This just blows my mind, because it shows how far we’ve come: robotic travel to Mars is now frequent enough that we can afford to let some Cubesats hitchhike along. Two microprobes dubbed MarCO and based on the Cubesat bus will be accompanying the InSight Mars lander, set to launch on the next Mars window. They will be released from the Centaur booster shortly before InSight is released, and after the long cruise to Mars will act as a data relay during the critical atmosphere entry phase of the mission. They carry cold gas thrusters for tweaking their course, but it will not be enough to get them into Mars orbit; thus, they’ll make a flyby of the red planet, the first Cubesats ever to accomplish such a feat, and then zip onwards in heliocentric orbit.
Pretty cool. 😉