Eyes on Earth Episode 134 – Data Accuracy: The Calibration and Validation of Landsat

Exotic annual grasses, or EAGs, are invasive species. They outcompete native grasses. They are extremely flammable. And they are expanding into higher elevations. Targeted sheep grazing is one way to combat these invasive grasses, manage fire risk, and help restore native sagebrush in western states.The EROS team releases weekly EAG maps during the peak green-up in late April to early June, along with annual phenology maps to show the seasonal timing of the green-up. Dr. Kelly Hopping at Boise State University is using these maps to see whether targeted sheep grazing can help manage EAGs. The maps help researchers work with sheep producers to know when is the best time to move the sheep into those areas so their grazing can do the most good. The sheep then, as a part of the team solving the problem of invasive grasses, get to eat in the field when they might not otherwise have grazing available. Learn more in this episode of Eyes on Earth.

Landsat has been accurate and reliable for over 50 years because of the diligent calibration and validation work done by the team at EROS. One of the ways the team validates what they have so carefully calibrated is to take measurements on the ground while Landsat passes by overhead. For this Eyes on Earth podcast episode, we go out to the EROS test site during a Landsat pass to get a sense of what that work is like. Learn about the instruments used for this work and why it’s important to keeping Landsat as the gold standard for Earth observations.

Landsat is the longest-running, continuously operating record of Earth observations, and it’s the gold standard reference point that other civil and commercial satellite programs trust. If a researcher is studying multiple Landsat images of the same spot on Earth, and there is something in those images that suggests a change, that researcher needs to have the confidence that that change is a real change on the landscape and not because of something that changed or degraded in the sensor. Think of it this way. We are using a system to quantify changes on the Earth—we need to make sure the system itself is not changing.

Declassified spy satellite imagery, distributed by the USGS EROS Center, is finding fascinating uses since being made available to the public starting in the 1990s. In this episode of Eyes on Earth, we talk with Philipp Barthelme from the University of Edinburgh, who used imagery from the declassified HEXAGON and CORONA satellites to map bomb craters and herbicide spray lines from the Vietnam War. These features appear in the black and white photos quite clearly, so Barthelme worked out machine learning methods to automatically detect them. This method can help narrow down where to search for unexploded weapons and focus on the areas that are most contaminated.

Eyes on Earth tackles artificial intelligence (AI) in a 2-part episode. AI is quickly becoming a necessary part of geospatial work at EROS, helping us efficiently do science to better manage our world. In Part 1, we talked about AI’s current and upcoming impact on our work at EROS and clarified some of the AI jargon. The successful use of AI to make NLCD an annual product was a key example.In Part 2, we discuss another potential application of AI—keeping Landsat satellites safe and healthy in orbit. Additionally, guests comment on how readily staff are adapting to using this rapidly evolving technology. They discuss the biggest benefits and challenges we face in using AI. Among the benefits are making EROS data products more accurate and reliable and getting them to the public in a more timely fashion.

Eyes on Earth tackles artificial intelligence (AI) in a 2-part episode. AI is quickly becoming a necessary part of geospatial work at EROS, helping us efficiently do science to better manage our world. In Part 1, EROS Director Pete Doucette discusses AI and its current and upcoming impact on our work at EROS. To help clarify AI terminology such as machine learning, deep learning, neural networks, transformers, and foundation models, we also talk to scientists who are using AI. And we learn about how AI enabled the National Land Cover Database (NLCD) to become an annual product.Part 2 will discuss one more potential application of AI—keeping Landsat satellites safe and healthy in orbit. We also have all of our guests comment on AI’s challenges and benefits.

Every pixel has a story. At least that’s how land remote sensing scientist Jo Horton sees it. The new Annual National Land Cover Database (NLCD) was just released in October 2024. NLCD is widely used for land cover and change research in the U.S. That’s why the Reference and Validation team provides accuracy metrics to users, and this work allows EROS to move land cover mapping science forward. Learn about what the Reference and Validation team does and what they are looking for when they closely examine thousands of Landsat sample pixels across the conterminous U.S. It sometimes involves some detective work as they figure out the stories of each pixel across time.

In this episode of Eyes on Earth, we talk to ground station technicians to find out how Landsat satellite data gets from the spacecraft to EROS and then to the archive. We see what it’s like in EROS’s Landsat operations room and what the technicians do before, during, and after a Landsat pass. The task of making sure those bits of data make their way to the archive so it can be used for land change science occurs for them several times a day. As routine as it might be sometimes, they are a small but important part of a large mission that is documenting global land change.

In this episode of Eyes on Earth, we mingle at the 2024 EROS Fall Poster Session. A poster session is essentially a way for scientists to share their work with their colleagues in a public forum. About 30 posters were on display in the EROS atrium from EROS staff and several students from South Dakota State University and the University of South Dakota. We talked to a few of them to get quick summaries of their research.

In this episode of Eyes on Earth, we talk about the incredible career of Landsat 7, which collected science imagery of the Earth for nearly 25 years. The Flight Operations Team at NASA Goddard Space Flight Center and engineers at EROS work together to collect imagery, send commands to the satellite, and keep it healthy. After over 133,000 orbits and 3.3 million images collected, Landsat 7 stopped acquiring imagery in 2024. We talked with some of the people who helped keep Landsat 7 flying to make sure it could keep doing its job during its long life. They talk about the close calls, different types of maneuvers, working on holidays, and creatively solving problems to keep it flying and operating. And as always, we discuss the importance of the Landsat mission, its global legacy, and the continuity of the long record that goes back to 1972.