Structures and Mechanisms
The Structures and Mechanisms subsystem provides the mechanical framework supporting all spacecraft components and handles any moving parts (deployments).
Core Functions
- Support and protect subsystems against launch loads.
- Provide stable foundation for precise alignments.
- Enable deployable elements (solar arrays, antennas, booms).
Key Design Drivers
| Driver | Driven By | Impact |
|---|---|---|
| Launch Vehicle Loads | G-forces, vibration | Structural strength/stiffness |
| Stability | Precise pointing reqs | Material selection (low CTE) |
| Deployable Mechanisms | Solar arrays, antennas | Latching, release actuation |
| Shock/Acoustic | Stage separation, pyro firings | Design for peak stress |
Structural Loads
- Axial & Lateral Gās near stage burnout.
- Acoustic & Vibration from launch environment.
- Shock from stage separations or deployable releases.
Load Isolation
- Some missions use isolation systems (springs/dampers) to filter high-frequency loads from the LV.
Materials & Design
- Honeycomb panels with composite face-sheets for stiff, lightweight primary structures.
- Carbon-fiber or graphite-epoxy for low thermal expansion and high strength.
- Aluminum alloys remain common for secondary structures.
Mechanisms
- Deployments: Hinged solar arrays, antenna booms.
- Released by EEDs (explosive bolts) or non-explosive actuators.
- Often includes springs to ensure positive deployment.
- Motors & Gears: Occasionally used for re-pointing arrays/antennas in flight.
Gravity Offload Testing
- Ground testing a zero-g deployment can be challenging. Use jigs, offload rigs, or partial gravity simulations.
Cross-Links
- See Spacecraft Thermal Control System regarding structural conduction paths for heat.
- See Spacecraft Propulsion System for thruster mounting and load alignment.