MOMENTUM CONTROL DEVICE
Reaction wheels help rotate and accurately reorient the satellite in specific increments. Rather than using fuel, a reaction wheel adjusts a satellite's orientation by changing speed. Since reaction wheels only rotate on a single axis, multiple reaction wheels may be installed to provide three-axis attitude control.
GNC
SUBSYSTEM
Guidance, navigation and control, or GNC, manages a satellite’s attitude, position and velocity. Sensors (e.g., star trackers, GPS, etc.) are used to determine inertial attitude, angular rate and position/velocity. Actuators (e.g., thrusters, torque coils, reaction wheels, etc.) enable six degrees of freedom in space.
ATTITUDE SENSOR
A star tracker is an optical device that helps determine a satellite’s attitude,or orientation, in relation to stars. To assist with attitude, a star trackerobtains images of nearby stars and compares them to a star catalog. Common startrackers include a camera, photocells and telescope.
GNC
SUBSYSTEM
Guidance, navigation and control, or GNC, manages a satellite’s attitude, position and velocity. Sensors (e.g., star trackers, GPS, etc.) are used to determine inertial attitude, angular rate and position/velocity. Actuators (e.g., thrusters, torque coils, reaction wheels, etc.) enable six degrees of freedom in space.
GPS
A global positioning system, or GPS, is a component that measures position, time and velocity. GPS uses a space-based radio navigation software to receive radio frequency transmissions and compute position and velocity.
GNC
SUBSYSTEM
Guidance, navigation and control, or GNC, manages a satellite’s attitude, position and velocity. Sensors (e.g., star trackers, GPS, etc.) are used to determine inertial attitude, angular rate and position/velocity. Actuators (e.g., thrusters, torque coils, reaction wheels, etc.) enable six degrees of freedom in space.
TORQUE COILS
Torque coils are coiled wires that generate a magnetic field. This magnetic field interacts with the Earth’s magnetic field to apply external torque to the spacecraft, which changes the spacecraft’s angular momentum.
GNC
SUBSYSTEM
Guidance, navigation and control, or GNC, manages a satellite’s attitude, position and velocity. Sensors (e.g., star trackers, GPS, etc.) are used to determine inertial attitude, angular rate and position/velocity. Actuators (e.g., thrusters, torque coils, reaction wheels, etc.) enable six degrees of freedom in space.
RADIO
The transceiver is a radio device used to receive and transmit data and radio frequencies between a satellite and ground station. The data will include commands sent to the satellite and payload data and health and status telemetry from the satellite.
TT&C
SUBSYSTEM
Tracking, telemetry and command, or TT&C, relays communication and transmits data. TT&C enables communication between the ground/user segments and on-orbit satellites.
ANTENNAS
A satellite’s antennas are responsible for sending and receiving radio frequency signals. Antennas collect electromagnetic waves to route the signal back to the receiver and strengthen signals in specific directions. These radio frequencies are used for two-way communication between satellites and their ground systems.
TT&C
SUBSYSTEM
Tracking, telemetry and command, or TT&C, relays communication and transmits data. TT&C enables communication between the ground/user segments and on-orbit satellites.
SOLAR ARRAYS
Solar arrays are a group of solar cells or panels arranged in specific formations on a satellite. They are the primary method of power generation. Solar arrays are responsible for harnessing the sun’s energy and converting it into power for the satellite.
EPS
SUBSYSTEM
The electrical power subsystem, or EPS, manages spacecraft power. The sun’s energy is collected using solar panels and stored in batteries. Power is distributed to units via switches controlled on the power switch board. EPS includes batteries, solar cells, solar panels, solar arrays and power switch boards.
BATTERIES
Batteries act as a main source of power storage. Solar arrays generate power. Power switch boards distribute power to other components in a satellite. Specific battery types within a satellite are chosen according to power-to-mass optimization.
EPS
SUBSYSTEM
The electrical power subsystem, or EPS, manages spacecraft power. The sun’s energy is collected using solar panels and stored in batteries. Power is distributed to units via switches controlled on the power switch board. EPS includes batteries, solar cells, solar panels, solar arrays and power switch boards.
POWER SWITCH BOARD
The power switch board, or PSB, distributes power across a satellite through a series of switches, working with the rest of the electrical power subsystem for power and load management. Common loads within a satellite include heaters, batteries and radios. The power switch board communicates with the flight computer to manage switch state.
EPS
SUBSYSTEM
The electrical power subsystem, or EPS, manages spacecraft power. The sun’s energy is collected using solar panels and stored in batteries. Power is distributed to units via switches controlled on the power switch board. EPS includes batteries, solar cells, solar panels, solar arrays and power switch boards.
FLIGHT COMPUTER
The flight computer assists with data processing, input and output processes and data management. It is continuously analyzing data, acting as a satellite’s central processing unit. The flight computer works with all other subsystems to carry and store data across the satellite.
CD&H
SUBSYSTEM
The command and data handling subsystem, or C&DH, controls all spacecraft functions and data management. Common components include the flight computer and avionics system. C&DH works alongside the tracking, telemetry and command subsystem to communicate data back to a ground station.
HEATERS
Heaters are composed of etched foil, or wire, sandwiched between temperature resistant elements. They provide additional heat to components, ensuring individual components operate at their optimal temperature needs.
TCS
SUBSYSTEM
The thermal control subsystem, or TCS, keeps the satellite within normal operating temperatures throughout launch, deployment and operations. Normal operating temperatures typically range between -30C and +61C, but can vary based on the individual component or mechanism. Maintaining each component’s ideal operating temperature is critical for the satellite’s survivability and operation while on orbit. Common TCS components include heaters, temperature sensors, multi-layer insulation and radiator coatings.
TEMPERATURE SENSORS
Temperature sensors sense the internal temperature of a satellite. Thermistors are the primary tool used to accurately measure temperature across various ranges by measuring resistance.
TCS
SUBSYSTEM
The thermal control subsystem, or TCS, keeps the satellite within normal operating temperatures throughout launch, deployment and operations. Normal operating temperatures typically range between -30C and +61C, but can vary based on the individual component or mechanism. Maintaining each component’s ideal operating temperature is critical for the satellite’s survivability and operation while on orbit. Common TCS components include heaters, temperature sensors, multi-layer insulation and radiator coatings.
SPACECRAFT STRUCTURE
The spacecraft structure is the mechanical design used to support and protect the satellite. Structure ensures that each component fits within available volume and mass constraints and that subsystems are placed according to their needs within the satellite body. The spacecraft structure is dependent on launch requirements and works with all other subsystems to ensure mission success. The structure is generally made of aluminum, carbon fiber, titanium, and steel.
SUBSYSTEM
LAUNCH & DEPLOYMENT
The launch adapter enables the mating of the satellite structure to the launch vehicle. Deployment mechanisms work in tandem with the launch adapter to deploy a satellite. It is designed to release and push the satellite away from the launch vehicle.
SUBSYSTEM
PAYLOAD
A payload enables the mission and can refer to a physical object, software, or area within the satellite. Common payloads include scientific experiments, observation equipment and specialized computers.
SUBSYSTEM
SMALL SATELLITES 101
A satellite is defined as a natural or man-made object that orbits around a body. There are natural satellites (such as the moon and Earth) and man-made satellites composed of mechanical components. A small satellite, also known as a SmallSat, is a classification of satellite that is compact and falls under a specific mass line. Individual components of a satellite work together to execute specific functions while in orbit. These functions can include observation of astronomical objects, movement, and communication through space. Small satellites can work independently or in a versatile network to execute specialized missions such as observation, communication, or scientific experiments.
