NASA’s CASALS Lidar Eliminates Gaps in Earth Surface Maps

A team at NASA’s Goddard Space Flight Center built CASALS with support from the Earth Science Technology Office. According to Phys.org, the instrument is designed to eliminate blind spots between lidar tracks on Earth’s surface.

CASALS steers light by changing its wavelength instead of moving mirrors. The system uses a fast‑pulsing, tunable seed laser centered at 1040 nanometers. It cycles through 256 unique wavelengths as the pulses pass through a transmission grating. Diffraction then directs each pulse to a distinct position across the flight path, creating a continuous 3‑D swath.

The detector array on CASALS has a quantum efficiency of 80%. According to NASA, this high efficiency means the instrument wastes almost no light that returns to the sensor. With such efficiency, CASALS can detect weaker return signals from darker surfaces or dense vegetation.

In November 2024, a prototype flew on a NASA B200 King Air aircraft. The flight reached an altitude of roughly five kilometers. According to both sources, the instrument achieved 22‑centimeter horizontal resolution and produced science‑quality datasets on its first campaign.

The team plans to fly CASALS again in summer 2027 as part of the Airborne Surface, Cryosphere, Ecosystem, and Nearshore Topography (ASCENT) campaign. They also intend to improve the instrument’s swath width and prepare a space‑ready prototype. The goal is to provide continuous 3‑D maps that fill gaps left by legacy spaceborne lidars.