(29075) 1950 DA

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(29075) 1950 DA
1950 DA.png
Radar image of 1950 DA taken at Arecibo in March 2001, from a distance of 22  LD or 0.052  AU
Discovery [1]
Discovered by Carl A. Wirtanen
Discovery site Lick Obs.
Discovery date23 February 1950
Designations
(29075) 1950 DA
1950 DA ·2000 YK66 ·Object Wirtanen [2]
NEO  · Apollo  · PHA [1] [3]  · risk listed
Orbital characteristics [3]
Epoch 17 October 2024 (JD  2460600.5)
Uncertainty parameter 0
Observation arc 74.87  yr (27,345 d)
Aphelion 2.5614  AU
Perihelion 0.8364 AU
1.6989 AU
Eccentricity 0.5077
2.214 yr (809 d)
223.31°
0° 26m 42.36s / day
Inclination 12.16°
356.59°
224.76°
Earth  MOID 0.03853 AU (14.9948  LD)
Proper orbital elements [4]
Precession of perihelion
13.655  arcsec  / yr
Precession of the ascending node
−35.824  arcsec  / yr
Physical characteristics
Dimensions 1.39  km × 1.46  km × 1.07  km [5]
Mass >4×1012  kg [a]
Mean density
>3.5  g/cm3 [5]
2.12160±0.00004  h [5]

    (29075) 1950 DA (provisional designation 1950 DA) is a risk-listed asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.3 kilometers (0.81 miles) in diameter. [5] It once had the highest known probability of impacting Earth. [12] In 2002, it had the highest Palermo scale rating with a value of 0.17 and a probability of 1 in 306 (0.33%) for a possible collision in 2880. [13] [6] Since that time, the estimated risk has been updated several times. In December 2015, the odds of an Earth impact were revised to 1 in 8,300 (0.012%) with a Palermo scale rating of −1.42. [12] As of February 2025, it is listed on the Sentry Risk Table with the highest cumulative Palermo scale rating of −0.92. [14] [15] 1950 DA is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future. As of 2 February 2025, the odds of an Earth impact are 1 in 2,600 (0.039%). [14] [12]

    Contents

    Discovery and nomenclature

    1950 DA was first discovered on 23 February 1950 by Carl A. Wirtanen at Lick Observatory. [3] It was observed for seventeen days [6] and then lost because this short observation arc resulted in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered at Lowell Observatory and was announced as 2000 YK66 on 4 January 2001. [16] Just two hours later it was recognized as 1950 DA. [6] [17]

    Observations

    1950 DA (color).png
    Asteroid 1950 DA, Arecibo Observatory radar image (coloured version)
    1950 DA radar movie.gif
    Arecibo radar movie of 1950 DA obtained during 48 minutes (37% of a rotation) on 4 March 2001

    On 5 March 2001, 1950 DA made a close approach to Earth at a distance of 0.05207  AU (7.790 million  km ; 4.840 million  mi ; 20.26  LD ). [18] It was studied by radar at the Goldstone and Arecibo observatories from March 3 to 7, 2001. [6]

    The studies showed that the asteroid has a mean diameter of 1.1 km, assuming that 1950 DA is a retrograde rotator. [19] Optical lightcurve analysis by Lenka Šarounová and Petr Pravec shows that its rotation period is 2.1216±0.0001 hours. Due to its short rotation period and high radar albedo, 1950 DA is thought to be fairly dense (more than 3.5 g/cm3, assuming that it has no internal strength) and likely composed of nickeliron. [5] In August 2014, scientists from the University of Tennessee determined that 1950 DA is a rubble pile rotating faster than the breakup limit for its density, implying the asteroid is held together by van der Waals forces rather than gravity. [20] [21]

    1950 DA made distant approaches to Earth on 20 May 2012, 5 February 2021 and 5 February 2023. [18] However, at these times it was a quarter to half an AU away from Earth, preventing more useful astrometrics and timing that occurs when an object is closer to Earth. The next close approach that presents a good opportunity to observe the asteroid will be on 2 March 2032, when it will be 0.076 AU (11.4 million km) from Earth. The following table lists the approaches closer than 0.1 AU until the year 2500. [22] By 2136 the close approach solutions are becoming notably more divergent.[ citation needed ]

    Position uncertainty and increasing divergence [22]
    Date JPL SBDB
    nominal geocentric
    distance (AU)
    uncertainty
    region
    (1-sigma)
    2 March 20320.075752 AU (11,332,300 km)±10 km
    19 March 20740.095459 AU (14,280,500 km)±30 km
    10 March 21050.036316 AU (5,432,800 km)±43 km
    11 March 21360.042596 AU (6,372,300 km)±387 km
    8 March 21870.035224 AU (5,269,400 km)±1717 km
    20 March 22180.084849 AU (12,693,200 km)±8712 km
    18 March 23730.058991 AU (8,824,900 km)±2508 km
    6 March 24550.087706 AU (13,120,600 km)±1650 km
    Impact probability at different times
    DateJPL SolutionImpact probability
    5 April 2002 [6] 1/306
    7 December 2015 [23] 1/8300
    29 March 2022 [24] 1/34000
    18 June 2024 [25] 1/2600
    23 January 2025JPL2761/2600

    Possible Earth impact

    1950 DA has one of the best-determined asteroid orbital solutions. This is due to a combination of: [6]

    Main-belt asteroid 78 Diana (~125 km in diameter) will pass about 0.003  AU (450,000  km ; 280,000  mi ) from 1950 DA on 5 August 2150. [6] At that distance and size, Diana will perturb 1950 DA enough so that the change in trajectory is notable by 2880 (730 years later). In addition, over the intervening time, 1950 DA's rotation will cause its orbit to slightly change as a result of the Yarkovsky effect. If 1950 DA continues on its present orbit, it may approach Earth on 16 March 2880, though the mean trajectory passes many millions of kilometres from Earth, so 1950 DA does not have a significant chance of impacting Earth. As of February 2025, according to the latest solution dated 2 February 2025, the probability of an impact in 2880 is 1 in 2,600 (0.039%). [12]

    The energy released by a collision with an object the size of 1950 DA would cause major effects on the climate and biosphere, which would be devastating to human civilization. The discovery of the potential impact heightened interest in asteroid deflection strategies.

    See also

    Notes

    References

    1. 1 2 3
    2. 1 2 3 4 5 6
    3. 1 2 3 4 5 6 7 8
    4. 1 2 3 4 5 6 7 8 9
    5. 1 2 3
    6. 1 2 3 4
    7. 1 2
    8. 1 2 3 4
    9. 1 2
    10. "Impact threat analysis update completed for 1950 DA". European Space Agency. 29 March 2022.
    11. "MPEC 2001-A22 : 2000 YK66". Minor Planet Center. 4 January 2001. Retrieved 23 February 2018.
    12. "MPEC 2001-A26 : 1950 DA = 2000 YK66". Minor Planet Center. 4 January 2001. Retrieved 23 February 2018.
    13. 1 2
    14. 1 2 "Close-approach results". JPL Horizons. Retrieved 7 December 2024. Soln.date: 2024-Dec-05 05:58:05
    15. Farnocchia, D.; Chesley, S.R.; Chamberlin, A.B.; Tholen, D.J. (January 2015). "Star catalog position and proper motion corrections in asteroid astrometry". Icarus. 245: 94–111. arXiv: 1407.8317 . Bibcode:2015Icar..245...94F. doi:10.1016/j.icarus.2014.07.033.
    16. "Sentry: Earth Impact Monitoring".
    17. Fuentes-Muñoz, Oscar; Farnocchia, Davide; Naidu, Shantanu P.; Park, Ryan S. (1 June 2024). "Asteroid Orbit Determination Using Gaia FPR: Statistical Analysis". The Astronomical Journal. 167 (6): 290. Bibcode:2024AJ....167..290F. doi: 10.3847/1538-3881/ad4291 .