Mars Cube One (MarCO) is a pair of cereal box-size spacecraft scheduled to be launched in 2018 along with NASA’s Mars lander InSight. The two tiny CubeSats will piggyback with the InSight lander to help relay communications during the probe's entry, descent and landing phase.The 6U CubeSats, named 'Mars Cube One' (MarCO) , are identical. They measure 60×10×10 cm with one of them serving as backup. They will flyby Mars during the landing phase and relay InSight‍‍ '​‍s telemetry in real time MarCO is a technology capability demonstration of communications relay system. (Image credit: NASA' s JPL)