Satellites that photograph the land are expensive, slow to build and in orbit for years, so it matters a great deal whether they measure what people actually need. The U.S. Geological Survey's Requirements, Capabilities, and Analysis for Earth Observations project — RCA-EO — exists to answer that question for the nation's civil land imaging program, including Landsat.
An ash and smoke plume from an active volcano on Russia's Kamchatka Peninsula, captured by Landsat 8 in 2018. Image: U.S. Geological Survey.
Needs first, technology second
RCA-EO records what users need to measure, not which instrument should measure it. Over the past 10 years it has interviewed hundreds of subject-matter experts and gathered more than a thousand user needs, across agriculture, forestry, geology and minerals, wildfire, energy, water quality and more.
Its work runs in four steps:
| Step | What happens |
|---|---|
| Connect | build relationships across the land-imaging community, so data users have a say in the data they will get |
| Collect | face-to-face interviews with scientists and other users, plus public details of U.S. government, international and commercial satellites |
| Analyze | model systems and compare them with the needs |
| Influence | turn the results into recommendations for the National Land Imaging Program — investments, mission plans, products |
The RCA-EO cycle: community engagement, data collection, modeling, analysis, and recommendations and actions, all aimed at societal benefit. Graphic: U.S. Geological Survey.
What gets recorded
| A user need has five core attributes | A system is described by |
|---|---|
| the geophysical feature to observe | its sensor's spectral bands |
| the geographic area | its geographic coverage |
| the spatial resolution | its spatial resolution |
| how often it must be observed | its altitude |
| the accuracy and quality required | how often it revisits a place |
The needs span a wide range of resolutions, frequencies and phenomena. Putting both sides in the same terms is what lets them be compared.
The analysis
- Characterization and modeling. Each satellite system, product or dataset is documented — resolution, altitude, timing, spectral bands. Beyond single satellites, the team can model virtual constellations (several satellites used together) and advanced products from U.S., international or commercial sources.
- User-needs analysis. Then it measures how well a system meets each need, on resolution, frequency, coverage and spectral accuracy.
The results help decide which land-imaging systems and products to develop, which data to buy, and which partnerships to pursue for data from missions the USGS does not run.
An example: minerals and Landsat
During the 2018 Landsat architecture study, RCA-EO carried the mineral-mapping community's need for additional spectral bands into the design discussion (Wu and others, 2019) — the path from an interview to a recommendation, in one case.
In summer 2025 the team supported NASA's Sustainable Land Imaging Mission Alternatives Assessment Team, evaluating more than 300 possible mission architectures against more than 400 user needs to shape plans for future Landsat missions.
RCA-EO milestones, 2018 to 2025. Graphic: U.S. Geological Survey.
More: usgs.gov/RCA-EO.
Sources
Written from Requirements, Capabilities, and Analysis for Earth Observations—From User Needs to Earth Observation Solutions, by Iris J. Garthwaite and Ellen Wengert, U.S. Geological Survey Fact Sheet 2026–3014 (doi:10.3133/fs20263014); a work of the United States government in the public domain. It cites Wu and others (2019), User needs for future Landsat missions. Its graphics and Landsat image are reproduced from the fact sheet.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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