Astronomy:4179 Toutatis

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Short description: Near-Earth asteroid of the Apollo and Alinda group
4179 Toutatis
Asteroid 4179 Toutatis close-up.jpg
Toutatis imaged by Chang'e 2 during its flyby
Discovery [1]
Discovered byChristian Pollas
Discovery siteCaussols
Discovery date4 January 1989
Designations
(4179) Toutatis
Pronunciation/taʊˈteɪtɪs/
Named afterToutatis (Celtic mythology)[2]
  • 1989 AC
  • 1934 CT
Minor planet category
AdjectivesToutatian[4]
Orbital characteristics [3]
Epoch 27 November 2008 (JD 2454797.5)
Uncertainty parameter 0
Observation arc83.29 yr (30,422 days)
Earliest precovery date10 February 1934
|{{{apsis}}}|helion}}4.1242 AU
|{{{apsis}}}|helion}}0.9399 AU
2.5321 AU
Eccentricity0.6288
Orbital period4.03 yr (1,472 days)
Mean anomaly5.1220°
Mean motion0° 14m 40.56s / day
Inclination0.4460°
Longitude of ascending node124.30°
278.75°
Earth MOID0.0064 AU (2.5 LD)
Physical characteristics
Dimensions
  • 4.75 × 1.95 km[5]
  • 4.26 × 2.03 × 1.70 km[6]
Mean diameter2.45 km[6]
Mass1.9×1013 kg[7]
Mean density2.5 g/cm3[7]
Rotation period176 h (7.3 d)[8]
Geometric albedo0.13[3]
Sk (SMASSII)[3]
Apparent magnitude8.8–22.4[9][10]
Absolute magnitude (H)15.30[3]


4179 Toutatis (provisional designation 1989 AC) is an elongated, stony asteroid and slow rotator,[11] classified as a near-Earth object and potentially hazardous asteroid of the Apollo asteroid group, approximately 2.5 kilometers in diameter. Discovered by French astronomer Christian Pollas at Caussols in 1989, the asteroid was named after Toutatis from Celtic mythology.[1][2]

Toutatis is also a Mars-crosser asteroid with a chaotic orbit produced by a 3:1 resonance with the planet Jupiter, a 1:4 resonance with the planet Earth, and frequent close approaches to the terrestrial planets, including Earth.[12] In December 2012, Toutatis passed within about 18 lunar distances of Earth. The Chinese lunar probe Chang'e 2 flew by the asteroid at a distance of 3.2 kilometers and a relative velocity of 10.73 km/s.[13] Toutatis approached Earth again in 2016, but will not make another notably close approach until 2069.[14]

Properties

Toutatis was first sighted on 10 February 1934, as object 1934 CT, but lost soon afterwards.[15] It remained a lost asteroid for several decades until it was rediscovered on 4 January 1989 by France astronomer Christian Pollas, and was named after the Celtic god of tribal protection Toutatis (Teutates). The name of this god is very familiar in France due to the catchphrase Par Toutatis! by the Gauls in the comics Asterix.[16]

The spectral properties suggest that this is an S-type, or stony asteroid, consisting primarily of silicates. It has a moderate Bond albedo of 0.13.[3] Radar imagery shows that Toutatis is a highly irregular body consisting of two distinct lobes, with maximum widths of about 4.6 km and 2.4 km, respectively. It is hypothesized that Toutatis formed from two originally separate bodies which coalesced at some point (a contact binary), with the resultant asteroid being compared to a rubble pile.

Its rotation combines two separate periodic motions into a non-periodic result; to someone on the surface of Toutatis, the Sun would seem to rise and set in apparently random locations and at random times at the asteroid's horizon. It has a rotation period around its long axis (Pψ) of 5.38 days. This long axis is precessing with a period (Pφ) of 7.38 days.[17] The asteroid may have lost most of its original angular momentum and entered into this tumbling motion as a result of the YORP effect.[18]

Orbit

Animation of 4179 Toutatis's orbit around the Sun
  4179 Toutatis   Sun  ·    Earth  ·    Jupiter

With a semimajor axis of 2.5294 AU, or roughly 2.5 times the distance between Earth and the Sun, Toutatis has a 3:1 orbital resonance with Jupiter and a near-1:4 resonance with Earth making it a member of the Alinda asteroid group.[12][19] It thus completes one orbit around the Sun for every 4.02 annual orbits of Earth. The gravitational perturbations caused by frequent close approaches to the terrestrial planets lead to chaotic behavior in the orbit of Toutatis,[20] making precise long-term predictions of its location progressively inaccurate over time.[20] Estimates in 1993 put the Lyapunov time horizon for predictability at around 50 years,[20] after which the uncertainty region becomes larger with each close approach to a planet. Without the perturbations from the terrestrial planets the Lyapunov time would be close to 10,000 years.[20] The initial observations that showed its chaotic behavior were made by Wiśniewski.[21]

The low inclination (0.47°) of the orbit allows frequent transits, where the inner planets Mercury, Venus, Earth, and Mars can appear to cross the Sun as seen from the perspective of Toutatis. Earth did this in January 2009, July 2012, July 2016 and 2020.[22]

Close approaches and collision risk

Close approaches[14]
Year AU LD
1985 0.28 109
1988 0.12 45
1992 0.02 9
1996 0.03 14
2000 0.07 29
2004 0.01 4
2008 0.05 20
2012 0.05 18
2016 0.25 98
2065 0.36 142
2069 0.02 8

Toutatis makes frequent close approaches to Earth, with a currently minimum possible distance (Earth MOID) of just 0.006 AU (2.3 times as far as the Moon).[3] The approach on 29 September 2004 was particularly close, at 0.0104 AU[23] (within 4 lunar distances) from Earth, presenting a good opportunity for observation, with Toutatis having an apparent magnitude of 8.8 at its brightest.[9] A close approach of 0.0502 astronomical unit|AU (7,510,000 km; 4,670,000 mi) happened on 9 November 2008.[14][23] The most recent close approach was on 12 December 2012, at a distance of 0.046 AU (6,900,000 km; 4,300,000 mi),[14][23] with a magnitude of 10.7.[24] At magnitude 10.7, Toutatis was not visible to the naked eye, but just visible to experienced observers using high-end binoculars. During the 2012 encounter Toutatis was recovered on 21 May 2012, by the Siding Spring Survey at apparent magnitude 18.9.[25] A close approach will be 5 November 2069, at 0.01985 AU (2,970,000 km).[14]

Given that Toutatis makes many close approaches to Earth, such as in 1992, 1996, 2000, 2004, 2008, 2012, and 2016, it is listed as a potentially hazardous object.[14] With an uncertainty parameter of 0,[3] the orbit of Toutatis is very well determined for the next few hundred years.[14] The probability of the orbit intersecting Earth is essentially zero for at least the next six centuries.[26] The likelihood of collision in the distant future is considered to be very small.[27] As a planet-crossing asteroid, Toutatis is likely to be ejected from the inner Solar System within a few million years. In 2004 a chain e-mail falsely claimed that Toutatis had a 63% chance of impacting Earth then. In fact, Toutatis passed by at 1.5 million kilometres, or about four Earth–Moon distances, as predicted.[28]

In 2006 Toutatis came closer than 2 AU to Jupiter; its orbit lies inside of Jupiter's.[14] In the 2100s, it will approach Jupiter many times at a similar distance.[14]

History of close approaches of large near-Earth objects since 1908 (A)
PHA Date Approach distance (lunar dist.) Abs.
mag
(H) 		Diameter (C)
(m) 		Ref (D)
Nomi-
nal(B) 		Mini-
mum 		Maxi-
mum
(33342) 1998 WT24 1908-12-16 3.542 3.537 3.547 17.9 556–1795 data
(458732) 2011 MD5 1918-09-17 0.911 0.909 0.913 17.9 556–1795 data
(7482) 1994 PC1 1933-01-17 2.927 2.927 2.928 16.8 749–1357 data
69230 Hermes 1937-10-30 1.926 1.926 1.927 17.5 668–2158 data
69230 Hermes 1942-04-26 1.651 1.651 1.651 17.5 668–2158 data
(137108) 1999 AN10 1946-08-07 2.432 2.429 2.435 17.9 556–1795 data
(33342) 1998 WT24 1956-12-16 3.523 3.523 3.523 17.9 556–1795 data
(163243) 2002 FB3 1961-04-12 4.903 4.900 4.906 16.4 1669–1695 data
(192642) 1999 RD32 1969-08-27 3.627 3.625 3.630 16.3 1161–3750 data
(143651) 2003 QO104 1981-05-18 2.761 2.760 2.761 16.0 1333–4306 data
2017 CH1 1992-06-05 4.691 3.391 6.037 17.9 556–1795 data
(170086) 2002 XR14 1995-06-24 4.259 4.259 4.260 18.0 531–1714 data
(33342) 1998 WT24 2001-12-16 4.859 4.859 4.859 17.9 556–1795 data
4179 Toutatis 2004-09-29 4.031 4.031 4.031 15.30 2440–2450 data
2014 JO25 2017-04-19 4.573 4.573 4.573 17.8 582–1879 data
(137108) 1999 AN10 2027-08-07 1.014 1.010 1.019 17.9 556–1795 data
(35396) 1997 XF11 2028-10-26 2.417 2.417 2.418 16.9 881–2845 data
(154276) 2002 SY50 2071-10-30 3.415 3.412 3.418 17.6 714–1406 data
(164121) 2003 YT1 2073-04-29 4.409 4.409 4.409 16.2 1167–2267 data
(385343) 2002 LV 2076-08-04 4.184 4.183 4.185 16.6 1011–3266 data
(52768) 1998 OR2 2079-04-16 4.611 4.611 4.612 15.8 1462–4721 data
(33342) 1998 WT24 2099-12-18 4.919 4.919 4.919 17.9 556–1795 data
(85182) 1991 AQ 2130-01-27 4.140 4.139 4.141 17.1 1100 data
314082 Dryope 2186-07-16 3.709 2.996 4.786 17.5 668–2158 data
(137126) 1999 CF9 2192-08-21 4.970 4.967 4.973 18.0 531–1714 data
(290772) 2005 VC 2198-05-05 1.951 1.791 2.134 17.6 638–2061 data
(A) List includes near-Earth approaches of less than 5 lunar distances (LD) of objects with H brighter than 18.
(B) Nominal geocentric distance from the Earth's center to the object's center (earth radius≈6400 km).
(C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y.
(D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD)
(E) Color codes:   unobserved at close approach   observed during close approach   upcoming approaches

Physical characteristics

Goldstone radar image (1996)
Computer model of Toutatis

Large amounts of data of Toutatis were obtained during Chang'e 2's flyby. Toutatis is not a monolith, but most likely a coalescence of shattered fragments. This bifurcated asteroid is shown to be mainly consisting of a head (small lobe) and a body (large lobe). The two major parts are not round in shape, and their surfaces have a number of large facets. In comparison with radar models, the proximate observations from Chang'e 2's flyby have revealed several remarkable discoveries concerning Toutatis, among which the presence of the giant basin at the big end appears to be one of the most compelling geological features, and the sharply perpendicular silhouette in the neck region that connects the head and body is also quite novel. A large number of boulders and several short linear structures are also apparent on the surface.[5]

Giant basin

The giant basin at the big end of Toutatis has a diameter of ~805 m, suggesting that one or more impactors may have collided with it there. The most significant feature is the ridge around the largest basin. The wall of this basin has a relatively high density of lineaments, some of which seem to be concentric to the basin. These ridges are indicative of an internal structure of small bodies and most of the ridges near the largest basin at the big end are most likely related to the huge stress energy during impact.[5]

Observation

Toutatis has been observed with radar imaging from the Arecibo Observatory and the Goldstone Solar System Radar during the asteroid's prior Earth flybys in 1992, 1996, 2000, 2004, and 2008. It was also observed with radar during the December 2012 flyby and observed more distant flyby with radar in December 2016.[29] After 2016, Toutatis will not pass close to Earth again until 2069.

Resolution of the radar images is as fine as 3.75 m per pixel,[30] providing data to model Toutatis's shape and spin state.

Exploration

Images of Toutatis taken by Chang'e 2 probe
Images of Toutatis taken by Chang'e 2 probe

The Chinese lunar probe Chang'e 2 departed from the Sun–Earth L2 point in April 2012[31] and made a flyby of Toutatis on 13 December 2012, with closest approach being 3.2 kilometers and a relative velocity of 10.73 km/s, when Toutatis was near its closest approach to Earth.[13][32][33] It took several pictures of the asteroid, revealing it to be a dusty red/orange color.

See also

References

  1. ↑ 1.0 1.1 1.2 "4179 Toutatis (1989 AC)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=4179. 
  2. ↑ 2.0 2.1 Schmadel, Lutz D. (2007). "(4179) Toutatis". Dictionary of Minor Planet Names – (4179) Toutatis. Springer Berlin Heidelberg. pp. 357–358. doi:10.1007/978-3-540-29925-7_4150. ISBN 978-3-540-00238-3. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 "JPL Small-Body Database Browser: 4179 Toutatis (1989 AC)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2004179. 
  4. ↑ Hudson, "Gravitational Isopotentials on Toutatis"
  5. ↑ 5.0 5.1 5.2 Huang, Jiangchuan; Ji, Jianghui; Ye, Peijian; Wang, Xiaolei; Yan, Jun; Meng, Linzhi; Wang, Su; Li, Chunlai et al. (2013). "The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2 : Scientific Reports : Nature Publishing Group". Scientific Reports 3: 3411. doi:10.1038/srep03411. PMID 24336501. Bibcode: 2013NatSR...3E3411H. 
  6. ↑ 6.0 6.1 Hudson, R. S.; Ostro, S. J.; Scheeres, D. J. (February 2003). "High-resolution model of Asteroid 4179 Toutatis". Icarus 161 (2): 346–355. doi:10.1016/S0019-1035(02)00042-8. Bibcode: 2003Icar..161..346H. 
  7. ↑ 7.0 7.1 Scheeres, D. J.; Ostro, S. J.; Hudson, R. S. (March 1998). "Dynamics of Orbits Close to Asteroid 4179 Toutatis". Icarus 132 (1): 53–79. doi:10.1006/icar.1997.5870. 
  8. ↑ "LCDB Data for (4179) Toutatis". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=4179%7CToutatis. 
  9. ↑ 9.0 9.1 "AstDys (4179) Toutatis Ephemerides for 2004". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2004&m0=9&d0=28&h0=0&mi0=0&y1=2004&m1=9&d1=30&h1=0&mi1=0&ti=1&tiu=hours. 
  10. ↑ "AstDys (4179) Toutatis Ephemerides 2059". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2059&m0=8&d0=31&h0=0&mi0=0&y1=2059&m1=9&d1=14&h1=0&mi1=0&ti=1.0&tiu=days. 
  11. ↑ "Asteroid 4179 Toutasis". https://echo.jpl.nasa.gov/asteroids/4179_Toutatis/toutatis.html. 
  12. ↑ 12.0 12.1 "Trick or Treat: It's Toutatis!". Science@Nasa. 2000-10-31. https://science.nasa.gov/headlines/y2000/ast31oct_1.htm. 
  13. ↑ 13.0 13.1 Lakdawalla, Emily (2012-12-14). "Chang'E 2 imaging of Toutatis succeeded beyond my expectations!". The Planetary Society. http://www.planetary.org/blogs/emily-lakdawalla/2012/12141551-change-2-imaging-of-toutatis.html. 
  14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 "JPL Close-Approach Data: 4179 Toutatis (1989 AC)". https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Toutatis;cad=1#cad. 
  15. ↑ "(4179) Toutatis = 1934 CT = 1989 AC". IAU Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=4179&page=1. 
  16. ↑ "By Toutatis! France unveils statue to Asterix creator" (in en). 2020-01-23. https://www.france24.com/en/20200123-by-toutatis-france-unveils-statue-to-asterix-creator. 
  17. ↑ Mueller, Béatrice E. A.; Samarasinha, Nalin H.; Belton, Michael J. S. (August 2002). "The Diagnosis of Complex Rotation in the Lightcurve of 4179 Toutatis and Potential Applications to Other Asteroids and Bare Cometary Nuclei". Icarus 158 (2): 305–311. doi:10.1006/icar.2002.6892. Bibcode: 2002Icar..158..305M. 
  18. ↑ Bottke, William Jr. (October 2007). "Implications of the YORP Effect for Our Understanding of Asteroid Evolution". Bulletin of the American Astronomical Society 39: 416. Bibcode: 2007DPS....39.0507B. 
  19. ↑ "Toutatis is in a 3:1 mean-motion resonance with Jupiter (rotating frame)". Gravity Simulator. http://www.orbitsimulator.com/gravity/articles/toutatis.html. 
  20. ↑ 20.0 20.1 20.2 20.3 Whipple, L.; Shelus, Peter J. (1993). "Long-Term Dynamical Evolution of the Minor Planet (4179) Toutatis". Icarus 105 (2): 408–419. doi:10.1006/icar.1993.1137. Bibcode: 1993Icar..105..408W. 
  21. ↑ "The Minor Planet Bulletin". Association of Lunar and Planetary Onservers. 1994. http://www.minorplanet.info/MPB/MPB_21-2.pdf. 
  22. ↑ "Solex by Aldo Vitagliano". http://chemistry.unina.it/~alvitagl/solex/. 
  23. ↑ 23.0 23.1 23.2 "NEODys (4179) Toutatis Close Approaches". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/neodys/index.php?pc=1.1.8&n=Toutatis. 
  24. ↑ "NEODys (4179) Toutatis Ephemerides for December 2012". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2012&m0=12&d0=12&h0=0&mi0=0&y1=2012&m1=12&d1=19&h1=0&mi1=0&ti=3&tiu=hours. 
  25. ↑ "(4179) Toutatis = 1934 CT = 1989 AC". IAU Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=4179&page=4. 
  26. ↑ Ostro, S. J.; Hudson, R. S.; Rosema, K. D.; Giorgini, J. D. et al. (1998). "Asteroid 4179 Toutatis: 1996 Radar Observations". Icarus 137 (1): 122–139. doi:10.1006/icar.1998.6031. Bibcode: 1999Icar..137..122O. https://trs.jpl.nasa.gov/bitstream/2014/19433/1/98-0808.pdf. 
  27. ↑ "Close call for earth ahead? – possible collision with asteroid Toutatis". USA Today (Society for the Advancement of Education). 1993. http://findarticles.com/p/articles/mi_m1272/is_n2577_v121/ai_13953460/. 
  28. ↑ David Morrison (27 September 2004). "Close Flyby This Week from Asteroid Toutatis". Asteroid and Comet Impact Hazards (NASA). http://impact.arc.nasa.gov/news_detail.cfm?ID=151. 
  29. ↑ "2012 Goldstone Radar Observations of (4179) Toutatis". http://echo.jpl.nasa.gov/asteroids/Toutatis2012/Toutatis2012_planning.html. 
  30. ↑ "Big Asteroid Tumbles Harmlessly Past Earth". https://science.nasa.gov/science-news/science-at-nasa/2012/12dec_toutatis/. 
  31. ↑ Lakdawalla, Emily (2012-06-14). "Chang'E 2 has departed Earth's neighborhood for.....asteroid Toutatis!?". The Planetary Society. http://www.planetary.org/blogs/emily-lakdawalla/2012/20120614-change-2-toutatis.html. 
  32. ↑ ""Pseudo-MPEC" for 2010-050A = SM999CF = Chang'e 2 probe". http://www.projectpluto.com/pluto/mpecs/cheprob3.htm. 
  33. ↑ "[视频]"嫦娥二号"飞越探测小行星_新闻台_中国网络电视台". News.cntv.cn. http://news.cntv.cn/china/20121215/100850.shtml. 

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