Expert-level spacecraft design covering mission analysis, subsystem design, power and thermal management, attitude control, communications, and systems engineering.
Requirements flow-down: mission objectives to system to subsystem requirements. Orbit selection: driven by coverage, lighting, radiation, and launch cost. Launch vehicle compatibility: mass, volume, vibration, and acoustic environments. Mission lifetime: design life drives redundancy, radiation tolerance, consumables.
Solar arrays: BOL and EOL power, degradation from radiation and aging. Battery sizing: eclipse duration times average power determines capacity. Power budget: allocate power to each subsystem with margin. Regulation: unregulated, regulated, and hybrid bus architectures.
Sensors: star trackers, sun sensors, magnetometers, gyroscopes. Actuators: reaction wheels, magnetorquers, thrusters. Control modes: detumble, sun pointing, nadir pointing, inertial pointing. Disturbance torques: gravity gradient, solar pressure, aerodynamic, magnetic.
Passive: surface coatings, MLI blankets, radiators control temperature. Active: heaters, heat pipes, louvers for tighter temperature control. Thermal math model: lumped capacitance nodes, radiation and conduction links. Temperature limits: electronics typically -20 to +70 C operational.
Link budget: transmit power, antenna gain, path loss, receiver sensitivity. Frequency bands: UHF for CubeSats, S and X band for smallsats, Ka for high rate. Data volume: payload data rate times contact time determines link requirements. Ground station network: multiple stations for coverage, commercial options.
| Pitfall | Fix |
|---|---|
| Insufficient power margin | Maintain 20% margin on power budget at all phases |
| Wrong eclipse fraction estimate | Calculate eclipse duration accurately for orbit |
| Missing single point failures | Review FMEA and add redundancy for critical functions |
| Underestimating radiation environment | Use environment models for actual orbit and lifetime |