Apparent retrograde motion notable on Mars which has two natural satellites, Phobos and Deimos. Both moons orbit Mars in an eastward (prograde) direction, however Deimos has an orbital period of 1.23 Martian sidereal days, making it supersynchronous, whereas Phobos has an orbital period of 0.31 Martian sidereal days making it subsynchronous. Consequently, although both moons are travelling in an eastward (prograde) direction, they appear to be travelling in opposite directions when viewed from the surface of Mars due to their orbital periods in relation to the rotational period of the planet. All other planetary bodies in the Solar System also appear to periodically
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