# Deimos

Mars II

Deimos [DEE-mos] (panic) is a moon of Mars and was named after an attendant of the Roman war god Mars. Deimos is a dark body that appears to be composed of C-type surface materials. It is similar to the C-type (blackish carbonaceous chondrite) asteroids that exist in the outer asteroid belt. Some scientists speculate that Deimos and Phobos (the other martian moon), are captured asteroids; however, other scientists present arguments counter to this theory. Both Deimos and Phobos are saturated with craters. Deimos has a smoother appearance caused by partial filling of some of its craters.

## Deimos Statistics

    Discovered by .................................... Asaph Hall
    Date of discovery ...................................... 1877

    Mass (kg) ........................................... 1.8e+15
    Mass (Earth = 1) ................................. 3.0120e-10
    Radius (km) ..................................... 7.5x6.1x5.5
    Radius (Earth = 1) ............................... 1.1759e-03
    Mean density (gm/cm^3) .................................. 1.7

    Mean distance from Mars (km) ......................... 23,460
    Rotational period (days) ............................ 1.26244
    Orbital period (days) ............................... 1.26244
    Mean orbital velocity (km/sec) ......................... 1.36

    Orbital eccentricity ................................... 0.00
    Orbital inclination ................................. 0.9-2.7°

    Escape Velocity (km/sec) ............................. 0.0057

    Visual geometric albedo ................................ 0.07
    Magnitude (Vo) ........................................ 12.40

## Views of Deimos

Mosaic of Deimos (GIF, 181K)
Measuring 16 by 12 km (10 by 7.5 mi) Deimos circles Mars every 30 hours. Craters of varying age dot its surface, which is somewhat smoother than the surface of Phobos. (Courtesy NASA/JPL)

Deimos (GIF, 13K)
This image was taken by the Viking Orbiter spacecraft in 1977. (Courtesy NSSDC/NASA)

Deimos (GIF, 50K; JPEG, 8K)
This image shows a slightly different view of Deimos. It was acquired by the Viking Orbiter spacecraft. (Credit: Calvin J. Hamilton)

Map of Deimos (GIF, 102K; caption)
This image is a photomosaic of Deimos, the outer satellite of Mars. The leading side faces forwards in the orbit of Deimos. The trailing side faces backwards along the orbit. Longitude 0 is at the blunter end with the most prominent craters, and faces Mars. As with all conformal (true shape) projections, the scale in these maps varies, increasing from the centre to the outer edge. (Courtesy Phil Stooke, NSSDC, and NASA)

Mars Phobos

##### Author: Calvin J. Hamilton.