Spacecraft are designed to transport payloads to specific locations within our solar system. Launched on rockets, once separated from them they utilize their own propulsion and navigation systems to continue on their path towards their destinations.
Spacecraft primary structures consist of instrument plates (reinforced carbon honeycomb composite facesheet panels) connected by cylindrical supports for spreading load-bearing loads evenly on their structures.
Structure
Spacecraft structures provide mechanical stability and thermal control. They house components requiring livable conditions within pressurized crew compartments such as cockpit and living quarters as well as experimental payloads or spacecraft avionics that require pressurization for optimal operation.
The structure subsystem also plays an essential role in protecting the spacecraft from radiation and micrometeoroid impacts, with Kevlar blankets used as shielding against micrometeoroid impacts. Radiation shielding is essential, since orbital conditions degrade surface properties over time and alter absorptivity and emissivity properties of surfaces; this changes transmission rates of radiation as well as heat dissipation from electrical heaters.
According to mission requirements, spacecraft structures may either be commercial off-the-shelf (COTS) or custom machined. An increasing number of SmallSats utilize COTS structures in order to simplify development; however, choosing which structure to use ultimately comes down to mission requirements: these could include needing to balance structural load with mass distribution for spin/thermal stability as well as optimizing surface area for charge dissipation, assembly integration and assembly as well as pointing accuracy.
Thermal Control
Thermal control on spacecrafts is essential to keeping specific components within their required temperature ranges for mission success, as sudden temperature shifts can damage electronics, degrade materials and alter sensor or instrument performance.
Prevent temperature variations caused by changing environmental radiative fluxes and minimize thermal gradients are two important goals to pursue.
Efficient heat management also involves absorbing and dissipating excess heat accumulation to avoid its accumulation, with various techniques including multilayer insulation blankets (MLI) or coatings designed to reflect or absorb infrared radiation being deployed as solutions.
Active thermal control techniques such as heaters and pumps may require power that may not be available on small satellites. Passive thermal control uses materials and design features like insulation, radiators, surface coatings to regulate temperatures without moving parts or input from external power sources – these methods are particularly advantageous in keeping CubeSats light and low in mass; for instance they include louvers that are thermally activated to change their average IR emissivity rating of the surface they cover.
Propulsion
Space travel necessitates movement for survival and mission fulfillment, and spacecraft propulsion systems use Sir Isaac Newton’s Third Law of Motion — every action has an equal and opposite reaction — to generate thrust to propel an aerospace vehicle forward.
Spacecraft components must endure the hostile environment of space for long periods, which can be particularly harsh on delicate components that are subjected to temperature variations, micrometeoroid bombardment, and vibration.
Thermal control systems use both passive and active temperature management strategies to offset these effects, such as employing thermal blankets of 20-24 different layers to reflect away external heat while radiating internal heat away from spacecraft elements.
Communications
As spacecraft must transmit data back and forth from Earth, this requires an intricate interplay of technologies ranging from ground networks to relay satellites. As NASA extends their missions further away from home, overcoming communications challenges becomes ever more essential and this necessitates continuous innovation within this sector.
Spacecraft communication subsystems transmit payload mission data and housekeeping commands directly from their spacecraft to operators at an operations center, where these commands are then relayed back through antennae of the communication system back to its antennae onboard the spacecraft.
Navigation systems ensure spacecraft are in their intended orbits and on target with their targets, as well as being guided to specific points on Earth by using electronic “eyes” that detect Sun and stars as guides; additional methods include using pulsars (magnetised, swiftly rotating dying stars that emit beams of electrons). Navigation systems continue to improve to meet ever-increasing performance demands – including increasing bandwidth as faster data transmission is a priority for many missions.