NASA's CASALS Lidar Promises Continuous 3D Maps of Earth's Surface, Eliminating Gaps in Data

Instrument uses wavelength steering and machine learning to create swath-based topography

By LineZotpaper

Published21 October 2026

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NASA researchers have developed a new lidar instrument called CASALS that uses wavelength-steering technology to create continuous three-dimensional swaths of Earth's surface, eliminating the large unmapped gaps left by traditional space-based laser instruments. An airborne prototype flew successfully in November 2024, producing science-quality datasets at 22-centimeter horizontal resolution.

A team at NASA's Goddard Space Flight Center has built the Concurrent Artificially-intelligent Spectrometry Lidar System (CASALS), an instrument designed to bridge the blind spots between narrow lines of lidar data. Current space-based lidars measure Earth's forests and terrain one narrow line at a time, leaving millions of acres of land never directly measured.

CASALS steers its laser using wavelength itself rather than mechanical mirrors. A fast-pulsing, tunable 'seed' laser centered at 1040 nanometers cycles through 256 unique wavelengths as it pulses through a transmission grating. Because light bends at slightly different angles depending on wavelength, the grating naturally steers each pulse into a distinct position across the flight path, painting a continuous 3D swath.

'The team's really done a great job of sticking together and keeping on task and on schedule,' said John Yorks, a physical research scientist at GSFC and principal investigator for CASALS. 'We are being funded to optimize and improve the performance, and we're also then looking at ways to take the technologies used in the airborne instrument and mature them and prepare them for a spaceborne version in the future.'

The instrument's detector operates at 80% quantum efficiency, meaning it wastes almost none of the returning light. This allows CASALS to detect weaker signals from darker surfaces or through denser vegetation. The elimination of moving parts also reduces size, weight, and power requirements, improving reliability for space.

An airborne prototype flew aboard NASA's B200 King Air aircraft in November 2024 during a campaign over the Great Cypress Swamp in Delaware. Yorks praised the team: 'I'm very impressed with Guang Yang, Jeffrey Chen, and all our engineers, and how well CASALS performed. This worked really well from the first time we flew it, which is pretty impressive.'

The team plans to fly CASALS again as part of the Airborne Surface, Cryosphere, Ecosystem, and Nearshore Topography (ASCENT) campaign scheduled for summer 2027. Further work includes widening the instrument's swath and adding onboard data processing software before creating a space-ready prototype. If successful, CASALS could become the first spaceborne lidar capable of mapping Earth's forests and terrain as continuous three-dimensional swaths.

Analysis

Why This Matters

Continuous 3D mapping of forests and terrain would give scientists a dramatically more complete picture of Earth's surface, particularly in remote and under-sampled regions.
Improved lidar data is critical for estimating carbon stocks, tracking deforestation, and monitoring changes in ecosystems and topography over time.
A successful space mission based on CASALS could transform Earth observation, providing data with resolution and coverage that current instruments cannot achieve.

Background

Space-based lidar instruments like NASA's ICESat-2 measure the Earth's surface along a single track or a few tracks, leaving large gaps between swaths. These blind spots mean scientists must interpolate or rely on models for vast areas. CASALS builds on the same fundamental lidar principles but uses a novel transmitter and optical grating system to create a continuous swath. The project is supported by NASA's Earth Science Technology Office (ESTO) and involves partnerships with the University of California, Santa Barbara and Virginia Tech. An airborne prototype has already demonstrated the concept.

Key Perspectives

NASA CASALS team: The instrument performed beyond expectations on its first flight and is on schedule for further improvements. The team sees a clear path from the airborne prototype to a spaceborne version that could fill a critical gap in Earth remote sensing. Earth science community: Researchers who use lidar data for ecosystem, cryosphere, and topography studies are likely to welcome a tool that eliminates gaps and provides higher resolution, enabling new types of analysis. Space mission planners: The compact, low-power design of CASALS makes it an attractive candidate for future NASA Earth science missions, but transitioning from a successful airborne prototype to a flight-ready space instrument remains a significant engineering challenge.

What to Watch

The next airborne demonstration of CASALS during the ASCENT campaign in summer 2027, which will test improvements including a wider swath.
Progress on maturing the space-ready prototype and any announcement of opportunity from NASA for a future Earth science mission that could host CASALS.
Comparisons with other emerging lidar technologies from other space agencies or commercial providers that may offer alternative approaches to wide-swath mapping.

Sources

NASA’s CASALS Instrument Bridges Gaps in 3D Maps of Earth’s Surface · NASA

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12 claims in this story checked against 1 source: 12 supported.

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SupportedCASALS promises continuous 3D maps of Earth’s surface that eliminate gaps in data.NASA: “Rather than mechanically steering a laser with moving mirrors, CASALS steers light using wavelength itself, generating a continuous, 3D swath of the ground below.”
SupportedThe summary says CASALS uses wavelength steering and machine learning to create swath-based topography.NASA: “NASA’s CASALS instrument will blend machine learning with an ultra-compact lidar instrument to adaptively ‘sweep’ large swaths of Earth’s surface.”
SupportedYorks said the team was sticking together and on schedule, and was funded to improve the instrument and prepare its technology for a future spaceborne version.NASA: ““The team’s really done a great job of sticking together and keeping on task and on schedule. We are being funded to optimize and improve the performance, and we’re also then looking at ways to take the technologies used in the airborne instrument and mature them and prepare them for a spaceborne version in the future,” said Yorks.”
SupportedYorks said he was impressed with the team and that CASALS worked well from its first flight.NASA: ““I’m very impressed with Guang Yang, Jeffrey Chen, and all our engineers, and how well CASALS performed. This worked really well from the first time we flew it, which is pretty impressive,” said Yorks.”
SupportedNASA researchers developed CASALS, which steers its laser by wavelength to create continuous 3D swaths and eliminate gaps between lidar data lines.NASA: “A team of researchers at NASA’s Goddard Space Flight Center (GSFC) has developed a new instrument designed to eliminate blind spots between lines of lidar data on the Earth’s surface.”
SupportedAn airborne prototype flew in November 2024 and produced science-quality datasets at 22-centimeter horizontal resolution.NASA: “In November 2024, an airborne CASALS prototype flew aboard NASA’s B200 King Air aircraft. The instrument produced science-quality datasets on its first campaign”
SupportedThe source identifies Yorks as a GSFC physical research scientist and CASALS principal investigator.NASA: “John Yorks, a physical research scientist at GSFC and Principal Investigator for CASALS”
SupportedTraditional space-based lidars measure forests and terrain one narrow line at a time, leaving millions of acres never directly measured.NASA: “From orbit, today’s space-based laser instruments measure Earth’s forests and terrain one narrow line at a time. Between those lines are enormous gaps that include millions of acres of land scientists never directly measure.”
SupportedCASALS uses a seed laser centered at 1040 nanometers and cycles through 256 wavelengths through a transmission grating.NASA: “CASALS uses a fast-pulsing, tunable “seed” laser centered at 1040 nanometers, rapidly cycling through 256 unique wavelengths as it pulses through an optical component with a microscopic pattern of ridges called a transmission grating.”
SupportedCASALS’s detector operates at 80% quantum efficiency, enabling it to detect weaker returns from darker surfaces or denser vegetation.NASA: “CASALS operates at 80% QE. This means CASALS wastes almost none of the light that makes it back to the sensor. With QE that high, CASALS can detect much weaker return signals, allowing it to collect useful measurements from darker surfaces or through denser vegetation.”
SupportedThe airborne prototype flew aboard NASA’s B200 King Air over the Great Cypress Swamp in Delaware.NASA: “Video from a CASALS flight over the Great Cypress Swamp in Delaware on Nov. 12, 2024”
SupportedThe team plans to fly CASALS again during the ASCENT campaign scheduled for summer 2027.NASA: “The team aims to fly CASALS again as part of the Airborne Surface, Cryosphere, Ecosystem, and Nearshore Topography (ASCENT) campaign, scheduled for summer 2027.”