
  • Secular external torques (solar radiation pressure and aerodynamic drag) eventually saturate reaction wheels; 3-axis magnetorquers must apply τ_desat = m × B continuously to dump accumulated momentum.
  • Moving from 437 MHz UHF (9.6 kbps) to 2.2 GHz S-band (1–4 Mbps) and 8.025–8.400 GHz X-band (50–150 Mbps, DVB-S2 8PSK/16APSK) allows 3U/6U CubeSats to downlink gigabytes of multispectral or SAR imagery per ground pass.

Engineering Check

Why must a 3U/6U CubeSat equipped with 3-axis reaction wheels also carry magnetorquer rods (or thrusters)?

SatWiki Entry →Interactive Lab Tool →

Printable Engineering Reference Cards

CARD 01 — GEOMETRY & SCALING

1P PocketQube vs. 1U CubeSat Scaling

Linear ratio L_1P / L_1U
1 : 2 (50 mm vs. 100 mm)
Surface area ratio A_1P / A_1U
1 : 4 (150 cm² vs. 600 cm²)
Volume ratio V_1P / V_1U
1 : 8 (125 cm³ vs. 1000 cm³)
Max mass limit
250 g (1P) vs. 1330–2000 g (1U)
Principal inertia ratio I_1P / I_1U
≈ 1 : 21 (~1.0×10⁻⁴ vs. 2.2×10⁻³ kg·m²)
Orbit-average tumbling power
0.52 W (1P) vs. 2.15 W (1U)

CARD 02 — KEY EQUATIONS

First-Order Sizing Equations

Mean projected area (convex tumbler)
A_proj = A_total / 4
Ballistic parameter B
B = C_D · A_proj / m [m²/kg]
Free-space path loss (FSPL)
L_fs = (4π d f / c)²
Friis carrier-to-noise density
C/N₀ = EIRP − L_path + G/T − k_B
Single-node thermal time constant
τ = m · c_p / (4 · ε · σ · A_total · T₀³)
Tsiolkovsky rocket equation
Δv = I_sp · g₀ · ln(m₀ / m_f)

CARD 03 — COMPLIANCE THRESHOLDS

Qualification & Compliance Limits

Outgassing (ECSS-Q-ST-70-02C / ASTM E595)
TML < 1.00%, CVCM < 0.10%
FCC / IADC post-mission disposal
≤ 5 years in LEO (≤ ~525 km for 1P)
Li-ion charge inhibit threshold
T_cell ≥ 0 °C (heater required below 0 °C)
Minimum structural fundamental mode f₁
f₁ ≥ 100–120 Hz (launch vehicle requirement)
UHF link margin design rule
≥ 3.0 dB at 10°–20° minimum elevation
Stress-corrosion cracking (ECSS-Q-ST-70-36C)
Class 1 alloys: Al 6061-T6, Al 7075-T7351

CubeSat & PocketQube Flight Heritage Timeline (1999–2026)

1999

CubeSat Standard (1U = 10 cm)

CalPoly & Stanford (Puig-Suari & Twiggs)

Standardised the 100 × 100 × 113.5 mm containerised P-POD interface, enabling university rideshare launches.

2003-06

First 6 Pioneer CubeSats in Orbit

Eurockot Launch — XI-IV, CUTE-1, CanX-1, AAUSAT, DTUsat-1, QuakeSat

First orbital CubeSat cluster deployed from Plesetsk; University of Tokyo’s XI-IV and Tokyo Tech’s CUTE-1 operated for well over a decade.

2009

PocketQube Concept (1P = 5 cm)

Prof. Bob Twiggs & Morehead State

Proposed a 50 mm cube (1/8 the volume of 1U) sized to fit inside a personal coat pocket and reduce launch fees.

2013-11

First 4 PocketQubes & FUNcube-1 / Dove-3

Dnepr Launch — $50Sat, WREN, BeakerSat-1, QubeScout-S1, FUNcube-1

Deployed the first 4 PocketQubes alongside landmark 1U/3U CubeSats; $50Sat operated 22 months while FUNcube-1 (AO-73) passed a decade in orbit.

2017–2018

QB50 Thermosphere Constellation, MarCO Deep-Space & PQ Standard Issue 1

36 University CubeSats (incl. BeEagleSat & HAVELSAT), MarCO-A/B at Mars

QB50 united 28+ universities for multi-point thermosphere sensing, JPL’s 6U MarCO-A/B relayed InSight Mars EDL telemetry from 1 AU, and PocketQube Standard Issue 1 was ratified.

2019–2021

SMOG-P, ATL-1, SMOG-1, OPS-SAT & RainCube

1P Spectrum Monitors & 3U/6U Radar / Reconfigurable CubeSats

BME Budapest mapped global DVB-T spectrum pollution with 1P PocketQubes while ESA’s 3U OPS-SAT and JPL’s 6U RainCube proved flying software laboratories and Ka-band weather radar.

2022

Transporter-3 PocketQube Cluster, LICIACube & CAPSTONE

Grizu-263A, Delfi-PQ, DART LICIACube (6U) & Lunar NRHO CAPSTONE (12U)

Transporter-3 proved multi-year 1P/3P PocketQube operations (Grizu-263A, Delfi-PQ), while ASI’s 6U LICIACube imaged the DART asteroid impact at 11 million km.

2023–2026

Commercial IoT Constellations, Hera 6U Probes & 5-Year Deorbit Rule

Hello Space, FOSSA, Plan-S Connecta, ESA Milani/Juventas & FCC Mandate

Operational convergence of 1P–3P PocketQubes and 3U–6U CubeSats across LoRa/IoT constellations, interplanetary CubeSat probes, and strict ≤5-year LEO disposal.