Wednesday, July 21, 2010

Best chance for life beyond Earth # 3: Europa

Europa (pronounced /jʊˈroʊpə/ ( listen); or as Greek Ευρώπη) is the sixth moon of the planet Jupiter, and the smallest of its four Galilean satellites. Europa was discovered in 1610 by Galileo Galilei (and possibly independently by Simon Marius), and named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete.

Roughly the size of Earth's Moon, Europa is primarily made of silicate rock and likely has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and streaks, while craters are relatively infrequent. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably serve as an abode for extraterrestrial life.[12] This hypothesis proposes that heat energy from tidal flexing causes the ocean to remain liquid and drives geological activity similar to plate tectonics.[13]

Although only fly-by missions have visited the moon, the intriguing characteristics of Europa have led to several ambitious exploration proposals. The Galileo mission provided the bulk of current data on Europa. A new mission to Jupiter's icy moons, the Europa Jupiter System Mission (EJSM), is proposed for a launch in 2020.[14] Conjecture on extraterrestrial life has ensured a high profile for the moon and has led to steady lobbying for future missions.

Discovery: Jan 7, 1610 by Galileo Galilei
Diameter (km): 3,138
Mass (kg): 4.8e22 kg
Mass (Earth = 1) 0.0083021
Surface Gravity (Earth = 1): 0.135
Mean Distance from Jupiter (km): 670,900
Mean Distance From Jupiter (Rj): 9.5
Mean Distance from Sun (AU): 5.203
Orbital period (days): 3.551181
Rotational period (days): 3.551181
Density (gm/cm³) 3.01
Orbit Eccentricity: 0.009
Orbit Inclination (degrees): 0.470
Orbit Speed (km/sec): 13.74
Escape velocity (km/sec): 2.02
Visual Albedo: 0.64
Surface Composition: Water Ice

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