(172034) 2001 WR1

, provisional designation:, is a sub-kilometer near-Earth object of the Amor group, approximately 650 m in diameter. The S-type asteroid has been identified as a potential flyby target of the Hayabusa2 mission. It was discovered on 17 November 2001, by astronomers with the Lincoln Near-Earth Asteroid Research at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. The asteroid has a rotation period of 8.0 hours and possibly an elongated shape. It remains unnamed since its numbering in December 2007.

Orbit and classification


 is an Amor asteroid – a subgroup of near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it. The object orbits the Sun at a distance of 1.02–1.54 AU once every 17 months (527 days; semi-major axis of 1.28 AU). Its orbit has an eccentricity of 0.20 and an inclination of 25° with respect to the ecliptic. The body's observation arc begins with its first observation in February 1953, more than 48 years prior to its official discovery observation at Socorro. The precovery was taken at Palomar Observatory and published by the Digitized Sky Survey.

Close encounters
 has an Earth minimum orbital intersection distance of 0.0747 AU which corresponds to 29.1 lunar distances. In September 1926, it approached Earth to 0.1496 AU, its closest approach of all close encounters since 1900. Only in September 2199, it will approach Earth at a similar distance of 0.1514 AU.

Hayabusa2 mission
 was proposed as a target of the Hayabusa2 extended mission for a flyby planned to occur on 27 June 2023. When the spacecraft returned to Earth and delivered the sample capsule in December 2020, it was expected to retain 30 kg of xenon propellant, which can be used to extend its service and flyby new targets to explore. However, this asteroid was not selected as a target for Hayabusa2; two other asteroids were selected instead.

Numbering and naming
This minor planet was numbered by the Minor Planet Center on 24 December 2007 (M.P.C. 61443). , it has not been named.

Physical characteristics
 has been characterized as a common, stony S-type asteroid.

Rotation period
In March 2018, a rotational lightcurve of  was obtained from photometric observations by Brian Warner at the Palmer Divide Station in California. Lightcurve analysis gave a rotation period of $0.631 km$ hours with a brightness amplitude of 0.95 magnitude (U=3), indicative of a non-spherical shape.

Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer,  has an albedo of 0.34 and measures 0.63 and 0.66 kilometers in diameter, respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 0.818 kilometers based on an absolute magnitude of 17.8.