NASA's InSight lander will make its way to the red planet with two smaller companions: briefcase-sized CubeSats called Mars Cube One (MarCO). Each one measures 14.4 x 9.5 x 4.6 inches and is comprised of six 4-inch square cube satellites. All three of them will be ferried to space aboard an Atlas V rocket, but the smaller solar-powered spacecraft will be operating independently from InSight to act as its link with the ground team. See, the MarCOs are actually communications-relay satellites, programmed to fly over the planet while the lander is descending. Without them, InSight will first have to radio its landing and descent info to the Mars Reconnaissance Orbiter, which will then forward it to Earth.