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— CH. 1 · MISSION GENESIS AND LAUNCH —

Philae (spacecraft)

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  • The European Space Agency launched the Philae lander from French Guiana on the 2nd of March 2004 at 07:17 UTC. This Ariane 5G+ rocket carried both the Rosetta orbiter and the Philae probe into space for a journey lasting 3,907 days. The original target was comet 46P/Wirtanen, but a launch failure in 2003 forced mission planners to switch targets. They selected 67P/Churyumov, Gerasimenko instead, which required significant engineering changes to the landing gear due to its larger mass. Scientists hoped the new target would allow them to study cometary material up close without destroying it like previous impact missions. The spacecraft traveled through deep space for over ten years before reaching their destination in August 2014.

  • Philae touched down on the 12th of November 2014 at 15:34:04 UTC SCET after a twenty-eight-minute signal delay reached Earth. The anchoring harpoons failed to deploy because the nitrocellulose charge inside them proved unreliable in vacuum conditions. A thruster designed to hold the probe against the surface also did not fire as planned. The lander rebounded off the ground and rose to an altitude of approximately one kilometer before falling back. It struck a surface prominence during the first bounce, slowing rotation from every thirteen seconds to once every twenty-four seconds. The craft bounced twice more before coming to rest at 17:31:17 UTC SCET. Final analysis showed the initial impact was softer than expected but left Philae wedged in rough terrain at a thirty-degree angle.

  • Despite the chaotic landing, instruments returned data revealing unexpected properties of comet 67P/Churyumov, Gerasimenko. The SESAME instrument found water ice beneath granular material about five centimeters thick with high mechanical strength. MUPUS could not hammer far into the surface despite increased power, indicating consistency similar to solid ice or pumice. COSAC detected sixteen organic compounds including acetamide, acetone, methyl isocyanate, and propionaldehyde. Four of these molecules appeared for the first time on any comet. The SD2 drill system attempted to collect samples but failed to deliver material to the ovens due to hard ice blocking entry. Later reports confirmed low-strength primitive ice inside cometary boulders formed roughly 4.5 billion years ago.

  • Mission controllers received an eighty-five-second transmission from Philae on the 13th of June 2015 at 20:28 UTC after months of silence. Solar panels had recharged batteries enough to wake the lander from safe mode during brief periods of sunlight exposure. Seven intermittent contacts occurred between mid-June and early July 2015 as the comet approached its closest point to the Sun. Each connection lasted only two minutes while orientation issues limited data transmission capabilities. The final communication arrived on the 9th of July 2015 when the lander sent measurement data from the CONSERT radar instrument. Controllers acknowledged no further communications were likely by January 2016. ESA officially switched off the Electrical Support System Processor Unit on the 27th of July 2016 at 09:00 UTC ending all contact possibilities.

  • Search teams identified Philae's resting place using images taken by Rosetta on the 2nd of September 2016. The orbiter descended closer to the comet surface to capture high-resolution photographs revealing the probe wedged in a dark crevice. Telemetry data combined with visual comparisons narrowed the search area to within tens of meters before confirmation. The lander sat on its side beneath the shadow of a cliff or crater wall explaining the lack of power generation. Knowing the exact location helped scientists interpret the two days of science data collected earlier. The discovery provided context for understanding why instruments failed to operate fully after the initial touchdown sequence ended.

  • The project relied on contributions from numerous European nations including Germany, France, Italy, and Poland. German Aerospace Center managed overall operations while developing thermal subsystems and landing gear systems. French Space Agency provided battery assembly and CIVA camera systems alongside ground segment engineering. Italian Space Agency developed the SD2 sampling drill system and photovoltaic assembly components. Polish Academy of Sciences built MUPUS sensors measuring density and mechanical properties. Austrian researchers created anchor mechanisms integrated into sensor tips. British institutions designed Ptolemy isotope analyzers and momentum wheels stabilizing descent phases. Swiss companies manufactured active descent systems guiding the probe toward its target zone. Each nation contributed specialized expertise ensuring the complex mission succeeded despite technical challenges.

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Common questions

When did the European Space Agency launch the Philae lander from French Guiana?

The European Space Agency launched the Philae lander on the 2nd of March 2004 at 07:17 UTC. This Ariane 5G+ rocket carried both the Rosetta orbiter and the Philae probe into space for a journey lasting 3,907 days.

What happened when the Philae lander touched down on comet 67P/Churyumov Gerasimenko on the 12th of November 2014?

Philae touched down on the 12th of November 2014 at 15:34:04 UTC SCET after a twenty-eight-minute signal delay reached Earth. The anchoring harpoons failed to deploy because the nitrocellulose charge inside them proved unreliable in vacuum conditions and the lander rebounded off the ground before falling back.

Which organic compounds did the COSAC instrument detect on the surface of comet 67P/Churyumov Gerasimenko during the Philae mission?

COSAC detected sixteen organic compounds including acetamide acetone methyl isocyanate and propionaldehyde. Four of these molecules appeared for the first time on any comet according to final analysis results from the Philae lander instruments.

When did mission controllers receive the last transmission from the Philae lander before switching it off permanently?

Mission controllers received an eighty-five-second transmission from Philae on the 13th of June 2015 at 20:28 UTC after months of silence. ESA officially switched off the Electrical Support System Processor Unit on the 27th of July 2016 at 09:00 UTC ending all contact possibilities.

How did search teams identify the resting place of the Philae lander using images taken by Rosetta on the 2nd of September 2016?

Search teams identified Philae's resting place using images taken by Rosetta on the 2nd of September 2016 which revealed the probe wedged in a dark crevice beneath the shadow of a cliff or crater wall. Telemetry data combined with visual comparisons narrowed the search area to within tens of meters before confirmation.

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All sources

139 references cited across the entry

  1. 1webPhilaeNational Space Science Data Center
  2. 2webPhilae lander fact sheetsGerman Aerospace Center
  3. 3press releaseThree Touchdowns For Rosetta's LanderEuropean Space Agency — 14 November 2014
  4. 4press releasePhilae found!European Space Agency — 5 September 2016
  5. 5webLander InstrumentsEuropean Space Agency
  6. 6encyclopediaphilaeRandom House
  7. 7newsSpace probe scores a 310-million-mile bull's-eye with comet landingDave Gilbert — 12 November 2014
  8. 8newsRosetta Spacecraft Set for Unprecedented Close Study of a CometKenneth Chang — 5 August 2014
  9. 9newsOpinion: In Pursuit of an Oddly Shaped Comet23 November 2014
  10. 10journalRosetta Lander—Philae: Implications of an alternative missionS. Ulamec et al. — April 2006
  11. 11journalThe Experiments Onboard the ROSETTA LanderJens Biele — June 2002
  12. 12press releaseRosetta: To Chase a CometD. C. Agle et al. — NASA — 17 January 2014
  13. 13press releaseRosetta's 'Philae' Makes Historic First Landing on a CometD. C. Agle et al. — NASA — 12 November 2014
  14. 14newsEuropean Space Agency's Spacecraft Lands on Comet's SurfaceKenneth Chang — 12 November 2014
  15. 15newsPhilae lander 'bounced twice' on comet but is now stable, Rosetta mission scientists confirmAdam Withnall — 13 November 2014
  16. 16newsRosetta: Battery will limit life of Philae comet landerJonathan Amos — 13 November 2014
  17. 17newsEurope's comet chaserEuropean Space Agency — 16 January 2014
  18. 18press releasePioneering Philae completes main mission before hibernationEuropean Space Agency — 15 November 2014
  19. 19journalThe Philae lander reveals low-strength primitive ice inside cometary bouldersLaurence O'Rourke et al. — 28 October 2020
  20. 20newsOn a comet 10 years away, Philae conks out, maybe for goodBen Brumfield et al. — 18 November 2014
  21. 21journalPhilae comet lander wakes up and phones homeCeleste Biever et al. — 14 June 2015
  22. 22newsComet lander Philae awakes from hibernation14 June 2015
  23. 23webRosetta and Philae status updateEmily Baldwin — European Space Agency — 20 July 2015
  24. 24newsNo Longer Missing: Rosetta's Philae Spacecraft Located on CometDaniel Victor — 5 September 2016
  25. 25newsGoodbye, Rosetta! Spacecraft Crash-Lands on Comet in Epic Mission FinaleMegan Gannon — 30 September 2016
  26. 26webRosetta Lander Control CenterGerman Aerospace Center
  27. 27newsThe tech behind the Rosetta comet chaser: From 3D printing to solar power to complex mappingLyndsey Gilpin — 14 August 2014
  28. 28journalThe Rosetta Lander ("Philae") InvestigationsJ.-P. Bibring et al. — February 2007
  29. 29press release'J' Marks the Spot for Rosetta's LanderMarkus Bauer — European Space Agency — 15 September 2014
  30. 30newsHistoric Comet Landing Site Has a New Name: AgilkiaMiriam Kramer — 5 November 2014
  31. 31webRosetta and Philae Go for separationEmily Baldwin — European Space Agency — 12 November 2014
  32. 32press releaseRosetta to Deploy Lander on 12 NovemberEuropean Space Agency — 26 September 2014
  33. 33press releaseRosetta Races Toward Comet TouchdownJane Platt — NASA — 6 November 2014
  34. 34newsProbe makes historic comet landing12 November 2014
  35. 35webPhilae Has Landed! UpdatedEmily Lakdawalla — The Planetary Society — 12 November 2014
  36. 36press releaseRosetta's Comet Lander Landed Three TimesD. C. Agle et al. — NASA — 13 November 2014
  37. 37webDid Philae graze a crater rim during its first bounce?Emily Baldwin — European Space Agency — 28 November 2014
  38. 38newsEuropean Probe Survived Comet Landing with Luck and Great DesignMike Wall — 14 November 2014
  39. 39newsPhilae's Wild Comet Landing: Crater Grazing, Spinning And Landing In Parts UnknownElizabeth Howell — 2 December 2014
  40. 40magazinePhilae Wins Race to Return Comet FindingsJ. Kelly Beatty — 15 November 2014
  41. 41webHoming in on Philae's final landing siteEmily Baldwin — European Space Agency — 21 November 2014
  42. 42newsRosetta space mission: Philae probe lands on Comet 67PSteve Connor — 12 November 2014
  43. 43newsPhilae touches down on the surface of a cometDave Gilbert — 12 November 2014
  44. 44magazineProblems hit Philae after historic first comet landingJacob Aron — 13 November 2014
  45. 45newsESA skrev til danske raketbyggere om eksplosiv-problem på PhilaeThomas Djursing — 13 November 2014
  46. 46webPhilae status, a day laterEmily Lakdawalla — The Planetary Society — 13 November 2014
  47. 47newsKometsonden Philae står skævt under en klippe og får for lidt sollysThomas Djursing — 13 November 2014
  48. 48webPhilae update: My last day in Darmstadt, possibly Philae's last day of operationsEmily Lakdawalla — The Planetary Society — 14 November 2014
  49. 49newsPhilae comet lander sends more data before losing powerJonathan Amos — 15 November 2014
  50. 50webNow Philae down to sleepEmily Lakdawalla — The Planetary Society — 15 November 2014
  51. 51newsLoss of contact with PhilaeWilliam Harwood — 15 November 2014
  52. 52webOur Lander's AsleepDaniel Scuka — European Space Agency — 15 November 2014
  53. 53newsSurprising Comet Discoveries by Rosetta's Philae Lander UnveiledMike Wall — 30 July 2015
  54. 54webChuryumov-Gerasimenko – hard ice and organic moleculesGerman Aerospace Center — 17 November 2014
  55. 55newsPhilae reveals presence of large amount of water ice on the cometKounteya Sinha — 18 November 2014
  56. 56magazineComet Lander Makes a Hard DiscoveryJoAnna Wendel — American Geophysical Union — 31 July 2015
  57. 57newsRosetta mission lander detects organic molecules on surface of cometRichard Gray — 19 November 2014
  58. 58tweetCOSAC PI: Drill tried to deliver sample. Ovens heated up. But data show no actual delivery. "There's nothing in it." #CometLandingEric Hand — 17 November 2014
  59. 59newsPhilae probe finds evidence that comets can be cosmic labsFrank Jordans — 30 July 2015
  60. 60press releaseScience on the Surface of a CometEuropean Space Agency — 30 July 2015
  61. 61journalPhilae's First Days on the CometJ.-P. Bibring et al. — 31 July 2015
  62. 62webRosetta's lander Philae wakes up from hibernationEmily Baldwin — European Space Agency — 14 June 2015
  63. 63webRosetta and Philae in contact againClaudia Mignone — European Space Agency — 19 June 2015
  64. 64newsRosetta and Philae: Searching for a good signalEmily Baldwin — European Space Agency — 26 June 2015
  65. 65press releasePhilae wake-up triggers intense planningEuropean Space Agency — 15 June 2015
  66. 66newsComet lander Philae renews contactJonathan Amos — 19 June 2015
  67. 67press releaseNew communication with Philae – commands executed successfullyGerman Aerospace Center — 10 July 2015
  68. 68newsEurope's comet lander makes 2nd contact after waking upGeir Moulson — 15 June 2015
  69. 69newsControllers wait on Philae linkJonathan Amos — 17 June 2015
  70. 70newsRosetta team struggles with Philae link29 June 2015
  71. 71newsComet's fizzing all over during closest approach to the SunPaul Sutherland — 14 August 2015
  72. 72newsRosetta sends software patch to fix PhilaePaul Sutherland — 20 July 2015
  73. 73magazinePhilae lander fails to respond to last-ditch efforts to wake itJacob Aron — 11 January 2016
  74. 74webFarewell, silent PhilaeClaudia Mignone — European Space Agency — 26 July 2016
  75. 75newsPhilae comet lander goes quiet for goodElizabeth Gibney — 26 July 2016
  76. 76webThe quest to find PhilaeEmily Baldwin — European Space Agency — 11 June 2015
  77. 77newsRosetta: Date fixed for historic comet landing attemptJonathan Amos — 26 September 2014
  78. 78newsRosetta mission: Potential comet landing sites chosenJonathan Amos — 25 August 2014
  79. 79press releaseExpedition to primeval matterThorsten Dambeck — Max Planck Society — 20 January 2014
  80. 80webAbout the Upcoming Philae Separation, Descent and LandingHermann Böhnhardt — Max Planck Institute for Solar System Research — 10 November 2014
  81. 81bookDeep Impact as a World Observatory Event: Synergies in Space, Time, and WavelengthJ. Biele et al. — Springer — 2009
  82. 82conferencePreparing for Landing on a Comet – The Rosetta Lander PhilaeJens Biele et al. — Lunar and Planetary Institute — March 2013
  83. 83newsWill Philae successfully land on comet? Thruster trouble heightens dramaPete Spotts — 12 November 2014
  84. 84webWhy was 67P/Churyumov-Gerasimenko selected as the target comet instead of Wirtanen?European Space Agency
  85. 85webHighlights from the Rosetta mission thus farEuropean Space Agency — 14 November 2014
  86. 86webAPXSEuropean Space Agency
  87. 87journalCIVAJean-Pierre Bibring et al. — 2007
  88. 88journalCapabilities of Philae, the Rosetta LanderJ. Biele et al. — July 2008
  89. 89webComet nucleus Infrared and Visible Analyser (CIVA)National Space Science Data Center
  90. 90webÇIVAEuropean Space Agency
  91. 91journalThe Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT): A Short Description of the Instrument and of the Commissioning StagesW. Kofman et al. — February 2007
  92. 92webCONSERTEuropean Space Agency
  93. 93journalCOSAC Onboard Rosetta: A Bioastronomy Experiment for the Short-Period Comet 67P/Churyumov-GerasimenkoFred Goesmann et al. — October 2005
  94. 94webCOSACEuropean Space Agency
  95. 95webMUPUSEuropean Space Agency
  96. 96journalPtolemy: An Instrument to Measure Stable Isotopic Ratios of Key Volatiles on a Cometary NucleusI. P. Wright et al. — February 2007
  97. 97conferencePtolemy: An Instrument aboard the Rosetta Lander Philae, to Unlock the Secrets of the Solar SystemD. J. Andrews et al. — Lunar and Planetary Institute — March 2006
  98. 98webEurofusion Ptolemy acknowledgementEUROfusion
  99. 99webROLISEuropean Space Agency
  100. 100webRosetta Lander Imaging System (ROLIS)National Space Science Data Center
  101. 101webROMAPEuropean Space Agency
  102. 102webIntroducing SD2: Philae's Sampling, Drilling and Distribution instrumentPierluigi Di Lizia — European Space Agency — 9 April 2014
  103. 103webPhilae SD2Politecnico di Milano
  104. 104conferenceComet sample acquisition for ROSETTA lander missionM. Marchesi et al. — European Space Agency — September 2001
  105. 105webDrill BoxPolitecnico di Milano
  106. 106webOvensPolitecnico di Milano
  107. 107webCarouselPolitecnico di Milano
  108. 108webVolume CheckerPolitecnico di Milano
  109. 109newsRosetta, anche l'Italia sbarca sulla cometa12 November 2014
  110. 110journalSesame – An Experiment of the Rosetta Lander Philae: Objectives and General DesignK. J. Seidensticker et al. — February 2007
  111. 111webRosettaInstitut für Weltraumforschung — 8 June 2014
  112. 112newsBelgië mee aan boord van Rosetta kometenjagerKris Christiaens — 6 November 2014
  113. 113newsRosettaKris Christiaens — 19 July 2009
  114. 114webSpace weather report for RosettaDaniel Scuka — European Space Agency — 12 November 2014
  115. 115newsTwo Canadian Firms Play Small but Key Roles in Comet LandingMaclean's — 13 November 2014
  116. 116press releaseRosetta "The Comet Chaser" – The Canadian ConnectionADGA Group — 13 November 2014
  117. 117press releaseLander successfully touches down on the comet surfaceFinnish Meteorological Institute — 12 November 2014
  118. 118webActive Descent SystemMoog Inc.
  119. 119webMPS-BeteiligungenMax Planck Institute for Solar System Research
  120. 120web12 November, 2014 A Space Probe landed on the Surface of a Comet for the first time in Space ResearchWigner Research Centre for Physics — 14 November 2014
  121. 121webCDMSSGF Ltd.
  122. 122webReferencesSpace Research Group — 2013
  123. 123webIndustrial Involvement in the Rosetta MissionEuropean Space Agency — 24 June 2014
  124. 124webComet chaser 'Rosetta' has technology from 2 Irish companies on boardEnterprise Ireland — 17 January 2014
  125. 125webCAPTEC's Fred Kennedy explains its role in the Rosetta ProjectRTE News — 20 January 2014
  126. 126press releaseMaynooth University scientists play key role in historic Rosetta missionMaynooth University — 12 November 2014
  127. 127press releaseRosetta Mission: Italy's decisive technological contributionItalian Ministry of Foreign Affairs and International Cooperation — 13 November 2014
  128. 128webThe MUPUS Instrument for Rosetta mission to comet Churyumov-GerasimenkoLaboratorium Mechatroniki i Robotyki Satelitarnej — 2014
  129. 129webPresentación de PowerPoint – Space ActivitiesAASpace
  130. 130newsTecnología española para aterrizar sobre un cometa13 November 2014
  131. 131webCIVA Project2014
  132. 132newsUK space industry behind Rosetta comet missionAlan Tovey — 11 November 2014
  133. 133press releaseLive updates: Rosetta mission comet landingEuropean Space Agency — 12 November 2014
  134. 134press releaseCall for Media Opportunities to follow Rosetta mission's historic comet landingEuropean Space Agency — 16 October 2014
  135. 135newsRosetta comet: One giant leap for Europe (not Nasa)Patrick Jackson — 13 November 2014
  136. 136newsPhilae: Google Doodle marks Rosetta's historic comet landingOlivia Solon — 12 November 2014
  137. 137newsGoogle doodle wraps up year in animated '2014 trending topics'Trisha Mukherjee — 31 December 2014
  138. 138webLandingMunroe Randall — 12 November 2014
  139. 139newsxkcd Animates The Philae Comet Landing—And It's AdorableLauren Davis — 12 November 2014