Rewind on Satellite platform and subsystems

Satellite Platform and Subsystems

Overview

graph TD
    A[**Subsystems**]:::main
    A --> B[**Payload**]
    A --> C[**Power Subsystem**]
    A --> D[**Propulsion Subsystem**]
    A --> E[**Structure Subsystem**]
    A --> F[**Thermal Subsystem**]
    A --> G[**AOCS**<br>**Attitude and Orbit Control System**]
    A --> H[**TM/TC Subsystem**]
    A --> I[**OBC Subsystem**]

    classDef main font-size:30px, font-weight:bold, color:#ffffff;
    classDef payload fill:#a05a87, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef power fill:#5f8b95, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef propulsion fill:#999999, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef structure fill:#4a66a1, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef thermal fill:#c49d1d, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef aocs fill:#7f4f7f, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef tmtc fill:#a69d19, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;
    classDef obc fill:#3b9cc4, stroke:#000, stroke-width:1px, font-size:24px, color:#ffffff;

    class B payload;
    class C power;
    class D propulsion;
    class E structure;
    class F thermal;
    class G aocs;
    class H tmtc;
    class I obc;

Power Subsystem

  • Components:
    • Solar Panels: Generate electrical power by converting solar energy.
    • Batteries: Store energy for use when the satellite is in Earth’s shadow.
  • Purpose: Provides and regulates power for all satellite subsystems.
  • Power Output: Typically between 10 and 20 kW, depending on satellite design and mission requirements.

graph TD
    A[Power Subsystem] --> B[Solar Panels]
    A --> C[Batteries]
    B --> D[Generate Power]
    C --> E[Store Power]

Propulsion Subsystem

  • Functions:
    • Positioning (Initial Orbit Insertion): Places the satellite in its intended geostationary orbit.
    • Station Keeping: Maintains satellite’s position against gravitational forces.
    • Deorbiting: Ensures controlled descent at the end of the mission, removing the satellite from orbit.
  • Types of Propulsion:
    • Chemical Propulsion: Provides high thrust for orbit changes.
    • Electric Propulsion: Efficient for station-keeping maneuvers, using less fuel over time.

graph TD
    F[Propulsion Subsystem] --> G[Positioning]
    F --> H[Station Keeping]
    F --> I[Deorbiting]
    G --> J[Chemical Propulsion]
    H --> K[Electric Propulsion]

Structure Subsystem

  • Purpose: Provides mechanical integrity, ensuring satellite withstands the physical stresses during launch and operation.
  • Stress Factors:
    • Acceleration: Up to 4.5 g during launch.
    • Acoustic Pressure: Up to 140 dB due to intense launch sounds.
  • Components: Reinforced frame and materials designed for durability in the harsh space environment.

graph TD
    L[Structure Subsystem] --> M[Handles Launch Stresses]
    M --> N[Acceleration: up to 4.5 g]
    M --> O[Acoustic Pressure: up to 140 dB]

Thermal Subsystem

  • Function: Manages satellite temperature, preventing overheating or freezing of sensitive components.
  • Challenges:
    • Space Temperature Variability: -120°C to +150°C.
  • Optimal Temperature Ranges:
    • Batteries: 0°C to +10°C.
    • Electronics: 10°C to +45°C.
    • Antennas: -150°C to +80°C.
  • Thermal Control Techniques:
    • Radiators and Heat Pipes: Dissipate excess heat.
    • Insulation: Protects against extreme cold.

graph TD
    P[Thermal Subsystem] --> Q[Temperature Management]
    Q --> R[Space Temperature: -120 to +150 degrees celsius]
    Q --> S[Controlled Ranges]
    S --> T[Batteries: 0  to +10 degrees celsius]
    S --> U[Electronics: 10  to +45 degrees celsius]
    S --> V[Antennas: -150 to +80 degrees celsius]

Attitude and Orbit Control System (AOCS)

  • Purpose: Maintains the satellite’s orientation and ensures it remains in its designated orbital position.
  • Components:
    • Gyroscopes: Measure orientation.
    • Reaction Wheels: Control attitude without expending fuel.
    • Thrusters: Adjust orbit as needed for station keeping.
  • Positioning Requirements: Accuracy within a few kilometers, with specific orientations for antenna alignment and solar panel exposure.

graph TD
    W[Attitude and Orbit Control System AOCS]
    W --> X[Maintains Orientation]
    W --> Y[Controls Orbital Position]
    X --> Z[Gyroscopes & Reaction Wheels]
    Y --> AA[Thrusters]

Telemetry and Telecommand (TM/TC) Subsystem

  • Telemetry (TM): Continuously monitors satellite status and transmits data to ground control.
  • Telecommand (TC): Receives commands from ground control to execute operational tasks.
  • Example Operations: Power adjustments, orbit corrections, and data collection from sensors.

graph TD
    AB[Telemetry & Telecommand Subsystem TM/TC]
    AB --> AC[Telemetry]
    AB --> AD[Telecommand]
    AC --> AE[Sends Data to Ground]
    AD --> AF[Receives Commands from Ground]

Onboard Computer (OBC) Subsystem

  • Role: Acts as the satellite’s central processing unit, managing operations and coordinating responses to commands.
  • Functions:
    • Processes data from sensors and telemetry.
    • Executes control commands to other subsystems.
    • Stores critical mission data.
  • Example: The OBC on ESA’s BepiColombo mission, which provides autonomous operations for deep space.

graph TD
    AG[Onboard Computer OBC Subsystem]
    AG --> AH[Processes Data]
    AG --> AI[Executes Commands]
    AG --> AJ[Stores Mission Data]

Source of Illustrations: Diagrams inspired by ESA and CNES for satellite subsystems and visualizations of Insat 3A, an Indian telecommunications satellite. ```

This expanded Markdown file provides a thorough breakdown of each subsystem, accompanied by Mermaid diagrams to illustrate their components and functions. Let me know if you would like to add further details or additional diagrams.