Types of Sensors Used in CubeSats

CubeSats employ a variety of sensors for attitude determination, including star sensors, sun sensors, gyroscopes, and more, each serving specific roles based on mission requirements.

Sun Sensors

Overview

Sun sensors measure the angle of sunlight to determine the satellite’s orientation relative to the sun. Due to their simplicity and reliability, they are widely used in CubeSats. Sun sensors provide coarse attitude information, critical for initial orientation (detumbling) after launch and as a backup for other sensors. The sun’s reliability as a reference point in space makes these sensors versatile for various missions. They are lightweight and low-power, ideal for the constrained resources of CubeSats.

Key Considerations:

• Field of View (FOV)
• Accuracy
• Power and Mass
• Environmental Tolerance

Star Trackers

Overview

Also known as star trackers, are optical devices that determine satellite orientation by recognizing star patterns in the sky. Star Trackers provide precise three-axis attitude information, making them ideal for high-accuracy applications like Earth observation or inter-satellite communication. Their autonomy and high update rates ensure reliable performance even in challenging conditions.

Key Considerations:

• Field of View
• Update Frequency and Latency
• Radiation Tolerance
• Thermal Operating Range

Magnetometers

Overview

Measure Earth’s magnetic field to help determine the satellite’s orientation. Magnetometers provide attitude information relative to Earth’s magnetic field, useful for reducing satellite tumbling and coarse pointing. They are cost-effective, lightweight, and widely used, particularly in low Earth orbit (LEO) where magnetic fields are stronger.

Key Considerations:

• Accuracy
• Calibration
• Cost and Size

Gyroscopes

Overview

Measure the satellite’s angular velocity, or rotation rate. Gyroscopes can be mechanical (spinning mass), optical (ring laser), or MEMS-based. They detect orientation changes by measuring rotational motion, providing real-time data for attitude control.

Key Considerations:

• Drift
• Type
• Environmental Adaptability

Inertial Measurement Units (IMUs)

IMUs are integrated systems combining gyroscopes, accelerometers, and sometimes magnetometers to provide comprehensive motion data. IMUs provide a versatile solution for attitude determination, seamlessly delivering both rotational and linear motion data. Moreover, they are particularly useful for missions requiring complex maneuvers or precise positioning.

Key Considerations:

• Data Fusion
• Power Consumption
• Size and Cost

Factors in Selecting Sensors for CubeSat ADCS:

• Mission Requirements
• Size, Weight, and Power (SWaP) Constraints
• Cost
• Environmental Factors