(231937) 2001 FO32
Radar images of 2001 FO32 from Goldstone on 22 March 2021
Discovery[1][2]
Discovered byLINEAR
Discovery siteLincoln Lab ETS
Discovery date23 March 2001
Designations
2001 FO32
NEO · Apollo · PHA[3]
Orbital characteristics[3]
Epoch 17 December 2020 (JD 2459200.5)
Uncertainty parameter 0
Observation arc20.00 yr (7,304 days)
Aphelion3.106 AU
Perihelion0.2958 AU
1.701 AU
Eccentricity0.82613
2.22 yr
299.160°
0° 26m 39.193s / day
Inclination38.982°
181.732°
2 May 2021 23:01 UT[3]
123.314°
Earth MOID0.00375 AU (561,000 km)
Mercury MOID0.03566 AU (5,335,000 km)[1]
Venus MOID0.07461 AU (11,161,000 km)[1]
Physical characteristics
Mean diameter
550±110 m[3]
39.89±0.05 hr[4]
Sr[5]
15.0 (current)[6]
17.7[3][1]

    (231937) 2001 FO32 is a near-Earth asteroid classified as a potentially hazardous asteroid of the Apollo group. With an estimated diameter around 550 m (1,800 ft), it was discovered by the Lincoln Near-Earth Asteroid Research at Socorro, New Mexico on 23 March 2001. The asteroid safely passed by Earth on 21 March 2021 16:03 UTC from a closest approach distance of 0.0135 AU (2.02 million km; 1.25 million mi), or 5.25 lunar distances (LD). During the day before closest approach, 2001 FO32 reached a peak apparent magnitude of 11.7 and was visible to ground-based observers with telescope apertures of at least 20 cm (8 in).[7][8] It is the largest and one of the fastest asteroids to approach Earth within 10 LD (3.8 million km; 2.4 million mi) in 2021.[8][9]

    With an observation arc of 20 years, 2001 FO32 has a well-determined orbit, and its trajectory is well known through the year 2196.[3] The asteroid's orbit is only potentially hazardous on a time scale of thousands of years.

    Discovery

    2001 FO32 was discovered on 23 March 2001 by the Lincoln Near-Earth Asteroid Research (LINEAR) at Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico.[1] The asteroid was first observed in the constellation Hydra at an apparent magnitude of 15.6. Shortly after discovery, follow-up observations were carried out by four other observatories until the asteroid's subsequent confirmation by the Minor Planet Center on 24 March 2003.[2] The asteroid was given the provisional designation 2001 FO32 and was recognized as a potentially hazardous asteroid.[2] The accredited LINEAR observers are M. Blythe, F. Shelly, M. Bezpalko, R. Huber, L. Manguso, and S. Adams.[2]

    Orbit and classification

    Orbit diagram illustrating 2001 FO32's close approach to Earth in 2021

    2001 FO32 is a member of the dynamical Apollo group of Earth-crossing near-Earth asteroids with orbital semi-major axes greater than 1 astronomical unit (AU).[3][1] It follows a highly elongated orbit around the Sun at a distance of 0.3–3.1 AU once every 2.22 years (810 days; semi-major axis of 1.7 AU). Its orbit has a high eccentricity of 0.83 and an inclination of 39° with respect to the ecliptic. With its highly eccentric orbit, it crosses the orbits of all four inner planets of the Solar System.[3]

    Having a long observation arc nearly 20 years, the orbit of 2001 FO32 is well-defined with a condition code of 0.[3] Although it is classified as a potentially hazardous asteroid due to its large size combined with its small minimum orbit intersection distance (MOID) of 0.00375 AU (1.46 lunar distances) from Earth's orbital path, the asteroid will not make any close approaches within 0.01 AU (3.9 LD) over the next 200 years.[3] The asteroid's orbit is only potentially hazardous on a time scale of thousands of years.[8]

    Close approaches

    Over the course of its highly eccentric orbit, 2001 FO32 makes numerous close encounters with the inner planets—most often Mercury, Venus, and Earth.[3] Its MOIDs from Mercury and Venus are 0.036 AU (5.4 million km; 3.3 million mi) and 0.075 AU (11.2 million km; 7.0 million mi), respectively.[1] 2001 FO32's most recent close encounter with either one of those planets was on 16 January 2008, when it passed by Mercury from a distance of 0.094 AU (14.1 million km; 8.7 million mi).

    On 21 March 2021, 2001 FO32 passed by Earth from a distance of 0.0135 AU (2.02 million km; 1.25 million mi) or 5.25 LD and made its closest approach at 16:03 UTC.[3] During the few days leading up to closest approach, 2001 FO32 steadily became brighter and peaked at apparent magnitude 11.7 on 21 March 2021 2:00 UTC.[7] Although its maximum brightness was too faint to be seen with the naked eye, it was visible to observers using telescopes with apertures of at least 20 cm (8 in).[8] Due to its highly inclined and eccentric orbit, its relative velocity to Earth during the close approach is 34.4 km/s (21.4 mi/s), making it one of the fastest asteroids to pass by Earth in 2021.[8][10] By the time 2001 FO32 makes its closest approach to Earth, its solar elongation (angular separation from the Sun) would be 64°, too small to be observable from Earth.[7]

    In the next 100 years, 2001 FO32 will not make any close approaches to Earth closer than the 21 March 2021 encounter. It will make a similarly close approach to Earth on 22 March 2052 18:57±00:03 UTC, from a slightly farther nominal distance of 0.0189 AU (2.83 million km; 1.76 million mi) or 7.37 LD.[3][10]

    Observations

    Preliminary observations by NEOWISE show that 2001 FO32 appears to be faint in infrared wavelengths of light, indicating that the asteroid is likely less than 1 kilometer in diameter.[10] Based on this, the diameter is estimated around 550 ± 110 m (1,800 ± 360 ft).[3] Near-infrared spectral data obtained by NASA's Infrared Telescope Facility in 2018 suggests that 2001 FO32 is a stony asteroid classified under the Sr spectral class.[5]

    2001 FO32 was first observed with radar on 21 March 2021 at Canberra, Australia and Narrabri, New South Wales, which provided refinement of its orbit. One day after its closest approach, bistatic radar observations were carried out by NASA's Goldstone Deep Space Communications Complex in California and Green Bank Telescope in West Virginia. The radar images revealed that the asteroid has a bilobate shape.[11]

    February 2021 observations of 2001 FO32 by the La Silla Observatory show that it displays a light curve amplitude of 0.9 magnitudes.[12] The preliminary photometry indicates that the body is tumbling with a long main rotation period of 39.89±0.05 hours.[4]

    References

    1. 1 2 3 4 5 6 7 "(231937) = 2001 FO32". Minor Planet Center. International Astronomical Union. Retrieved 3 March 2021.
    2. 1 2 3 4 "MPEC 2001-F30 : 2001 FO32". Minor Planet Electronic Circular. Minor Planet Center. 24 March 2001. Retrieved 3 March 2021.
    3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 "JPL Small-Body Database Browser: 231937 (2001 FO32)" (2021-03-22 last obs.). Jet Propulsion Laboratory. Retrieved 1 April 2021.
    4. 1 2 Pravec, Petr (12 March 2021). "Re: (231937) 2001 FO32 -- good lightcurve target for southern hemisphere". groups.io. Retrieved 6 April 2021.
    5. 1 2 Binzel, R. P.; DeMeo, F. E.; Turtelboom, E. V.; Bus, S. J.; Tokunaga, A.; Burbine, T. H.; et al. (May 2019). "Compositional distributions and evolutionary processes for the near-Earth object population: Results from the MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS)". Icarus. 324: 41–76. arXiv:2004.05090. Bibcode:2019Icar..324...41B. doi:10.1016/j.icarus.2018.12.035. S2CID 125100787.
    6. ↑ "(231937) 2001FO32". Near Earth Objects – Dynamic Site. Department of Mathematics, University of Pisa, Italy. Retrieved 3 March 2021.
    7. 1 2 3 "JPL Horizons On-Line Ephemeris for 231937 (2001 FO32)". JPL Horizons On-Line Ephemeris System. Jet Propulsion Laboratory. Retrieved 3 March 2021. Ephemeris Type: OBSERVER, Target Body: Asteroid 231937 (2001 FO32), Observer Location: Geocentric [500], Start=2021-Mar-19, Stop=2021-Mar-22, Step=1 h
    8. 1 2 3 4 5 Irizarry, Ezzie (6 January 2021). "Biggest asteroid to pass Earth in 2021 also one of the fastest". EarthSky. Retrieved 2 March 2021.
    9. ↑ "NEO Earth Close Approaches". Center for Near Earth Object Studies. Jet Propulsion Laboratory. Retrieved 3 March 2021.
    10. 1 2 3 Greicius, Tony (11 March 2021). "Asteroid 2001 FO32 Will Safely Pass by Earth March 21". NASA. Retrieved 11 March 2021.
    11. ↑ "Goldstone Radar Observations of Asteroid 2001 FO32". Jet Propulsion Laboratory. NASA. 5 April 2021. Retrieved 7 April 2021.
    12. ↑ Pravec, Petr (15 March 2021). "Re: (231937) 2001 FO32 -- good lightcurve target for southern hemisphere". groups.io. Retrieved 6 April 2021.
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