Starmad - STARMAD Software Structure - Spacecraft Subsystems Design

Spacecraft Subsystems Design

It is composed of all main subsystems required to build a satellite.

• Spacecraft preliminary sizing, in terms of mass, power, volume, area and moments of inertia of S/C body and solar array.
• Attitude control, composed of two sections:

- Torque estimates: where orbit characteristics, environmental torques and slew characteristics are calculated.
- Attitude control sizing: evaluating main parameters of Momentum wheel, Reaction wheel, Thrusters and Magnetic Torquer.

• Communications:

- Uplink: setting ground transmitter parameters, this section evaluates outputs for Ground and spacecraft transmitter, Geometry and Atmosphere perturbations, Link budget in terms of EIRP, space loss, atmospheric attenuation, rain attenuation, G/T, Antenna pointing losses, Eb/No, C/No, Margin.
- Downlink: setting the Spacecraft Transmitter parameters, this section evaluates outputs for Ground and Spacecraft transmitter, Geometry and Atmosphere perturbations, Link budget in terms of EIRP, space loss, atmospheric attenuation, rain attenuation, G/T, Antenna pointing losses, Eb/No, C/No, Margin.

• Power subsystem sizing, which is subdivided into 3 sections:

- Solar array;
- Secondary battery;
- Other primary sources
to calculate solar array mass and power budgets, battery capacity and mass, power and mass for fuel cells, solar thermal dynamics, radioisotope, nuclear reactor (if on board).

• Propulsion subsystem, composed of the following sections:

- Sizing, which principally calculates mass, power, mass flow rate, thrust for both chemical and electric propulsion system;
- Thermodynamics, evaluating specific impulses, combustion chamber and nozzle characteristics. Additionally, it performs a complete sizing for the liquid propulsion system;
- Storage and Feed, where oxidiser and fuel characteristics plus bulk density and volume are determined.

• Structural Analysis for:

- Monocoque Structure;
- Semi-Monocoque Structure
to calculate loads, axial and lateral deflections, stress, bending moment, margins of safety.

• Thermal control to perform analyses on the spacecraft body and solar array. Main parameters evaluated are: solar and albedo energy absorbed, maximum and minimum equilibrium temperature, maximum and minimum planet IR energy absorbed, possible changes in S/C to reduce maximum equilibrium temperature to specified upper limit, heater requirements during eclipse.
• System Sizing Summary resuming the main feature of the designed spacecraft.