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| background = #FFC2E0 | background = #FFC2E0
| image = 1950 DA.png | image = 1950 DA.png
| image_size = 250 | image_scale =
| caption = ] of {{mp|1950 DA}} taken at ] in March 2001, from a distance of 22 ] or 0.052 ] | caption = ] of {{mp|1950 DA}} taken at ] in March 2001, from a distance of 22 ] or 0.052 ]
| discovery_ref = <ref name="MPC-object" /> | discovery_ref = <ref name="MPC-object" />
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| mp_category = ]{{·}}]{{·}}]<ref name="MPC-object" /><ref name="jpldata" />{{·}}] | mp_category = ]{{·}}]{{·}}]<ref name="MPC-object" /><ref name="jpldata" />{{·}}]
| orbit_ref = <ref name="jpldata" /> | orbit_ref = <ref name="jpldata" />
| epoch = 31 January 2012 (]&nbsp;2455957.5) | epoch = 31 March 2024 (]&nbsp;2460400.5)
| uncertainty = 0 | uncertainty = 0
| observation_arc = 67.96&nbsp;] (24,823&nbsp;d) | observation_arc = 73.61&nbsp;] (26,885&nbsp;d)
| aphelion = 2.5619&nbsp;] | aphelion = 2.5614&nbsp;]
| perihelion = 0.8350&nbsp;AU | perihelion = 0.8355&nbsp;AU
| semimajor = 1.6985&nbsp;AU | semimajor = 1.6985&nbsp;AU
| eccentricity = 0.5083 | eccentricity = 0.5081
| period = 2.21&nbsp;yr (809&nbsp;d) | period = 2.214&nbsp;yr (809&nbsp;d)
| mean_anomaly = 315.94] | mean_anomaly = 134.33]
| mean_motion = {{Deg2DMS|0.4453|sup=ms}} / day | mean_motion = {{Deg2DMS|0.4453|sup=ms}} / day
| inclination = 12.175° | inclination = 12.17°
| asc_node = 356.74° | asc_node = 356.64°
| arg_peri = 224.61° | arg_peri = 224.70°
| moid = 0.0406&nbsp;AU (15.8169&nbsp;]) | moid = 0.04011&nbsp;AU (15.609&nbsp;])
| p_orbit_ref = <ref name="Proper" /> | p_orbit_ref = <ref name="Proper" />
| node_rate = −35.824 | node_rate = −35.824
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| dimensions = {{val|1.39|x|1.46|x|1.07|ul=km}}<ref name="Busch-2007b" /> | dimensions = {{val|1.39|x|1.46|x|1.07|ul=km}}<ref name="Busch-2007b" />
| mean_diameter = {{Ubl | mean_diameter = {{Ubl
| {{val|1.1|ul=km}}<ref name="Busch-2007b" /><ref name="Giorgini-2002" /> | {{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|1.25|0.12|u=km}}<ref name="Busch-2007b" />
| {{val|2.00|0.20|u=km}}<ref name="Mainzer-2016" /> | {{val|2.00|0.20|u=km}}<ref name="Mainzer-2016" />
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| spectral_type = {{Ubl | spectral_type = {{Ubl
| ]<ref name="Dandy-2003" /><ref name="lcdb" /> | ]<ref name="Dandy-2003" /><ref name="lcdb" />
⚫ | EM<ref name=Neodys/>
| ] {{=}} {{val|0.862|0.077}}<ref name="Dandy-2003" /> | ] {{=}} {{val|0.862|0.077}}<ref name="Dandy-2003" />
| ] {{=}} {{val|0.494|0.069}}<ref name="Dandy-2003" /> | ] {{=}} {{val|0.494|0.069}}<ref name="Dandy-2003" />
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}} }}
| abs_magnitude = {{Ubl | abs_magnitude = {{Ubl
⚫ | 16.83<ref name="Busch-2007b" />
| 17.00<ref name="Mainzer-2016" /> | 17.00<ref name="Mainzer-2016" />
| 17.1<ref name="MPC-object" /><ref name="jpldata" /> | 17.28<ref name="MPC-object" /><ref name="jpldata" />
| {{val|17.55|0.3}} {{small|(R)}}<ref name=Neodys/><ref name="lcdb" /> | 17.2<ref name=Neodys/>
| 18.0<ref name="lcdb" /><ref name="Busch-2007b" /> | 17.1<ref name="lcdb" />
}} }}
}} }}
'''{{mp|(29075) 1950 DA}}''', provisional designation ''{{mp|1950 DA}}'', is a risk-listed ], classified as a ] and ] of the ], approximately {{convert|1.1|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 for a possible collision in 2880.<ref name="NEO-1950DA"/> 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 2022, It is listed on the ] with the second highest cumulative Palermo rating of −2.05 (impact risk of 1-in-34,000).<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. '''{{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 -0.92.<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 19 December 2024, the odds of an Earth impact are 1 in 2,600 (0.039%).<ref name="risk-table" /><ref name="impact-risk-summary"/>


== Discovery and nomenclature == == Discovery and nomenclature ==
⚫ {{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>

⚫ ''{{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 ==
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}} }}


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" /> 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" />


The studies showed that the asteroid has a mean diameter 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 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" />


''{{mp|1950 DA}}'' made a distant approach to Earth on 5 February 2021.<ref name=jpl-close/> However, at that time it was 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|0.075|AU|e6km|abbr=unit|lk=off}} from Earth. The following table lists next five approaches closer than 0.10&nbsp;AU.<ref name=jpl-close/> By 2136 the close approach solutions are becoming notably more divergent. {{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}}


{| class="wikitable sortable" style="font-size: 0.9em;" {| class="wikitable sortable" style="font-size: 0.9em;"
|+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>
|+Position uncertainty and increasing divergence<ref name=jpl-close/>
! Date ! Date
! ]<br />] geocentric<br />distance (]) ! ]<br />] geocentric<br />distance (])
! uncertainty<br />region<br/>(]) ! uncertainty<br />region<br/>(])
|- |-
|2032 March 02 ||{{Convert|0.0757523|AU|e6km|abbr=unit}} || ±52 km | 2 March 2032 ||{{Convert|0.075752|AU|km|abbr=unit}} || ±10&nbsp;km
|- |-
|2074 March 19 ||{{Convert|0.0954596|AU|e6km|abbr=unit}} || ±131 km |19 March 2074 ||{{Convert|0.095459|AU|km|abbr=unit}} || ±30&nbsp;km
|- |-
|2105 March 10 ||{{Convert|0.0363159|AU|e6km|abbr=unit}} || ±22 km |10 March 2105 ||{{Convert|0.036316|AU|km|abbr=unit}} || ±43&nbsp;km
|- |-
|2136 March 01 ||{{Convert|0.0425957|AU|e6km|abbr=unit}} || ±1010 km |11 March 2136 ||{{Convert|0.042596|AU|km|abbr=unit}} || ±387&nbsp;km
|- |-
|2187 March 08 ||{{Convert|0.0352249|AU|e6km|abbr=unit}} || ±2795 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
⚫ == Possible Earth impact ==
! 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
|-
|}


⚫ == Possible Earth impact ==
That ''{{mp|1950 DA}}'' has one of the best-determined asteroid orbital solutions is due to a combination of:<ref name="Giorgini-2002" /> {{mp|1950 DA}} has one of the best-determined asteroid orbital solutions. This is due to a combination of:<ref name="Giorgini-2002" />
* an orbit moderately ] (12 degrees)<ref name=jpldata/> to the ] (reducing in-plane ]); * an orbit moderately ] (12 degrees)<ref name=jpldata/> to the ] (reducing in-plane ]);
* high-precision radar astrometry, which provides its distance and is complementary to the measurements of angular positions; * high-precision radar astrometry, which provides its distance and is complementary to the measurements of angular positions;
* a 68-year ];<ref name=jpldata/> * a 74-year ];<ref name=jpldata/>
* an uncertainty region controlled by ].<ref name="Giorgini-2002" /> * 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 the 7 December 2015 solution, the probability of an impact in 2880 is 1 in 8,300 (0.012%).<ref name=impact-risk-summary/> 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 11 December 2024, the probability of an impact in 2880 is 1 in 2,600 (0.039%).<ref name=impact-risk-summary/>


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 ]. 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 ].


== See also == == See also ==
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<ref name="jpldata">{{cite web <ref name="jpldata">{{cite web
|type = 2018-02-09 last obs. |type = 2023-10-03 last obs.
|title = JPL Small-Body Database Browser: 29075 (1950 DA) |title = JPL Small-Body Database Browser: 29075 (1950 DA)
|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2029075 |url = https://ssd.jpl.nasa.gov/tools/sbdb.cgi?sstr=2029075
|publisher = ] |publisher = ]
|access-date = 5 July 2018}}</ref> |access-date = 18 June 2024}}</ref>


<ref name="MPC-object">{{cite web <ref name="MPC-object">{{cite web
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|work = Minor Planet Center |work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=29075 |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=29075
|access-date = 5 July 2018}}</ref> |access-date = 24 February 2024}}</ref>


<ref name=jpl-close>{{cite web <ref name=jpl-close>{{cite web
|type=last observation: 2018-02-09; ]: 67.96 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=https://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
|access-date=11 March 2018}}</ref> |access-date=18 June 2024}}</ref>


<ref name="NEO-1950DA">{{cite web <ref name="NEO-1950DA">{{cite web
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|publisher=NASA/JPL Near-Earth Object Program Office |publisher=NASA/JPL Near-Earth Object Program Office
|url=http://neo.jpl.nasa.gov/1950da/ |url=http://neo.jpl.nasa.gov/1950da/
|access-date=2011-10-14 |access-date=14 October 2011
|archive-url=https://web.archive.org/web/20110721050545/http://neo.jpl.nasa.gov/1950da/ |archive-url=https://web.archive.org/web/20110721050545/http://neo.jpl.nasa.gov/1950da/
|archive-date=July 21, 2011 |archive-date=21 July 2011
|url-status=dead }}</ref> |url-status=dead}}</ref>


<ref name="Proper">{{cite web <ref name="Proper">{{cite web
|title=(29075) 1950DA NeoDys{{Snd}} Proper Elements |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 |url=https://newton.spacedys.com/neodys/index.php?pc=1.1.6&n=29075
|access-date=11 March 2018}}</ref> |access-date=24 February 2024}}</ref>


<ref name=Neodys>{{cite web <ref name=Neodys>{{cite web
|type=Physical Info |title=(29075) 1950DA
|title=NeoDys Near Earth Objects Dynamic Site |website=NeoDys Near Earth Objects Dynamic Site
|url=https://newton.spacedys.com/neodys/index.php?pc=1.1.9&n=29075 |url=https://newton.spacedys.com/neodys/index.php?pc=1.1.0&n=29075
|access-date=11 March 2018}}</ref> |access-date=24 February 2024}}</ref>


<ref name="impact-risk-summary">{{cite web <ref name="impact-risk-summary">{{cite web
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|publisher=NASA/JPL Near-Earth Object Program Office |publisher=NASA/JPL Near-Earth Object Program Office
|url=https://cneos.jpl.nasa.gov/sentry/details.html#?des=29075 |url=https://cneos.jpl.nasa.gov/sentry/details.html#?des=29075
|date=7 December 2015 |date=6 February 2022
|access-date=11 March 2018}}</ref> |access-date=18 June 2024}}</ref>


<ref name="risk-table">{{cite web <ref name="risk-table">{{cite web
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|publisher=NASA/JPL Near-Earth Object Program Office |publisher=NASA/JPL Near-Earth Object Program Office
|url=https://cneos.jpl.nasa.gov/sentry/ |url=https://cneos.jpl.nasa.gov/sentry/
|access-date=2018-03-20}} (Use Unconstrained Settings)</ref> |access-date=18 June 2024}} (Use Unconstrained Settings)</ref>


<ref name="tntoday">{{cite web <ref name="tntoday">{{cite web
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|publisher = Asteroid Lightcurve Database (LCDB) |publisher = Asteroid Lightcurve Database (LCDB)
|url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=29075%7C |url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=29075%7C
|access-date = 5 July 2018}}</ref> |access-date = 24 February 2024}}</ref>


<ref name="Busch-2007b">{{Cite journal <ref name="Busch-2007b">{{Cite journal
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|bibcode = 2007Icar..190..608B |bibcode = 2007Icar..190..608B
|doi = 10.1016/j.icarus.2007.03.032 |doi = 10.1016/j.icarus.2007.03.032
|access-date= 5 July 2018}}</ref> |access-date = 24 February 2024}}</ref>


<ref name="Giorgini-2002">{{Cite journal <ref name="Giorgini-2002">{{Cite journal
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|date = April 2002 |date = April 2002
|title = Asteroid 1950 DA's Encounter with Earth in 2880: Physical Limits of Collision Probability Prediction |title = Asteroid 1950 DA's Encounter with Earth in 2880: Physical Limits of Collision Probability Prediction
|url = http://neo.jpl.nasa.gov/1950da/1950da.pdf |url = https://cneos.jpl.nasa.gov/doc/1950da/1950da_published.pdf
|archive-url = https://web.archive.org/web/20080704103055/http://neo.jpl.nasa.gov/1950da/1950da.pdf
|url-status = dead
|archive-date = 2008-07-04
|journal = Science |journal = Science
|volume = 296 |volume = 296
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|bibcode = 2002Sci...296..132G |bibcode = 2002Sci...296..132G
|doi = 10.1126/science.1068191 |doi = 10.1126/science.1068191
|pmid = 11935024 |pmid = 11935024}}</ref>
|access-date= 5 July 2018}}</ref>


<ref name="Mainzer-2016">{{cite journal <ref name="Mainzer-2016">{{cite journal
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|url = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_COMPIL_5_NEOWISEDIAM_V1_0/data/neowise_mainbelt.tab |url = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_COMPIL_5_NEOWISEDIAM_V1_0/data/neowise_mainbelt.tab
|journal = NASA Planetary Data System |journal = NASA Planetary Data System
|pages = EAR-A-COMPIL-5-NEOWISEDIAM-V1.0 |bibcode = 2016PDSS..247.....M |volume = 247
|pages = EAR-A-COMPIL-5-NEOWISEDIAM-V1.0
|bibcode = 2016PDSS..247.....M
|access-date= 5 July 2018}}</ref> |access-date= 5 July 2018}}</ref>


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|journal = Nature |journal = Nature
|volume = 512 |volume = 512
|issue = 7513 |issue = 7513
|pages = 174–176 |pages = 174–176
|doi = 10.1038/nature13632 |doi = 10.1038/nature13632
|pmid = 25119234 |pmid = 25119234
|bibcode = 2014Natur.512..174R}}</ref>
|url = http://oro.open.ac.uk/44912/1/BR_1950DA_accepted.pdf
}}</ref>


}} <!-- end of reflist--> }} <!-- end of reflist-->


== External links == == External links ==
{{Commons category|(29075) 1950 DA}} {{Commons category}}
* (K00Y66K). '']'' 4 January 2001 * (K00Y66K). '']'' 4 January 2001
* Rotating model of the asteroid (preferred rotation model is ''retrograde'', ) * Rotating model of the asteroid (preferred rotation model is ''retrograde'', )
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{{Planetary defense}} {{Planetary defense}}
{{Portal bar|Astronomy|Stars|Spaceflight|Outer space|Solar System}} {{Portal bar|Astronomy|Stars|Spaceflight|Outer space|Solar System}}
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{{DEFAULTSORT:1950 DA}} {{DEFAULTSORT:1950 DA}}
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Latest revision as of 16:38, 23 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 -0.92. 1950 DA is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future. As of the 19 December 2024, the odds of an Earth impact are 1 in 2,600 (0.039%).

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

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 11 December 2024, the probability of an impact in 2880 is 1 in 2,600 (0.039%).

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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