How we build a space laser: To build a satellite that will measure all the bumps and dips of our dynamic Earth, engineers started with a black box, built of a composite honeycomb material to make it as light as possible. The structure was precisely manufactured with an opening to allow lasers to beam to Earth, and other windows sized for a telescope that will capture photons that bounce off our planet and return to the satellite. The box was measured and marked to denote where the assembly of aligned mirrors, electronics, lasers and photon detectors would be attached. ICESat-2’s Advanced Topographic Laser Altimeter System, or ATLAS, will measure the elevation of Earth’s surfaces, from ice sheets to forests to oceans. Its six laser beams will generate a more detailed elevation portrait than single beam of original ICESat, which flew from 2003 to 2009. And with the beams paired, scientists will be able to measure surface slope and better calculate height changes. To measure elevation, ...