2007 WD 5 - a near - Earth asteroid from the Apollo group, which is characterized by a highly elongated orbit intersecting the orbit of Mars . It was discovered on November 20, 2007 by the Italian astronomer Andrea Boattini [2] as part of the program for the search for potentially dangerous near-Earth objects (NEO).
2007 WD 5 | |
---|---|
Asteroid | |
Asteroid Span 2007 WD 5 near Mars | |
Opening | |
Discoverer | Andrea Boatini |
Detection point | Catalina Review |
Date of discovery | November 20, 2007 |
Category | NEA ( Apollo ) |
Orbital characteristics [1] | |
The Age of September 30, 2012 JD 2456200.5 | |
Eccentricity ( e ) | 0.5979990 |
Semi-axis ( a ) | 368.165 million km (2.4610281 a. E.) |
Perihelion ( q ) | 148.003 million km (0.9893358 a. E.) |
Afhelia ( Q ) | 588.327 million km (3.9327204 a. E.) |
Period of circulation ( P ) | 1410,176 days (3,861 g. ) |
Average orbital speed | 17,147 km / s |
Inclination ( i ) | 2.42604 ° |
Ascending node longitude (Ω) | 68,41968 ° |
Perihelion Argument (ω) | 309.77692 ° |
Mean Anomaly ( M ) | 101.70194 ° |
physical characteristics | |
Diameter | 50 m |
Apparent magnitude | 27.37 m (current) |
Absolute magnitude | 24,308 m |
Current distance from the Sun | 1.277 a. e. |
Current distance from Earth | 2,197 a. e. |
A surge of interest in this asteroid among the scientific community was triggered when calculations showed that the asteroid has a very high probability of colliding with Mars on January 30, 2008, which was originally estimated at 1 out of 25 [3] . However, more accurate measurements carried out during its approach to the Earth to a distance of 1.5 million km made it possible to refine the parameters of its orbit and significantly reduce the probability of its collision with Mars to 1 in 10,000 [4] . As a result of observations made at the end of January 2008, it turned out that a collision did not occur - an asteroid passed near Mars at a distance of only 6.5 radii of the planet, which led to the strongest gravitational perturbations of its orbit from this planet. Because of the impossibility of obtaining more accurate data on this convergence, the scientists did not manage to establish how the asteroid's orbit changed, and to calculate its new orbital parameters. Therefore, it is currently considered “lost” [5] .
Opening
The discovery of the asteroid was made at an observatory located on Mount Lemmon , near Tucson in Arizona as part of the Catalina survey using a 1.5-meter telescope [6] . 2007 WD 5 was noticed 19 days after the confrontation with Earth in the constellation Taurus and had a brightness 400,000 times lower than that which a person can distinguish with the naked eye on a dark night in the absence of city illumination , having the appearance of a dim asterisk 20.2 m of magnitude [2] . And at the time of its approach to Mars, the brightness of the asteroid was 25.9 m , which was 190 times less than at the time of discovery [7] .
Convergence with Mars
Chronology of observations
- November 1, 2007 - nineteen days before its discovery, the asteroid passes 7.5 million km (0.0476 AU) from the Earth [6] ;
- November 20, 2007 - the discovery of the asteroid Andrea Boattini as part of the Catalina review [2] ;
- December 21, 2007 - an asteroid traveled half way between Earth and Mars (12.5 km / s speed). At that time, the probability of an asteroid colliding with Mars on January 30, 2008 is estimated to be 1 to 25. It was believed that if a collision does not occur, the asteroid will fly 50,000 km from the planet;
- December 28, 2007 is the official announcement about the discovery of the asteroid 2007 WD 5 from three photos taken on November 8, 2007. The asteroid's orbit in the area of approach to Mars is refined: the zone of uncertainty around Mars through which the asteroid must pass has decreased from 1 million to 400,000 km [3] . The asteroid was supposed to fly no more than 21,000 km from Mars and only 16,000 km from Deimos [8] ;
- January 2, 2008 - According to the results of asteroid observation by Bill Ryan on the 2.4-meter telescope of the Magdalena Ridge Observatory (Eng.), The probability of an asteroid colliding with Mars was reduced to 1 to 28, and the area of uncertainty around Mars was reduced to 200 000 km, while still blocking the planet [9] ;
- January 8, 2008 - according to the results of the asteroid observation on the 3.5-meter telescope of the Kalar-Alto Observatory, the probability of a collision decreased to 1 to 40, and the uncertainty zone was 3 times as large [10] ;
- January 9, 2008 - after several more observations and orbit refinement, the probability of a collision was reduced to 1 in 10,000 [4] , and the uncertainty zone to 26,000 km from the center of the planet (7 radii of Mars) [11] . According to calculations, the likelihood of subsequent convergence of the asteroid with Mars or Earth in the XXI century is extremely small.
- January 30, 2008 - an asteroid flew past Mars, which at the same time greatly changed its trajectory as a result of which the asteroid was lost. Most likely, he safely passed the planet at a distance of 3.25 the diameter of Mars.
As you can see, as we approach the planet and refine the data, the probability of a collision decreases steadily. A similar tendency is very characteristic when observing asteroids and earlier (in December 2004) was already observed in the study of asteroid (99942) Apophis threatening to collide with the Earth in 2029 - at this stage the probability of this event is 2.7%.
Collision impact assessments
According to the calculations of scientists, in the event of an asteroid colliding with Mars, it would crash into it at a speed of 13.5 km / s, and the explosion energy would be about 3 megatons in TNT . The thin atmosphere of Mars could not significantly affect the integrity of the asteroid, so that it would reach the surface of the planet almost intact, forming a crater with a diameter of 0.8 km [12] . The fall site would be just north of the landing site of the Opportuny rover .
Phenomena such as the Arizona crater or Tunguska meteorite were most likely caused by the fall of objects of approximately the same size to Earth as this asteroid. The collision of the Earth with bodies of this size occurs about once every several hundred years [13] . Since the mass of Mars is 10 times smaller than Earth and, as a result, it has less gravity, it also attracts much less asteroids from the surrounding space, so the fall of such large meteorites to Mars occurs about once a thousand years [1] .
Future convergence
Interestingly, in July 2003, the asteroid was already moving closer to Mars, having passed 1.8 million km (0.012 AU) from it [11] , and after 5 years already flew past it. The rapprochement of 2003 caused far less critical changes in the asteroid's orbit than the rapprochement of 2008, so it is difficult to say where the asteroid can now be and whether it will still come closer to Mars or to any other planet. Although Mars is not such a large planet as Jupiter and is not able to throw an asteroid outside the solar system , however, such a close approach can very seriously change the orbit of the asteroid. It is very difficult to calculate this change, therefore at the moment an asteroid is considered “lost” [5] . If we assume that the asteroid has successfully flown past Mars, then, due to the strongly elongated and slightly inclined orbit at the initial stage of approach, it is unlikely to come close to Earth or Mars in the near future.
See also
- Asteroid list
- Small Planet Classifications
- D / 1993 F2 (Shoemakers - Levy)
Notes
- ↑ 1 2 Astronomers Monitor Asteroid to Pass Near Mars . NASA / JPL (December 21, 2007). The date of circulation is December 22, 2007. Archived December 24, 2007.
- 2 1 2 3 Lori Stiles, University Communications. Catalina Sky That Could Hit Mars . The University of Arizona (December 21, 2007). The appeal date is December 23, 2007. Archived December 10, 2012.
- ↑ 1 2 Don Yeomans, Paul Chodas and Steve Chesley. Mars Impact Probability Increases to 4 Percent . NASA / JPL Near-Earth Object Program Office (December 28, 2007). Circulation date December 28, 2007. Archived December 29, 2007.
- ↑ 1 2 Steve Chesley, Paul Chodas and Don Yeomans. 2007 WD5 Mars Collision Effectively Ruled Out - Impact Odds now 1 in 10,000 (Unavailable (not available link) . NASA / JPL Near-Earth Object Program Office (January 9, 2008). The date of circulation is January 9, 2008. Archived January 11, 2008.
- ↑ 1 2 Lakdawalla, Emily WD5 most likely missed Mars (but we can never know (February 4, 2008). The appeal date is February 24, 2008. Archived February 8, 2008.
- ↑ 1 2 Steve Chesley and Paul Chodas. Recently Discovered Asteroid Could Hit Mars in January . NASA / JPL Near-Earth Object Program Office (December 21, 2007). The appeal date is December 21, 2007. Archived December 24, 2007.
- ↑ A 100-fold increase in luminous flux corresponds to a reduction in the apparent magnitude of exactly 5 units (25.9 - 20.2) = −2.5 lg (L1 / L2) = 190x
- ↑ Horizons Archive Mars / Earth 2003/2008 . The appeal date is December 23, 2007. Archived December 10, 2012.
- ↑ Don Yeomans, Paul Chodas and Steve Chesley. New Observations Slightly Decrease Mars Impact Probability (not available link) . NASA / JPL Near-Earth Object Program Office (January 2, 2008). The date of circulation is January 2, 2008. Archived January 5, 2008.
- ↑ Steve Chesley, Paul Chodas and Don Yeomans. Mars Impact Seems Less Likely (Unavailable (inaccessible link) . NASA / JPL Near-Earth Object Program Office (January 8, 2008). The date of circulation is January 8, 2008. Archived January 12, 2008.
- ↑ 1 2 Horizons Output Mars / Earth 2003/2008 . The appeal date is January 9, 2008. Archived December 10, 2012
- ↑ Johnson Jr., John . Mars hit , Science , Los Angeles Times (December 21, 2007). Archived December 22, 2007. The appeal date is December 21, 2007.
- ↑ David Morrison. Tunguska Revision, and a Possible NEA Impact on Mars (not available link) . Asteroid and Comet Impact Hazards ( NASA ) (December 21, 2007). The date of circulation is January 3, 2008. Archived January 2, 2008.
Links
- NASA JPL Database on Small Bodies of the Solar System (2007 WD5) (English)
- MPC Database on Small Bodies of the Solar System (2007) (eng.)
- Asteroid 2007 WD5 may collide with Mars (Inaccessible link) . Archived March 6, 2008.
- Asteroid orbit elements
- Near Earth Object Program (at NASA.gov )
- A Meteoroid Hits the Moon (inaccessible link) . Archived June 16, 2006. (25 cm wide) on May 2, 2006
- Gravity Simulator of Mars Passage (based on 23 orbital elements)
- Computing Crater Size from Projectile Diameter (not available link) . Archived November 17, 2014. (H. Jay Melosh and Ross A. Beyer)
- Solar System Collisions (Send an asteroid or comet hurtling towards your favorite planet!)
- Science Friday Podcast with Don Yeomans (Inaccessible link) . Archived January 1, 2008. (2007-12-28)
- Possible Asteroid Strike on Mars: Scientific Paydirt Unreferenced (inaccessible link) . Archived July 20, 2008. (2008-01-03)