Adrastea (moon)
Adrastea or Jupiter XV, is the second closest moon to Jupiter. It was found by David C. Jewitt and G. Edward Danielson in Voyager 2 probe photographs taken in 1979 and received the designation S/1979 J 1.[5][6] In 1983, it was named after the mythological Adrastea,[7] who was a daughter of Jupiter and Ananke.
Discovery | |
---|---|
Discovered by | David C. Jewitt G. Edward Danielson |
Discovery date | July 8, 1979 |
Orbital characteristics | |
Mean orbit radius | 129,000 km[1][2] |
Eccentricity | 0.0015[1][2] |
0.29826 d (7 h 9.5 min)[1][2] | |
Average orbital speed | 31.378 km/s[3] |
Inclination | 0.03° (to Jupiter's equator)[1][2] |
Satellite of | Jupiter |
Physical characteristics | |
Dimensions | 20×16×14 km[4] |
Mean radius | 8.2 ± 2.0 km[4] |
Volume | ~2,345 km³[3] |
Mass | ~2×1015 kg[3] |
Mean density | 0.86 g/cm³ (assumed) |
~0.002 m/s² (0.0004 g)[3] | |
~0.008 km/s[3] | |
synchronous | |
zero[4] | |
Albedo | ~0.1 ± 0.045[4] |
Temperature | ~122 K |
Adrastea was the first moon to be found from images taken by an interplanetary spacecraft, rather than through telescopic photography.
Physical characteristics
Adrastea is non-spherical and measures 20x16x14 km³ across.[4] What Adrastea is made of and the mass of Adrastea are not known, but assuming that its mean density is like that of Amalthea (~0.86 g/cm³)[8] its mass can be estimated at ~2×1015 kg. Amalthea's density implies that moon is composed of water ice with a porosity of 10-15%, and Adrastea may be similar.[8]
No surface details of Adrastea are known, due to the low resolution of available images.[4]
Orbit
Adrastea is the smallest and second closest member of the closer moons to Jupiter. It orbits Jupiter at ~129,000 km (1.806 Jupiter radii) within the planet's Main Ring. The orbital eccentricity of ~0.0015 and inclination of ~ 0.03° relative to the equator of Jupiter are very small.[2]
Exploration
Adrastea was found in Voyager 1 and 2 images, but appeared only as a dot.[6] The Galileo spacecraft was able to see its shape, but the images remain poor.[4]
References
Other websites
- Adrastea Profile Archived 2013-03-17 at the Wayback Machine by NASA's Solar System Exploration