Optical PAyload for Lasercomm Science (OPALS) is a spacecraft communication instrument developed at the Jet Propulsion Laboratory that was tested on the International Space Station (ISS) from 18 April 2014 to 17 July 2014 to demonstrate the technology for laser communications systems between spacecraft and ground stations.

[2] The purpose of OPALS is to do research into replacing traditional radio-frequency (RF) communications which are currently used on spacecraft.

[3] It launched from Cape Canaveral to the ISS on 18 April 2014 on a Falcon 9 SpaceX CRS-3 Dragon capsule resupply.

[6] The goal of the OPALS mission was to demonstrate a downlink of a short video from space using laser communication.

[7] To avoid this, the gimbal is designed with mechanical stops and electromechanical limit switches so that its field of regard (the area where it can point) is limited to 36° wide in elevation and 106° in azimuth, where the azimuthal axis is generally in the direction of motion of the ISS.

[7] Because of the gimbal field of regard geometry, the flight system can only perform downlinks when the ISS is north of the ground station.

[13] The list of directions for the gimbal to point was calculated based on the ISS GPS state vector and attitude quaternion.

[7] Signal is received through a 3 nanometer bandpass 1550 nanometer spectral filter in front of an indium gallium arsenide acquisition camera and an avalanche photodiode detector, which keeps the receiver from being overwhelmed by sunlight backscattered by Earth's atmosphere during day passes.