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WT1190F

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WT1190F
WT1190F entering the atmosphere over Sri Lanka, viewed by the airborne observation team
Discovery
Discovered by
Discovery date
  • 26 October 2009
  • 18 February 2013
  • 29 November 2013
  • 3 October 2015
Designations
  • 9U01FF6
  • UDA34A3
  • UW8551D
Distant artificial satellite (before Jun 2009 to 13 November 2015)
Orbital characteristics[1]
Epoch3 October 2015 (JD2457298.5)
Periapsis21,222 km (13,187 mi) (0.055LD;3.33ER)
Apoapsis655,374 km (407,231 mi) (1.704 LD, 102.75 ER)
338,298 km (210,209 mi) (0.880 LD, 53.04 ER)
Eccentricity0.937269
22.66 days
1.1 km/s @ 0.00226 AU
6.191°
Inclination3.197°
311.556°
2 October 2015 14:39:00UT
314.044°
Satellite ofEarth
Physical characteristics
Dimensions0.7 to 2 meters (2 to 7 ft)
Mass250 to 2,000 kilograms (550 to 4,400 lb)
~100 kg/m3(6 lb/cu ft)[2]
0.75 seconds[3]
Albedo>0.1
~16–23
31.3

WT1190F(9U01FF6,UDA34A3,orUW8551D) was a small temporary satellite of Earth that impacted Earth on 13 November 2015 at 06:18:21.7 (± 0.1 seconds)UTC.[4]: 7–8 It is thought to have beenspace debrisfrom thetrans-lunar injectionstage of the 1998Lunar Prospectormission.[5][6]It was first discovered on 18 February 2013 by theCatalina Sky Survey.[2][7]It was then lost, and reacquired on 29 November 2013. It was again discovered on 3 October 2015 by astronomer Rose Garcia with the Catalina Sky Survey 60-inch telescope, and the object was soon identified to be the same as the two objects previously sighted by the team, who have been sharing their data through theInternational Astronomical Union'sMinor Planet Center(MPC).[8]An early orbit calculation showed that it was orbiting Earth in an extremely elliptical orbit, taking it from within thegeosynchronous satellite ringto nearly twice the distance of the Moon.[1]It was also probably the same object as 9U01FF6, another object on a similar orbit discovered on 26 October 2009.

WT1190F had been orbiting Earth as a temporary satellite (namedUWAIS) since mid-2009, if not longer. While it has not been positively identified with any known artificial satellites, its estimated density of 0.1 g/cm3was much lower than would be expected of a natural object as even water has a density of 1 g/cm3.Hence,European Space Agencyastronomers have concluded that the object was likely a fuel tank of some sort.[2][7]

After more observations, astronomers determined that the object would impact Earth on 13 November 2015 at 06:18 UTC (11:48 local time),[9]south ofSri Lanka.[2][7]Due to its small size, it was expected that most or all of the object would burn up in the atmosphere before impacting, but would be visible as a bright daytimefireballif the sky was not badlyovercast.[2][7]

A ground-based observational campaign was organized as a possible test for future collision events involving also natural bodies.[10]

Observations

[edit]
Bright object in the center is WT1190F as observed by the University of Hawaii 2.2-meter telescope.

WT1190F was first discovered by theMount Lemmon Survey,a participant in theCatalina Sky SurveyNear-Earth Objectsurveying program.[11]The object was identified with anapparent magnitude19.5 on 18 February 2013, and given the temporary designation UDA34A3, but was lost soon after, with anobservation arcof only 5 hours.[12]However, it was again seen by the same survey on 29 November 2013 and given the designation UW8551D and lost again, only being observed for 1 hour 35 minutes.[12]

Most recently, it was recovered on 3 October 2015 and given the designation WT1190F. Its orbit was soon calculated and found to be orbiting Earth, but not with the orbit of any known artificial satellite. The object's orbit was soon connected, allowing more observations to be made, and severalprecoveryobservations have been found of the object, dating back to June 2009.[13]

The type of orbit that WT1190F had was not stable long-term. An object in this type of orbit was likely to impact into Earth or the Moon, or acquire enoughorbital speedto be ejected into orbit around the Sun.[14]It was not likely that it had been orbiting Earth for decades.[14]In 2011 the orbit had aneccentricityof 0.33 andperigee(closest approach to Earth) of 248,000km(154,000mi).[13]It passed about 22,000 km (14,000 mi) from the Moon on 24 May 2012.[15]By 2013 the eccentricity had increased to 0.70 and the perigee decreased to 105,000 km (65,000 mi).[12]

Orbital evolution
Epoch Eccentricity Inclination Perigee
(km) 		Apogee
(km)
2011[13] 0.33 59 248383 495045
2013[12] 0.70 78 105639 598686
2015[1] 0.94 3 21221 655374

During WT1190F's orbit, it changed significantly in brightness, from anapparent magnitude16 atperigee,to magnitude 23 atapogee.It spent most of its time dimmer than magnitude 20.[1]This, combined withsolar pressure acceleration,theYarkovsky effect,and frequent orbital perturbations by the Moon, made it difficult to precisely predict its orbit and location. About one hour before atmospheric entry, the object had a R magnitude of 13.6,[16][a]roughly the brightness ofPluto.

Impact

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WT1190F madeatmospheric entryat 11 kilometers per second (25,000 miles per hour).[17]Whatever was left from the re-entry was calculated to have fallen into the ocean about 100 kilometres (62 mi) fromGalle,Sri Lanka.[8]The closest approach to Galle occurred during atmospheric flight when the object had an altitude of 45km and a distance of 51km.[18]For observers inColombo,Sri Lanka, the object started out[clarification needed]30 degrees above the horizon coming in from slightly south of due west.[19]Its mass was not sufficient to cause any risk to the area, but the event still produced a bright fireball. Scientists wanted to study WT1190F to better understand the trajectory and atmospheric entry of satellites, debris, and small asteroids from translunar orbit.[20][8]The International Astronomical Center (IAC) and theUnited Arab Emirates Space Agencyutilized aGulfstream 450jet to study the re-entry from above the clouds and haze.[20]The airborne observation team successfully captured the re-entry on video.[9][21]

Impact approach[22]
Date vmag Distance
(km) 		Velocity
wrt Earth
(km/s)[23]
05 20.8 602399 0.2
08 20.5 524608 0.5
10 20.0 420800 0.8
11 19.6 345999 1.0
12 19.0 246196 1.4
13 17.1 89914 2.8
Impact ~ –6[24] 0 11.3

Airborne observations

[edit]
Gulfstream 450 business jet rented for the mission

The International Astronomical Center (IAC) and theUnited Arab Emirates Space Agencyobserved WT1190F as it fell towards the Earth. The IAC chartered aGulfstream 450jet to bring researchers such asPeter Jenniskensto the area of WT1190F's impact, at a high altitude, to view the event over clouds or haze.[20]The Next TC3 Consortium Asteroid Detection and Early Warning team narrowed the atmospheric entry time to ± 1.3 seconds.[9]

Observers on the ground could not see the fireball because of rain, but the plane was able to find an opening in the clouds. The fireball was a brightnaked eyeobject.Spectroscopicdata was acquired to determine what the object was made of,[9]and the results published.[4]: 9 

See also

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Impacts by known objects

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Previous temporary satellites

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Notes

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  1. ^Even near apparent magnitude ~13.6 it was about 1000 times too faint to be seen by the naked eye.Math:

References

[edit]
  1. ^abcdGray, Bill."Pseudo-MPC for UDA34A3 = UW8551D = WT1190F".Project Pluto.Retrieved23 October2015.
  2. ^abcde"WT1190F comes back: ESA NEOCC watching rare reentry".Minor Planet Mailing List.Archived fromthe originalon 26 October 2015.Retrieved24 October2015.
  3. ^Peter Birtwhistle
  4. ^abJenniskens, Petrus; et al. (8 January 2016)."Airborne Observations of an Asteroid Entry for High Fidelity Modeling: Space Debris Object WT1190F"(PDF).SETI Institute.San Diego, CA.:AIAAScience and Technology Forum and Exposition (SciTech 2016).Retrieved22 August2022.
  5. ^Watson, Traci (13 January 2016)."Falling space debris traced to 1998 lunar mission".Nature.doi:10.1038/nature.2016.19162.Retrieved18 January2015.
  6. ^Watson, Traci (23 October 2015)."Incoming space junk a scientific opportunity".Nature News.Retrieved29 October2015.
  7. ^abcdWood, Chris (23 October 2015)."ESA to study rare rocket body reentry to improve predictive models".Gizmag.com.Retrieved27 October2015.
  8. ^abc"Reentry data will help improve prediction models".European Space Agency.Retrieved2 November2015.
  9. ^abcd"Rapid Response to the next Small Asteroid Impact".SETI Institute.Retrieved10 November2015.
  10. ^Micheli, Marco; Buzzoni, Alberto; Koschny, Detlef; Drolshagen, Gerhard; Perozzi, Ettore; Hainaut, Olivier; Lemmens, Stijn; Altavilla, Giuseppe; Foppiani, Italo; Nomen, Jaime; Sánchez-Ortiz, Noelia; Marinello, Wladimiro; Pizzetti, Gianpaolo; Soffiantini, Andrea; Fan, Siwei; Fruehm, Carolin (October 2017). "The observing campaign on the deep-space debris WT1190F as a test case for short-warning NEO impacts".Icarus.304:4–8.arXiv:1710.07684.Bibcode:2018Icar..304....4M.doi:10.1016/j.icarus.2017.10.006.S2CID119107218.
  11. ^"Catalina Sky Surveys".NASA.5 March 2013. Archived fromthe originalon 14 January 2004.Retrieved27 October2015.
  12. ^abcd""Pseudo-MPEC" for UDA34A3 = UW8551D ".Project Pluto.Retrieved27 October2015.
  13. ^abcGray, Bill (30 October 2015)."Pseudo-MPEC for UDA34A3 = UW8551D = WT1190F".Project Pluto.Retrieved8 November2015.
  14. ^abWT1190F FAQs– Bill Gray
  15. ^Gray, Bill (5 November 2015)."Pseudo-MPEC for UDA34A3 = UW8551D = WT1190F".Project Pluto.Retrieved8 November2015.
  16. ^"DASO Circular No. 537".Minor Planet Center.13 November 2015.[dead link]
  17. ^"ESA SPONSORS WT1190F OBSERVATIONS".esa blog. 30 October 2015.Retrieved10 November2015.
  18. ^Gray, Bill (11 November 2015)."Ephemerides for (Gal) Galle, Sri Lanka".Project Pluto.Retrieved12 November2015.[dead link]
  19. ^Gray, Bill (13 November 2015)."Ephemerides for (Col) Colombo, Sri Lanka".Project Pluto.Retrieved12 November2015.
  20. ^abcAl-Ashi, Sameh (4 November 2015)."UAE sponsors airborne campaign to observe November 13 entry of space debris WT1190F".IAC.Retrieved8 November2015.
  21. ^King, Bob (13 November 2015)."Spectacular Breakup of WT1190F Seen by Airborne Astronomers".Universe Today.Retrieved13 November2015.
  22. ^The Distant Artificial Satellites Observation Page[dead link]
  23. ^Ephemeris
  24. ^Can you see fireballs in daylight, and will a fireball leave a trail?
[edit]
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