(172034) 2001 WR1

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(172034) 2001 WR1
Discovery [1][2]
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date17 November 2001
MPC designation(172034) 2001 WR1
2001 WR1
NEO · Amor[1][3]
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc65.26 yr (23,837 d)
Aphelion1.5360 AU
Perihelion1.0185 AU
1.2773 AU
1.44 yr (527 d)
0° 40m 58.08s / day
Earth MOID0.0747 AU (29.1 LD)
Physical characteristics
Mean diameter
0.631±0.018 km[4][5]
0.66±0.17 km[6]
8.0475±0.0003 h[7][a]

(172034) 2001 WR1, provisional designation 2001 WR1, is a sub-kilometer near-Earth object of the Amor group, approximately 650 meters (2,100 feet) in diameter. The S-type asteroid has been identified as a potential flyby target of the Hayabusa2 mission.[10] 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.[1] The asteroid has a rotation period of 8.0 hours and possibly an elongated shape.[9] It remains unnamed since its numbering in December 2007.[1]

Orbit and classification[edit]

Animated orbital diagram for 2001 WR1 from 1 January 2020 to 31 December 2023
  2001 WR1 ·   Earth ·   Mars  ·   Sun

2001 WR1 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.[3] 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.[1]

Close encounters[edit]

2001 WR1 has an Earth minimum orbital intersection distance of 0.0747 AU (11,200,000 km) which corresponds to 29.1 lunar distances.[3] In September 1926, it approached Earth to 0.1496 AU (22,400,000 km), 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 (22,600,000 km).[3]

Hayabusa2 mission[edit]

2001 WR1 is currently the prime target of the Hayabusa2 mission for a flyby planned to occur on 27 June 2023.[10] When the spacecraft returns to Earth and delivers the sample capsule in December 2020, it is expected to retain 30 kg of xenon propellant, which can be used to extend its service and flyby new targets to explore.[10]

Numbering and naming[edit]

This minor planet was numbered by the Minor Planet Center on 24 December 2007 (M.P.C. 61443).[11] As of 2018, it has not been named.[1]

Physical characteristics[edit]

2001 WR1 has been characterized as a common, stony S-type asteroid.[8]

Rotation period[edit]

In March 2018, a rotational lightcurve of 2001 WR1 was obtained from photometric observations by Brian Warner at the Palmer Divide Station (U82) in California. Lightcurve analysis gave a rotation period of 8.0475±0.0003 hours with a brightness amplitude of 0.95 magnitude (U=3), indicative of a non-spherical shape.[7][a]

Diameter and albedo[edit]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 2001 WR1 has an albedo of 0.34 and measures 0.63 and 0.66 kilometers in diameter, respectively.[4][5][6] 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.[9]


  1. ^ a b Lightcurve plot of (172034) 2001 WR1 from Feb/Mar 2018 by Brian D. Warner at the Palmer Divide Observatory (U82). Rotation period 8.0475±0.0003 hours with a brightness amplitude of 0.95±0.03 mag. Quality code is 3. Summary figures at the CS3 and LCDB.


  1. ^ a b c d e f g "172034 (2001 WR1)". Minor Planet Center. Retrieved 22 September 2018.
  2. ^ "Asteroid (172034) 2001 WR1". Small Bodies Data Ferret. Retrieved 22 September 2018.
  3. ^ a b c d e f "JPL Small-Body Database Browser: 172034 (2001 WR1)" (2018-05-21 last obs.). Jet Propulsion Laboratory. Retrieved 22 September 2018.
  4. ^ a b c d Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System: EAR-A-COMPIL-5-NEOWISEDIAM-V1.0. Bibcode:2016PDSS..247.....M. Retrieved 22 September 2018.
  5. ^ a b c d Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117.
  6. ^ a b c d Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
  7. ^ a b Warner, Brian D. (July 2018). "Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2018 January-April". The Minor Planet Bulletin. 45 (3): 248–256. Bibcode:2018MPBu...45..248W. ISSN 1052-8091.
  8. ^ a b c Carry, B.; Solano, E.; Eggl, S.; DeMeo, F. E. (April 2016). "Spectral properties of near-Earth and Mars-crossing asteroids using Sloan photometry". Icarus. 268: 340–354. arXiv:1601.02087. Bibcode:2016Icar..268..340C. doi:10.1016/j.icarus.2015.12.047.
  9. ^ a b c d "LCDB Data for (172034)". Asteroid Lightcurve Database (LCDB). Retrieved 22 September 2018.
  10. ^ a b c Sarli, Bruno Victorino; Tsuda, Yuichi (September 2017). "Hayabusa 2 extension plan: Asteroid selection and trajectory design". Acta Astronautica. 138: 225–232. Bibcode:2017AcAau.138..225S. doi:10.1016/j.actaastro.2017.05.016.
  11. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 22 September 2018.

External links[edit]