(89959) 2002 NT7

(89959) 2002 NT7 (prov. designation: 2002 NT7) is a near-Earth object with a diameter of 1.4 kilometers and potentially hazardous asteroid of the Apollo group.[2][3] It has a well determined orbit with an observation arc of 64 years including precovery images by Palomar Observatory dating back to 1954.[3]

(89959) 2002 NT7
Discovery [1]
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date9 July 2002
Designations
(89959) 2002 NT7
2002 NT7
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2457800.5)
Uncertainty parameter 0
Observation arc62.68 yr (22,894 days)
Aphelion2.6529 AU
Perihelion0.8180 AU
1.7355 AU
Eccentricity0.5286
2.29 yr (835 days)
79.375°
0° 25m 51.96s / day
Inclination42.333°
132.08°
300.67°
Earth MOID0.0004 AU (60,000 km; 37,000 mi)
Physical characteristics
Mean diameter
1.407±0.085 km[4]
0.224±0.053[4]
16.4[2]

    2002 NT7 became the first object observed by NASA's NEO program to be assigned a positive rating on both the Torino Scale and the Palermo Technical Impact Hazard Scale,[5] for a small chance of an impact on 1 February 2019, although it has now been known for years that it would pass Earth at roughly 0.4078 AU (61,010,000 km; 37,910,000 mi) on 13 January 2019 with an uncertainty region of about ±108 km.[6]

    Discovery

    It was discovered on 9 July 2002 by the Lincoln Near-Earth Asteroid Research team (LINEAR) at the U.S. Lincoln Laboratory Experimental Test Site near Socorro, New Mexico.[1] At the time of discovery it only had a 6-day observation arc of 9–14 July[1] which poorly constrained possible future positions of the asteroid.

    Despite inflammatory press reports, the object had a "low probability" of impact of approximately one in a million for 1 February 2019.[7] On 22 July 2002, NEODyS posted a positive 0.18 Palermo Scale rating.[5] Further observations of the object quickly lowered the probability. On 25 July 2002, the hazard rating on the Palermo scale was lowered to -0.25. However, the discovery of the object with a Palermo initial rating of 0.06[8] was a historical event for the NEO observation program.

    2002 NT7 was removed from the Sentry Risk Table on 1 August 2002, (23 days after discovery) so there is no risk of an impact by it in the next 100 years.[9] On 13 January 2019, the asteroid safely passed 0.4078 AU (61,010,000 km; 37,910,000 mi) from Earth with a 3-sigma uncertainty region of about ±108 km.[6] Between 1900 and 2195 the closest approach to Earth will occur on 15 January 2099 at a distance of roughly 0.3739 AU (55,930,000 km; 34,760,000 mi) with uncertainty region of about ±430 km.[6]

    On 30 January 2020, the asteroid safely passed 0.02718 AU (4,066,000 km; 2,527,000 mi) from 2 Pallas.[10]

    References
    1. "MPEC 2002-N38 : 2002 NT7". IAU Minor Planet Center. July 14, 2002. (K02N07T)
    2. "JPL Small-Body Database Browser: 89959 (2002 NT7)" (2017-03-15 last obs.). Jet Propulsion Laboratory. Retrieved April 26, 2017.
    3. "89959 (2002 NT7)". Minor Planet Center. Retrieved April 26, 2017.
    4. Mainzer, A.; Grav, T.; Bauer, J.; Masiero, J.; McMillan, R. S.; Cutri, R. M.; et al. (December 2011). "NEOWISE Observations of Near-Earth Objects: Preliminary Results". The Astrophysical Journal. 743 (2): 17. arXiv:1109.6400. Bibcode:2011ApJ...743..156M. doi:10.1088/0004-637X/743/2/156. Retrieved April 26, 2017.
    5. "How A/CC broke the 2002 NT7 story". hohmanntransfer. March 29, 2003. Retrieved April 25, 2019.
    6. "JPL Close-Approach Data: 89959 (2002 NT7)" (last observation: 2011-09-12; arc: 57 years). Retrieved November 4, 2011.
    7. Asteroid 2002 NT7 Under Watch, But Probably Not Coming Our Way Archived 2006-04-05 at the Wayback Machine (25 July 2002)
    8. "Space rock 'on collision course'". BBC News. July 24, 2002. Retrieved December 28, 2007.
    9. "Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Retrieved May 6, 2011.
    10. "NEODyS-2 Close Approaches for (89959) 2002NT7". Near Earth Objects – Dynamic Site. Retrieved November 5, 2011.
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