Mars Fact Sheet

All this information came from a NASA employee: David R willams

Mars/Earth Comparison

Bulk parameters

                                   Mars           Earth     Ratio (Mars/Earth)

Mass (1024 kg)                     0.6419          5.9736         0.107

Volume (1010 km3)                 16.318         108.321          0.151  

Equatorial radius (km)             3397           6378            0.533

Polar radius (km)                  3375           6356            0.531

Volumetric mean radius (km)        3390           6371            0.532

Core radius (km)                   1700           3485            0.488

Ellipticity                        0.0065          0.0034         1.912

Mean density (kg/m3)               3933           5520            0.713 

Surface gravity (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                        0.16            0.385          0.416

Visual geometric albedo            0.150           0.367          0.409

Visual magnitude V(1,0)           -1.52           -3.86             -

Solar irradiance (W/m2)             595           1380            0.431

Black-body temperature (K)       216.6           247.3            0.875

Topographic range (km)               36             20            1.800

Moment of inertia (I/MR2)          0.366           0.3308         1.106

J2 (x 10-6)                     1960.45         1082.63           1.811

Orbital parameters

                                   Mars           Earth     Ratio (Mars/Earth)

Semimajor axis (106 km)          227.9           149.6            1.524

Sidereal orbit period (days)     686.980         365.256          1.881

Tropical orbit period (days)     686.930         365.242          1.881

Perihelion (106 km)              206.6           147.1            1.404       

Aphelion (106 km)                249.2           152.1            1.638

Synodic period (days)            779.94             -               -

Mean orbital velocity (km/s)      24.13           29.79           0.810

Orbit inclination (deg)            1.85            0.00             -

Orbit eccentricity                 0.0934          0.0167         5.593

Sidereal rotation period (hrs)    24.6229         23.9345         1.029

Obliquity to orbit (deg)          25.19           23.45           1.074

Mars Observational Parameters

Discoverer:      Unknown

Discovery Date:  Prehistoric



Apparent diameter from Earth

        Maximum (seconds of arc)   25.7

        Minimum (seconds of arc)    3.5

Distance from Earth

        Minimum (106 km)           54.5

        Maximum (106 km)          401.3

Apparent magnitude at opposition   -2.0

Mars Mean Orbital Elements (J2000)

Semimajor axis (AU)                  1.52366231  

Orbital eccentricity                 0.09341233   

Orbital inclination (deg)            1.85061   

Longitude of ascending node (deg)   49.57854  

Longitude of perihelion (deg)      336.04084   

Mean Longitude (deg)               355.45332

Martian Atmosphere


Surface Pressure:  ~6.1 mb (variable) [6.9 mb to 9 mb (Viking 1 Lander site)]

Surface Density: ~0.020 kg/m3

Scale height:  11.1 km

Average temperature:  ~210 K

Diurnal temperature range: 184 K to 242 K (Viking 1 Lander site)

Wind speeds:  2-7 m/s (summer), 5-10 m/s (fall), 17-30 m/s (dust storm) (Viking Lander sites)

Mean molecular weight: 43.34 g/mole 

Atmospheric composition (by volume): 

    Major      : Carbon Dioxide (CO2) - 95.32% ; Nitrogen (N2) - 2.7%

                 Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08% 

    Minor (ppm): Water (H2O) - 210; Nitrogen Oxide (NO) - 100; Neon (Ne) - 2.5;

                 Hydrogen-Deuterium-Oxygen (HDO) - 0.85; Krypton (Kr) - 0.3; 

                 Xenon (Xe) - 0.08

Satellites of Mars

                                    Phobos         Deimos

Mean distance from Mars (km)         9377          23436

Sidereal orbit period (days)        0.31891        1.26244

Orbital inclination (deg)            1.08           1.79

Orbital eccentricity                0.0151         0.00033

Major axis radius (km)                13              8

Minor axis radius (km)                 9              5

Mass (1015 kg)                       10.8            1.8

Mean density (kg/m3)                 1900           1750 

Geometric albedo                      0.06           0.07

Visual magnitude V(1,0)             +11.8          +12.89