Ida Asteroid 243

Astronomical specifications: Discovery   Orbital characteristics: Distance from Sun   km Perihelion   (106 km) Aphelion   (106 km) Inclination   deg Eccentricity   Orbital periode rond Sun   days Main orbital speed   km/s Inclination to Sun equator   deg Number of moons  1 Rings   Physical characteristics: Dimensions   km Radius   km Surface area   km² Volume   106 km³ Mass   1024 kg Density   g/cm³ Equatorial surface gravity   m/s² Escape velocity   km/s Rotation period   days Surface temperature   K Axial tilt   deg Atmospheric composition

Asteroid Ida and its satellite Dactyl in Enhanced Color. The Galileo spacecraft surveyed Ida in 1993 on its way to explore the Jupiter system in 1995-97. This color picture was made from images taken by the imaging system on the Galileo spacecraft about 14 minutes before its closest approach to asteroid 243 Ida on August 28, 1993. The range from the spacecraft was about 10,500 kilometers.

Descriptions:

• Ida is a heavily cratered, irregularly shaped asteroid in the main asteroid belt between Mars and Jupiter -- the 243rd asteroid to be discovered since the first one was found at the beginning of the 19th century. Ida is placed by scientists in the S class (stony or stony iron meteorites). It is a member of the Koronis family, which scientists believe was created when a larger body perhaps 200 to 300 kilometers (120 to 180 miles) in diameter was smashed relatively recently -- at least considerably after the solar system formed some 4.5 billion years ago.
• Ida is about 56 x 24 x 21 kilometers (35 x 15 x 13 miles) in size, more than twice as large as Gaspra. It has a period of rotation of 4 hours, 38 minutes. Its density has been estimated to be between 2.2 and 2.9 grams per cubic centimeter. Ida's age is somewhat baffling. Its surface is heavily cratered suggesting that it has existed in its present form for at least a billion years and perhaps much longer. It is also considerably older than estimates for the Koronis breakup.

Mission details:

On August 28, 1993 Galileo came within 2,400 kilometers (1,500 miles) of 243 Ida, the second asteroid ever encountered by a spacecraft. They passed each other at a relative velocity of 12.4 km/sec (28,000 mph). At the time of the encounter, Ida and Galileo were 441 million kilometers from the Sun.

Ida missions: