Science. 1994 Sep 9;265(5178):1543-7. doi: 10.1126/science.265.5178.1543.
The first images of the asteroid 243 Ida from Galileo show an irregular object measuring 56-kilometers by 24 kilometers by 21 kilometers. Its surface is rich in geologic features, including systems of grooves, blocks, chutes, albedo features, crater chains, and a full range of crater morphologies. The largest blocks may be distributed nonuniformly across the surface; lineaments and dark-floored craters also have preferential locations. Ida is interpreted to have a substantial regolith. The high crater density and size-frequency distribution (-3 differential power-law index) indicate a surface in equilibrium with saturated cratering. A minimum model crater age for Ida-and therefore for the Koronis family to which Ida belongs-is estimated at 1 billion years, older than expected.
伽利略号拍摄到的小行星 243 号 Ida 的首张照片显示，这颗不规则物体的尺寸分别为 56 千米、24 千米和 21 千米。其表面富含地质特征，包括沟槽系统、块状物、滑道、反照率特征、链状陨石坑和各种形态的陨石坑。最大的块状物可能不均匀地分布在表面上；线性特征和具有暗底的陨石坑也有优先的位置。Ida 被解释为具有大量的表土。高陨石坑密度和大小频率分布（-3 个差分幂律指数）表明表面与饱和陨石坑形成处于平衡状态。 Ida 的最小模型陨石坑年龄（因此也是 Ida 所属的 Koronis 族的最小模型陨石坑年龄）估计为 10 亿年，比预期的要老。
