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2020 PN₁
Discovery
Discovered by	ATLAS-HKO
Discovery site	Haleakalā Observatory
Discovery date	12 August 2020
Designations
Designation	2020 PN1
Minor planet category	Aten; NEO; Earth crosser;
Orbital characteristics
	Epoch 31 May 2020 (JD 2459000.5)
	Uncertainty parameter 0
Observation arc	361 days
Aphelion	1.12482093 AU
Perihelion	0.8713906 AU
Semi-major axis	0.998105754 AU
Eccentricity	0.1269557
Orbital period (sidereal)	1.00 y (364.219560 d)
Mean anomaly	32.06964°
Inclination	4.80807°
Longitude of ascending node	145.63610°
Argument of perihelion	55.40365°
Earth MOID	0.0248258 AU
Physical characteristics
Dimensions	10–50 m[a]
Absolute magnitude (H)	25.5

2020 PN₁ is a sub-kilometer asteroid, classified as a near-Earth object of the Aten group, that is a temporary horseshoe companion to the Earth. There are dozens of known Earth horseshoe librators, some of which switch periodically between the quasi-satellite and the horseshoe co-orbital states.^[6]

Discovery

2020 PN₁ was discovered on 12 August 2020 by L. Denneau, J. Tonry, A. Heinze, and H. Weiland observing for the ATLAS-HKO Survey.^[7] As of 20 January 2021, it has been observed 41 times with an observation arc of 361 days.^[2]

Orbit and orbital evolution

2020 PN₁ is currently an Aten asteroid (Earth-crossing but with a period less than a year). Its semi-major axis (currently 0.998105754 AU) is similar to that of Earth (0.999789 AU), but it has a moderate eccentricity (0.1269557) and low orbital inclination (4.80807°). It alternates between being an Aten asteroid and being an Apollo asteroid, although its orbital evolution is not fully stable and it can be considered as a temporary co-orbital companion to the Earth.^[6]

Physical properties

With an absolute magnitude of 25.5 mag, it has a diameter in the range 10–50 meters (for an assumed albedo range of 0.04–0.20, respectively).

Exploration

2020 PN₁ was pre-selected for an exploration by a Chinese mission of planetary defense including an impactor and a separate orbiter planned to launch in 2026.^[8] However, in April 2023, the new target is 2019 VL₅.^[9]

Notes

^{^} This is assuming an albedo of 0.20–0.04.

References

^ List Of Aten Minor Planets
^ ^a ^b ^c ^d
2020 PN1 at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters
Retrieved 2021-01-20
^ AstDys-2 on 2020 PN1 Retrieved 2021-01-20
^ NEODyS-2 on 2020 PN1 Retrieved 2021-01-20
^ Absolute-magnitude conversion table (H)
^ ^a ^b de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (March 2021). "Using Mars co-orbitals to estimate the importance of rotation-induced YORP break-up events in Earth co-orbital space". Monthly Notices of the Royal Astronomical Society. 501 (4): 6007–6025. arXiv:2101.02563. Bibcode:2021MNRAS.501.6007D. doi:10.1093/mnras/stab062.
^ Discovery MPEC
^ Andrew Jones (July 12, 2022). "China to target near-Earth object 2020 PN1 for asteroid deflection mission". SpaceNews. Retrieved September 29, 2022.
^ Andrew Jones (April 11, 2023). "China to target asteroid 2019 VL5 for 2025 planetary defense test". SpaceNews. Retrieved April 21, 2023.

Further reading

Understanding the Distribution of Near-Earth Asteroids Bottke, W. F., Jedicke, R., Morbidelli, A., Petit, J.-M., Gladman, B. 2000, Science, Vol. 288, Issue 5474, pp. 2190–2194.
A Numerical Survey of Transient Co-orbitals of the Terrestrial Planets Christou, A. A. 2000, Icarus, Vol. 144, Issue 1, pp. 1–20.
Debiased Orbital and Absolute Magnitude Distribution of the Near-Earth Objects Bottke, W. F., Morbidelli, A., Jedicke, R., Petit, J.-M., Levison, H. F., Michel, P., Metcalfe, T. S. 2002, Icarus, Vol. 156, Issue 2, pp. 399–433.
Transient co-orbital asteroids Brasser, R., Innanen, K. A., Connors, M., Veillet, C., Wiegert, P., Mikkola, S., Chodas, P. W. 2004, Icarus, Vol. 171, Issue 1, pp. 102–109.
A trio of horseshoes: past, present and future dynamical evolution of Earth co-orbital asteroids 2015 XX₁₆₉, 2015 YA and 2015 YQ₁ de la Fuente Marcos, C., de la Fuente Marcos, R. 2016, Astrophysics and Space Science, Vol. 361, Issue 4, article 121 (13 pp).