This Air Quality Instrument Really Measures Up

The Landsat program, initiated by NASA in collaboration with the U.S. Geological Survey, represents a pioneering effort in Earth observation and remote sensing. Launched in 1972, the program has been instrumental in providing a consistent and comprehensive record of the Earth's surface over several decades. Landsat satellites capture high-resolution imagery across multiple spectral bands, enabling scientists, researchers, and policymakers to monitor changes in land use, track environmental shifts, and study various Earth processes. With a history spanning multiple generations of satellites, the Landsat program has contributed significantly to our understanding of global environmental changes, climate patterns, and natural resource management.

When hearing about space-based technologies like those deployed in the Landsat program, they can seem far out of reach (no pun intended) to the casual hobbyist. But much of the instrumentation aboard these satellites is actually readily available for purchase, and inexpensively at that. For this reason, members of the Landsat team have created the STELLA (Science and Technology Education for Land/Life Assessment) project to educate people about the technology and spur on new discoveries. This is great news for the hobbyist that wants to understand how real science is done, or just make some really cool instruments of their own.

The latest addition to the STELLA line of DIY devices is the STELLA-AQ — an instrument designed to assess air quality. The STELLA-AQ requires no soldering, 3D printing, or any other complexities or equipment that would prevent even beginners from jumping in. That simplicity does come with a few notable drawbacks. For starters, the entire device is attached to a ruler for support. Moreover, the large number of breakout boards that are included in the design make it quite large. But while it may not be pretty, it is functional.

The STELLA-AQ is built around an Adafruit Feather STM32F405 Express development board with a powerful STM32F405 Cortex M4 microcontroller. This device is CircuitPython-compatible to make the software side of the equation a snap. A 128 x 128 pixel grayscale display is also included to show the measurements captured by the many sensors. These included sensors can measure temperature, air pressure, humidity, CO2, air quality, and more. The entire system is powered by a rechargeable lithium-ion battery. As it is laid out in the project write-up, the components can be purchased for around $200. However, there is plenty of flexibility if one wishes to include a different set of sensors.

The assembly process, which is detailed in the build guide, is as simple as connecting some Qwiic/STEMMA-QT connectors for I2C communication, and attaching Velcro tape to the ruler and components to secure them. Programming instructions and source code are also included, so if you want to build the STELLA-AQ as it is described, the work has already been done for you.

If this project appeals to you, you might want to check out the other STELLA devices as well. The previous devices focus on how one can build a working spectrometer, which is a critical component of the actual Landsat project.