9950 ESA

Orbit and classification

ESA is an Amor asteroid – a subgroup of near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it. It orbits the Sun at a distance of 1.1–3.7 AU once every 3 years and 10 months (1,390 days). Its orbit has an eccentricity of 0.53 and an inclination of 15° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Caussols in November 1990.

Close approaches

ESA has an Earth minimum orbit intersection distance of 0.2806 AU, which corresponds to 109.3 lunar distances. It approached the Earth at 0.393 AU on 18 October 1990, three weeks prior to its discovery, and made two more close approaches in August and September 2013, respectively. Its next close encounter with Earth will be in October 2032, at distance of 0.3043 AU.

The eccentric asteroid is also a Mars-crosser. In March 1987, it approached the Red Planet at 0.0990 AU.

Physical characteristics

ESA is an assumed stony S-type asteroid.

Rotation period

In 2013, three rotational lightcurves of ESA were obtained from photometric observations by the EURONEAR Lightcurve Survey and by American astronomers Brian Warner and Robert Stephens at the Center for Solar System Studies (U81/U82). Lightcurve analysis gave a rotation period between 6.707 and 6.712 hours with a brightness variation of 0.44 to 0.89 magnitude (). A high brightness amplitude typically indicates that the body's shape is irregular and elongated, rather than spherical.

Diameter and albedo

In the early 1990s, David Tholen at the Institute for Astronomy of the University of Hawaii estimated a diameter of 3 kilometers for ESA. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.71 kilometers based on an absolute magnitude of 16.2.

Naming

This minor planet was named after the European Space Agency (ESA), which formed in 1974. The name was suggested by French astronomer Jean Louis Heudier, after whom the asteroid 4602 Heudier was named. The official naming citation was published by the Minor Planet Center on 15 December 2005 (M.P.C. 55720).

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