Moons of Mars binary asteroid that separated under tidal forces. Phobos could be a second-generation Solar System object that coalesced in orbit after Mars formed, rather than forming concurrently out of the same birth cloud as Mars. Another hypothesis is that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a large planetesimal. The high porosity of the interior of Phobos (based on the density of 1.88 g/cm, voids are estimated to comprise 25 to 35 percent of Phobos' volume) is inconsistent with an asteroidal origin. Observations of Phobos in the thermal
Mars Cube One Mars Cube One Mars Cube One (or MarCO) is a Mars flyby mission that was launched on 5 May 2018 alongside NASA's "InSight" Mars lander mission. It consists of two nanospacecraft, MarCO-A and MarCO-B, that were able to provide a real-time communications link to Earth for "InSight" during its entry, descent, and landing (EDL) on 26 November 2018 - when "InSight" was out of line of sight from the Earth. Both are of the 6U CubeSat format, and the mission is a test of new miniaturized communications and navigation technologies. These are the first CubeSats designed to operate beyond Earth