Lidar

An instrument that fires rapid laser pulses at the surface and times how long the light takes to bounce back. Those travel times reveal precise heights and the shape of what the pulse hit.

Why it matters

Lidar measures heights with stunning precision — the tops and structure of forests, the thickness of ice sheets, the height of clouds — giving 3D detail that flat images cannot capture.

Where you’ll meet it

• GEDI on the ISS uses lidar to measure forest canopy height and the carbon stored in trees.
• ICESat-2 fires a lidar to track the changing elevation of ice sheets, sea ice, and land.
• CALIPSO, an earlier mission, used lidar to profile clouds and aerosols by altitude.

In plain terms

It’s like a bat’s echolocation, but with light instead of sound — sending out a pulse and timing the echo to learn exactly how far away and how tall something is.