May 3, 2018
In this undated photo made available by NASA on March 29, 2018, engineer Joel Steinkraus uses sunlight to test the solar arrays on one of the Mars Cube One (MarCO) spacecraft at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The MarCOs will be the first CubeSats - a kind of modular, mini-satellite - flown into deep space. They're designed to fly along behind NASA's InSight lander on its cruise to Mars. (NASA/JPL-Caltech via AP)