# 2020 SO

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Space junk

2020 SO The orbit of 2020 SO around Earth and Sun from Nov. 2020 to Mar. 2021 Discovery[1][2] Discovered by Pan-STARRS 1 Discovery site Haleakalā Obs. Discovery date 17 September 2020 Designations Alternative designations P116rK2[3] Minor planet category NEO · Apollo (May 2020)[4] Atira (Dec 2020)[2] Orbital characteristics[2] Epoch 17 December 2020 (JD 2459200.5) Uncertainty parameter 2 Observation arc 167 days Earliest precovery date 19 August 2020 Aphelion 0.988 AU Perihelion 0.985 AU Semi-major axis 0.986 AU Eccentricity 0.00181 Orbital period (sidereal) 0.98 yr (357.9 d) Mean anomaly 276.388° Mean motion 1° 0m 21.877s / day Inclination 0.1389° Longitude of ascending node 216.656° Argument of perihelion 311.989° Earth MOID 0.01628 AU (May 2020)[4] 0.00106 AU (Dec 2020) Physical characteristics Mean diameter 6–12 m (assumed)[5] Synodic rotation period 0.0026080±0.0000001 h[6] or 9.39 s Apparent magnitude 22.4 (at discovery)[1] 14.1 (1 Dec 2020)[7] Absolute magnitude (H) 27.66±0.34[4] 28.43[2]

**2020 SO**[a] is a [near-Earth object](/source/Near-Earth_object) identified to be the [Centaur](/source/Centaur_(rocket_stage)) upper stage used on 20 September 1966 to launch the [Surveyor 2](/source/Surveyor_2) spacecraft. The object was discovered by the [Pan-STARRS 1](/source/Pan-STARRS) survey at the [Haleakala Observatory](/source/Haleakala_Observatory) on 17 September 2020. It was initially suspected to be an [artificial](/source/Artificial) object due to its low velocity relative to Earth and later on the noticeable effects of [solar radiation pressure](/source/Solar_radiation_pressure) on its orbit. [Spectroscopic](/source/Spectroscopy) observations by NASA's [Infrared Telescope Facility](/source/Infrared_Telescope_Facility) in December 2020 found that the object's spectrum is similar to that of [stainless steel](/source/Stainless_steel), confirming the object's artificial nature.[8] Following the object's confirmation as [space debris](/source/Space_debris), the object was removed from the [Minor Planet Center](/source/Minor_Planet_Center)'s database on 19 February 2021.[9]

## Overview

As it approached Earth, the trajectory indicated the geocentric [orbital eccentricity](/source/Orbital_eccentricity) was less than 1 by 15 October 2020,[10][b] and the object became [temporarily captured](/source/Temporary_satellite) on 8 November when it entered Earth's [Hill sphere](/source/Hill_sphere).[11] It entered via the outer [Lagrange point](/source/Lagrange_point) [L2](/source/Lagrange_point#L2) and will exit via Lagrange point [L1](/source/Lagrange_point#L1). During its [geocentric orbit](/source/Geocentric_orbit) around Earth, 2020 SO made a close approach to Earth on 1 December 2020 at a [perigee](/source/Perigee) distance of approximately 0.13 [lunar distances](/source/Lunar_distance_(astronomy)) (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](/source/Atlas-Centaur) rocket booster at launch in 1966

[Paul Chodas](https://en.wikipedia.org/w/index.php?title=Paul_Chodas&action=edit&redlink=1) of the [Jet Propulsion Laboratory](/source/Jet_Propulsion_Laboratory) suspects 2020 SO of being the [Surveyor 2](/source/Surveyor_2) [Centaur](/source/Atlas-Centaur) rocket [booster](/source/Centaur_(rocket_stage)), launched on 20 September 1966.[11][12][13] The Earth-like orbit and low [relative velocity](/source/Relative_velocity) suggest a possible artificial object. [Spectroscopy](/source/Spectroscopy) may help determine if it is covered in white [titanium dioxide](/source/Titanium_dioxide) paint.[14] [Goldstone radar](/source/Goldstone_Deep_Space_Communications_Complex) produced bistatic observations on 30 November 2020 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](/source/Apparent_magnitude) 14.1,[7] and required a telescope with roughly a 150mm (6") [objective lens](/source/Objective_(optics)#Telescopes) to be seen visually.[17] It displays a large [light curve](/source/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](/source/Main-belt_asteroid).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia: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](/source/J002E3) – a near-Earth object discovered in 2002 that was identified as the [S-IVB](/source/S-IVB) third stage of the [Apollo 12](/source/Apollo_12) [Saturn V](/source/Saturn_V) rocket

- [WT1190F](/source/WT1190F) – temporarily orbiting space debris that entered Earth's atmosphere in 2015

- [2018 AV2](/source/2018_AV2) – an artificial object discovered in a temporary orbit around Earth in 2018, now suspected to be the *Snoopy* module from [Apollo 10](/source/Apollo_10)

- [6Q0B44E](/source/6Q0B44E) – another artificial object discovered in orbit around Earth in 2018

- [Space debris](/source/Space_debris)

- [Temporary satellite](/source/Temporary_satellite)

## Notes

1. **[^](#cite_ref-8)** 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](/source/Provisional_designation_in_astronomy#New-style_provisional_designation).

1. ^ [***a***](#cite_ref-geocentric_12-0) [***b***](#cite_ref-geocentric_12-1) The [JPL Horizons On-Line Ephemeris System](/source/JPL_Horizons_On-Line_Ephemeris_System) shows the geocentric [orbital eccentricity](/source/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](/source/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.

1. **[^](#cite_ref-ec_21-0)** [Orbital eccentricity](/source/Orbital_eccentricity) must be below 1 to be orbiting the central body.

1. **[^](#cite_ref-hill_22-0)** An object needs to be within Earth's [Hill sphere](/source/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***](#cite_ref-MPEC-2020-S78_1-0) [***b***](#cite_ref-MPEC-2020-S78_1-1) [***c***](#cite_ref-MPEC-2020-S78_1-2) ["MPEC 2020-S78 : 2020 SO"](https://minorplanetcenter.net/mpec/K20/K20S78.html). *Minor Planet Electronic Circular*. [Minor Planet Center](/source/Minor_Planet_Center). 19 September 2020. Retrieved 20 September 2020.

1. ^ [***a***](#cite_ref-MPC-object_2-0) [***b***](#cite_ref-MPC-object_2-1) [***c***](#cite_ref-MPC-object_2-2) [***d***](#cite_ref-MPC-object_2-3) [***e***](#cite_ref-MPC-object_2-4) ["2020 SO"](https://web.archive.org/web/20210211232012/https://minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2020+SO). *Minor Planet Center*. International Astronomical Union. Archived from [the original](http://www.minorplanetcenter.net/db_search/show_object?object_id=2020+SO) on 11 February 2021. Retrieved 20 September 2020.

1. **[^](#cite_ref-NEO-Exchange_3-0)** ["2020 SO"](https://neoexchange.lco.global/target/60113/). *NEO Exchange*. [Las Cumbres Observatory](/source/Las_Cumbres_Observatory). 18 September 2020. Retrieved 20 September 2020.

1. ^ [***a***](#cite_ref-jpldata_4-0) [***b***](#cite_ref-jpldata_4-1) [***c***](#cite_ref-jpldata_4-2) [***d***](#cite_ref-jpldata_4-3) [***e***](#cite_ref-jpldata_4-4) [***f***](#cite_ref-jpldata_4-5) [***g***](#cite_ref-jpldata_4-6) [***h***](#cite_ref-jpldata_4-7) ["JPL Small-Body Database Browser: 2020 SO"](https://web.archive.org/web/20210126034627/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=54054450) (2020-12-01 last obs.). [Jet Propulsion Laboratory](/source/Jet_Propulsion_Laboratory). Archived from [the original](https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=54054450;cad=1) on 26 January 2021. Retrieved 20 September 2020.

1. **[^](#cite_ref-CNEOS_5-0)** ["NEO Earth Close Approaches"](https://cneos.jpl.nasa.gov/ca/). *Center for Near Earth Object Studies*. Jet Propulsion Laboratory. Retrieved 10 October 2020.

1. ^ [***a***](#cite_ref-Birtwhistle_6-0) [***b***](#cite_ref-Birtwhistle_6-1) Peter Birtwhistle (Great Shefford Observatory). ["Light curve"](http://birtwhistle.org.uk/images/2020_SO_20201201.06_PBirtwhistle.png).

1. ^ [***a***](#cite_ref-NEODy20201201_7-0) [***b***](#cite_ref-NEODy20201201_7-1) ["2020SO Ephemerides for 1 December 2020"](https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2020SO&oc=500&y0=2020&m0=11&d0=30&h0=0&mi0=0&y1=2020&m1=12&d1=2&h1=0&mi1=0&ti=1.0&tiu=hours). [NEODyS](/source/NEODyS) (Near Earth Objects – Dynamic Site). [Archived](https://web.archive.org/web/20200926055241/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2020SO&oc=500&y0=2020&m0=11&d0=30&h0=0&mi0=0&y1=2020&m1=12&d1=2&h1=0&mi1=0&ti=1.0&tiu=hours) from the original on 26 September 2020. Retrieved 26 September 2020.

1. **[^](#cite_ref-NASA-20201202_9-0)** Talbert, Tricia (2 December 2020). ["New Data Confirm 2020 SO to be the Upper Centaur Rocket Booster from the 1960's"](https://www.nasa.gov/feature/new-data-confirm-2020-so-to-be-the-upper-centaur-rocket-booster-from-the-1960-s). NASA. Retrieved 2 December 2020.

1. **[^](#cite_ref-MPEC-2021-D62_10-0)** ["MPEC 2021-D62 : DELETION OF 2020 SO"](https://minorplanetcenter.net/mpec/K21/K21D62.html). *Minor Planet Electronic Circular*. [Minor Planet Center](/source/Minor_Planet_Center). 19 February 2020. Retrieved 19 February 2020.

1. ^ [***a***](#cite_ref-horizons_11-0) [***b***](#cite_ref-horizons_11-1) [***c***](#cite_ref-horizons_11-2) [***d***](#cite_ref-horizons_11-3) [Horizons](/source/JPL_Horizons_On-Line_Ephemeris_System) output. ["Geocentric Orbital Elements for Asteroid (2020 SO)"](https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2020SO). Retrieved 27 September 2020. ("Ephemeris Type" select "Orbital Elements" **·** "Center" select 500 for Geocentric. Output lists Eccentricity as "EC".)

1. ^ [***a***](#cite_ref-NASA2020-216_13-0) [***b***](#cite_ref-NASA2020-216_13-1) Greicius, Tony (12 November 2020). ["Earth May Have Recaptured a 1960s-Era Rocket Booster"](https://web.archive.org/web/20201113043252/http://www.nasa.gov/feature/jpl/earth-may-have-recaptured-a-1960s-era-rocket-booster/). NASA. Archived from [the original](https://www.nasa.gov/feature/jpl/earth-may-have-recaptured-a-1960s-era-rocket-booster/) on 13 November 2020. Retrieved 12 November 2020.

1. ^ [***a***](#cite_ref-phys20201011_14-0) [***b***](#cite_ref-phys20201011_14-1) Dunn, Marcia (11 October 2020). ["Fake asteroid? NASA expert IDs mystery object as old rocket"](https://phys.org/news/2020-10-fake-asteroid-nasa-expert-ids.html). *[phys.org](/source/Phys.org)*. Retrieved 12 October 2020.

1. **[^](#cite_ref-groups_15-0)** Harris, Alan (20 September 2020). ["Re: another natural satellite of Earth... again"](https://groups.io/g/mpml/message/35849). *groups.io*. Retrieved 20 September 2020.

1. **[^](#cite_ref-16)** B., Mark (12 October 2020). ["NASA Expert Believes New "Asteroid" is a Discarded Rocket Part"](https://www.sciencetimes.com/articles/27663/20201012/nasa-expert-believes-new-asteroid-discarded-rocket-part.htm). *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.

1. **[^](#cite_ref-goldstone_17-0)** ["Goldstone Radar Observations Planning: 2020 SO"](https://echo.jpl.nasa.gov/asteroids/2020SO/2020so.2020.goldstone.planning.html). Asteroid Radar Research. Retrieved 30 November 2020.

1. ^ [***a***](#cite_ref-:0_18-0) [***b***](#cite_ref-:0_18-1) ["2020 SO · IAA RAS"](http://iaaras.ru/en/observations/echo/2020so/). *iaaras.ru*. Retrieved 10 December 2020.

1. **[^](#cite_ref-limiting_19-0)** ["Limiting Magnitude"](https://web.archive.org/web/20201117161329/https://www.twcac.org/Tutorials/limiting_magnitude_table.htm). The Wilderness Center Astronomy Club. Archived from [the original](https://www.twcac.org/Tutorials/limiting_magnitude_table.htm) on 17 November 2020. Retrieved 26 September 2020.

1. **[^](#cite_ref-Masi2020_20-0)** Masi, Gianluca (2 December 2020). ["Near-Earth object 2020 SO: rotation and time-lapse – 01 Dec. 2020"](https://www.virtualtelescope.eu/2020/12/02/near-earth-object-2020-so-rotation-and-time-lapse-01-dec-2020/). *Virtual Telescope Project*. Retrieved 2 December 2020.

## External links

- ["Pseudo-MPEC" for 2020 SO = Surveyor 2 Centaur](https://www.projectpluto.com/pluto/mpecs/66084b.htm), Bill Gray, *Project Pluto*, 31 January 2021

- [Earth May Have Recaptured a 1960s-Era Rocket Booster](https://www.nasa.gov/feature/jpl/earth-may-have-recaptured-a-1960s-era-rocket-booster)[*[dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot)*], Tony Greicius, [NASA](/source/NASA), 12 November 2020

- [Animation of the Line of Variation (via clone orbits) stretching out from December 2020 to May 2021](https://vimeo.com/460375036/4f799b6bf5)

- [01 Dec 2020 image and rotation](https://www.virtualtelescope.eu/2020/12/01/near-earth-object-2020-so-extremely-close-encounter-image-and-rotation-01-dec-2020/) – Virtual Telescope Project / G. Masi

- [01 Dec 2020 time-lapse and photometry](https://www.virtualtelescope.eu/2020/12/02/near-earth-object-2020-so-rotation-and-time-lapse-01-dec-2020/) – Virtual Telescope Project / G. Masi

- [2020 SO](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.0) at *NeoDyS-2, Near Earth Objects—Dynamic Site* - [Ephemerides](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.3.0) **·** [Observation prediction](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.4.0) **·** [Orbital info](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.1) **·** [MOID](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.5) **·** [Proper elements](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.6) **·** [Observational info](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.7.0) **·** [Close approaches](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.8) **·** [Physical info](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.9) **·** [Orbit animation](https://newton.spacedys.com/neodys/index.php?n=2020so&pc=1.1.A)

v t e Surveyor program Test flights Surveyor-Model 1 (11 Dec 1964) Surveyor SD-1 (2 Mar 1965) Surveyor SD-2 (11 Aug 1965) Surveyor-Model 2 (8 Apr 1966) Surveyor-Model 3 (26 Oct 1966) Missions Surveyor 1 (30 May 1966) Surveyor 2 (20 Sepr 1966) Surveyor 3 (17 Apr 1967) Surveyor 4 (14 Jul 1967) Surveyor 5 (8 Sep 1967) Surveyor 6 (7 Nov 1967) Surveyor 7 (7 Jan 1968) Related Surveyor (crater) 2020 SO (Centaur upper stage) List of missions to the Moon

v t e 2020 in space « 2019 2021 » Space probe launches Solar Orbiter (Feb 2020) Hope (Jul 2020) Tianwen-1 (Jul 2020) Mars 2020 (Jul 2020) Perseverance rover Mars Helicopter Ingenuity Chang'e 5 (lunar sample return mission; Nov 2020) Impact events 2020 China bolide Selected NEOs Asteroid close approaches 594913 ꞌAylóꞌchaxnim (809875) 2020 BX12 2020 CW 2020 CD3 (temporary satellite) (52768) 1998 OR2 2020 HS7 2020 JJ 2020 LD (163348) 2002 NN4 2020 OY4 2020 QG 2011 ES4 2018 VP1 2020 SO (space debris) 2020 SW 2020 SL1 2020 UA 2020 VV 2020 VT4 (153201) 2000 WO107 (501647) 2014 SD224 (614689) 2020 XL5 Exoplanets AU Mic b Gliese 414 Ab Ac Gliese 433 b c d GJ 1151 b radio emissions K2-315b Kepler-1649c KOI-456.04 Lacaille 9352 b c M51-ULS-1b OGLE-2016-BLG-1928L (rogue planet) Tau Ceti j (predicted) TOI-561 b c d e TOI-700 b c d TOI-732 b c TOI-1338 b TOI-1339 b c d TYC 8998-760-1 c WD 1856+534 b Discoveries Betelgeuse dimming FRB 180916 location and periodicity Radcliffe wave Ophiuchus Supercluster explosion PSO J03094+27 (distant blazar) 2MASS J1047+21 wind speed measurements SGR 1935+2154 (soft gamma ray repeater) HR 6819 black hole hypothesis PHL 293B ending of P Cygni profile hydrogen emission lines Swift J1818.0–1607 (young magnetar) GW190814 (announced) South Pole Wall GW190521 (announced) Phosphine detection in the atmosphere of Venus Water detection on the sunlit surface of the Moon Comets C/2019 Y4 (ATLAS) P/2019 LD2 (ATLAS) C/2017 T2 (PANSTARRS) C/2020 F8 (SWAN) C/2019 U6 (LEMMON) C/2020 F3 (NEOWISE) 2P/Encke 88P/Howell C/2020 M3 (ATLAS) 156P/Russell–LINEAR C/2020 S3 (Erasmus) Space exploration Spitzer retirement (Jan 2020) BepiColombo (Earth gravity assist; Apr 2020, Venus gravity assist; Oct 2020) OSIRIS-REx (sample collection from asteroid Bennu; Oct 2020) Hayabusa2 (sample return from asteroid Ryugu; Dec 2020) Chang'e 5 (lunar sample return; Dec 2020) Outer space portal Category:2019 in outer space — Category:2020 in outer space — Category:2021 in outer space

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Adapted from the Wikipedia article [2020 SO](https://en.wikipedia.org/wiki/2020_SO) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/2020_SO?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.