Editing Rosetta (spacecraft) (section)

=== ''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"/>