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→top: clarify the primary purpose for the reentry burn, per sources; all three burns, of course, also control to keep the descending 1st stage on the correct trajectory |
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The program was announced in 2011. SpaceX first achieved a [[Falcon 9 Flight 20|successful landing and recovery of a first stage]] in December 2015. The [[SES-10|first re-flight of a landed first stage]] occurred in March 2017<ref name=sn20170330/> with the second occurring in June 2017, that one only five months after the maiden flight of the booster.<ref name=sir-20170626 /> The third attempt occurred in October 2017 with the [[SES-11]]/[[EchoStar-105]] mission. Reflights of refurbished first stages then became routine. In May 2021, B1051 became the first booster to launch ten missions.<ref>{{Cite web|last1=Sesnic|first1=Trevor|last2=Fletcher|first2=Colin|last3=Kanayama|first3=Lee|date=2021-05-08|title=SpaceX flies historic 10th mission of a Falcon 9 as Starlink constellation expands|url=https://www.nasaspaceflight.com/2021/05/historic-10th-falcon9-reflight/|access-date=2021-05-19|website=NASASpaceFlight.com|language=en-US|archive-date=May 16, 2021|archive-url=https://web.archive.org/web/20210516121203/https://www.nasaspaceflight.com/2021/05/historic-10th-falcon9-reflight/|url-status=live}}</ref>
The [[reusable launch system]] technology was initially developed for the first stage of [[Falcon 9]].<ref name=sn20141024/> After [[Separation event|stage separation]], the booster flips around (an optional '''boostback burn'''<!-- bolded per [[WP:MOSBOLD]] as a redirect link --> reverses its course), a reentry burn
SpaceX planned from at least 2014 to develop reusable second stages, a more challenging engineering problem because the vehicle is travelling at [[Orbital speed#Tangential velocities at altitude|orbital velocity]].<ref name=nsf20160927/><ref name=sn20141024/><ref name=nsf20140307/>
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