Analysis of information sources in references of the Wikipedia article "Phobos (moon)" in English language version.
When the error bars are taken into account, only one of these, Phobos, has a porosity below 0.2...
The total delta-v required for a mission to land on Phobos and come back is startlingly low—only about 80 percent that of a round trip to the surface of Earth's moon. (That is in part because of Phobos's feeble gravity; a well-aimed pitch could launch a softball off its surface.)
It is light, with a density less than twice that of water, and orbits just 5,989 kilometers (3,721 mi) above the Martian surface.
One idea is that Phobos and Deimos, Mars's other moon, are captured asteroids.
One of the most striking features of Phobos, aside from its irregular shape, is its giant crater Stickney. Because Phobos is only 28 by 20 kilometers (17 by 12 mi), it must have been nearly shattered from the force of the impact that caused the giant crater. Grooves that extend across the surface from Stickney appear to be surface fractures caused by the impact.
The currently available data on the lithologic composition of the Kaidun meteorite– primarily the composition of the main portion of the meteorite, corresponding to CR2 carbonaceous chondrites and the presence of clasts of deeply differentiated rock – provide weighty support for considering the meteorite's parent body to be a carbonaceous chondrite satellite of a large differentiated planet. The only possible candidates in the modern Solar System are Phobos and Deimos, the moons of Mars.
When the error bars are taken into account, only one of these, Phobos, has a porosity below 0.2...
The total delta-v required for a mission to land on Phobos and come back is startlingly low—only about 80 percent that of a round trip to the surface of Earth's moon. (That is in part because of Phobos's feeble gravity; a well-aimed pitch could launch a softball off its surface.)
