Estimating the Mass of Asteroid 253 Mathilde from Tracking Data During the NEAR Flyby

• Published in: Science (American Association for the Advancement of Science) Vol. 278; no. 5346; pp. 2106 - 2109
• Main Authors: Yeomans, D. K., J.-P. Barriot, Dunham, D. W., Farquhar, R. W., Giorgini, J. D., Helfrich, C. E., Konopliv, A. S., McAdams, J. V., Miller, J. K., Owen, W. M., Scheeres, D. J., Synnott, S. P., Williams, B. G.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 19.12.1997; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Asteroids; Asteroids (minor planets); Astronomy; Average linear density; Density; Earth, ocean, space; Ephemerides; Exact sciences and technology; Geometric planes; Gravity; Light; Mass; Navigation; Observations; Opportunities; Orbit determination; Physics; Pixels; Planets, their satellites and rings. Asteroids; Scientific Concepts; Solar system; Spacecraft; Spacecraft orbits; Mass; Flyby missions; Space probe observation; Density; Asteroids
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.278.5346.2106

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (± 0.044) x 10$^{20}$ grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.