Spinach Leaves to Satellites: Ahadu, working as both engineer and scientist

Arizona State University undergraduate Ahadu Assegued spent a year asking a practical question about Earth observation: how do the spectral readings from STELLA, a low-cost open-source spectrometer developed at NASA's Goddard Space Flight Center, compare with those from research-grade hyperspectral imaging and satellite data? To find out, he took STELLA into a spinach field, working alongside a doctoral study on how cadmium affects the crop, and measured control plots against affected ones. He ran the same comparison in the lab with toxic and non-toxic algae. The trends from the low-cost sensor tracked the high-fidelity HySpex Mjolnir imager, even with added noise. The satellite data told a different story, and that difference became one of the most useful findings of the project. In this conversation with Michael Taylor of NASA Goddard Space Flight Center, Assegued and his faculty mentor Dr. Saurav Kumar discuss what the comparison revealed, why the size of a satellite pixel forced a rethinking of the entire experiment, and what it takes to move a scientific instrument from a university lab toward the hands of farmers, students, and community scientists. The interview returns often to a division that this project made difficult to maintain. Reading a reflectance curve required Assegued to understand integration time, band design, and the geometry of the sensor's field of view. Working around a hardware limit required him to know what the science demanded. Dr. Kumar describes that overlap as central to how students should learn remote sensing, and both discuss what changes when learners can build, calibrate, and keep an instrument rather than borrow one from a shared lab. Agriculture runs through the whole discussion, from the spinach field and the cadmium work to nitrate and phosphorus monitoring on small farms, and to the gap in ground measurements that satellites need for validation. STELLA, which stands for Science and Technology Education for Land and Life Assessment, is designed and supported by the Earth Sciences Division at NASA's Goddard Space Flight Center. The instrument is open source and built from published designs and a public parts list.