Global InformationWT1190F information
 WT1190F entering the atmosphere over Sri Lanka, viewed by the airborne observation team | |
| Discovery | |
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| Discovered by |
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| Discovery date |
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| Designations | |
Alternative names |
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Minor planet category | Distant artificial satellite (before Jun 2009 to 13 November 2015) |
| Orbital characteristics[1] | |
| Epoch 3 October 2015 (JD 2457298.5) | |
| Periapsis | 21,222 km (13,187 mi) (0.055 LD; 3.33 ER) |
| Apoapsis | 655,374 km (407,231 mi) (1.704 LD, 102.75 ER) |
Semi-major axis | 338,298 km (210,209 mi) (0.880 LD, 53.04 ER) |
| Eccentricity | 0.937269 |
Orbital period (sidereal) | 22.66 days |
Average orbital speed | 1.1 km/s @ 0.00226 AU |
Mean anomaly | 6.191° |
| Inclination | 3.197° |
Longitude of ascending node | 311.556° |
Time of perihelion | 2 October 2015 14:39:00 UT |
Argument of perihelion | 314.044° |
| Satellite of | Earth |
| Physical characteristics | |
| Dimensions | 0.7 to 2 meters (2 to 7 ft) |
| Mass | 250 to 2,000 kilograms (550 to 4,400 lb) |
Mean density | ~100 kg/m3 (6 lb/cu ft)[2] |
Synodic rotation period | 0.75 seconds[3] |
| Albedo | >0.1 |
Apparent magnitude | ~16–23 |
Absolute magnitude (H) | 31.3 |
WT1190F (9U01FF6, UDA34A3, or UW8551D) 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 been space debris from the trans-lunar injection stage of the 1998 Lunar Prospector mission.[5][6] It was first discovered on 18 February 2013 by the Catalina 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 the International Astronomical Union's Minor Planet Center (MPC).[8] An early orbit calculation showed that it was orbiting Earth in an extremely elliptical orbit, taking it from within the geosynchronous satellite ring to 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 (named UWAIS) 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/cm3 was much lower than would be expected of a natural object as even water has a density of 1 g/cm3. Hence, European Space Agency astronomers 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 of Sri 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 daytime fireball if the sky was not badly overcast.[2][7]
A ground-based observational campaign was organized as a possible test for future collision events involving also natural bodies.[10]
- ^ a b Gray, Bill. "Pseudo-MPC for UDA34A3 = UW8551D = WT1190F". Project Pluto. Retrieved 23 October 2015.
- ^ a b c d e "WT1190F comes back: ESA NEOCC watching rare reentry". Minor Planet Mailing List. Archived from the original on 26 October 2015. Retrieved 24 October 2015.
- ^ Peter Birtwhistle
- ^ Jenniskens, 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.: AIAA Science and Technology Forum and Exposition (SciTech 2016). Retrieved 22 August 2022.
- ^ Watson, Traci (13 January 2016). "Falling space debris traced to 1998 lunar mission". Nature. doi:10.1038/nature.2016.19162. Retrieved 18 January 2015.
- ^ Watson, Traci (23 October 2015). "Incoming space junk a scientific opportunity". Nature News. Retrieved 29 October 2015.
- ^ a b c d Wood, Chris (23 October 2015). "ESA to study rare rocket body reentry to improve predictive models". Gizmag.com. Retrieved 27 October 2015.
- ^ "Reentry data will help improve prediction models". European Space Agency. Retrieved 2 November 2015.
- ^ Cite error: The named reference
SETIwas invoked but never defined (see the help page). - ^ 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. S2CID 119107218.