{{Short description|Near-Earth asteroid}} {{Use dmy dates|date=April 2026}} {{DISPLAYTITLE:{{mp|2015 XF|261}}}} {{Infobox planet | minorplanet = yes | name = {{mp|2015 XF|261}} | discovery_ref = <ref name="MPC-object"/> | discoverer = | discovered = 8 December 2015 (Initial reported obs.) | discovery_site = | mpc_name = {{mp|2015 XF|261}} | mp_category = {{Hlist | [[Near-Earth object|NEO]] | [[Aten asteroid|Aten]] }} | orbit_ref = <ref name="jpldata"/> | epoch = 21 November 2025 ([[Julian day|JD]] 2461000.5) | uncertainty = 1 | observation_arc = 2,991 days | aphelion = 1.306 [[Astronomical unit|AU]] | perihelion = 0.674 AU | semimajor = 0.990 AU | eccentricity = 0.319 | period = 0.985 years | inclination = 0.794° | asc_node = 209.818° | mean_anomaly = 126.230° | mean_motion = 1.001°/day | arg_peri = 100.882° | moid = 0.00244 AU | jupiter_moid = 3.928 AU | physical_ref = | abs_magnitude = 25.25<ref name="jpldata"/> }}
'''{{mp|2015 XF|261}}''' is an [[Aten asteroid|Aten]]-type [[Near-Earth object|near-Earth asteroid]] with an estimated diameter of around {{convert|16|m|abbr=on}}. It completes one orbit around the [[Sun]] every 359.7 days, placing it near the 1:1 [[mean-motion resonance]] with Earth. It is the target asteroid for a planned asteroid redirect mission by the [[China National Space Administration]] (CNSA).
==Orbit== {{mp|2015 XF|261}} is a [[Near-Earth object|near-Earth asteroid]] following an elliptical orbit around the Sun, with a [[semi-major axis]] of 0.99 [[astronomical unit]]s (AU), an [[orbital period]] of about 359.7 days, and an [[orbital inclination]] of 0.79°. Due to an [[orbital eccentricity]] of 0.32, its distance from the Sun varies from 0.67 AU at [[perihelion]] to 1.31 AU at [[aphelion]].<ref name="jpldata"/> Since it is an Earth-crossing asteroid with a semi-major axis under 1 AU, it is classified as an [[Aten asteroid]].<ref name="jpldata"/><ref name=NEO-groups/> Its orbital period nearly matches with Earth's, placing it in a near-1:1 [[mean-motion resonance]] with Earth.<ref name="Zhang2025"/>{{rp|2}}
==2029 mission== {{mp|2015 XF|261}} is the target for an asteroid-deflecting mission planned by China in 2029, launching in 2027, two years after its previous launch target of 2025. Its original target was {{mpl|2019 VL|5}}. The spacecraft is planned to be launched on a [[Long March 3B]] in 2027, making a flyby of [[Venus]] before arriving at the asteroid in early 2029, and colliding with the asteroid in April 2029 at an estimated speed of {{convert|10|km/s|abbr=on}}.<ref name="spacenews202407"/>
==See also== *[[Double Asteroid Redirection Test]] (DART), another asteroid-deflecting mission which collided with [[Dimorphos]]
==References== <references> <ref name="MPC-object">{{cite web |title = 2015 XF261 |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=2015+XF261 |publisher = Minor Planet Center |access-date = 9 November 2025 |url-status = live }} (38 obs)</ref> <ref name="jpldata">{{cite web |type = 2024-02-15 last obs. |title = JPL Small-Body Database Lookup: (2015 XF261) |url = https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2015%20XF261 |publisher = [[Jet Propulsion Laboratory]] |access-date = 16 April 2026 |url-status = live }}</ref>
<ref name=NEO-groups>{{cite web |title=NEO Groups |publisher=NASA/JPL Near-Earth Object Program Office |url=http://neo.jpl.nasa.gov/neo/groups.html |archive-url=https://web.archive.org/web/20020202160655/http://neo.jpl.nasa.gov/neo/groups.html |url-status=dead |archive-date=2002-02-02 |access-date=2012-06-04}}</ref> <ref name="spacenews202407">{{cite news|last=Foust|first=Jeff|title=China reschedules planetary defense mission for 2027 launch|url=https://spacenews.com/china-reschedules-planetary-defense-mission-for-2027-launch/|website=spacenews.com|date=16 July 2024|accessdate=23 July 2024}}</ref>
<ref name="Zhang2025">{{cite journal |last1=Zhang |first1=Nan |last2=Wu |first2=Di |last3=Zhang |first3=Zhong |last4=Li |first4=Haiyang |last5=Baoyin |first5=Hexi |title=Preliminary trajectory design of implementing the asteroid rendezvous and impact in a single launch |date=April 2025 |journal=Aerospace Science and Technology |volume=159 |doi=10.1016/j.ast.2025.109959 }}</ref> </references>
==External links== * {{JPL small body|id=3736497}} * {{Cite journal|last1=Zou|first1=Yongliao|last2=Xue|first2=Changbin|last3=Jia|first3=Yingzhuo|last4=Li|first4=Mingtao|last5=Xu|first5=Haitao|last6=Lyu|first6=Bohan|last7=Gu|first7=Zhang|last8=Tang|first8=Yuhua|last9=Chen|first9=Qi|last10=Wang|first10=Chi|date=April 2024|title=小行星防御试验任务科学目标设计与有效载荷配置|trans-title=Scientific Objectives and Configuration Payloads of Asteroid Defense Test Missions|url=https://jdse.bit.edu.cn/sktcxb/en/article/doi/10.15982/j.issn.2096-9287.2024.20230020|language=Chinese|journal=Journal of Deep Space Exploration|volume=11|issue=2|pages=169–176|doi=10.15982/j.issn.2096-9287.2024.20230020}}
[[Category:Aten asteroids]] [[Category:Minor planet object articles (unnumbered)]] [[Category:Astronomical objects discovered in 2015]] [[Category:Minor planets to be visited by spacecraft]]
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