Deimos and Phobos Interior Explorer Deimos and Phobos Interior Explorer Deimos and Phobos Interior Explorer (DePhine) is a European mission concept to use a dedicated orbiter to explore the two Moons of Mars: Phobos and Deimos. The mission concept was proposed in 2016 to the European Space Agency's Cosmic Vision programme for launch in 2030, but it was not chosen as a finalist for the M5 mission class. DePhine was proposed in 2016 to ESA's Cosmic Vision programme as an M-class (medium class) mission for launch in 2030 as the M5 mission. It was proposed by the Institute of Planetary Research of the German Aerospace
Phobos (moon) seen from Phobos, Mars would appear 6,400 times larger and 2,500 times brighter than the full Moon appears from Earth, taking up a quarter of the width of a celestial hemisphere. The Mars–Phobos Lagrangian L1 is above Stickney, which is unusually close to the surface. An observer situated on the Martian surface, in a position to observe Phobos, would see regular transits of Phobos across the Sun. Several of these transits have been photographed by the Mars Rover "Opportunity". During the transits, Phobos's shadow is cast on the surface of Mars; an event which has been photographed by several spacecraft.