Narration: Ryan Fitzgibbons


0.2 microradians. That's the angle of pointing stability of the ATLAS laser. If you placed a silver dollar 28 miles away from ATLAS, the laser's center would stay on the coin. That kind of stability is absolutely critical for the spacecraft to measure the height of Earth from orbit. To ensure pointing stability, ATLAS uses the Beam Steering Mechanism, which is a motorized mirror that moves to compensate for thermal changes that happen in orbit and prevents the ATLAS beams from bending as they head for Earth.