NEAR'S CLOSE FLYBY OF C-TYPE ASTEROID 253 MATHILDE

作     者：James F.Bell III the NEAR Science Team 

作者机构：Cornell University Department of Astronomy Ithaca NY 14853-6801 USA 

出 版 物：《紫金山天文台台刊》 

年 卷 期：1998年第2期

页      面：44-50页

学科分类：07[理学] 0704[理学-天文学] 

主　　题：小行星 飞船 紫金山 天文台 探测 

摘      要：On June 27, 1997, the Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 1200km of the main belt asteroid 253 Mathilde. Previous observations of Mathilde had revealed it to be a C-type asteroid with an astonishingly-long rotation period of 17.4 days, an albedo of 3.8%, and a mean diameter of 60 km. Observations by NEAR reveal that Mathilde has a roughly triaxial shape of 66 × 48 × 46 km diameter and a mass of 1. 02 × 10 g, implying a mean density of only 1. 3g/cm3 . The surface of Mathilde was observed to be saturated with large impact craters, showing a range of visible topography in excess of 5 km. Multispectral observations did not reveal any substantial color differences across the surface, and coverage at multiple phase angles was used to derive a preliminary albedo of 3. 5 % to 5% .The low observed density, lack of color variations, and low albedo all suggest that Mathilde may be a primitive, carbon - rich object with an interior that contains substantial pore space.