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Monitoring the Earth: Valerie Thomas and Satellite Image Processing

(originally published on Medium on 02.13.2022

Valerie Thomas. Source: Wikicommons

Early life

Valerie Thomas was born in 1943. Growing up, she had a keen interest in how things worked: she longed to tinker, and would borrow books from the library, once one was present in her community, on how things worked. Notably, these books had such titles as The Boys First Book in Electronics, indicating the path she noticed as she progressed through junior high and high school that in those days, gender-norms clearly indicated that she shouldn’t be tinkering. Instead, she excelled at mathematics and took a course in physics that helped answer her question of “how do things work?”. She then majored in physics at Morgantown State University and began work at NASA less than two weeks after her graduation.


When Thomas first began at NASA, she had “never seen a computer except in science fiction movies.” [1] She threw herself into learning about computers and learning computer programming, working with scientists conducting research with the Orbiting Geophysical Observatory (OGO), transforming the data into a format that scientists could use. When the Landsat program (resulting in the launch of the Earth Resources Technology Satellite in 1972 and continuing today with the launch of Landsat 9 in 2021) first began, Dr. Thomas began to learn the format of the digital tapes and images to be used for Landsat. She was well prepared for this challenge given her mathematics background and previous work on OGO.

Landsat 9. Source: Wikimedia Commons

Dr. Thomas taught herself Fortran to shorten the time it took to read in digital tape data and transform the data to a format that was easy to read and was in charge of managing the software systems for processing the images. Her Fortran code that she wrote to ensure the accuracy of the data became the quality control tool used in the process for Landsat research, earning the name the “ValDump” in her honor. Eventually, so many scientists globally contacted her to ask questions about the data from Landsat that she wrote a document that became the basis for all future versions of that section of the Landsat documentation.

Figure from [3]: see references below

The Large Area Crop Inventory Experiment (LACIE), an early experiment to look at global crop yields, was developed using Landsat data, and was a collaboration with three government agencies of the United States, including NASA. Dr. Thomas was in charge of managing the image processing systems and later was in charge of the Goddard Flight Space Center’s LACIE contributions. One of her key responsibilities on LACIE was to develop the digital image processing system to produce the images for the test sites per day, with enough accuracy to ensure the exact same area on the ground was covered for the entire growing season. [1]. LACIE as a project was an early proof of concept of a type of project we take for granted now: using satellite data for monitoring of local and global conditions and Dr. Thomas’ early work on the project placed her as a pioneer in data science and image processing.

Figure from [3]. (see references below)

In addition to her project management and technical roles at NASA, Dr. Thomas is famed as the inventor of the illusion transmitter. While attending a seminar in the late 1970s, she saw an illusion of a light bulb remaining lit even after being unscrewed using concave mirrors. After ideating and experimentation, she invented the illusion transmitter, which uses parabolic mirrors to reproduce an image at a remote site and was granted a patent for her discovery in 1980. NASA continues to use the technology to this day and it has been examined for use in entertainment systems as well.

Mentoring and DEI

Many organizations these days have included or are beginning to include Diversity, Inclusion, and Equity (DEI) as part of their human resources departments. During Dr. Thomas’ time at NASA, she organized events and an organization called Humanitarian United Effort that united managers with a diverse group representing “African-American women, Hispanics, people with disabilities” [2] to demonstrate to management the importance of diversity and to highlight the work these individuals did.

Throughout her career and into retirement, Dr. Thomas has continued to advocate for the advancement of traditionally marginalized groups in STEM fields and gave talks and presentations in schools to encourage students to go into science and engineering, while continuing to judge science fairs. In 2021, the 78-year-old Valerie Thomas is well into her retirement. She was giving talks to students over Zoom during the pandemic and aiding in the design of a science center that is “a combination space port and theme park” [2] that will highlight contributions to science by African Americans.


[1] A Face Behind Landsat Images: Meet Dr. Valerie L. Thomas

[2] 78-year-old Valerie Thomas Invented Technology That Led to the Invention of 3-D Imaging

[3] The LACIE Experiment in Satellite-Aided Monitoring of Global Crop Production.

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