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

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 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 around ±108 km.

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. At the time of discovery it only had a 6-day observation arc of 9–14 July, which poorly constrained possible future positions of the asteroid.

Despite inflammatory press reports, the object had a "low probability" of impact, approximately one in a million, for 1 February 2019. On 22 July 2002, NEODyS posted a positive 0.18 Palermo Scale rating. Further observations, especially from Erich Meyer, 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 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), meaning there is no risk of an impact by it in the next 100 years. 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. 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 an uncertainty region of about ±430 km.

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

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. S2CID 239991. Retrieved April 26, 2017.
5. ^ "How A/CC broke the 2002 NT7 story". hohmanntransfer. March 29, 2003. Archived from the original on November 6, 2020. 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. Archived from the original on June 2, 2002. Retrieved May 6, 2011.
10. "NEODyS-2 Close Approaches for (89959) 2002NT7". Near Earth Objects – Dynamic Site. Retrieved November 5, 2011.

External links

• Simulation of the shrinking uncertainty region for 2019 Jan 28 – Peter Thomas
• (89959) 2002 NT7 at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• (89959) 2002 NT7 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• (89959) 2002 NT7 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Apollo asteroids
• Discoveries by LINEAR
• Near-Earth objects removed from the Sentry Risk Table
• Potentially hazardous asteroids
• Near-Earth objects in 2019
• Astronomical objects discovered in 2002