Deimos (also M2 Deimos) is the second satellite of Mars.  The
    following properties are from K.R. Lang, 'Astrophysical Data:
    Planets and Stars', pp.70-73:
 
      Distance from planet center:    23.52e03    km
                                       6.90       planet radii
                   Orbital period:     1.262      days
                     Eccentricity:     0.0008     degrees
                      Inclination:     0.9 to 2.7 degrees (variable)
 
                           Radius:     8 x 6      km
                             Mass:     2.0e-5     1.e23 grams
                          Density:  <= 2          grams/cm^3
               Visual Magnitude
                    at Opposition:    12.7
                 at Unit Distance:   +13.0
          Geometric Visual Albedo:     0.07