Mars Exploring The Planets Mars

Mars and Satellites

Mars Data

Mean distance from Sun:   1.524 AU
(228,000,000 km/141,700,000 mi)
Diameter:   6,792 km (4,220 mi)
Length of year:   687 days
Rotation period:   24 hr 37 min
Mean orbital velocity:   24.14 km/sec (15 mi/sec)
Inclination of axis:   25.2°
Mean density:   3.95 grams/cm³
Inclination to ecliptic:   1.85°
Number of observed satellites:   2
     
Comparisons with Earth:
Average distance from Sun:   1.52 x Earth
Diameter:   0.532 x Earth
Mass:   0.108 x Earth
Density:   0.7 x Earth
     

Mars Satellites

Mars is orbited by two small, potato-shaped satellites, Phobos and Deimos. These tiny Martian satellites are thought to be captured asteroids composed of dark, carbon-rich rock. Each satellite has been heavily cratered by impacting meteoritic debris.

 

Phobos



Mean radius: 21 km (13 mi)
Distance from Mars: 9,380 km (5,830 mi)
Period of Rotation: 0.3188 days
74k GIF
Viking Orbiter Image
     

 


173K GIF

MOC release #50103a
image from Malin Space Science Systems/NASA

Mars Global Surveyor View of Phobos
 

This image of Phobos was taken in August of 1998 by the Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor spacecraft. The high-resolution image shows new details of the surface of Phobos, the largest of two satellites orbiting the red planet. At the top of the image is Phobos' largest crater "Stickney", 10 km (6 miles) in diameter. Features visible in the crater and along its rim offer clues to how the crater was formed and the mixed composition of materials that make up this satellite.

Mars Global Surveyor views of Phobos

 

Deimos


  Mean radius: 12 km (8 mi)
Distance from Mars: 23,460 km (14,580 mi)
Period of rotation: 1.2625 days
133k GIF
30k JPEG
Viking Orbiter Image

     


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