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{{Short description|Most hazardous risk–listed near-Earth asteroid}}
<!-- Additional parameters for this template are available at ]. -->{{Infobox Planet
{{Use dmy dates|date=March 2020}}<!-- MOS:RETAIN -->
| image= ]
{{Infobox planet
| caption = ] ] image of 1950 DA on 4 March 2001, from a distance of 0.052&nbsp;] (22&nbsp;]s)
| minorplanet = yes
| discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0 |
name=(29075) 1950 DA | name = (29075) 1950 DA
| background = #FFC2E0
| discoverer=]
| image = 1950 DA.png
| discovered=February 22, 1950<ref name=jpldata/>
| image_scale =
| alt_names={{mp|2000 YK|66}}<ref name="MPEC2001-A26"/>
| caption = ] of {{mp|1950 DA}} taken at ] in March 2001, from a distance of 22&nbsp;] or 0.052&nbsp;]
| mp_category=]
| orbit_ref = <ref name="jpldata"/> | discovery_ref = <ref name="MPC-object" />
| discoverer = ]
| epoch=2011-Aug-27 (] 2455800.5)<br>(]=0)<ref name=jpldata/>
| discovery_site = ]
| semimajor=1.6985 ]<br>(254.09 Gm)
| discovered = 23 February 1950
| perihelion=0.83529 AU<br>(124.95 Gm)
| mpc_name = (29075) 1950 DA
| aphelion=2.5618 ]<br>(383.23 ]m)
| alt_names = 1950 DA{{·}}{{mp|2000 YK|66}}
| eccentricity=0.50823
| pronounced =
| period=808.59 ] (2.21 ])
| named_after = <!--]<br />{{small|()}}<ref name="MPC-object" />-->
| inclination=12.175]
| mp_category = ]{{·}}]{{·}}]<ref name="MPC-object" /><ref name="jpldata" />{{·}}]
| asc_node=356.74°
| orbit_ref = <ref name="jpldata" />
| arg_peri=224.59°
| epoch = 31 March 2024 (]&nbsp;2460400.5)
| mean_anomaly=246.03°
| uncertainty = 0
| avg_speed=21.30 km/]
| observation_arc = 73.61&nbsp;] (26,885&nbsp;d)
| dimensions=1.1&ndash;1.4 km<br>1.1 km (mean)<ref name="NEO-1950DA"/>
| aphelion = 2.5614&nbsp;]
| mass=>2{{e|12}} kg<ref name=estimate/>
| perihelion = 0.8355&nbsp;AU
| density=>3.0 g/cm³
| semimajor = 1.6985&nbsp;AU
| surface_grav=
| eccentricity = 0.5081
| escape_velocity=
| period = 2.214&nbsp;yr (809&nbsp;d)
| rotation=0.0884 d (2.1216 h)<ref name=jpldata/>
| mean_anomaly = 134.33]
| spectral_type=E or M
| mean_motion = {{Deg2DMS|0.4453|sup=ms}} / day
| abs_magnitude=17.0<ref name=jpldata/>
| inclination = 12.17°
| albedo=0.2–0.25
| asc_node = 356.64°
| single_temperature=
| arg_peri = 224.70°
| moid = 0.04011&nbsp;AU (15.609&nbsp;])
| p_orbit_ref = <ref name="Proper" />
| node_rate = −35.824
| perihelion_rate = 13.655
| dimensions = {{val|1.39|x|1.46|x|1.07|ul=km}}<ref name="Busch-2007b" />
| mean_diameter = {{Ubl
| {{val|1.3|ul=km}}<ref name="Busch-2007b" />
| {{val|1.1|ul=km}}<ref name="Giorgini-2002" />
| {{val|1.25|0.12|u=km}}<ref name="Busch-2007b" />
| {{val|2.00|0.20|u=km}}<ref name="Mainzer-2016" />
}}
| mass = >{{val|4|e=12|ul=kg}}{{efn|name=estimate}}
| density = >{{val|3.5|ul=g/cm3}}<ref name="Busch-2007b" />
| rotation = {{val|2.12160|0.00004|ul=h}}<ref name="Busch-2007b" />
| albedo = {{Ubl
| {{val|0.070}}<ref name="Mainzer-2016" />
| {{val|0.25}}<ref name="Rivkin-2005a" />
}}
| spectral_type = {{Ubl
| ]<ref name="Dandy-2003" /><ref name="lcdb" />
| ] {{=}} {{val|0.862|0.077}}<ref name="Dandy-2003" />
| ] {{=}} {{val|0.494|0.069}}<ref name="Dandy-2003" />
| ] {{=}} {{val|0.816|0.067}}<ref name="Dandy-2003" />
}}
| abs_magnitude = {{Ubl
| 16.83<ref name="Busch-2007b" />
| 17.00<ref name="Mainzer-2016" />
| 17.28<ref name="MPC-object" /><ref name="jpldata" />
| 17.2<ref name=Neodys/>
| 17.1<ref name="lcdb" />
}}
}} }}
'''(29075) 1950 DA''' is a ]. It is notable for having the highest known ] of ] ] (between 0 and 0.33%).<ref name="NEO-1950DA"/> It has the highest ] with a value of 0.17 for a possible collision in the year 2880.<ref name="NEO-1950DA"/> For a brief period in late December 2004, asteroid ] held the record for Palermo scale values, with a value of 1.10.<ref name="mirror"/> '''{{mp|(29075) 1950 DA}}''' (] '''{{mp|1950 DA}}''') is a risk-listed ], classified as a ] and ] of the ], approximately {{convert|1.3|km|abbr=off|sp=us}} in diameter.<ref name="Busch-2007b" /> It once had the highest known ] of ].<ref name="impact-risk-summary"/> In 2002, it had the highest ] with a value of 0.17 and a probability of 1 in 306 (0.33%) for a possible collision in 2880.<ref name="NEO-1950DA"/><ref name="Giorgini-2002"/> 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 rating of −1.42.<ref name="impact-risk-summary"/> {{As of|2024|12}}, it is listed on the ] with the highest cumulative Palermo rating of -0.93.<ref name="risk-table" /><ref name="ESASSP_2022">{{Cite web|url=https://neo.ssa.esa.int/-/impact-threat-analysis-update-completed-for-1950-da|title=Impact threat analysis update completed for 1950 DA|date=29 March 2022|publisher=European Space Agency}}</ref> {{mp|1950 DA}} is not assigned a ] rating, because the 2880 date is over 100 years in the future. As of the 26 December 2024, the odds of an Earth impact are 1 in 2,600 (0.038%).<ref name="risk-table" /><ref name="impact-risk-summary"/>


==Discovery and name== == Discovery and nomenclature ==
1950 DA was first discovered on February 23, 1950, by ] at ].<ref name=jpldata/> It was observed for seventeen days<ref name=Giorgini2002/> and then ] because the short observation arc resulted in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered as {{mp|2000 YK|66}} and 2 hours later was recognized as 1950 DA.<ref name=Giorgini2002/> {{mp|1950 DA}} was first discovered on 23 February 1950 by ] at ].<ref name=jpldata/> It was observed for seventeen days<ref name="Giorgini-2002" /> and then ] because this short observation arc resulted in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered at ] and was announced as {{mp|2000 YK|66}} on 4 January 2001.<ref>{{cite web|url=https://minorplanetcenter.net/mpec/K01/K01A22.html|title=MPEC 2001-A22 : 2000 YK66|publisher=Minor Planet Center|date=4 January 2001|access-date=23 February 2018}}</ref> Just two hours later it was recognized as {{mp|1950 DA}}.<ref name="Giorgini-2002" /><ref>{{cite web|url=https://minorplanetcenter.net/mpec/K01/K01A26.html|title=MPEC 2001-A26 : 1950 DA = 2000 YK66|publisher=Minor Planet Center|date=4 January 2001|access-date=23 February 2018}}</ref>


==Observations== == Observations ==
{{multiple image
On March 5, 2001, 1950 DA made a close approach to the Earth of {{convert|0.0520726|AU|km mi|abbr=on|lk=on}}.<ref name=jpl-close/> It was studied by radar at the ] and ] observatories from March 3 to 7 2001.<ref name=Giorgini2002/>
|direction = vertical
] radar image]]
|align = left
The studies showed that the asteroid has a mean diameter of 1.1–1.4&nbsp;km (3,600-4,600&nbsp;ft). Optical ] analysis by Lenka Sarounova and ] shows that its rotation period is 2.1216 ± 0.0001 hours. Due to its short rotation period and high radar ], 1950 DA is thought to be fairly dense (more than 3 g/cm³) and likely composed of nickel-iron.<ref name=NEO> on the ] website (last accessed on October 7, 2007). (''Broken'')</ref>
|width = 215
|image1 = 1950 DA (color).png
|image2 = 1950 DA radar movie.gif
|caption1 = Asteroid ''{{mp|1950 DA}}'', ] radar image (coloured version)
|caption2 = Arecibo radar movie of {{mp|1950 DA}} obtained during 48 minutes (37% of a rotation) on 4 March 2001
}}


On 5 March 2001, {{mp|1950 DA}} made a close approach to Earth at a distance of {{convert|0.05207|AU|e6km e6mi LD|abbr=unit|lk=on}}.<ref name=jpl-close/> It was studied by radar at the ] and ] observatories from March 3 to 7, 2001.<ref name="Giorgini-2002" />
==Possible Earth impact==
That 1950 DA has one of the best-determined asteroid orbital solutions is due to a combination of:<ref name=Giorgini2002/>
*an orbit moderately ] (12 degrees)<ref name=jpldata/> to the ] (reducing in-plane ])
*high-precision radar astrometry that is more accurate than visual-wavelength measurements
*a 60-year observation arc<ref name=jpldata/>
*an uncertainty region controlled by ]


The studies showed that the asteroid has a ] of 1.1&nbsp;km, assuming that {{mp|1950 DA}} is a retrograde rotator.<ref name="Farnocchia-2014" /> Optical ] analysis by ] and ] shows that its rotation period is {{val|2.1216|0.0001}} hours. Due to its short rotation period and high radar ], {{mp|1950 DA}} is thought to be fairly dense (more than 3.5&nbsp;g/cm<sup>3</sup>, assuming that it has no internal strength) and likely composed of ]–].<ref name="Busch-2007b" /> In August 2014, scientists from the ] determined that ''{{mp|1950 DA}}'' is a ] rotating faster than the breakup limit for its density, implying the asteroid is held together by ]s rather than gravity.<ref name="Rozitis-2014" /><ref name="tntoday" />
The next radar opportunity for 1950 DA is in 2032.<ref name=Giorgini2002/>


{{mp|1950 DA}} made distant approaches to Earth on 20 May 2012, 5 February 2021 and 5 February 2023.<ref name=jpl-close/> However, at these times it was a quarter to half an AU away from Earth, preventing more useful ] 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 {{convert|0.076|AU|e6km|abbr=unit|lk=off}} from Earth. The following table lists the approaches closer than 0.1&nbsp;AU until the year 2500.<ref name="jpl-close-hor"/> By 2136 the close approach solutions are becoming notably more divergent.{{citation needed|date=June 2024}}
If 1950 DA continues on its present orbit, it will approach near to the Earth on March 16, 2880.<ref name="NEO-1950DA"/> However, over the intervening time, its rotation will cause its orbit to slightly change as a result of the ]. Available radar and optical data suggest two possible pole directions;<ref name="NEO-1950DA"/> one trajectory misses the Earth by tens of millions of kilometers, while the other has an impact probability of roughly 1 in 300.<ref name="NEO-1950DA"/>


{| class="wikitable sortable" style="font-size: 0.9em;"
The energy released by a collision with an object the size of 1950 DA would cause major effects on the ] and ] which would be devastating to ] ]. The discovery of the potential impact has heightened interest in ].
|+Position uncertainty and increasing divergence<ref name="jpl-close-hor">{{Cite web|url=https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%2729075%27&EPHEM_TYPE=%27APPROACH%27&CA_TABLE_TYPE=%27EXTENDED%27&CALIM_SB=%270.10%27&START_TIME=%272020-01-01%27&STOP_TIME=%272500-01-01%27|title=Close-approach results|work=JPL Horizons|access-date=7 December 2024}} Soln.date: 2024-Dec-05 05:58:05</ref>
! Date
! ]<br />] geocentric<br />distance (])
! uncertainty<br />region<br/>(])
|-
| 2 March 2032 ||{{Convert|0.075752|AU|km|abbr=unit}} || ±10&nbsp;km
|-
|19 March 2074 ||{{Convert|0.095459|AU|km|abbr=unit}} || ±30&nbsp;km
|-
|10 March 2105 ||{{Convert|0.036316|AU|km|abbr=unit}} || ±43&nbsp;km
|-
|11 March 2136 ||{{Convert|0.042596|AU|km|abbr=unit}} || ±387&nbsp;km
|-
| 8 March 2187 ||{{Convert|0.035224|AU|km|abbr=unit}} || ±1717&nbsp;km
|-
|20 March 2218 ||{{Convert|0.084849|AU|km|abbr=unit}} || ±8712&nbsp;km
|-
|18 March 2373 ||{{Convert|0.058991|AU|km|abbr=unit}} || ±2508&nbsp;km
|-
| 6 March 2455 ||{{Convert|0.087706|AU|km|abbr=unit}} || ±1650&nbsp;km
|}
{| class="wikitable sortable" style="font-size: 0.9em;"
|+Impact probability at different times


! Date
==See also==
! JPL Solution
* ]
! Impact probability
* ]
|-
* ]
| 5 April 2002 ||<ref name="Giorgini-2002"/>
|| 1/306
|-
|7 December 2015 ||<ref>{{cite journal |last1=Farnocchia |first1=D. |last2=Chesley |first2=S.R. |last3=Chamberlin |first3=A.B. |last4=Tholen |first4=D.J. |title=Star catalog position and proper motion corrections in asteroid astrometry |journal=Icarus |date=January 2015 |volume=245 |pages=94–111 |doi=10.1016/j.icarus.2014.07.033 |arxiv=1407.8317 |bibcode=2015Icar..245...94F }}</ref> || 1/8300
|-
|29 March 2022 ||<ref>{{cite web | url=https://cneos.jpl.nasa.gov/sentry/notes.html | title=Sentry: Earth Impact Monitoring }}</ref> || 1/34000
|-
|18 June 2024 ||<ref>{{cite journal |last1=Fuentes-Muñoz |first1=Oscar |last2=Farnocchia |first2=Davide |last3=Naidu |first3=Shantanu P. |last4=Park |first4=Ryan S. |title=Asteroid Orbit Determination Using Gaia FPR: Statistical Analysis |journal=The Astronomical Journal |date=1 June 2024 |volume=167 |issue=6 |pages=290 |doi=10.3847/1538-3881/ad4291 |doi-access=free |bibcode=2024AJ....167..290F }}</ref> || 1/2600
|-
| 9 December 2024 ||JPL270|| 1/2500
|-
|20 December 2024 ||JPL271 || 1/2600
|-
|22 December 2024 ||JPL272|| 1/2600
|-
|26 December 2024 ||JPL273|| 1/2600
|-
|}


== Possible Earth impact ==
==References==
{{mp|1950 DA}} has one of the best-determined asteroid orbital solutions. This is due to a combination of:<ref name="Giorgini-2002" />
{{reflist
* an orbit moderately ] (12 degrees)<ref name=jpldata/> to the ] (reducing in-plane ]);
| refs =
* high-precision radar astrometry, which provides its distance and is complementary to the measurements of angular positions;
* a 74-year ];<ref name=jpldata/>
* an uncertainty region controlled by ].<ref name="Giorgini-2002" />


Main-belt asteroid ] (~125&nbsp;km in diameter) will pass about {{convert|0.003|AU|km mi|abbr=on|lk=on}} from {{mp|1950 DA}} on 5 August 2150.<ref name="Giorgini-2002" /> At that distance and size, Diana will perturb {{mp|1950 DA}} enough so that the change in trajectory is notable by 2880 (730 years later). In addition, over the intervening time, {{mp|1950 DA}}'s rotation will cause its orbit to slightly change as a result of the ]. If {{mp|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 {{mp|1950 DA}} does not have a significant chance of impacting Earth. {{As of|2024|12}}, according to the latest solution dated 26 December 2024, the probability of an impact in 2880 is 1 in 2,600 (0.038%).<ref name=impact-risk-summary/>
<ref name=jpldata>{{cite web

|date=2010-10-04 last obs (arc=60.61 years)
The energy released by a collision with an object the size of {{mp|1950 DA}} would cause major effects on the ] and ], which would be devastating to ] ]. The discovery of the potential impact heightened interest in ].
|title=JPL Small-Body Database Browser: 29075 (1950 DA)

|url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1950DA
== See also ==
|publisher=Jet Propulsion Laboratory
*{{Section link|List of exceptional asteroids|Landmark asteroids}}
|accessdate=2011-11-19}}</ref>
*]
*]
*]

== Notes ==
{{notelist|refs=
{{efn|name=estimate|1=A reported volume of 1.14&nbsp;km<sup>3</sup> × density of 3.5&nbsp;g/cm<sup>3</sup> yields a mass (m = d × v) of {{Val|3.99e12|u=kg}}}}

}} <!-- end of notelist -->

== References ==
{{reflist|refs=

<ref name="jpldata">{{cite web
|type = 2023-10-03 last obs.
|title = JPL Small-Body Database Browser: 29075 (1950 DA)
|url = https://ssd.jpl.nasa.gov/tools/sbdb.cgi?sstr=2029075
|publisher = ]
|access-date = 18 June 2024}}</ref>

<ref name="MPC-object">{{cite web
|title = 29075 (1950 DA)
|work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=29075
|access-date = 24 February 2024}}</ref>


<ref name=jpl-close>{{cite web <ref name=jpl-close>{{cite web
|date=2010-10-04 last obs (arc=60.61 years) |type=solution: 2024-04-24; last observation: 2023-10-03; ]: 73.61 years
|title=JPL Close-Approach Data: 29075 (1950 DA) |title=JPL Close-Approach Data: 29075 (1950 DA)
|url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1950DA;cad=1#cad |url=https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1950%20DA&view=OPC
|accessdate=2011-11-19}}</ref> |access-date=18 June 2024}}</ref>

<ref name="mirror">{{cite web
|date=Dec 27, 2004
|title=2004 MN4 Earth Impact Risk Summary (computed on Dec 27, 2004)
|publisher=The Cosmic Mirror
|author=Daniel Fischer
|url=http://www.astro.uni-bonn.de/~dfischer/mirror/285neo041227.html
|accessdate=2011-11-04}}</ref>


<ref name="NEO-1950DA">{{cite web <ref name="NEO-1950DA">{{cite web
|title=Asteroid 1950 DA |title=Asteroid 1950 DA
|publisher=NASA/JPL Near-Earth Object Program Office
|url=http://neo.jpl.nasa.gov/1950da/
|access-date=14 October 2011
|archive-url=https://web.archive.org/web/20110721050545/http://neo.jpl.nasa.gov/1950da/
|archive-date=21 July 2011
|url-status=dead}}</ref>

<ref name="Proper">{{cite web
|title=(29075) 1950DA NeoDys{{Snd}} Proper Elements
|website=NeoDys Near Earth Objects Dynamic Site
|url=https://newton.spacedys.com/neodys/index.php?pc=1.1.6&n=29075
|access-date=24 February 2024}}</ref>

<ref name=Neodys>{{cite web
|title=(29075) 1950DA
|website=NeoDys Near Earth Objects Dynamic Site
|url=https://newton.spacedys.com/neodys/index.php?pc=1.1.0&n=29075
|access-date=24 February 2024}}</ref>

<ref name="impact-risk-summary">{{cite web
|title=29075 (1950 DA) Earth Impact Risk Summary
|publisher=NASA/JPL Near-Earth Object Program Office |publisher=NASA/JPL Near-Earth Object Program Office
|url=http://neo.jpl.nasa.gov/1950da/ |url=https://cneos.jpl.nasa.gov/sentry/details.html#?des=29075
|date=6 February 2022
|accessdate=2011-10-14| archiveurl= http://web.archive.org/web/20110721050545/http://neo.jpl.nasa.gov/1950da/| archivedate= 21 July 2011<!--Added by DASHBot-->}}</ref>
|access-date=18 June 2024}}</ref>


<ref name=Giorgini2002>{{cite journal <ref name="risk-table">{{cite web
|title=Sentry Risk Table
|last=Giorgini |first=J. D.
|publisher=NASA/JPL Near-Earth Object Program Office
|coauthors=Ostro, S. J; Benner, L. A. M.; Chodas, P.W.; Chesley, S.R.; et al.
|url=https://cneos.jpl.nasa.gov/sentry/
|title=Asteroid 1950 DA's Encounter With Earth in 2880: Physical Limits of Collision Probability Prediction
|access-date=18 June 2024}} (Use Unconstrained Settings)</ref>
|journal=Science
|volume=296 |issue=5565 |pages=132–136 |year=2002
|url=http://neo.jpl.nasa.gov/1950da/1950da.pdf
|doi=10.1126/science.1068191
|arxiv=
|bibcode= 2002Sci...296..132G|pmid=11935024}}</ref>


<ref name="MPEC2001-A26">{{Cite web <ref name="tntoday">{{cite web
|title=MPEC 2001-A26 : 1950 DA = 2000 YK66 |title=UT Research uncovers forces that hold asteroid together
|publisher=IAU Minor Planet Center |publisher=University of Tennessee
|date=2001-01-04 |date=13 August 2014
|url=http://tntoday.utk.edu/2014/08/13/ut-research-uncovers-forces-hold-gravitydefying-nearearth-asteroid/
|url=http://www.minorplanetcenter.net/iau/mpec/K01/K01A26.html
|accessdate=2011-11-19}} (K00Y66K)</ref> |access-date=17 August 2015}}</ref>


<ref name="Farnocchia-2014">{{Cite journal
<ref name=estimate>use a spherical radius of {{Convert|0.55|km|abbr=on}}; ] * density of 3 g/cm<sup>3</sup> yields a mass (m=d*v) of 2.09{{e|12}} kg</ref>
|first1 = D. |last1 = Farnocchia
|first2 = S. R. |last2 = Chesley
|date = February 2014
|title = Assessment of the 2880 impact threat from Asteroid (29075) 1950 DA
|journal = Icarus
|volume = 229
|pages = 321–327
|bibcode = 2014Icar..229..321F
|doi = 10.1016/j.icarus.2013.09.022
|arxiv = 1310.0861}}</ref>


<ref name="lcdb">{{cite web
}}
|title = LCDB Data for (29075)
|publisher = Asteroid Lightcurve Database (LCDB)
|url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=29075%7C
|access-date = 24 February 2024}}</ref>

<ref name="Busch-2007b">{{Cite journal
|display-authors = 6
|first1 = Michael W. |last1 = Busch
|first2 = Jon D. |last2 = Giorgini
|first3 = Steven J. |last3 = Ostro
|first4 = Lance A. M. |last4 = Benner
|first5 = Raymond F. |last5 = Jurgens
|first6 = Randy |last6 = Rose
|first7 = Michael D. |last7 = Hicks
|first8 = Petr |last8 = Pravec
|first9 = Peter |last9 = Kusnirak
|first10 = Michael J. |last10 = Ireland
|first11 = Daniel J. |last11 = Scheeres
|first12 = Stephen B. |last12 = Broschart
|first13 = Christopher |last13 = Magri
|first14 = Michael C. |last14 = Nolan
|first15 = Alice A. |last15 = Hine
|first16 = Jean-Luc |last16 = Margot
|date = October 2007
|title = Physical modeling of near-Earth Asteroid (29075) 1950 DA
|url = https://echo.jpl.nasa.gov/asteroids/29075_1950DA/busch.etal.2007.1950da.pdf
|journal = Icarus
|volume = 190
|issue = 2
|pages = 608–621
|bibcode = 2007Icar..190..608B
|doi = 10.1016/j.icarus.2007.03.032
|access-date = 24 February 2024}}</ref>

<ref name="Giorgini-2002">{{Cite journal
|display-authors = 6
|first1 = J. D. |last1 = Giorgini
|first2 = S. J. |last2 = Ostro
|first3 = L. A. M. |last3 = Benner
|first4 = P. W. |last4 = Chodas
|first5 = S. R. |last5 = Chesley
|first6 = R. S. |last6 = Hudson
|first7 = M. C. |last7 = Nolan
|first8 = A. R. |last8 = Klemola
|first9 = E. M. |last9 = Standish
|first10 = R. F. |last10 = Jurgens
|first11 = R. |last11 = Rose
|first12 = A. B. |last12 = Chamberlin
|first13 = D. K. |last13 = Yeomans
|first14 = J.-L. |last14 = Margot
|date = April 2002
|title = Asteroid 1950 DA's Encounter with Earth in 2880: Physical Limits of Collision Probability Prediction
|url = https://cneos.jpl.nasa.gov/doc/1950da/1950da_published.pdf
|journal = Science
|volume = 296
|issue = 5565
|pages = 132–136
|bibcode = 2002Sci...296..132G
|doi = 10.1126/science.1068191
|pmid = 11935024}}</ref>

<ref name="Mainzer-2016">{{cite journal
|display-authors = 6
|first1 = A. K. |last1 = Mainzer
|first2 = J. M. |last2 = Bauer
|first3 = R. M. |last3 = Cutri
|first4 = T. |last4 = Grav
|first5 = E. A. |last5 = Kramer
|first6 = J. R. |last6 = Masiero
|first7 = C. R. |last7 = Nugent
|first8 = S. M. |last8 = Sonnett
|first9 = R. A. |last9 = Stevenson
|first10 = E. L. |last10 = Wright
|date = June 2016
|title = NEOWISE Diameters and Albedos V1.0
|url = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_COMPIL_5_NEOWISEDIAM_V1_0/data/neowise_mainbelt.tab
|journal = NASA Planetary Data System
|volume = 247
|pages = EAR-A-COMPIL-5-NEOWISEDIAM-V1.0
|bibcode = 2016PDSS..247.....M
|access-date= 5 July 2018}}</ref>

<ref name="Dandy-2003">{{Cite journal
|first1 = C. L. |last1 = Dandy
|first2 = A. |last2 = Fitzsimmons
|first3 = S. J. |last3 = Collander-Brown
|date = June 2003
|title = Optical colors of 56 near-Earth objects: trends with size and orbit
|journal = Icarus
|volume = 163
|issue = 2
|pages = 363–373
|bibcode = 2003Icar..163..363D
|doi = 10.1016/S0019-1035(03)00087-3}}</ref>

<ref name="Rivkin-2005a">{{Cite journal
|first1 = A. S. |last1 = Rivkin
|first2 = R. P. |last2 = Binzel
|first3 = S. J. |last3 = Bus
|date = May 2005
|title = Constraining near-Earth object albedos using near-infrared spectroscopy
|journal = Icarus
|volume = 175
|issue = 1
|pages = 175–180
|bibcode = 2005Icar..175..175R
|doi = 10.1016/j.icarus.2004.11.005}}</ref>

<ref name="Rozitis-2014">{{Cite journal
|first1 = Ben |last1 = Rozitis
|first2 = Eric |last2 = MacLennan
|first3 = Joshua P. |last3 = Emery
|date = 13 August 2014
|title = Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA
|journal = Nature
|volume = 512
|issue = 7513
|pages = 174–176
|doi = 10.1038/nature13632
|pmid = 25119234
|bibcode = 2014Natur.512..174R}}</ref>


}} <!-- end of reflist-->
==External links==
{{Commons category|(29075) 1950 DA}}
* from JPL (Java) /


== External links ==
{{MinorPlanets Navigator|(29074) 5160 T-3|(29076) 1972 TR8}}
{{Commons category}}
{{MinorPlanets Footer}}
* (K00Y66K). '']'' 4 January 2001
{{Impact cratering on Earth}}
* Rotating model of the asteroid (preferred rotation model is ''retrograde'', )
{{Use mdy dates|date=September 2010}}
* , query form ( {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }})
* {{Snd}} Observatoire de Genève, Raoul Behrend
* {{Snd}} Minor Planet Center
* {{NeoDys|29075}}
* {{JPL small body|id=29075}}


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Latest revision as of 21:00, 31 December 2024

Most hazardous risk–listed near-Earth asteroid

(29075) 1950 DA
Radar image of 1950 DA taken at Arecibo in March 2001, from a distance of 22 LD or 0.052 AU
Discovery
Discovered byCarl A. Wirtanen
Discovery siteLick Obs.
Discovery date23 February 1950
Designations
MPC designation(29075) 1950 DA
Alternative designations1950 DA · 2000 YK66
Minor planet categoryNEO · Apollo · PHA · risk listed
Orbital characteristics
Epoch 31 March 2024 (JD 2460400.5)
Uncertainty parameter 0
Observation arc73.61 yr (26,885 d)
Aphelion2.5614 AU
Perihelion0.8355 AU
Semi-major axis1.6985 AU
Eccentricity0.5081
Orbital period (sidereal)2.214 yr (809 d)
Mean anomaly134.33°
Mean motion0° 26 43.08 / day
Inclination12.17°
Longitude of ascending node356.64°
Argument of perihelion224.70°
Earth MOID0.04011 AU (15.609 LD)
Proper orbital elements
Precession of perihelion13.655 arcsec / yr
Precession of the ascending node−35.824 arcsec / yr
Physical characteristics
Dimensions1.39 km × 1.46 km × 1.07 km
Mean diameter
  • 1.3 km
  • 1.1 km
  • 1.25±0.12 km
  • 2.00±0.20 km
Mass>4×10 kg
Mean density>3.5 g/cm
Synodic rotation period2.12160±0.00004 h
Geometric albedo
  • 0.070
  • 0.25
Spectral type
Absolute magnitude (H)
  • 16.83
  • 17.00
  • 17.28
  • 17.2
  • 17.1

(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. It once had the highest known probability of impacting Earth. In 2002, it had the highest Palermo rating with a value of 0.17 and a probability of 1 in 306 (0.33%) for a possible collision in 2880. 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 rating of −1.42. As of December 2024, it is listed on the Sentry Risk Table with the highest cumulative Palermo rating of -0.93. 1950 DA is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future. As of the 26 December 2024, the odds of an Earth impact are 1 in 2,600 (0.038%).

Discovery and nomenclature

1950 DA was first discovered on 23 February 1950 by Carl A. Wirtanen at Lick Observatory. It was observed for seventeen days 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. Just two hours later it was recognized as 1950 DA.

Observations

Asteroid 1950 DA, Arecibo Observatory radar image (coloured version)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). It was studied by radar at the Goldstone and Arecibo observatories from March 3 to 7, 2001.

The studies showed that the asteroid has a mean diameter of 1.1 km, assuming that 1950 DA is a retrograde rotator. 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/cm, assuming that it has no internal strength) and likely composed of nickel–iron. 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.

1950 DA made distant approaches to Earth on 20 May 2012, 5 February 2021 and 5 February 2023. 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. By 2136 the close approach solutions are becoming notably more divergent.

Position uncertainty and increasing divergence
Date JPL SBDB
nominal geocentric
distance (AU) 		uncertainty
region
(1-sigma)
2 March 2032 0.075752 AU (11,332,300 km) ±10 km
19 March 2074 0.095459 AU (14,280,500 km) ±30 km
10 March 2105 0.036316 AU (5,432,800 km) ±43 km
11 March 2136 0.042596 AU (6,372,300 km) ±387 km
8 March 2187 0.035224 AU (5,269,400 km) ±1717 km
20 March 2218 0.084849 AU (12,693,200 km) ±8712 km
18 March 2373 0.058991 AU (8,824,900 km) ±2508 km
6 March 2455 0.087706 AU (13,120,600 km) ±1650 km
Impact probability at different times
Date JPL Solution Impact probability
5 April 2002 1/306
7 December 2015 1/8300
29 March 2022 1/34000
18 June 2024 1/2600
9 December 2024 JPL270 1/2500
20 December 2024 JPL271 1/2600
22 December 2024 JPL272 1/2600
26 December 2024 JPL273 1/2600

Possible Earth impact

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

  • an orbit moderately inclined (12 degrees) to the ecliptic plane (reducing in-plane perturbations);
  • high-precision radar astrometry, which provides its distance and is complementary to the measurements of angular positions;
  • a 74-year observation arc;
  • an uncertainty region controlled by resonance.

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. 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 December 2024, according to the latest solution dated 26 December 2024, the probability of an impact in 2880 is 1 in 2,600 (0.038%).

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

  1. A reported volume of 1.14 km × density of 3.5 g/cm yields a mass (m = d × v) of 3.99×10 kg

References

  1. ^ "29075 (1950 DA)". Minor Planet Center. Retrieved 24 February 2024.
  2. ^ "JPL Small-Body Database Browser: 29075 (1950 DA)" (2023-10-03 last obs.). Jet Propulsion Laboratory. Retrieved 18 June 2024.
  3. "(29075) 1950DA NeoDys – Proper Elements". NeoDys Near Earth Objects Dynamic Site. Retrieved 24 February 2024.
  4. ^ Busch, Michael W.; Giorgini, Jon D.; Ostro, Steven J.; Benner, Lance A. M.; Jurgens, Raymond F.; Rose, Randy; et al. (October 2007). "Physical modeling of near-Earth Asteroid (29075) 1950 DA" (PDF). Icarus. 190 (2): 608–621. Bibcode:2007Icar..190..608B. doi:10.1016/j.icarus.2007.03.032. Retrieved 24 February 2024.
  5. ^ Giorgini, J. D.; Ostro, S. J.; Benner, L. A. M.; Chodas, P. W.; Chesley, S. R.; Hudson, R. S.; et al. (April 2002). "Asteroid 1950 DA's Encounter with Earth in 2880: Physical Limits of Collision Probability Prediction" (PDF). Science. 296 (5565): 132–136. Bibcode:2002Sci...296..132G. doi:10.1126/science.1068191. PMID 11935024.
  6. ^ Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System. 247: EAR-A-COMPIL-5-NEOWISEDIAM-V1.0. Bibcode:2016PDSS..247.....M. Retrieved 5 July 2018.
  7. Rivkin, A. S.; Binzel, R. P.; Bus, S. J. (May 2005). "Constraining near-Earth object albedos using near-infrared spectroscopy". Icarus. 175 (1): 175–180. Bibcode:2005Icar..175..175R. doi:10.1016/j.icarus.2004.11.005.
  8. ^ Dandy, C. L.; Fitzsimmons, A.; Collander-Brown, S. J. (June 2003). "Optical colors of 56 near-Earth objects: trends with size and orbit". Icarus. 163 (2): 363–373. Bibcode:2003Icar..163..363D. doi:10.1016/S0019-1035(03)00087-3.
  9. ^ "LCDB Data for (29075)". Asteroid Lightcurve Database (LCDB). Retrieved 24 February 2024.
  10. "(29075) 1950DA". NeoDys Near Earth Objects Dynamic Site. Retrieved 24 February 2024.
  11. ^ "29075 (1950 DA) Earth Impact Risk Summary". NASA/JPL Near-Earth Object Program Office. 6 February 2022. Retrieved 18 June 2024.
  12. "Asteroid 1950 DA". NASA/JPL Near-Earth Object Program Office. Archived from the original on 21 July 2011. Retrieved 14 October 2011.
  13. ^ "Sentry Risk Table". NASA/JPL Near-Earth Object Program Office. Retrieved 18 June 2024. (Use Unconstrained Settings)
  14. "Impact threat analysis update completed for 1950 DA". European Space Agency. 29 March 2022.
  15. "MPEC 2001-A22 : 2000 YK66". Minor Planet Center. 4 January 2001. Retrieved 23 February 2018.
  16. "MPEC 2001-A26 : 1950 DA = 2000 YK66". Minor Planet Center. 4 January 2001. Retrieved 23 February 2018.
  17. ^ "JPL Close-Approach Data: 29075 (1950 DA)" (solution: 2024-04-24; last observation: 2023-10-03; arc: 73.61 years). Retrieved 18 June 2024.
  18. Farnocchia, D.; Chesley, S. R. (February 2014). "Assessment of the 2880 impact threat from Asteroid (29075) 1950 DA". Icarus. 229: 321–327. arXiv:1310.0861. Bibcode:2014Icar..229..321F. doi:10.1016/j.icarus.2013.09.022.
  19. Rozitis, Ben; MacLennan, Eric; Emery, Joshua P. (13 August 2014). "Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA". Nature. 512 (7513): 174–176. Bibcode:2014Natur.512..174R. doi:10.1038/nature13632. PMID 25119234.
  20. "UT Research uncovers forces that hold asteroid together". University of Tennessee. 13 August 2014. Retrieved 17 August 2015.
  21. ^ "Close-approach results". JPL Horizons. Retrieved 7 December 2024. Soln.date: 2024-Dec-05 05:58:05
  22. 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.
  23. "Sentry: Earth Impact Monitoring".
  24. 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.

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