Did you know UAF students are using NASA technology in a hand-held gadget to study the environment?

October 11, 2023

What is STELLA? STELLA – short for NASA’s Science and Technology Education for Land / Life Assessment – is a hand-held tool that allows students, educators, and citizen scientists to scan, record, and analyze features of the natural environment, such as plant health, using the same technology that NASA uses to study the Earth. STELLA instruments use rudimentary sensors to measure the amount of energy emitted (in this case, reflected) at each wavelength from a radiant sample. One key feature of the instrument is that you can hold it in hand and view the measurements in real-time. 

The STELLA project was developed by Chief Engineer Paul Mirel and NASA’s Landsat CPE Team to help students understand remote sensing technology, and introduce them to the science of Landsat with a learn-by-doing approach. STELLA, both the name of the gadget and the program, is a basic instrument used as an entry point for learning elementary remote sensing concepts. 

Since 2019, the science project at NASA’s Goddard Space Flight Center has supported the development of STELLA because it is a valuable tool to demonstrate how the imaging instruments on Landsat satellites work. Though the device is not yet a “valid” instrument, in the sense of being scientifically proven, it offers a unique value to educators and learners engaging with this technology in a tactile way.

A screenshot of live STELLA dataA screenshot of live STELLA instrument data on Dataviewer

What is Landsat? The consists of a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey (USGS). Since 1972, Landsat satellites have continuously acquired images of the Earth’s land surface and provided an uninterrupted data archive to assist land managers, planners, and policymakers in making more informed decisions about natural resources and the environment. 

How did UAF get one? In addition to making the build instructions freely available, 40 instruments were built by NASA interns and sent across the U.S. in a loaner program, including to UAF. To calibrate the instruments, the interns handed the instruments off to team member Jesse Barber for calibration and validation work using a sun simulation sphere.

Accessibility is key: Using STELLA instruments, students, teachers, and young scientists gain hands-on experience in science, technology, and engineering as they follow freely available online plans, instructions, and activities. With state-of-the-art sensors, STELLA measures the intensity of light reflected from surfaces across 12 different wavelength ranges in the visible and near-infrared regions of the electromagnetic spectrum. 

Real-World scenarios: One application is to study plant health. STELLA measurements of leaf temperature and air temperature – and the difference between them – can hint at how well-watered a plant is. At the press of a button, a small screen displays a numerical readout of a dozen or so measurements – things like temperature, humidity, and light intensity. 

Another potential application could be using the device to measure urban heat island effects. Students could go out on rooftops to take readings and compare those to ground readings or readings from under the shade. STELLA could also provide valuable data to farmers and foresters assessing the health of their crops and trees in times of drought and heat.

The focus right now is testing the instruments already in existence. The data collected will help scientists see how STELLAs perform in the real world.

Build your own: The Landsat team is also making it possible for anyone to build their own instruments. This additional component beyond the loaner program allows for students to take part in the assembly, utilizing mechanical and electrical engineering and understanding the instrument from start to finish. Assembly directions are available freely online from NASA’s Landsat website and parts for the instrument should come in under $200. There are three different STELLA models, the simplest of which requires neither soldering nor 3D printing and can be taped together on a pair of tongue depressors. Each instrument takes about two hours to put together. Calibration can be simulated by testing the reflective surface of a foam board. 

A STELLA held up to a house plant

An example STELLA during testing at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. In this test experiment, the two plants were given different amounts of water. STELLA readings were taken regularly to monitor and compare the plants’ relative health.
(PHOTO: NASA’s Goddard Space Flight Center/Sophia Rentschler)

A global community: With STELLA in hand, students become citizen scientists making Landsat-like spectral measurements wherever they are. Students and educators can head to the to connect their devices, learn about the project, and check out and compare data with other users. They can even join the public forum which offers lesson plans and best practices.

Though the loaner program exists only in the U.S., there is growing interest from as far as Greece and Niger, Africa, in learning how to build their own STELLA and contribute to this fledgling community of DIY data collectors.


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