Red Planet and Satellites

MARS PLANET

Mars is the fourth planet from the Sun and the seventh largest

Mars (Greek: Ares) is the god of War.

The planet probably got this name due to its red color

orbit: 227,940,000 km (1.52 AU) from Sun
diameter: 6,794 km
mass: 6.4219e23 kg

Volume (1010 km3) 16.318 108.321 0.151
Equatorial radius (km) 3396.2 6378.1 0.532
Polar radius (km) 3376.2 6356.8 0.531
Volumetric mean radius (km) 3389.5 6371.0 0.532
Core radius (km) 1700 3485 0.488
Ellipticity (Flattening) 0.00648 0.00335 1.93
Mean density (kg/m3) 3933 5515 0.713
Surface gravity (m/s2) 3.71 9.80 0.379
Surface acceleration (m/s2) 3.69 9.78 0.377
Escape velocity (km/s) 5.03 11.19 0.450
GM (x 106 km3/s2) 0.04283 0.3986 0.107
Bond albedo 0.250 0.306 0.817
Visual geometric albedo 0.150 0.367 0.409
Visual magnitude V(1,0) -1.52 -3.86 -
Solar irradiance (W/m2) 589.2 1367.6 0.431
Black-body temperature (K) 210.1 254.3 0.826
Topographic range (km) 30 20 1.500
Moment of inertia (I/MR2) 0.366 0.3308 1.106
J2 (x 10-6) 1960.45 1082.63 1.811
Number of natural satellites 2 1
Planetary ring system No No
The first spacecraft to visit Mars was Mariner 4 in 1965.

Several others followed including Mars 2, the first spacecraft to land on Mars and the two Viking landers in 1976. Ending a long 20 year hiatus, Mars Pathfinder landed successfully on Mars on 1997 July 4. In 2004 the Mars Expedition Rovers "Spirit" and "Opportunity" landed on Mars sending back geologic data and many pictures; they are still operating after more than three years on Mars. In 2008, Phoenix landed in the northern plains to search for water. Three Mars orbiters (Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Express) are also currently in operation.

Mars' Satellites Mars has two tiny satellites which orbit very close to the martian surface: Distance Radius Mass
Satellite (000 km) (km) (kg) Discoverer Date
--------- -------- ------ ------- ---------- ----
Phobos 9 11 1.08e16 Hall 1877
Deimos 23 6 1.80e15 Hall 1877