(175706) 1996 FG3


is a carbonaceous asteroid and binary system, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately in diameter. The primary has a spheroidal shape. Its minor-planet moon measures approximately in diameter.
It was discovered on 24 March 1996, by Australian astronomer Robert McNaught at Siding Spring Observatory in New South Wales, Australia. was also a target of a rejected mission-proposal for the Marco Polo spacecraft. In 2017, scientist from the Chinese Academy of Sciences' Purple Mountain Observatory revealed a plan to land a probe on this asteroid in 2029, as part of an asteroid exploration mission.

Orbit and classification

orbits the Sun at a distance of 0.7–1.4 AU once every 1 years and 1 month. Its orbit has an eccentricity of 0.35 and an inclination of 2° with respect to the ecliptic. It has an Earth minimum orbital intersection distance of, which corresponds to 11.0 lunar distances. As no precoveries were taken, and no prior identifications were made, the body's observation arc begins with its official discovery observation at Siding Spring.

Target of rejected Marco Polo mission

Due to its binary nature and its low delta-v heliocentric orbit , this asteroid was selected for MarcoPolo-R, which was the Marco Polo spacecraft first proposed mission. MarcoPolo-R was originally selected for the assessment study phase in the M3 slot of ESA's Cosmic Vision program, but :Category:Cancelled spacecraft|rejected in favor of PLATO by the end of 2012.

Target of planned Chinese mission

China plans to land a probe on after 2020 as part of its asteroid exploration mission. The mission includes plans for fly-by of three asteroids, and land on to conduct in situ sampling analysis on the surface, according to Ji Jianghui, a researcher at the Purple Mountain Observatory of the Chinese Academy of Sciences and a member of the expert committee for scientific goal argumentation of deep space exploration in China. The probe is also expected to conduct a fly-by of a third asteroid to be determined at a later time. The entire mission is expected to take about six years.

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 21 February 2008. As of 2018, it has not been named.

Physical characteristics

The carbonaceous body is characterized as a rare B-type and hydrated C-type asteroid, respectively.

Lightcurves

Several rotational lightcurves of this asteroid were obtained from photometric observations taken by astronomers Petr Pravec, Petr Scheirich and Stefano Mottola, as well as by the Very Large Telescope VISR instrument. Lightcurve analysis gave a well-defined rotation period of 3.594 to 3.595 hours with a brightness variation of 0.08 to 0.10 magnitude. The asteroid is an oblate ellipsoid with a nearly spherical shape.

Diameter and albedo

According to numerous observations, including the EXPLORENEOs survey, NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission and the Spitzer Space Telescope, the asteroid measures between 1.55 and 1.90 kilometers in diameter and its surface has a low albedo of 0.03 to 0.05. The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.04 and a diameter of 1.90 kilometers.

Satellite

During the photometric observations in December 1998, the binary nature of this asteroid was revealed. It was the first binary near-Earth asteroid for which eclipse events were detected in the visible spectrum. The binary system has a diameter ratio of, a density of 1.4 g/cm3, and an ecliptic latitude of -84° for its mutual spin axis. The asteroid moon has a diameter of approximately 490 meters and an orbital period of 16.1508 hours. Its orbit is nearly circular, with an eccentricity of 0.1 and a semi-major axis of approximately 3.4 primary radii. The moon's rotation period remains unknown.