Editing Rosetta (spacecraft) (section)

== History ==

=== Background ===
During the 1986 approach of [[Halley's Comet]], international space probes were sent to explore the comet, most prominent among them being [[European Space Agency|ESA]]'s [[Giotto (spacecraft)|''Giotto'']].<ref name="vice20160314">{{cite news |url=https://www.vice.com/en/article/happy-anniversary-giotto-the-probe-that-flew-by-halleys-comet-30-years-ago/ |title=Happy Anniversary Giotto, the Probe That Flew By Halley's Comet 30 Years Ago |work=[[Vice (magazine)|Vice]] |series=Motherboard |first=Victoria |last=Turk |date=14 March 2016 |access-date=1 October 2016}}</ref> After the probes returned valuable scientific information, it became obvious that follow-ons were needed that would shed more light on cometary composition and answer new questions.<ref name="Altwegg2001">{{cite book |chapter-url=https://books.google.com/books?id=6aQRBwAAQBAJ&pg=PA1280 |chapter=The constituents of cometary nuclei |title=The Century of Space Science |publisher=Kluwer Academic |editor1-first=Johan A. M. |editor1-last=Bleeker |editor2-first=Johannes |editor2-last=Geiss |editor3-first=Martin C. E. |editor3-last=Huber |first1=Kathrin |last1=Altwegg|author1-link=Kathrin Altwegg |first2=Wesley T. Jr. |last2=Huntress |page=1280 |date=2001 |isbn=978-0-7923-7196-0}}</ref>

Both ESA and [[NASA]] started cooperatively developing new probes. The NASA project was the [[Comet Rendezvous Asteroid Flyby]] (CRAF) mission.<ref name="Neugebauer1987">{{cite journal |title=The Comet Rendezvous Asteroid Flyby Mission |journal=Advances in Space Research |first1=M. |last1=Neugebauer |first2=R. F. |last2=Draper |volume=7 |issue=12 |pages=201–204 |date=1987 |doi=10.1016/0273-1177(87)90218-3 |bibcode=1987AdSpR...7l.201N |hdl=2060/19930010071|hdl-access=free }}</ref> The ESA project was the follow-on Comet Nucleus Sample Return (CNSR) mission.<ref name="Schwehm1989">{{cite journal |title=Rosetta - Comet Nucleus Sample Return |journal=Advances in Space Research |first=G. H. |last=Schwehm |volume=9 |issue=6 |pages=185–190 |date=1989 |doi=10.1016/0273-1177(89)90228-7 |bibcode=1989AdSpR...9f.185S}}</ref> Both missions were to share the [[Mariner Mark II]] spacecraft design, thus minimising costs. In 1992, after NASA cancelled CRAF due to budgetary limitations, ESA decided to develop a CRAF-style project on its own.<ref name="Moltenbrey2016">{{cite book |chapter-url=https://books.google.com/books?id=Bf_NCgAAQBAJ&pg=PA223 |chapter=Exploration of Small Solar System Bodies |title=Dawn of Small Worlds: Dwarf Planets, Asteroids, Comets |publisher=Springer |series=Astronomer's Universe |first=Michael |last=Moltenbrey |pages=223–224 |date=2016 |isbn=978-3-319-23002-3 |doi=10.1007/978-3-319-23003-0}}</ref> By 1993 it was evident that the ambitious sample return mission was infeasible with the existing ESA budget, so the mission was redesigned and subsequently approved by the ESA, with the final flight plan resembling the cancelled CRAF mission: an asteroid flyby followed by a comet rendezvous with in-situ examination, including a lander.<ref name="Moltenbrey2016" /> After the spacecraft launch, [[Gerhard Schwehm]] was named mission manager; he retired in March 2014.<ref name="techrep">{{cite news |url=http://www.techrepublic.com/article/the-tech-behind-the-rosetta-comet-chaser-from-3d-printing-to-solar-power-to-complex-mapping/ |title=The tech behind the Rosetta comet chaser: From 3D printing to solar power to complex mapping |work=[[TechRepublic]] |first=Lyndsey |last=Gilpin |date=14 August 2014}}</ref>

The ''Rosetta'' mission included generational team management; this allowed mission continuity over the long period of the mission and for special knowledge to be maintained and passed on to future team members. In particular, several younger scientists were brought on as principal science investigators, and regular training sessions were conducted.<ref name="FAQ" />

=== Naming ===
The probe was named after the [[Rosetta Stone]],<ref>{{cite web |title=Rosetta |url=https://blogs.esa.int/rosetta/2014/10/17/naming-rosetta-an-interview-with-eberhard-grun/ |website=Naming Rosetta – An interview with Eberhard Grün |access-date=4 February 2022}}</ref> a [[stele]] of [[Ancient Egypt|Egyptian]] origin featuring a [[decree]] in three scripts. The lander was named after the [[Philae obelisk]], which bears a bilingual Greek and Egyptian hieroglyphic inscription. A comparison of its hieroglyphs with those on the Rosetta Stone catalysed the deciphering of the Egyptian writing system. Similarly, it was hoped that these spacecraft would result in better understanding of comets and the early [[Solar System]].<ref name="space20140115">{{cite news |url=http://www.space.com/24292-rosetta-spacecraft.html |title=Rosetta Spacecraft: To Catch a Comet |publisher=Space.com |first=Tim |last=Sharp |date=15 January 2014 |access-date=25 January 2014}}</ref><ref name="esaint20040205">{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Unlocking_the_secrets_of_the_universe_Rosetta_lander_named_Philae |title=Unlocking the secrets of the universe: Rosetta lander named Philae |publisher=European Space Agency |date=5 February 2004 |access-date=25 January 2014}}</ref> In a more direct analogy to its namesake, the ''Rosetta'' spacecraft also carried a micro-etched pure nickel prototype of the [[Rosetta Project|Rosetta disc]] donated by the [[Long Now Foundation]]. The disc was inscribed with 6,500 pages of language translations.<ref name="RosettaDisc">{{cite web |url=http://blog.longnow.org/02014/06/06/esas-rosetta-probe-begins-approach-of-comet-67p/ |title=ESA's Rosetta Probe begins approach of comet 67P |work=Long Now |date=6 June 2014 |access-date=6 August 2014}}</ref><ref name="RosettaDiscPrototype">{{cite web |url=http://rosettaproject.org/blog/02008/aug/20/very-long-term-backup/ |title=Very Long-Term Backup – The Rosetta Project |last=Kelly |first=Kevin |date=20 August 2008 |publisher=The Rosetta Project |access-date=2 January 2017}}</ref>

=== Mission firsts ===
[[File:Rosetta and Philae at comet (11206660686).jpg|thumb|upright|Illustration of ''Rosetta'' and ''Philae'' at the comet]]
The ''Rosetta'' mission achieved many historic firsts.<ref>{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Europe_s_comet_chaser/ |title=Europe's Comet Chaser-historic mission |publisher=European Space Agency |date=16 January 2014 |access-date=5 August 2014}}</ref>

On its way to comet 67P, ''Rosetta'' passed through the main [[asteroid belt]], and made the first [[European Space Agency|European]] close encounter with several of these primitive objects. ''Rosetta'' was the first spacecraft to fly close to [[Jupiter]]'s orbit using solar cells as its main power source.<ref name="rosettafacts">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet |title=Rosetta Factsheet |publisher=European Space Agency |date=9 September 2016 |access-date=1 October 2016}}</ref>

''Rosetta'' was the first spacecraft to orbit a [[comet nucleus]],<ref>{{cite news |url=https://www.bbc.com/news/science-environment-28659783 |title=Europe's Rosetta probe goes into orbit around comet 67P |work=BBC News |date=6 August 2014 |access-date=6 August 2014}}</ref> and was the first spacecraft to fly alongside a comet as it headed towards the [[inner Solar System]]. It became the first spacecraft to examine at close proximity the activity of a frozen comet as it is warmed by the [[Sun]]. Shortly after its arrival at 67P, the ''Rosetta'' orbiter dispatched the ''[[Philae (spacecraft)|Philae]]'' lander for the first controlled touchdown on a comet nucleus. The robotic lander's instruments obtained the first images from a comet's surface and made the first ''[[in situ]]'' analysis of its composition.

=== Design and construction ===
The ''Rosetta'' [[satellite bus|bus]] was a {{convert|2.8|xx|2.1|xx|2.0|m|ft|abbr=on}} central frame and aluminium honeycomb platform. Its total mass was approximately {{convert|3000|kg|sigfig=2|abbr=on}}, which included the {{convert|100|kg|sigfig=2|adj=on|abbr=on}} ''Philae'' lander and {{convert|165|kg|abbr=on}} of science instruments.<ref>{{cite web|url=http://sci.esa.int/rosetta/47366-fact-sheet/ |title=Rosetta: Fact Sheet |publisher=European Space Agency |access-date=19 July 2016}}</ref> The Payload Support Module was mounted on top of the spacecraft and housed the scientific instruments, while the Bus Support Module was on the bottom and contained spacecraft support subsystems. Heaters placed around the spacecraft kept its systems warm while it was distant from the Sun. ''Rosetta''{{'s}} communications suite included a {{convert|2.2|m|ft|adj=on|abbr=on}} steerable high-gain parabolic dish antenna, a {{convert|0.8|m|ft|adj=on|abbr=on}} fixed-position medium-gain antenna, and two omnidirectional low-gain antennas.<ref name="nssdc-craft">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-006A |title=Rosetta |work=[[National Space Science Data Center]] |publisher=NASA |access-date=3 November 2014}}</ref>

Electrical power for the spacecraft came from two solar arrays totalling {{convert|64|m2}}.<ref name="ESA-RO">{{cite web|url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/The_Rosetta_orbiter |title=The Rosetta orbiter |publisher=European Space Agency |date=16 January 2014 |access-date=13 August 2014}}</ref> Each solar array was subdivided into five solar panels, with each panel being {{convert|2.25|xx|2.736|m|ft|2|abbr=on}}. The individual solar cells were made of silicon, 200 μm thick, and {{convert|61.95|xx|37.75|mm|2|abbr=on}}.<ref name="DAccolti2002">{{cite conference|title=The Solar Array Photovoltaic Assembly for the ROSETTA Orbiter and Lander Spacecraft's |conference=6th European Space Power Conference. 6–10 May 2002. Porto, Portugal. |first1=G. |last1=D'Accolti |first2=G. |last2=Beltrame |first3=E. |last3=Ferrando |first4=L. |last4=Brambilla |first5=R. |last5=Contini |first6=L. |last6=Vallini |first7=R. |last7=Mugnuolo |first8=C. |last8=Signorini |first9=H. |last9=Fiebrich |first10=A. |last10=Caon |display-authors=5 |year=2002 |bibcode=2002ESASP.502..445D}}</ref> The solar arrays generated a maximum of approximately 1,500 watts at [[perihelion]],<ref name="DAccolti2002"/> a minimum of 400 watts in hibernation mode at 5.2 AU, and 850 watts when comet operations begin at 3.4 AU.<ref name="nssdc-craft"/> Spacecraft power was controlled by a redundant [[Terma A/S|Terma]] power module also used in the ''[[Mars Express]]'' spacecraft,<ref name="Ingenioren20140119">{{cite news |url=http://ing.dk/artikel/terma-elektronik-vaekker-rumsonde-fra-aarelang-dvale-165600 |title=Terma-elektronik vækker rumsonde fra årelang dvale |work=[[Ingeniøren]] |first=Mie |last=Stage |date=19 January 2014 |access-date=2 December 2014}}</ref><ref name="Jensen2002">{{cite conference |title=Power Conditioning Unit for Rosetta/Mars Express |conference=6th European Space Power Conference. 6–10 May 2002. Porto, Portugal. |first1=Hans |last1=Jensen |first2=Johnny |last2=Laursen |year=2002 |bibcode=2002ESASP.502..249J}}</ref> and was stored in four 10-[[ampere hour|A·h]] [Li-ion] batteries supplying 28 volts to the bus.<ref name="nssdc-craft"/>

Main propulsion comprised 24 paired bipropellant 10&nbsp;[[Newton (unit)|N]] thrusters,<ref name="ESA-RO" /> with four pairs of thrusters being used for [[delta-v|delta-''v'']] burns. The spacecraft carried {{convert|1719.1|kg|abbr=on}} of propellant at launch: {{convert|659.6|kg|lb|abbr=on}} of [[monomethylhydrazine]] fuel and {{convert|1059.5|kg|abbr=on}} of [[dinitrogen tetroxide]] oxidiser, contained in two {{convert|1108|L|adj=on}} [[Ti6Al4V|grade 5 titanium alloy]] tanks and providing delta-''v'' of at least {{convert|2300|m/s}} over the course of the mission. Propellant pressurisation was provided by two {{convert|68|L|adj=on}} high-pressure helium tanks.<ref name="Stram2004">{{cite conference|title=The Rosetta Propulsion System |conference=4th International Spacecraft Propulsion Conference. 2–9 June 2004. Sardinia, Italy. |first=D. |last=Stramaccioni |year=2004 |bibcode=2004ESASP.555E...3S}}</ref>

''Rosetta'' was built in a [[cleanroom|clean room]] according to [[COSPAR]] rules, but "[[Sterilization (microbiology)|sterilisation]] {{interp|was}} generally not crucial since comets are usually regarded as objects where you can find [[Abiogenesis|prebiotic]] [[molecule]]s, that is, molecules that are precursors of life, but not living [[microorganism]]s", according to Gerhard Schwehm, ''Rosetta''{{'s}} project scientist.<ref name="esa20020730">{{cite news |url=http://sci.esa.int/home/30313-no-bugs-please-this-is-a-clean-planet/ |title=No bugs please, this is a clean planet! |publisher=European Space Agency |date=30 July 2002 |access-date=7 March 2007}}</ref> The total cost of the mission was about €1.3&nbsp;billion (US$1.8&nbsp;billion).<ref name="nature20140717">{{cite news |url=http://www.nature.com/news/duck-shaped-comet-could-make-rosetta-landing-more-difficult-1.15579 |title=Duck-shaped comet could make Rosetta landing more difficult |journal=[[Nature (journal)|Nature]] |first=Elizabeth |last=Gibney |date=17 July 2014 |access-date=15 November 2014 |doi=10.1038/nature.2014.15579}}</ref>

=== Launch ===
[[File:Animation of Rosetta trajectory.gif|thumb|upright=1.4|Animation of ''Rosetta''{{'s}} trajectory from 2 March 2004 to 9 September 2016 <br/> {{legend2|magenta|''Rosetta''}}{{·}}{{legend2|lime|[[67P/Churyumov–Gerasimenko]]}}{{·}}{{legend2|Royalblue|[[Earth]]}}{{·}}{{legend2|maroon|[[Mars]]}}{{·}}{{legend2|Cyan|[[21 Lutetia]]}}{{·}}{{legend2|Gold|[[2867 Šteins]]}}]]
[[File:Rosetta 111106.jpg|thumb|upright=1.4|Trajectory of the ''Rosetta'' space probe]]
''Rosetta'' was set to be launched on 12 January 2003 to rendezvous with the comet [[46P/Wirtanen]] in 2011.<ref name="Altwegg2001" /> This plan was abandoned after the failure of an [[Ariane 5 ECA]] carrier rocket during [[Hot Bird 7]]'s launch on 11 December 2002, grounding it until the cause of the failure could be determined.<ref name="Harland2006">{{cite book |chapter-url=https://books.google.com/books?id=eszSE5VGvuMC&pg=PA149 |chapter=The Current Crop |title=Space Systems Failures |publisher=Springer-Praxis |first1=David M. |last1=Harland |first2=Ralph D. |last2=Lorenz |pages=149–150 |date=2006 |isbn=978-0-387-21519-8}}</ref> In May 2003, a new plan was formed to target the comet 67P/Churyumov–Gerasimenko, with a revised launch date of 26 February 2004 and comet rendezvous in 2014.<ref name="esa20030529">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/New_destination_for_Rosetta_Europe_s_comet_chaser |title=New destination for Rosetta, Europe's comet chaser |publisher=European Space Agency |date=29 May 2003 |access-date=7 October 2016}}</ref><ref name="nature20030522">{{cite journal |title=Spiralling costs dog comet mission |journal=[[Nature (journal)|Nature]] |first=Declan |last=Butler |volume=423 |issue=6938 |page=372 |date=22 May 2003 |doi=10.1038/423372b |pmid=12761511 |bibcode=2003Natur.423..372B|doi-access=free }}</ref> The larger mass and the resulting increased impact velocity made modification of the landing gear necessary.<ref>{{cite journal |title=Rosetta Lander—Philae: Implications of an alternative mission |journal=Acta Astronautica |first1=S. |last1=Ulamec |first2=S. |last2=Espinasse |first3=B. |last3=Feuerbacher |first4=M. |last4=Hilchenbach |first5=D. |last5=Moura |first6=H. |last6=Rosenbauer |first7=H. |last7=Scheuerle |first8=R. |last8=Willnecker |display-authors=5 |volume=58 |issue=8 |pages=435–441 |date=April 2006 |doi=10.1016/j.actaastro.2005.12.009 |bibcode=2006AcAau..58..435U}}</ref>

After two scrubbed launch attempts, ''Rosetta'' was launched on 2 March 2004 at 07:17&nbsp;[[UTC]] from the [[Guiana Space Centre]] in French Guiana, using [[Ariane 5 G+]] carrier rocket.<ref name="esa20040304" /> Aside from the changes made to launch time and target, the mission profile remained almost identical. Both co-discoverers of the comet, [[Klim Churyumov]] and [[Svetlana Gerasimenko]], were present at the spaceport during the launch.<ref name="esa54156">{{cite web |url=http://sci.esa.int/rosetta/54156-svetlana-gerasimenko-and-klim-churyumov-in-kourou/ |title=Svetlana Gerasimenko and Klim Churyumov in Kourou |series=Rosetta |publisher=European Space Agency |date=20 October 2014 |access-date=15 October 2016}}</ref><ref name="esa54598">{{cite web |url=http://sci.esa.int/rosetta/54598-klim-churyumov/ |title=Klim Churyumov – co-discoverer of comet 67P |series=Rosetta |publisher=European Space Agency |date=20 October 2014 |access-date=15 October 2016}}</ref>

=== Deep space manoeuvres ===
To achieve the required velocity to rendezvous with 67P, ''Rosetta'' used [[gravity assist]] manoeuvres to accelerate throughout the inner Solar System.<ref name="FAQ">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions |title=Rosetta's Frequently Asked Questions |publisher=European Space Agency |access-date=24 May 2014}}</ref> The comet's orbit was known before ''Rosetta''{{'s}} launch, from ground-based measurements, to an accuracy of approximately {{convert|100|km|abbr=on}}. Information gathered by the onboard cameras beginning at a distance of {{convert|24|e6km|mi}} were processed at ESA's Operation Centre to refine the position of the comet in its orbit to a few kilometres.{{Citation needed|date=September 2016}}

The first [[Earth]] flyby was on 4 March 2005.<ref name="Montagnon2006" />

On 25 February 2007, the craft was scheduled for a low-altitude flyby of [[Mars]], to correct the trajectory. This was not without risk, as the estimated altitude of the flyby was a mere {{convert|250|km}}.<ref name="eoportal">{{cite web|url=https://directory.eoportal.org/web/eoportal/satellite-missions/r/rosetta |title=Rosetta Rendezvous Mission with Comet 67P/Churyumov-Gerasimenko |work=eoPortal |publisher=European Space Agency |access-date=1 October 2016}}</ref> During that encounter, the solar panels could not be used since the craft was in the planet's shadow, where it would not receive any solar light for 15 minutes, causing a dangerous shortage of power. The craft was therefore put into standby mode, with no possibility to communicate, flying on batteries that were originally not designed for this task.<ref>{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta_correctly_lined_up_for_critical_Mars_swingby |title=Rosetta correctly lined up for critical Mars swingby |publisher=European Space Agency |date=15 February 2007 |access-date=21 January 2014}}</ref> This Mars manoeuvre was therefore nicknamed "The Billion Euro Gamble".<ref>{{cite news |url=http://www.physorg.com/news91439922.html |title=Europe set for billion-euro gamble with comet-chasing probe |publisher=[[Phys.org]] |date=23 February 2007 |archive-url=https://web.archive.org/web/20070225091756/http://www.physorg.com/news91439922.html |archive-date=25 February 2007}}</ref> The flyby was successful, with ''Rosetta'' even returning detailed images of the surface and atmosphere of the planet, and the mission continued as planned.<ref name="philaemars20070225"/><ref name="Mars fly-by" />

The second Earth flyby was on 13 November 2007 at a distance of {{convert|5700|km|mi||abbr=on}}.<ref>{{cite news|url=http://www.mps.mpg.de/en/aktuelles/pressenotizen/pressenotiz_20071115.html |title=First OSIRIS images from Rosetta Earth swing-by |publisher=Max Planck Institute for Solar System Research |first1=Horst Uwe |last1=Keller |first2=Holger |last2=Sierks |date=15 November 2007 |archive-url=https://web.archive.org/web/20080307051929/http://www.mps.mpg.de/en/aktuelles/pressenotizen/pressenotiz_20071115.html |archive-date=7 March 2008}}</ref><ref>{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2007/1216.html |title=Science plans for Rosetta's Earth flyby |publisher=The Planetary Society |first=Emily |last=Lakdawalla |date=2 November 2007 |access-date=21 January 2014}}</ref> In observations made on 7 and 8 November, ''Rosetta'' was briefly mistaken for a [[near-Earth object|near-Earth asteroid]] about {{convert|20|m|ft|abbr=on}} in diameter by an astronomer of the [[Catalina Sky Survey]] and was given the [[provisional designation in astronomy|provisional designation]] {{mp|2007 VN|84}}.<ref>{{cite web|title=M.P.E.C. 2007-V69 |url=http://www.minorplanetcenter.net/iau/mpec/K07/K07V69.html |archive-url=https://archive.today/20120523234959/http://www.minorplanetcenter.net/iau/mpec/K07/K07V69.html |url-status=dead |archive-date=23 May 2012 |publisher=Minor Planet Center |access-date=6 October 2015}}</ref> Calculations showed that it would pass very close to Earth, which led to speculation that it could impact Earth.<ref>{{cite news |url=https://www.skymania.com/wp/deadly-asteroid-is-spaceprobe/ |title='Deadly asteroid' is a spaceprobe |work=Skymania |first=Paul |last=Sutherland |date=10 November 2007 |access-date=21 January 2014}}</ref> However, astronomer [[Denis Denisenko]] recognised that the trajectory matched that of ''Rosetta'', which the [[Minor Planet Center]] confirmed in an editorial release on 9 November.<ref name="planetary-misidentification">{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2007/1227.html |title=That's no near-Earth object, it's a spaceship! |publisher=The Planetary Society |first=Emily |last=Lakdawalla |date=9 November 2007 |access-date=21 January 2014}}</ref><ref name="mpec20071109">{{cite web |url=http://www.minorplanetcenter.net/iau/mpec/K07/K07V70.html |title=MPEC 2007-V70: Editorial Notice |work=Minor Planet Electronic Circular |publisher=[[Minor Planet Center]] |first=A. U. |last=Tomatic |date=9 November 2007 |access-date=21 January 2014}}</ref>

The spacecraft performed a close flyby of asteroid [[2867 Šteins]] on 5 September 2008. Its onboard cameras were used to fine-tune the trajectory, achieving a minimum separation of less than {{convert|800|km|abbr=on}}. Onboard instruments measured the asteroid from 4 August to 10 September. Maximum relative speed between the two objects during the flyby was {{convert|8.6|km/s|mph km/h|abbr=on}}.<ref>{{cite journal|title=First Asteroid |journal=[[Aviation Week & Space Technology]] |volume=169 |issue=10 |page=18 |date=15 September 2008}}</ref>

''Rosetta''{{'s}} third and final flyby of Earth happened on 12 November 2009 at a distance of {{convert|2481|km|abbr=on}}.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/sci/tech/8355873.stm |title=Rosetta makes final home call |work=BBC News |date=12 November 2009 |access-date=22 May 2010}}</ref>

On 10 July 2010, ''Rosetta'' flew by [[21 Lutetia]], a large [[asteroid belt|main-belt]] [[asteroid]], at a minimum distance of {{val|3168|7.5|fmt=commas}}&nbsp;km ({{val|1969|4.7|fmt=commas}}&nbsp;mi) at a velocity of {{convert|15|km/s|mi/s}}.<ref name="science28102011">{{cite journal|title=Asteroid 21 Lutetia: Low Mass, High Density |journal=[[Science (journal)|Science]] |first1=M. |last1=Pätzold |first2=T. P. |last2=Andert |first3=S. W. |last3=Asmar |first4=J. D. |last4=Anderson |first5=J.-P. |last5=Barriot |first6=M. K. |last6=Bird |first7=B. |last7=Häusler |first8=M. |last8=Hahn |first9=S. |last9=Tellmann |first10=H. |last10=Sierks |first11=P. |last11=Lamy |first12=B. P. |last12=Weiss |display-authors=5 |volume=334 |issue=6055 |pages=491–492 |date=October 2011 |bibcode=2011Sci...334..491P |doi=10.1126/science.1209389 |pmid=22034429 |url=https://dspace.mit.edu/bitstream/1721.1/103947/1/Paetzold_2011_open_access.pdf |hdl=1721.1/103947|s2cid=41883019 |hdl-access=free}}</ref> The flyby provided images of up to {{convert|60|m|ft}} per pixel resolution and covered about 50% of the surface, mostly in the northern hemisphere.<ref name=BBC/><ref name="Sierks2011">{{cite journal|title=Images of Asteroid 21 Lutetia: A Remnant Planetesimal from the Early Solar System |journal=[[Science (journal)|Science]] |first1=H. |last1=Sierks |first2=P. |last2=Lamy |first3=C. |last3=Barbieri |first4=D. |last4=Koschny |first5=H. |last5=Rickman |first6=R. |last6=Rodrigo |first7=M. F. |last7=A'Hearn |first8=F. |last8=Angrilli |first9=M. A. |last9=Barucci |first10=J.-L. |last10=Bertaux |first11=I. |last11=Bertini |first12=S. |last12=Besse |first13=B. |last13=Carry |first14=G. |last14=Cremonese |first15=V. |last15=Da Deppo |first16=B. |last16=Davidsson |first17=S. |last17=Debei |first18=M. |last18=De Cecco |first19=J. |last19=De Leon |first20=F. |last20=Ferri |first21=S. |last21=Fornasier |first22=M. |last22=Fulle |first23=S. F. |last23=Hviid |first24=R. W. |last24=Gaskell |first25=O. |last25=Groussin |first26=P. |last26=Gutierrez |first27=W. |last27=Ip |first28=L. |last28=Jorda |first29=M. |last29=Kaasalainen |first30=H. U. |last30=Keller |first31=J. |last31=Knollenberg |first32=R. |last32=Kramm |first33=E. |last33=Kührt |first34=M. |last34=Küppers |first35=L. |last35=Lara |first36=M. |last36=Lazzarin |first37=C. |last37=Leyrat |first38=J. J. Lopez |last38=Moreno |first39=S. |last39=Magrin |first40=S. |last40=Marchi |first41=F. |last41=Marzari |first42=M. |last42=Massironi |first43=H. |last43=Michalik |first44=R. |last44=Moissl |first45=G. |last45=Naletto |first46=F. |last46=Preusker |first47=L. |last47=Sabau |first48=W. |last48=Sabolo |first49=F. |last49=Scholten |first50=C. |last50=Snodgrass |first51=N. |last51=Thomas |first52=C. |last52=Tubiana |first53=P. |last53=Vernazza |first54=J.-B. |last54=Vincent |first55=K.-P. |last55=Wenzel |first56=T. |last56=Andert |first57=M. |last57=Pätzold |first58=B. P. |last58=Weiss |display-authors=5 |volume=334 |issue=6055 |pages=487–90 |date=October 2011 |bibcode=2011Sci...334..487S |doi=10.1126/science.1207325 |pmid=22034428 |hdl=1721.1/110553|s2cid=17580478 |hdl-access=free}}</ref> The 462 images were obtained in 21 narrow- and broad-band filters extending from 0.24 to 1&nbsp;μm.<ref name=BBC/> Lutetia was also observed by the visible–near-infrared imaging spectrometer VIRTIS, and measurements of the magnetic field and plasma environment were taken as well.<ref name=BBC/><ref name=Sierks2011/>

[[File:Signal received from Rosetta (12055070794).jpg|thumb|left|''Rosetta''{{'s}} signal received at [[European Space Operations Centre|ESOC]] in [[Darmstadt]], Germany, on 20 January 2014]]
[[File:Crescent Earth from Rosetta.jpg|thumb|Earth from ''Rosetta'' during final flyby]]

After leaving its hibernation mode in January 2014 and getting closer to the comet, ''Rosetta'' began a series of eight burns in May 2014. These reduced the relative velocity between the spacecraft and 67P from {{convert|775|to|7.9|m/s|abbr=on}}.<ref name="OCM" />

=== Reaction control system problems ===
In 2006, ''Rosetta'' suffered a leak in its [[reaction control system]] (RCS).<ref name="FAQ" /> The system, which consists of 24 [[bipropellant]] 10-[[newton (unit)|newton]] thrusters,<ref name="OCM" /> was responsible for fine tuning the trajectory of ''Rosetta'' throughout its journey. The RCS operated at a lower pressure than designed due to the leak. While this may have caused the propellants to mix incompletely and burn 'dirtier' and less efficiently, ESA engineers were confident that the spacecraft would have sufficient fuel reserves to allow for the successful completion of the mission.<ref name="bbc20140521">{{cite news |url=https://www.bbc.co.uk/news/science-environment-27498534 |title=Rosetta comet-chaser initiates 'big burn' |work=BBC News |first=Jonathan |last=Amos |date=21 May 2014 |access-date=24 May 2014}}</ref>

Prior to ''Rosetta''{{'s}} deep space hibernation period, two of the spacecraft's four [[reaction wheel]]s began exhibiting increased levels of "bearing friction noise". Increased friction levels in Reaction Wheel Assembly (RWA)&nbsp;B were noted after its September 2008 encounter with asteroid Šteins. Two attempts were made to relubricate the RWA using an on-board oil reservoir, but in each case noise levels were only temporarily lowered, and the RWA was turned off in mid-2010 after the flyby of asteroid Lutetia to avoid possible failure. Shortly after this, RWA&nbsp;C also began showing evidence of elevated friction. Relubrication was also performed on this RWA, and methods were found to temporarily increase its operating temperature to better improve the transfer of oil from its reservoir. In addition, the reaction wheel's speed range was decreased to limit lifetime accumulated rotations. These changes resulted in RWA&nbsp;C{{'s}} performance stabilising.<ref name="McMahon2017">{{cite conference |url=http://esmats.eu/esmatspapers/pastpapers/pdfs/2017/mcmahon.pdf |title=Inorbit Maintenance of the Rosetta Reaction Wheels (RWAs) |conference=European Space Mechanisms and Tribology Symposium. 20–22 September 2017. Hatfield, United Kingdom. |first1=Paul |last1=McMahon |first2=Rene |last2=Seiler |first3=Andrea |last3=Accomazzo |first4=Sylvain |last4=Lodiot |first5=Patrick |last5=Van Put |first6=Roberto |last6=Port |display-authors=1 |date=2017}}</ref>

During the spacecraft's Deep Space Hibernation flight phase, engineers performed ground testing on a flight spare RWA at the [[European Space Operations Centre]]. After ''Rosetta'' exited hibernation in January 2014, lessons learned from the ground testing were applied to all four RWAs, such as increasing their operating temperatures and limiting their wheel speeds to below 1000&nbsp;rpm. After these fixes, the RWAs showed nearly identical performance data.<ref name="McMahon2017" /> Three RWAs were kept operational, while one of the malfunctioning RWAs was held in reserve. Additionally, new on-board software was developed to allow ''Rosetta'' to operate with only two active RWAs if necessary.<ref name="FAQ" /><ref name="sfnow20140129">{{cite news |url=https://spaceflightnow.com/rosetta/140129update/ |title=ESA says Rosetta in good shape after 31-month snooze |work=Spaceflight Now |first=Stephen |last=Clark |date=29 January 2014 |access-date=29 July 2014}}</ref> These changes allowed the four RWAs to operate throughout ''Rosetta''{{'s}} mission at 67P/Churyumov–Gerasimenko despite occasional anomalies in their friction plots and a heavy workload imposed by numerous orbital changes.<ref name="McMahon2017" />

=== Orbit around 67P ===
[[File:Animation of Rosetta trajectory around 67P.gif|thumb|Animation of ''Rosetta''{{'s}} trajectory around 67P from 1 August 2014 to 31 March 2015 <br/> {{legend2|magenta|''Rosetta''}}{{·}}{{legend2|lime|[[67P/Churyumov–Gerasimenko|67P]]}}]]
In August 2014, ''Rosetta'' rendezvoused with the comet [[67P/Churyumov–Gerasimenko]] (67P) and commenced a series of manoeuvres that took it on two successive triangular paths, averaging {{convert|100|and|50|km}} from the nucleus, whose segments are [[Hyperbolic trajectory|hyperbolic escape trajectories]] alternating with thruster burns.<ref name="Fischer2014-08-06" /><ref name="Bauer2014" /> After closing to within about {{convert|30|km|abbr=on}} from the comet on 10 September, the spacecraft entered actual [[orbit]] about it.<ref name="Fischer2014-08-06" /><ref name="Bauer2014" /><ref name="Lakdawalla2014-08-15" />{{update after|2014|11|12}}<!-- if it is now in an actual orbit, depending on the micro-gravity of the small comet, what is its orbital period? and what is the current/settled periapsis and apoapsis? -->

The surface layout of 67P was unknown before ''Rosetta''{{'s}} arrival. The orbiter mapped the comet in anticipation of detaching its lander.<ref name="esablog230714">{{cite web |url=http://blogs.esa.int/rosetta/2014/07/23/last-of-the-fatties/ |title=Last of the FATties |publisher=European Space Agency |first=Daniel |last=Scuka |date=23 July 2014 |access-date=31 July 2014}}</ref> By 25 August 2014, five potential landing sites had been determined.<ref name="NASA-20140825">{{cite web |url=http://www.jpl.nasa.gov/news/news.php?release=2014-289 |title=Rosetta: Landing site search narrows |work=[[NASA]] |last1=Agle |first1=D. C. |last2=Brown |first2=Dwayne |last3=Bauer |first3=Markus |date=25 August 2014 |access-date=26 August 2014}}</ref> On 15 September 2014, ESA announced Site&nbsp;J, named ''Agilkia'' in honour of [[Agilkia Island]] by an ESA public contest and located on the "head" of the comet,<ref name="bbcnews20141104">{{cite news |url=https://www.bbc.com/news/science-environment-29902456 |title=Rosetta comet mission: Landing site named 'Agilkia' |work=BBC News |last=Amos |first=Jonathan |date=4 November 2014 |access-date=5 November 2014}}</ref> as the lander's destination.<ref name="esa20140915">{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/J_marks_the_spot_for_Rosetta_s_lander |title='J' Marks the Spot for Rosetta's Lander |publisher=European Space Agency |first=Markus |last=Bauer |date=15 September 2014 |access-date=20 September 2014}}</ref>

=== ''Philae'' lander ===
{{Main|Philae (spacecraft)}}
[[File:Rosetta and Philae (crop).jpg|thumb|''Rosetta'' and ''Philae'']]
''[[Philae (spacecraft)|Philae]]'' detached from ''Rosetta'' on 12 November 2014 at 08:35 UTC, and approached 67P at a relative speed of about {{convert|1|m/s|km/h mph|abbr=on}}.<ref>{{cite news|url=https://www.telegraph.co.uk/news/science/space/11225469/Rosetta-mission-broken-thrusters-mean-probe-could-bounce-off-comet-into-space.html |archive-url=https://ghostarchive.org/archive/20220112/https://www.telegraph.co.uk/news/science/space/11225469/Rosetta-mission-broken-thrusters-mean-probe-could-bounce-off-comet-into-space.html |archive-date=12 January 2022 |url-access=subscription |url-status=live |title=Rosetta mission: broken thrusters mean probe could bounce off comet into space |work=[[The Daily Telegraph]] |first1=Sarah |last1=Knapton |date=12 November 2014 |access-date=12 November 2014}}{{cbignore}}</ref> It initially landed on 67P at 15:33 UTC, but bounced twice, coming to rest at 17:33 UTC.<ref name="skytel20141112">{{cite news |url=http://www.skyandtelescope.com/astronomy-news/philae-lands-three-times-111220143/ |title=Philae Lands on Its Comet – Three Times! |work=[[Sky & Telescope]] |first=Kelly |last=Beatty |date=12 November 2014 |access-date=26 November 2014}}</ref><ref name="indy20141113">{{cite news |url=https://www.independent.co.uk/news/science/philae-lander-bounced-twice-on-comet-and-may-still-not-be-stable-rosetta-mission-scientists-warn-9857551.html |title=Philae lander 'bounced twice' on comet but is now stable, Rosetta mission scientists confirm |work=[[The Independent]] |first1=Adam |last1=Withnall |first2=James |last2=Vincent |date=13 November 2014 |access-date=26 November 2014}}</ref> Confirmation of contact with 67P reached Earth at 16:03 UTC.<ref name="sfnow20141113">{{cite news |url=http://spaceflightnow.com/2014/11/13/rosetta-camera-captures-philaes-descent-to-the-comet/ |title=Rosetta camera captures Philae's descent to the comet |work=Spaceflight Now |date=13 November 2014 |access-date=26 November 2014}}</ref>

On contact with the surface, two [[harpoon]]s were to be fired into the comet to prevent the lander from bouncing off, as the comet's escape velocity is only around {{convert|1|m/s|km/h mph|abbr=on}}.<ref name="mpg20140121">{{cite news|url=http://www.mpg.de/8323012/expedition_primeval_matter |title=Expedition to primeval matter |publisher=Max-Planck-Gesellschaft |first=Thorsten |last=Dambeck |date=21 January 2014 |access-date=19 September 2014}}</ref> Analysis of telemetry indicated that the surface at the initial touchdown site is relatively soft, covered with a layer of granular material about {{convert|0.82|ft|m|abbr=off|sp=us}} deep,<ref>{{cite news|last=Wall |first=Mike |url=http://www.space.com/30100-comet-landing-discoveries-rosetta-philae-lander.html |title=Surprising Comet Discoveries by Rosetta's Philae Lander Unveiled |work=Space.com |date=30 July 2015 |access-date=31 July 2015}}</ref> and that the harpoons had not fired upon landing. After landing on the comet, ''Philae'' had been scheduled to commence its science mission, which included:
* Characterisation of the nucleus
* Determination of the chemical compounds present, including amino acid [[enantiomer]]s<ref name="Meierhenrich2008book">{{cite book |title=Amino Acids and the Asymmetry of Life |publisher=Springer-Verlag |first=Uwe |last=Meierhenrich |author-link=Uwe Meierhenrich |year=2008 |isbn=978-3-540-76885-2 |doi=10.1007/978-3-540-76886-9 |series=Advances in Astrobiology and Biogeophysics|bibcode=2008aaal.book.....M }}</ref>
* Study of comet activities and developments over time

After bouncing, ''Philae'' settled in the shadow of a cliff,<ref name="Philaefound" /> canted at an angle of around 30 degrees. This made it unable to adequately collect solar power, and it lost contact with ''Rosetta'' when its batteries ran out after three days, well before much of the planned science objectives could be attempted.<ref name="Philaefound" /><ref name="skytel20141115">{{cite news |url=http://www.skyandtelescope.com/astronomy-news/philae-lander-success-11152014/ |title=Philae Wins Race to Return Comet Findings |work=[[Sky & Telescope]] |first=Kelly |last=Beatty |date=15 November 2014 |access-date=2 November 2015}}</ref> Contact was briefly and intermittently reestablished several months later at various times between 13 June and 9 July, before contact was lost once again. There was no communication afterwards,<ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_s_lander_faces_eternal_hibernation |title=Rosetta's Lander Faces Eternal Hibernation |publisher=European Space Agency |first=Markus |last=Bauer |date=12 February 2016 |access-date=14 February 2016}}</ref> and the transmitter to communicate with ''Philae'' was switched off in July 2016 to reduce power consumption of the probe.<ref name="farewellphilae" /> The precise location of the lander was discovered in September 2016 when ''Rosetta'' came closer to the comet and took high-resolution pictures of its surface.<ref name="Philaefound">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Philae_found |title=Philae found! |publisher=European Space Agency |date=5 September 2016 |access-date=5 September 2016}}</ref> Knowing its exact location provides information needed to put Philae's two days of science into proper context.<ref name="Philaefound"/>

=== Notable results ===
[[File:Comet 67P on 31 January 2015 - NAVCAM.jpg|thumb|The comet in January 2015 as seen by ''Rosetta''{{'s}} NAVCAM]]
Researchers expect the study of data gathered will continue for decades to come. One of the first discoveries was that the magnetic field of 67P oscillated at 40–50 [[millihertz]]. A German composer and sound designer created an artistic rendition from the measured data to make it audible.<ref>{{cite web |url=http://blogs.esa.int/rosetta/2014/12/19/behind-the-scenes-of-the-singing-comet/ |title=Behind the scenes of 'The Singing Comet' |publisher=European Space Agency |first=Claudia |last=Mignone |date=19 December 2014 |access-date=18 October 2017}}</ref> Although it is a natural phenomenon, it has been described as a "song"<ref name="smithsonian20141112">{{cite news |url=http://www.smithsonianmag.com/smart-news/comet-has-welcome-song-rosetta-and-philae-180953303/?no-ist |title=Comet 67P Has a Welcome Song for Rosetta And Philae |publisher=Smithsonian.com |series=Smart News |first=Marissa |last=Fessenden |date=12 November 2014 |access-date=26 December 2014}}</ref> and has been compared to [[Continuum (Ligeti)|''Continuum'' for harpsichord]] by [[György Ligeti]].<ref name="classicfm20141114">{{cite news |url=http://www.classicfm.com/discover/music/singing-comet-67p-philae/ |title=Music emitted from Comet 67P sounds an awful lot like 20th-century harpsichord masterpiece |work=Classic FM |first=Tim |last=Edwards |date=14 November 2014 |access-date=26 December 2014}}</ref> However, results from ''Philae''{{'s}} landing show that the comet's nucleus has no magnetic field, and that the field originally detected by ''Rosetta'' is likely caused by the [[solar wind]].<ref name="esa20150414">{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_and_Philae_find_comet_not_magnetised |title=Rosetta and Philae Find Comet Not Magnetised |publisher=European Space Agency |first=Markus |last=Bauer |date=14 April 2015 |access-date=14 April 2015}}</ref><ref name="nature20150414">{{cite journal |title=Rosetta's comet has no magnetic field |journal=[[Nature (journal)|Nature]] |first=Quirin |last=Schiermeier |date=14 April 2015 |doi=10.1038/nature.2015.17327|s2cid=123964604 }}</ref>

The [[isotopic signature]] of water vapour from comet 67P, as determined by the ''Rosetta'' spacecraft, is substantially different from that found on Earth. That is, the ratio of [[deuterium]] to [[hydrogen]] in the water from the comet was determined to be three times that found for terrestrial water. This makes it very unlikely that water found on Earth came from comets such as comet 67P, according to the scientists.<ref name="NASA-20141210-DCA">{{cite web |url=http://www.jpl.nasa.gov/news/news.php?release=2014-423 |title=Rosetta Instrument Reignites Debate on Earth's Oceans |publisher=NASA |last1=Agle |first1=D.C. |last2=Bauer |first2=Markus |date=10 December 2014 |access-date=10 December 2014}}</ref><ref name="NYT-20141210-KC">{{cite news |url=https://www.nytimes.com/2014/12/11/science/rosetta-mission-data-rules-out-comets-as-a-source-for-earths-water.html |title=Comet Data Clears Up Debate on Earth's Water |work=[[The New York Times]] |last=Chang |first=Kenneth |date=10 December 2014 |access-date=10 December 2014}}</ref><ref name="BBC-20141211">{{cite news |url=https://www.bbc.co.uk/news/science-environment-30414519 |title=Rosetta results: Comets 'did not bring water to Earth' |work=BBC News |last=Morelle |first=Rebecca |author-link=Rebecca Morelle |date=10 December 2014 |access-date=11 December 2014}}</ref> On 22 January 2015, NASA reported that, between June and August 2014, the rate at which water vapour was released by the comet increased up to tenfold.<ref name="NASA-20150122">{{cite web |last1=Agle |first1=D. C. |last2=Brown |first2=Dwayne |last3=Bauer |first3=Markus |url=http://www.jpl.nasa.gov/news/news.php?release=2015-029 |title=Rosetta Comet 'Pouring' More Water Into Space |publisher=NASA |date=22 January 2015 |access-date=22 January 2015}}</ref> <!--Please mine the article for actual information: On 23 January 2015, the journal ''[[Science (journal)|Science]]'' published a special issue of scientific studies related to the comet.<ref name="SCI-20150123">{{cite journal |url=https://www.science.org/toc/science/347/6220 |title=Catching a Comet |series=Special Issue. |journal=[[Science (journal)|Science]] |volume=347 |issue=6220 |date=23 January 2015 |access-date=23 January 2015}}</ref> -->

On 2 June 2015, NASA reported that the [[#Instruments|Alice spectrograph]] on ''Rosetta'' determined that [[electron]]s within {{convert|1|km|mi|1|abbr=on}} above the comet nucleus&nbsp;— produced from photoionization of water [[molecule]]s, and not direct [[photon]]s from the Sun as thought earlier&nbsp;— are responsible for the degradation of water and [[carbon dioxide]] molecules released from the comet nucleus into its [[coma (cometary)|coma]].<ref name="NASA-20150602">{{cite news|url=http://www.jpl.nasa.gov/news/news.php?feature=4609 |title=NASA Instrument on Rosetta Makes Comet Atmosphere Discovery |publisher=NASA |last1=Agle |first1=D. C. |last2=Brown |first2=Dwayne |last3=Fohn |first3=Joe |last4=Bauer |first4=Markus |date=2 June 2015 |access-date=2 June 2015}}</ref><ref name="AA-20150602">{{cite journal |title=Measurements of the near-nucleus coma of comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta |journal=[[Astronomy and Astrophysics]] |volume=583 |at=A8 |last1=Feldman |first1=Paul D. |last2=A'Hearn |first2=Michael F. |last3=Bertaux |first3=Jean-Loup |last4=Feaga |first4=Lori M. |last5=Parker |first5=Joel Wm. |last6=Schindhelm |first6=Eric |last7=Steiffl |first7=Andrew J. |last8=Stern |first8=S. Alan |last9=Weaver |first9=Harold A. |last10=Sierks |first10=Holger |last11=Vincent |first11=Jean-Baptiste |display-authors=5 |date=2 June 2015 |doi=10.1051/0004-6361/201525925 |bibcode=2015A&A...583A...8F |arxiv=1506.01203|s2cid=119104807}}</ref>

=== End of mission ===
[[File:Rosetta rendezvous with a comet.jpg|thumb|''Rosetta'' rendezvous with a comet]]
As the orbit of comet 67P took it farther from the Sun, the amount of sunlight reaching ''Rosetta''{{'s}} solar panels decreased. While it would have been possible to put ''Rosetta'' into a second hibernation phase during the comet's aphelion, there was no assurance that enough power would be available to run the spacecraft's heaters to keep it from freezing. To guarantee a maximum science return, mission managers made the decision to instead guide ''Rosetta'' down to the comet's surface and end the mission on impact, gathering photographs and instrument readings along the way.<ref name="esa20160630">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_finale_set_for_30_September |title=Rosetta finale set for 30 September |publisher=European Space Agency |first=Markus |last=Bauer |date=30 June 2016 |access-date=7 October 2016}}</ref> On 23 June 2015, at the same time as a mission extension was confirmed, ESA announced that end of mission would occur at the end of September 2016 after two years of operations at the comet.<ref name="esa20150623">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_mission_extended |title=Rosetta mission extended |publisher=European Space Agency |first=Markus |last=Bauer |date=23 June 2015 |access-date=11 July 2015}}</ref>

{{blockquote|All stations and the briefing room, we've just had loss of signal at the expected time. This is another outstanding performance by flight dynamics. So we'll be listening for the signal from Rosetta for another 24 hours, but we don't expect any. This is the end of the Rosetta mission. Thank you, and goodbye.<br/>{{emdash}}Sylvain Lodiot, ''Rosetta'' Spacecraft Operations Manager, [[European Space Operations Centre]]<ref name="sfnow20160930" />}}

''Rosetta'' began a {{convert|19|km|mi|abbr=on}} descent with a 208-second thruster burn executed on 29 September 2016 at approximately 20:50&nbsp;[[UTC]].<ref name="esa20160930">{{cite web|url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Mission_complete_Rosetta_s_journey_ends_in_daring_descent_to_comet |title=Mission complete: Rosetta's journey ends in daring descent to comet |publisher=European Space Agency |date=30 September 2016 |access-date=7 October 2016}}</ref><ref name="eosjour20160930">{{cite journal |title=Rosetta Spacecraft Death-Dives into Comet Companion—On Purpose |journal=[[Eos (magazine)|Eos]] |first=Ron |last=Cowen |volume=97 |date=30 September 2016 |doi=10.1029/2016EO060243|doi-access=free}}</ref><ref name="sfnow20160930">{{cite news |url=https://spaceflightnow.com/2016/09/30/rosetta-mission-ends-with-comet-touchdown/ |title=Rosetta mission ends with comet touchdown |work=Spaceflight Now |first=Stephen |last=Clark |date=30 September 2016 |access-date=7 October 2016}}</ref> Its trajectory targeted a site in the Ma'at region near an area of dust- and gas-producing active pits.<ref name="nature20160930">{{cite journal |title=Mission accomplished: Rosetta crashes into comet |journal=[[Nature (journal)|Nature]] |first=Elizabeth |last=Gibney |volume=538 |issue=7623 |date=30 September 2016 |doi=10.1038/nature.2016.20705 |pages=13–14 |pmid=27708332 |bibcode=2016Natur.538...13G|doi-access=free }}</ref>

Impact on the comet's surface occurred 14.5 hours after its descent manoeuvre; the final data packet from ''Rosetta'' was transmitted at 10:39:28.895&nbsp;UTC ([[Spacecraft Event Time|SCET]]) by the OSIRIS instrument and was received at the [[European Space Operations Centre]] in Darmstadt, Germany, at 11:19:36.541&nbsp;UTC.<ref name="esa20160930" /><ref name="eosjour20160930" /><ref name="twitter781816617097392129">{{cite web |url=https://twitter.com/esaoperations/status/781816617097392129 |title=Screenshot of the last packet... |work=Twitter.com |publisher=ESA Operations |date=30 September 2016 |access-date=7 October 2016}} Note: Times in the left column are [[Spacecraft Event Time]], while the right column is Earth Received Time. All times are in [[UTC]].</ref> The spacecraft's estimated speed at the time of impact was {{convert|3.2|km/h|mph cm/s|abbr=on}},<ref name="space20160930" /> and its touchdown location, named ''Sais'' by the operations team after the Rosetta Stone's original temple home, is believed to be only {{convert|40|m|ft|abbr=on}} off-target.<ref name="nature20160930" /> The final complete image transmitted by the spacecraft of the comet was taken by its OSIRIS instrument at an altitude of {{convert|23.3|-|26.2|m|ft|abbr=on}} about 10 seconds before impact, showing an area {{convert|0.96|m|ft|abbr=on}} across.<ref name="nature20160930" /><ref name="esa20170928">{{cite web|url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Unexpected_surprise_a_final_image_from_Rosetta |title=Unexpected Surprise: A Final Image From Rosetta |publisher=European Space Agency |first1=Holger |last1=Sierks |first2=Matt |last2=Taylor |first3=Markus |last3=Bauer |date=28 September 2017 |access-date=3 December 2017}}</ref> ''Rosetta''{{'s}} computer included commands to send it into safe mode upon detecting that it had hit the comet's surface, turning off its radio transmitter and rendering it inert in accordance with [[International Telecommunication Union]] rules.<ref name="sfnow20160930" />

On 28 September 2017, a previously unrecovered image taken by the spacecraft was reported. This image was recovered from three data packets discovered on a server after completion of the mission. While blurry due to data loss, it shows an area of the comet's surface approximately one square meter in size taken from an altitude of {{convert|17.9|-|21.0|m|ft|abbr=on}}, and represents ''Rosetta''{{'s}} closest image of the surface.<ref name="esa20170928" /><ref name="GZM-20170928">{{cite news|url=https://gizmodo.com/scientists-unexpectedly-find-rosetta-s-final-image-of-c-1818966894 |title=Scientists Unexpectedly Find Rosetta's Final Image of Comet 67P/CG |work=[[Gizmodo]] |first=George |last=Dvorsky |date=28 September 2017 |access-date=28 September 2017}}</ref>