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The Astro Pi Sensors

The Astro Pi computers contain a range of sensors that will allow Mission Space Lab teams investigating life on Earth and life in space to do a wider range of experiments than ever before.

Check the list of sensors below for more information.

Sensors

PIR

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used as motion detectors.

Colour and luminosity sensor

A colour and luminosity sensor can detect the received light intensity for red, blue, and green respectively, making it possible to determine the colour of the target object. It can also measure illuminance, which can be used to measure more than the brightness of a light source. Because the illuminance decreases as the sensor moves away from a steady light, the light sensor can be used to gauge relative distance from the source.

Coral ML accelerator

The Astro Pi hardware includes the Coral Edge TPU, which is a machine learning peripheral device designed to speed up the calculations involved in running machine learning models in real time. Using the TensorFlow Lite framework with this specialised hardware, teams can run pre-trained machine learning models to perform real-time inference tasks such as object detection and image classification.

Gyroscope, accelerometer, and magnetometer IMU sensor

The gyroscope sensor can be used to measure angular velocity about three axes: pitch (x-axis), roll (y-axis), and yaw (z-axis). Inertial Measurement Units (IMUs) are used to measure acceleration, angular velocity, and magnetic fields, so you can write code to determine motion, orientation, and heading. Check out this great example of how a team used the sensor to determine the magnetic field of the Earth.

Temperature sensor

This sensor measures temperature readings on the ISS through electrical signals. The sensor is made up of two metals, which generate electrical voltage or resistance once there is a change in temperature. The sensor is located inside the flight unit itself and is affected by the internal temperature of the flight unit as well as the external environment. If you wish to measure the temperature of the ISS, you will need to compensate for this by running your own tests in a controlled environment and comparing the temperature readings received with the actual temperature of the controlled environment. You should be mindful, however, that the International Space Station is carefully regulated, so you will not see a wide range of temperature fluctuations.

Humidity sensor

This sensor reports relative humidity, which is the amount of moisture in the air compared to what the air can ‘hold’ at that temperature, given as a percentage. Since it is related to temperature, the same caveats apply: humidity readings will largely be affected by the internal temperature of the flight unit itself as opposed to accurately reflecting the external environment. You can compensate for this by testing in a controlled environment and comparing the humidity readings received with the actual relative humidity of the controlled environment. You should be mindful, however, that the International Space Station is carefully regulated, so you will not see a wide range fluctuation in humidity.

Pressure sensor

The air pressure sensor is a type of engine-management sensor commonly found on many vehicles. The sensor on the Astro Pi is responsible for measuring the atmospheric pressure of the environment on the International Space Station. Be mindful that the International Space Station is carefully regulated, so you will not see a wide range of fluctuation in pressure readings.

HQ Camera

The Raspberry Pi High Quality (HQ) Camera sensor from Raspberry Pi offers a 12 megapixels resolution. It comes with a 6mm, 3MP wide-angle lens, which offers a wide field of view to allow you to see more of the overall target area. Teams can choose to take either visible-light or near-infrared photos as part of their experiment.

Check out how this ‘Life on Earth’ team used IR photography to conduct NDVI analysis to analyse burn scars from forest fires. They even managed to get results over Chernobyl!

Contact us

For any questions regarding Astro Pi, please contact enquiries@astro-pi.org.

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