2020 SO

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2020 SO
Synodic rotation period
0.0026080±0.0000001 h[6]
or 9.39 s
22.4 (at discovery)[1]
14.1 (1 Dec 2020)[7]
27.66±0.34[4]
28.43[2]

2020 SO

Infrared Telescope Facility in December 2020 found that the object's spectrum is similar to that of stainless steel, confirming the object's artificial nature.[8] Following the object's confirmation as space debris, the object was removed from the Minor Planet Center's database on 19 February 2021.[9]

Overview

As it approached Earth, the trajectory indicated the geocentric

lunar distances (50,000 km; 31,000 mi).[4] It also made another close approach on 2 February 2021, at a perigee distance of approximately 0.58 LD (220,000 km; 140,000 mi).[4] Since discovery the time of uncertainty for February 2021 closest approach to Earth was reduced from ±3 days to less than 1 minute.[4] It left Earth's Hill sphere at around 8 March 2021.[12][b]

Photograph of the Surveyor 2 Atlas-Centaur rocket booster at launch in 1966

Paul Chodas of the Jet Propulsion Laboratory suspects 2020 SO of being the Surveyor 2 Centaur rocket booster, launched on 20 September 1966.[11][12][13] The Earth-like orbit and low relative velocity suggest a possible artificial object. Spectroscopy may help determine if it is covered in white titanium dioxide paint.[14] Goldstone radar will make bistatic observations transmitting from the 70-meter DSS-14 and receiving at the 34-meter DSS-13.[15] As a result of the bistatic DSS-14/RT-32 radar observations, a rotation period of about 9.5 seconds was obtained,[16] which corresponds to the photometric observations.[6] Obtained range-Doppler radar images[16] confirm that the object has an elongated shape with a length of about 10 meters and a width of about 3 meters.

Around the time of closest approach on 1 December 2020, the object was only brightened to about apparent magnitude 14.1,[7] and required a telescope with roughly a 150mm (6") objective lens to be seen visually.[17] It displays a large light curve amplitude of 2.5 magnitudes, signifying a highly elongated shape or albedo variations on its surface. It has a rotation period of approximately 9 seconds.[18]

At the time of its discovery, 2020 SO had unremarkable motion typical of a

main-belt asteroid.[citation needed] However, the four observations that Pan-STARRS obtained over the course of 1.4 hours showed non-linear motion due to the rotation of the observer around Earth's axis, which is a signature of a nearby object.[1][10]

Orbital Elements for May and December 2020
Parameter Epoch Orbit
type 		Period
(p) 		Aphelion
(Q) 		Perihelion
(q)
Semi-major
axis

(a) 		Inclination
(i) 		Heliocentric
eccentricity
(e) 		Geocentric
eccentricity
(e)[10][c]
Units (years) AU (°)
2020-May-31[4] Apollo 1.056 1.0722 1.0020 1.0371 0.14061° 0.03389 737
2020-Dec-17[2] Atira 0.980 0.9882 0.9847 0.9865 0.13842° 0.00180 0.89934
Animation of 2020 SO's orbit
Around the Sun
Around the Earth
  Sun ·    Earth ·    2020 SO ·    Moon

In January and February 2036, it will again approach Earth with a geocentric eccentricity less than 1 since the relative velocities will be small,[10] but will not be within Earth's Hill sphere of 0.01 AU (1.5 million km).[4][d]

See also

  • J002E3 – a near-Earth object discovered in 2002 that was identified as the S-IVB third stage of the Apollo 12 Saturn V rocket
  • WT1190F – temporarily orbiting space debris that entered Earth's atmosphere in 2015
  • 2018 AV2 – an artificial object discovered in a temporary orbit around Earth in 2018, now suspected to be the Snoopy module from Apollo 10
  • 6Q0B44E – another artificial object discovered in orbit around Earth in 2018
  • Space debris
  • Temporary satellite

Notes

  1. ^ This was the 14th object ("O") discovered in the first half (period "S") of September 2020. See Provisional designation in astronomy § New-style provisional designation.
  2. ^ a b The JPL Horizons On-Line Ephemeris System shows the geocentric orbital eccentricity dropping below 1 by 15 October 2020. But a second condition for capture is that the object is within Earth's Hill sphere which has a radius of roughly 0.01 AU (1.5 million km). Meeting both conditions is when the object is in a temporary satellite capture around Earth.
  3. ^ Orbital eccentricity must be below 1 to be orbiting the central body.
  4. ^ An object needs to be within Earth's Hill sphere to truly be in orbit. An object 1AU from Earth could have a geocentric e<1 if the relative velocities are small, but we would not say it is orbiting Earth.

References

  1. ^ a b c "MPEC 2020-S78 : 2020 SO". Minor Planet Electronic Circular. Minor Planet Center. 19 September 2020. Retrieved 20 September 2020.
  2. ^ a b c d e "2020 SO". Minor Planet Center. International Astronomical Union. Archived from the original on 11 February 2021. Retrieved 20 September 2020.
  3. ^ "2020 SO". NEO Exchange. Las Cumbres Observatory. 18 September 2020. Retrieved 20 September 2020.
  4. ^ a b c d e f g h "JPL Small-Body Database Browser: 2020 SO" (2020-12-01 last obs.). Jet Propulsion Laboratory. Archived from the original on 26 January 2021. Retrieved 20 September 2020.
  5. ^ "NEO Earth Close Approaches". Center for Near Earth Object Studies. Jet Propulsion Laboratory. Retrieved 10 October 2020.
  6. ^ a b Peter Birtwhistle (Great Shefford Observatory). "Light curve".
  7. ^ a b "2020SO Ephemerides for 1 December 2020". NEODyS (Near Earth Objects – Dynamic Site). Archived from the original on 26 September 2020. Retrieved 26 September 2020.
  8. ^ Talbert, Tricia (2 December 2020). "New Data Confirm 2020 SO to be the Upper Centaur Rocket Booster from the 1960's". NASA. Retrieved 2 December 2020.
  9. ^ "MPEC 2021-D62 : DELETION OF 2020 SO". Minor Planet Electronic Circular. Minor Planet Center. 19 February 2020. Retrieved 19 February 2020.
  10. ^ a b c d Horizons output. "Geocentric Orbital Elements for Asteroid (2020 SO)". Retrieved 27 September 2020. ("Ephemeris Type" select "Orbital Elements"  · "Center" select 500 for Geocentric. Output lists Eccentricity as "EC".)
  11. ^ a b Greicius, Tony (12 November 2020). "Earth May Have Recaptured a 1960s-Era Rocket Booster". NASA. Retrieved 12 November 2020.
  12. ^ a b Dunn, Marcia (11 October 2020). "Fake asteroid? NASA expert IDs mystery object as old rocket". phys.org. Retrieved 12 October 2020.
  13. ^ Harris, Alan (20 September 2020). "Re: another natural satellite of Earth... again". groups.io. Retrieved 20 September 2020.
  14. ^ B., Mark (12 October 2020). "NASA Expert Believes New "Asteroid" is a Discarded Rocket Part". The Science Times. Retrieved 3 November 2020. Spectroscopy on the surface of 2020 SO can also determine whether it has titanium dioxide - the paint material used on space rockets.
  15. ^ "Goldstone Radar Observations Planning: 2020 SO". Asteroid Radar Research. Retrieved 30 November 2020.
  16. ^ a b "2020 SO · IAA RAS". iaaras.ru. Retrieved 10 December 2020.
  17. ^ "Limiting Magnitude". The Wilderness Center Astronomy Club. Archived from the original on 17 November 2020. Retrieved 26 September 2020.
  18. ^ Masi, Gianluca (2 December 2020). "Near-Earth object 2020 SO: rotation and time-lapse – 01 Dec. 2020". Virtual Telescope Project. Retrieved 2 December 2020.

External links

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