Understanding the Systems Engineering Process Comprehend how the payload requirements drive the rest of the spacecraft design. Know a spacecraft’s major subsystems.

Space-systems Engineering Define payload. Explain how payload requirements affect spacecraft design. Describe the major spacecraft subsystems

The Systems-Engineering Process

Designing Payloads and Subsystems: The Payload The payload establishes “spin-off” requirements for the spacecraft bus: Where and how precisely the spacecraft must point The amount of data the bus must process and transmit How much electrical power the payload needs The acceptable range of operating temperatures The payload’s volume and mass

Designing Payload and Subsystems: The Spacecraft Bus The Spacecraft Bus exists solely to support the payload, with all the necessary housekeeping to keep it healthy and safe. The best way to visualize the relationship between the payload and bus is to picture a common, everyday, school bus.

Designing Payloads and Subsystems: Steering - Spacecraft Control On spacecraft, the subsystem that “steers” the vehicle is the Attitude and Orbit Control Subsystem (AOCS).

Designing Payloads and Subsystems: Communications and Data Handling (CDHS) We can easily identify the driver on the school bus. It’s the person in front, behind the steering wheel. On a spacecraft, the driver is less easy to pick out, but its role is just as important. The “driver” of the spacecraft bus is called the communication and data-handling subsystem (CDHS).

Designing Payloads and Subsystems: Electrical Power Just like the school bus, spacecraft depend on electrical power to keep components running. The electrical power on a spacecraft is no different from that used to run your television. Therefore, a spacecraft must produce its own electrical power from some energy source, usually the Sun.

Designing Payloads and Subsystems: Environmental Control and Life-Support Subsystem (ECLSS) The spacecraft’s Environmental Control and Life-Support Subsystem (ECLSS) maintains the required temperature, atmosphere, and other conditions needed to keep the payload (including astronauts!) healthy and functional.

Designing Payloads and Subsystems: Structures and Mechanisms A school bus’s structure holds it together. A spacecraft’s structure must be sturdy enough to handle all the stresses in space while holding all other subsystems in place.

Designing Payloads and Subsystems: Propulsion Subsystem A school bus has an engine and drive train that supply torque to the wheels, moving the bus where the driver wants it to go. In space we use rockets to expel mass in one direction, which causes the spacecraft to move in the other. Large rockets on launch vehicles produce the thrust needed to get the spacecraft into orbit. Once there, smaller rockets in its propulsion subsystem produce thrust to maneuver it between orbits and control its attitude.

The Design Process The spacecraft design process shows how a spacecraft’s subsystems depend on each other. When we adjust the design of one subsystem, we’re likely to have to adjust some, or all, of the others.

The Design Process: Design and Analysis Tools To help make complex design decisions, mission planners and systems engineers have many design and analysis tools in their toolkit. These range from: simple “back-of-the-envelope” calculations using a pencil, paper, and calculator (or spreadsheet) to complex computer simulations requiring hours of run time.

The Design Process: Validating the Design Too often, people responsible for specific subsystems get so involved in designing their own small piece of the mission that they lose sight of how their decisions affect other sub-systems and the mission’s overall performance.

The Design Process The Space Systems- Engineering Process

Understanding the Systems Engineering Process Comprehend how the payload requirements drive the rest of the spacecraft design. Know a spacecraft’s major subsystems.