67P/Churyumov–Gerasimenko
67P/Churyumov–Gerasimenko (abbreviated as 67P or 67P/C–G) is a Jupiter-family comet,[10] originally from the Kuiper belt,[11] with a current orbital period of 6.45 years,[1] a rotation period of approximately 12.4 hours[9] and a maximum velocity of 135,000 km/h (38 km/s; 84,000 mph).[12] Churyumov–Gerasimenko is approximately 4.3 by 4.1 km (2.7 by 2.5 mi) at its longest and widest dimensions.[13] It was first observed on photographic plates in 1969 by Soviet astronomers Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko, after whom it is named.[a] It most recently came to perihelion (closest approach to the Sun) on 2 November 2021,[4][2][14] and will next come to perihelion on 9 April 2028.[3]
Comet 67P/Churyumov–Gerasimenko in true colour, as seen by ESA's Rosetta Spacecraft on December 2014. | |
| Discovery | |
|---|---|
| Discovered by | Klim Ivanovich Churyumov Svetlana Ivanovna Gerasimenko |
| Discovery site | Almaty, Kazakh SSR, Soviet Union Kyiv, Ukrainian SSR, Soviet Union |
| Discovery date | 20 September 1969 |
| Designations | |
| 1969 R1, 1969 IV, 1969h, 1975 P1, 1976 VII, 1975i, 1982 VIII, 1982f, 1989 VI, 1988i[1] | |
| Orbital characteristics[2] | |
| Epoch 25 February 2023 (JD 2460000.5) | |
| Aphelion | 5.704 AU (853,300,000 km; 530,200,000 mi) |
| Perihelion | 1.210 AU (181,000,000 km; 112,500,000 mi) |
| 3.457 AU (517,200,000 km; 321,300,000 mi) | |
| Eccentricity | 0.64989 |
| 6.43 yr | |
| 73.57° | |
| Inclination | 3.8719° |
| 36.33° | |
| 9 April 2028[3] 2 November 2021 (previous)[4][2] | |
| 22.15° | |
| Physical characteristics | |
| Dimensions | |
| Volume | 18.7 km3 (4.5 cu mi)[6] |
| Mass | (9.982±0.003)×1012 kg[6] |
Mean density | 0.533 ± 0.006 g/cm3 [6][7] (0.01926 ± 0.00022 lb/cu in) |
| est. 1 m/s[8] | |
| 12.4043±0.0007 h[9] | |
| 52°[5] | |
North pole right ascension | 69.3°[5] |
North pole declination | 64.1°[5] |
| Albedo | 0.06[5] |
Churyumov–Gerasimenko was the destination of the European Space Agency's Rosetta mission, launched on 2 March 2004.[15][16][17] Rosetta rendezvoused with Churyumov–Gerasimenko on 6 August 2014[18][19] and entered orbit on 10 September 2014.[20] Rosetta's lander, Philae, landed on the comet's surface on 12 November 2014, becoming the first spacecraft to land on a comet nucleus.[21][22][23] On 30 September 2016, the Rosetta spacecraft ended its mission by landing on the comet in its Ma'at region.[24][25]
Discovery Edit
Churyumov–Gerasimenko was discovered in 1969 by Klim Ivanovich Churyumov of the Kyiv University's Astronomical Observatory,[26] who examined a photograph that had been exposed for comet Comas Solà by Svetlana Ivanovna Gerasimenko on 11 September 1969 at the Alma-Ata Astrophysical Institute, near Alma-Ata (now Almaty), the then-capital city of Kazakh Soviet Socialist Republic, Soviet Union. Churyumov found a cometary object near the edge of the plate, but assumed that this was comet Comas Solà.[27]
After returning to his home institute in Kyiv, Churyumov examined all the photographic plates more closely. On 22 October, about a month after the photograph was taken, he discovered that the object could not be Comas Solà, because it was about 1.8 degrees off the expected position. Further scrutiny produced a faint image of Comas Solà at its expected position on the plate, thus proving the other object to be a different body.[27]
Shape Edit
The comet consists of two lobes connected by a narrower neck, with the larger lobe measuring about 4.1 km × 3.3 km × 1.8 km (2.5 mi × 2.1 mi × 1.1 mi) and the smaller one about 2.6 km × 2.3 km × 1.8 km (1.6 mi × 1.4 mi × 1.1 mi).[5] With each orbit the comet loses matter, as gas and dust are evaporated away by the Sun. It is estimated that currently a layer with an average thickness of about 1 ± 0.5 m (3.3 ± 1.6 ft) is lost per orbit.[28] The comet has a mass of approximately 10 billion tonnes.[6]
The two-lobe shape of the comet is the result of a gentle, low-velocity collision of two objects, and is called a contact binary. The "terraces", layers of the interior of the comet that have been exposed by partial stripping of outer layers during its existence, are oriented in different directions in the two lobes, indicating that two objects fused to form Churyumov–Gerasimenko.[29][30]
Surface Edit
There are 26 distinct regions on Churyumov–Gerasimenko, with each named after an Egyptian deity; regions on the large lobe are named after gods, whereas those on the small lobe are named after goddesses. 19 regions were defined in the northern hemisphere prior to equinox.[31][32] Later, when the southern hemisphere became illuminated, seven more regions were identified using the same naming convention.[33][34]
| Region | Terrain | Region | Terrain | Region | Terrain |
|---|---|---|---|---|---|
| Ma'at | Dust covered | Ash | Dust covered | Babi | Dust covered |
| Seth | Pitted and brittle material | Hatmehit | Large-scale depression | Nut | Large-scale depression |
| Aten | Large-scale depression | Hapi | Smooth | Imhotep | Smooth |
| Anubis | Smooth | Maftet | Rock-like | Bastet | Rock-like |
| Serqet | Rock-like | Hathor | Rock-like | Anuket | Rock-like |
| Khepry | Rock-like | Aker | Rock-like | Atum | Rock-like |
| Apis | Rock-like | Khonsu | Rock-like | Bes | Rock-like |
| Anhur | Rock-like, rather friable | Geb | Rock-like | Sobek | Rock-like |
| Neith | Rock-like | Wosret | Rock-like |
Gates Edit
Features described as gates, twin prominences on the surface so named for their appearance,[clarification needed] were named after deceased members of the Rosetta team.[35]
| Name | Named after |
|---|---|
| C. Alexander Gate | Claudia Alexander |
| A. Coradini Gate | Angioletta Coradini |
Surface changes Edit
During Rosetta's lifetime, many changes were observed on the comet's surface, particularly when the comet was close to perihelion.[36][37][38] These changes included evolving patterns of circular shapes in smooth terrains that at some point grew in size by a few metres per day.[39][40] A fracture in the neck region was also observed to grow in size; boulders tens of metres wide were displaced, sometimes travelling more than 100 metres; and patches of the ground were removed to expose new features. A number of collapsing cliffs have also been observed. One notable example in December 2015 was captured by Rosetta's NAVCAM as a bright patch of light shining from the comet. Rosetta scientists determined that a large cliff had collapsed, making it the first landslide on a comet known to be associated with an outburst of activity.[41][42] An apparent outburst of the comet was observed on 14 November 2021.[43] According to the researchers, "At the time of the outburst discovery with ZTF, the comet was 1.23 au from the Sun and 0.42 au from the Earth. The comet's last perihelion passage was on 2021 Nov 2.".[43]
Cheops boulder Edit
Cheops is the largest boulder on the surface of the comet, measuring up to 45 meters. It is located in the comet's larger lobe. It was named for the pyramid in Giza because its shape is similar to that of a pyramid.[44][45][46]
Orbit and rotation Edit
| Perihelion distance at different epochs[14] | |||||||
| Epoch | Perihelion (AU) | ||||||
|---|---|---|---|---|---|---|---|
| 1821 | 2.44 | ||||||
| 1882 | 2.94 | ||||||
| 1956 | 2.74 | ||||||
| 1963 | 1.28 | ||||||
| 2021 | 1.21 | ||||||
| 2101 | 1.35 | ||||||
| 2223 | ≈0.8[47] | ||||||
Like the other comets of the Jupiter family, Churyumov–Gerasimenko probably originated in the Kuiper belt and was ejected towards the interior of the Solar System, where later encounters with Jupiter successively changed its orbit. These interactions will continue until the comet is eventually thrown out of the Solar System or collides with the Sun or a planet.
On 4 February 1959, a close encounter with Jupiter of 0.0515 AU (7.70 million km)[1] moved Churyumov–Gerasimenko's perihelion inward from 2.7 AU (400 million km) to 1.28 AU (191 million km), where it basically remains today.[14] In November 2220 the comet will pass about 0.14 AU (21 million km) from Jupiter[48] which will move perihelion inwards to about 0.8 AU (120 million km) from the Sun.[47]
Before Churyumov–Gerasimenko's perihelion passage in 2009, its rotational period was 12.76 hours. During this perihelion passage, it decreased to 12.4 hours, which likely happened because of sublimation-induced torque.[9]
2015 perihelion Edit
As of September 2014[update], Churyumov–Gerasimenko's nucleus had an apparent magnitude of roughly 20.[2] It came to perihelion on 13 August 2015.[49][4] From December 2014 until September 2015, it had an elongation less than 45 degrees from the Sun.[50] On 10 February 2015, it went through solar conjunction when it was 5 degrees from the Sun and was 3.3 AU (490 million km) from Earth.[50] It crossed the celestial equator on 5 May 2015 and became easiest to see from the Northern Hemisphere.[50] Even right after perihelion when it was in the constellation of Gemini, it only brightened to about apparent magnitude 12, and required a telescope to be seen.[4] As of July 2016[update], the comet had a total magnitude of about 20.[2]
2021 perihelion Edit
The 2021 apparition marked the closest approach to Earth since 1982.[1] The comet reached perihelion on 2 November 2021[4] and the closest approach to Earth was on November 12, 2021, at 00:50 UTC, at a distance of 38 million miles (61 million km).[51] The comet brightened to an apparent magnitude of 9, meaning it was visible with amateur telescopes.[51][52] Two outbursts were observed during the apparition, on 2021 October 29.940 and November 17.864 UTC, −3.12 days and +15.81 days respectively from the perihelion date. During the first outburst the comet brightened by 0.26 ± 0.03 mag in the outburst, with a 27% increase in the effective geometric cross-section and total outburst dust mass of 5.3×105 kg. The second outburst caused a brightening of 0.49 ± 0.08 mag with effective geometric cross-section and total outburst dust mass 2.5 times larger than the first event.[53]
Exploration Edit
Rosetta mission Edit
The Rosetta mission was the first mission to include an orbiter that accompanied a comet for several years, as well as a lander that collected close-up data from the comet's surface. The mission launched in 2004, arrived at comet 67P in 2014, and concluded with a touchdown on the comet's surface in 2016.
Advance work Edit
As preparation for the Rosetta mission, Hubble Space Telescope pictures taken on 12 March 2003 were closely analysed. An overall 3D model was constructed and computer-generated images were created.[54]
On 25 April 2012, the most detailed observations until that time were taken with the 2-metre Faulkes Telescope by N. Howes, G. Sostero and E. Guido while it was at its aphelion.[citation needed]
On 6 June 2014, water vapor was detected being released at a rate of roughly 1 litre per second (0.26 US gallons per second) when Rosetta was 360,000 km (220,000 mi) from Churyumov–Gerasimenko and 3.9 AU (580 million km) from the Sun.[55][56] On 14 July 2014, images taken by Rosetta showed that its nucleus is irregular in shape with two distinct lobes.[57] The size of the nucleus was estimated to be 3.5×4 km (2.2×2.5 mi).[58] Two explanations for its shape were proposed at the time: that it was a contact binary, or that its shape may have resulted from asymmetric erosion due to ice sublimating from its surface to leave behind its lobed shape.[19][17] By September 2015, mission scientists had determined that the contact binary hypothesis was unambiguously correct.[59][30]
Rendezvous and orbit Edit
Rosetta · 67P · Earth · Mars · 21 Lutetia · 2867 Šteins
Rosetta · 67P
Beginning in May 2014, Rosetta's velocity was reduced by 780 m/s (2,800 km/h; 1,700 mph) with a series of thruster firings.[17][60] Ground controllers rendezvoused Rosetta with Churyumov–Gerasimenko on 6 August 2014.[18][19] This was done by reducing Rosetta's relative velocity to 1 m/s (4 km/h; 2 mph). Rosetta entered orbit on 10 September, at about 30 km (19 mi) from the nucleus.[18][19][61]
Landing Edit
Descent of a small lander occurred on 12 November 2014. Philae is a 100 kg (220 lb) robotic probe that set down on the surface with landing gear.[17][62] The landing site has been christened Agilkia in honor of Agilkia Island, where the temples of Philae Island were relocated after the construction of the Aswan Dam flooded the island.[63] The acceleration due to gravity on the surface of Churyumov–Gerasimenko has been estimated for simulation purposes at 10−3 m/s2,[64] or about 1/10000 of that on Earth.
Because of its low relative mass, landing on the comet involved certain technical considerations to keep Philae anchored. The probe contains an array of mechanisms designed to manage Churyumov–Gerasimenko's low gravity, including a cold gas thruster, harpoons, landing-leg-mounted ice screws, and a flywheel to keep it oriented during its descent.[65][66][67] During the event, the thruster and the harpoons failed to operate, and the ice screws did not gain a grip. The lander bounced twice and only came to rest when it made contact with the surface for the third time,[68] two hours after first contact.[69]
Contact with Philae was lost on 15 November 2014 because of dropping battery power. The European Space Operations Centre briefly reestablished communications on 14 June 2015 and reported a healthy spacecraft but communications were lost again soon after.[70] On 2 September 2016, Philae was located in photographs taken by the Rosetta orbiter. It had come to rest in a crack with only its body and two legs visible. While the discovery solves the question of the lander's disposition, it also allows project scientists to properly contextualise the data it returned from the comet's surface.[71]
Physical properties Edit
The composition of water vapor from Churyumov–Gerasimenko, as determined by the Rosetta spacecraft, is substantially different from that found on Earth. 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 unlikely that water found on Earth came from comets such as Churyumov–Gerasimenko.[11][72][73] The water vapor is also mixed with significant amount of formaldehyde (0.5 wt%) and methanol (0.4 wt%), these concentrations falling within common range for Solar system comets.[74] On 22 January 2015, NASA reported that, between June and August 2014, the comet released increasing amounts of water vapor, up to tenfold as much.[75] On 23 January 2015, the journal Science published a special issue of scientific studies related to the comet.[76]
Measurements carried out before Philae's batteries failed indicate that the dust layer could be as much as 20 cm (8 in) thick. Beneath that is hard ice, or a mixture of ice and dust. Porosity appears to increase toward the center of the comet.[77]
The nucleus of Churyumov–Gerasimenko was found to have no magnetic field of its own after measurements were taken during Philae's descent and landing by its ROMAP instrument and Rosetta's RPC-MAG instrument. This suggests that magnetism may not have played a role in the early formation of the Solar System, as had previously been hypothesized.[78][79]
The ALICE spectrograph on Rosetta determined that electrons (within 1 km or 0.6 mi above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[80][81] Also, active pits, related to sinkhole collapses and possibly associated with outbursts are present on the comet.[82][83]
Measurements by the COSAC and Ptolemy instruments on the Philae's lander revealed sixteen organic compounds, four of which were seen for the first time on a comet, including acetamide, acetone, methyl isocyanate and propionaldehyde.[84][85][86] Astrobiologists Chandra Wickramasinghe and Max Wallis stated that some of the physical features detected on the comet's surface by Rosetta and Philae, such as its organic-rich crust, could be explained by the presence of extraterrestrial microorganisms.[87][88] Rosetta program scientists dismissed the claim as "pure speculation".[89] Carbon-rich compounds are common in the Solar System. Neither Rosetta nor Philae is equipped to search for direct evidence of organisms.[87] The only amino acid detected thus far on the comet is glycine, along with precursor molecules methylamine and ethylamine.[90]
Solid organic compounds were also found in the dust particles emitted by the comet; the carbon in this organic material is bound in "very large macromolecular compounds", analogous to the insoluble organic matter in carbonaceous chondrite meteorites. Scientists think that the observed cometary carbonaceous solid matter could have the same origin as the meteoritic insoluble organic matter, but suffered less modification before or after being incorporated into the comet.[91]
One of the most outstanding discoveries of the mission so far is the detection of large amounts of free molecular oxygen (O2) gas surrounding the comet. Current solar system models suggest the molecular oxygen should have disappeared by the time 67P was created, about 4.6 billion years ago in a violent and hot process that would have caused the oxygen to react with hydrogen and form water.[92][93] Molecular oxygen has never before been detected in cometary comas. In situ measurements indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance, suggesting that primordial O2 was incorporated into the nucleus during the comet's formation.[92] This interpretation was challenged by the discovery that O2 may be produced on the surface of the comet in water molecule collisions with silicates and other oxygen-containing materials.[94] Detection of molecular nitrogen (N2) in the comet suggests that its cometary grains formed in low-temperature conditions below 30 K (−243 °C; −406 °F).[95]
On 3 July 2018, researchers hypothesized that molecular oxygen may not be made on the surface of comet 67P in sufficient quantity, thus deepening the mystery of its origin.[96][97]
Future missions Edit
CAESAR was a proposed sample-return mission aimed at returning to 67P/Churyumov–Gerasimenko, capturing regolith from the surface, and returning it to Earth.[98][99] This mission was competing in NASA's New Frontiers mission 4 selection process, and was one of two finalists in the program.[100] In June 2019, it was passed over in favor of Dragonfly.[101][102]
Gallery Edit
-
A reconstruction of the nucleus's shape based on Hubble observations in 2003
-
As seen by the Very Large Telescope on 11 August 2014[103]
-
As seen by Rosetta on 22 August 2014
-
As seen by Rosetta on 14 September 2014
-
As seen by Rosetta on 28 March 2015
-
As seen by Rosetta on 2 May 2015
-
As seen by Rosetta on 7 July 2015
-
Image showing ragged cliffs, 10 December 2014
-
Phosphorus-bearing molecules found in a star-forming region and comet 67P.[104]
-
Comet 67P/Churyumov–Gerasimenko in enhanced colour, as imaged by ESA's Rosetta spacecraft in 2015.
See also Edit
Notes Edit
- ^ Both names are stressed on their penultimate syllable. In Ukrainian, the pronunciations are approximately churyúmow herasiménko, with the v pronounced like an English w and the g like an h.
References Edit
- ^ a b c d "JPL Small-Body Database Browser: 67P/Churyumov-Gerasimenko". NASA/Jet Propulsion Laboratory. Archived from the original on 13 December 2012. Retrieved 17 July 2023.
- ^ a b c d e "67P/Churyumov-Gerasimenko". Minor Planet Center. Retrieved 26 February 2017.
- ^ a b "Horizons Batch for 67P/Churyumov-Gerasimenko (90000696) on 2028-Apr-09" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. from the original on 28 June 2022. Retrieved 6 July 2023. (JPL#K213/5 Soln.date: 2023-May-04) (Records)
- ^ a b c d e Yoshida, Seiichi (30 December 2010). "67P/Churyumov-Gerasimenko". Aerith.net. Retrieved 9 February 2012.
- ^ a b c d e f g "Comet vital statistics". European Space Agency. 22 January 2015. Retrieved 24 January 2015.
- ^ a b c d Pätzold, M.; Andert, T.; et al. (4 February 2016). "A homogeneous nucleus for comet 67P/Churyumov–Gerasimenko from its gravity field". Nature. 530 (7588): 63–65. Bibcode:2016Natur.530...63P. doi:10.1038/nature16535. PMID 26842054. S2CID 4470894.
- ^ Lakdawalla, Emily (19 November 2015). "DPS 2015: A little science from Rosetta, beyond perihelion". The Planetary Society. Retrieved 8 December 2015.
- ^ Dambeck, Thorsten (21 January 2014). "Expedition to primeval matter". Max-Planck-Gesellschaft. Retrieved 19 September 2014.
- ^ a b c Mottola, S.; et al. (September 2014). "The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta". Astronomy & Astrophysics. 569. L2. Bibcode:2014A&A...569L...2M. doi:10.1051/0004-6361/201424590.
- ^ "List of Jupiter-Family and Halley-Family Comets". University of Central Florida: Physics. 28 July 2015. Retrieved 6 September 2015.
- ^ a b Borenstein, Seth (10 December 2014). "The mystery of where Earth's water came from deepens". Associated Press. Retrieved 15 August 2020.
- ^ "Rosetta's Frequently Asked Questions". European Space Agency. 2014. Retrieved 12 November 2014.
- ^ "Bigger than you think! Comet 67P compared to cities. HD". YouTube. 12 November 2014. Retrieved 17 November 2014.
- ^ a b c Kinoshita, Kazuo (1 December 2018). "67P/Churyumov-Gerasimenko past, present and future orbital elements". Comet Orbit. from the original on 24 July 2011. Retrieved 17 July 2023.
- ^ Krolikowska, Malgorzata (2003). "67P/Churyumov–Gerasimenko – potential target for the Rosetta mission". Acta Astronomica. 53: 195–209. arXiv:astro-ph/0309130. Bibcode:2003AcA....53..195K.
- ^ Agle, D. C.; et al. (17 January 2014). "Rosetta: To Chase a Comet". NASA. Release 2014-015. Retrieved 18 January 2014.
- ^ a b c d Chang, Kenneth (5 August 2014). "Rosetta Spacecraft Set for Unprecedented Close Study of a Comet". The New York Times. Retrieved 5 August 2014.
- ^ a b c Fischer, D. (6 August 2014). "Rendezvous with a crazy world". The Planetary Society. from the original on 6 August 2014. Retrieved 6 August 2014.
- ^ a b c d Bauer, Markus (6 August 2014). "Rosetta Arrives at Comet Destination". European Space Agency. from the original on 6 August 2014. Retrieved 6 August 2014.
- ^ Scuka, Daniel (10 September 2014). "Down, down we go to 29 km – or lower?". European Space Agency. Retrieved 20 September 2014.
- ^ Agle, D. C.; et al. (12 November 2014). "Rosetta's 'Philae' Makes Historic First Landing on a Comet". NASA. Retrieved 13 November 2014.
- ^ Chang, Kenneth (12 November 2014). "European Space Agency's Spacecraft Lands on Comet's Surface". The New York Times. Retrieved 12 November 2014.
- ^ "Probe makes historic comet landing". BBC News. 12 November 2014. Retrieved 12 November 2014.
- ^ Aron, Jacob (30 September 2016). "Rosetta lands on 67P in grand finale to two year comet mission". New Scientist. Retrieved 1 October 2016.
- ^ Gannon, Megan (30 September 2016). "Goodbye, Rosetta! Spacecraft Crash-Lands on Comet in Epic Mission Finale". Space.com. Retrieved 1 October 2016.
- ^ "Klim Ivanovich Churyumov". International Astronomical Union. Retrieved 8 August 2014.
- ^ a b Kronk, Gary W. & Meyer, Maik (2010). "67P/1969 R1 (Churyumov-Gerasimenko)". Cometography: A Catalog of Comets; Volume 5: 1960–1982. Cambridge University Press. pp. 241–245. ISBN 978-0-521-87226-3.
- ^ Bertaux, Jean-Loup (November 2015). "Estimate of the erosion rate from H2O mass-loss measurements from SWAN/SOHO in previous perihelions of comet 67P/Churyumov-Gerasimenko and connection with observed rotation rate variations". Astronomy & Astrophysics. 583. A38. Bibcode:2015A&A...583A..38B. doi:10.1051/0004-6361/201525992.
- ^ Lemonick, Michael D. (28 September 2015). "Why Comet 67P Looks Like a Rubber Ducky". National Geographic. Retrieved 29 September 2015.
- ^ a b Massironi, Matteo; et al. (28 September 2015). "Two independent and primitive envelopes of the bilobate nucleus of comet 67P". Nature. 526 (7573): 402–405. Bibcode:2015Natur.526..402M. doi:10.1038/nature15511. PMID 26416730. S2CID 4463714.
- ^ El-Maarry, M. R.; et al. (November 2015). "Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images" (PDF). Astronomy & Astrophysics. 583. A26. Bibcode:2015A&A...583A..26E. doi:10.1051/0004-6361/201525723.
- ^ Cofield, Calla (19 July 2015). "Gods Among the Stars: Why Egyptian Names Grace Comet 67P". Space.com. Retrieved 12 April 2016.
- ^ El-Maarry, M. R.; et al. (September 2016). "Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images: The southern hemisphere". Astronomy & Astrophysics. 593. A110. Bibcode:2016A&A...593A.110E. doi:10.1051/0004-6361/201628634.
- ^ Baldwin, Emily (24 February 2016). "Getting to know the comet's southern hemisphere". European Space Agency. Retrieved 3 May 2017.
- ^ Taylor, Matt (28 September 2015). "Rosetta Science Working Team dedication to deceased colleagues". European Space Agency. Retrieved 2 October 2015.
- ^ El-Maarry, M. Ramy; et al. (March 2017). "Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past" (PDF). Science. 355 (6332): 1392–1395. Bibcode:2017Sci...355.1392E. doi:10.1126/science.aak9384. PMID 28325842. S2CID 9579837.
- ^ Bauer, Markus; et al. (21 March 2017). "Before and after: Unique changes spotted on Rosetta's comet". European Space Agency. Retrieved 2 May 2017.
- ^ Agle, D. C.; et al. (21 March 2017). "The Many Faces of Rosetta's Comet 67P". NASA. Retrieved 2 May 2017.
- ^ Groussin, O.; et al. (November 2015). "Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko". Astronomy & Astrophysics. 583. A36. arXiv:1509.02794. Bibcode:2015A&A...583A..36G. doi:10.1051/0004-6361/201527020. S2CID 54177318.
- ^ Mignone, Claudia (18 September 2015). "Comet surface changes before Rosetta's eyes". European Space Agency. Retrieved 3 May 2017.
- ^ Pajola, Maurizio; et al. (21 March 2017). "The pristine interior of comet 67P revealed by the combined Aswan outburst and cliff collapse" (PDF). Nature Astronomy. 1 (5). 0092. Bibcode:2017NatAs...1E..92P. doi:10.1038/s41550-017-0092. S2CID 46870552.
- ^ Kaplan, Sarah (21 March 2017). "Scientists captured incredible photographic proof of a landslide on a comet". The Washington Post. Retrieved 21 March 2017.
- ^ a b Kelley, Michael S. P. (19 November 2021). "ATel #15053 – Apparent Outburst of Comet 67P/Churyumov-Gerasimenko". The Astronomer's Telegram. Retrieved 20 November 2021.
- ^ ESA (1 September 2019). "Boulder Cheops".
- ^ ANI. "Largest boulders on Rosetta's comet named after Egyptian pyramid 'Cheops'". Yahoo News. Retrieved 19 October 2020.
- ^ Howell, Elizabeth (13 October 2014). "Rosetta Spacecraft Spots 'Pyramid' Boulder on Comet (Photos)". Space.com. Retrieved 19 October 2020.
- ^ a b "Horizons Batch for 67P/Churyumov-Gerasimenko (90000696) on 2223-Feb-06" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 17 July 2023. (JPL#K213/5 Soln.date: 2023-May-04)
- ^ Tony Dunn. "67P @ Gravity Simulator". Gravity Simulator. Retrieved 21 July 2023.
- ^ . AP News. 13 August 2015. Archived from the original on 8 December 2015. Retrieved 14 August 2015.
- ^ a b c . Minor Planet Center. Archived from the original on 4 November 2014. Retrieved 9 August 2014.
- ^ a b Irizarry, Eddie (26 October 2021). "Heads up! Famous comet 67P/C-G nearly closest". earthsky.org. Retrieved 17 July 2023.
- ^ Olason, Mike (24 November 2021). "COMET 67P/CHURYUMOV-GERASIMENKO ON 2021 NOVEMBER 15". skyandtelescope.org. Retrieved 17 July 2023.
- ^ Sharma, Kritti; Kelley, Michael S. P.; Joharle, Simran; Kumar, Harsh; Swain, Vishwajeet; Bhalerao, Varun; Anupama, G. C.; Barway, Sudhanshu (3 December 2021). "Outbursts of Comet 67P/Churyumov-Gerasimenko". Research Notes of the AAS. 5 (12): 277. Bibcode:2021RNAAS...5..277S. doi:10.3847/2515-5172/ac3ee4. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.
- ^ Buckley, Michael; et al. (5 September 2003). "Hubble Assists Rosetta Comet Mission". HubbleSite.org.
- ^ Baldwin, Emily (23 June 2014). "First Detection of Water from 67P/C-G". European Space Agency. Retrieved 23 June 2014. Sungrazer Comets at Twitter.com.
- ^ Agle, D. C.; et al. (30 June 2014). "Rosetta's Comet Target 'Releases' Plentiful Water". NASA. Retrieved 30 June 2014.
- ^ "The twofold comet: Comet 67P/Churyumov-Gerasimenko". Astronomy.com. 17 July 2014. Retrieved 18 July 2014.
- ^ Temming, Maria (17 July 2014). "Rosetta's Comet has a Split Personality". Sky & Telescope. Retrieved 18 July 2014.
- ^ Bauer, Markus; et al. (28 September 2015). "How Rosetta's comet got its shape". European Space Agency. Retrieved 29 June 2019.
- ^ Gannon, Megan (4 August 2014). "Comet-chasing Euro-probe could make history Wednesday". The Christian Science Monitor. Retrieved 6 August 2014.
- ^ Lakdawalla, Emily (15 August 2014). "Finding my way around comet Churyumov-Gerasimenko". The Planetary Society. from the original on 15 August 2014. Retrieved 15 August 2014.
- ^ Chang, Kenneth (10 November 2014). "Philae Lander Nears a Cosmic Touchdown". The New York Times. Retrieved 11 November 2014.
- ^ Amos, Jonathan (4 November 2014). "Rosetta comet mission: Landing site named 'Agilkia'". BBC News. Retrieved 9 November 2014.
- ^ Hilchenbach, M. (2004). (PDF). SIMPACK User Meeting. 9–10 November 2004. Wartburg/Eisenach, Germany. p. 25. Archived from the original (PDF) on 26 November 2014. Retrieved 6 August 2014.
- ^ Ellis, Ralph (13 November 2014). "Space probe scores a 310-million-mile bull's-eye with comet landing". CNN. Retrieved 13 November 2014.
Comet 67P has a very weak gravity, so anchoring harpoons were designed to shoot into the comet to fix the spacecraft to the surface.
- ^ Parnell, Brid-Aine (12 November 2014). "Bouncy bouncy: Comet probot Philae may have landed twice". The Register. Retrieved 13 November 2014.
Philae's flywheel was part of its landing gear and stopped the craft from rotating while it was operational, but it was switched off once the probot indicated it had touched down.
- ^ O'Neill, Ian (12 November 2014). . Discovery News. Archived from the original on 15 November 2014. Retrieved 13 November 2014.
As there was a real risk of the lander bouncing off the comet, harpoons, landing leg ice screws and thrusters needed to work in concert to ensure Philae stayed in place.
- ^ Agle, D. C.; et al. (13 November 2014). "Rosetta's Comet Lander Landed Three Times". NASA. Retrieved 13 November 2014.
- ^ Beatty, Kelly (12 November 2014). "Philae Lands on Its Comet – Three Times!". Sky & Telescope. Retrieved 26 November 2014.
- ^ Biever, Celeste & Gibney, Elizabeth (14 June 2015). "Philae comet lander wakes up and phones home". Nature. doi:10.1038/nature.2015.17756. Retrieved 14 June 2015.
- ^ Beatty, Kelly (5 September 2016). "Finally, ESA Locates Comet Lander Philae". Sky & Telescope. Retrieved 10 September 2016.
- ^ Agle, D. C. & Bauer, Markus (10 December 2014). "Rosetta Instrument Reignites Debate on Earth's Oceans". NASA. Retrieved 10 December 2014.
- ^ Chang, Kenneth (10 December 2014). "Comet Data Clears Up Debate on Earth's Water". The New York Times. Retrieved 10 December 2014.
- ^ Schuhmann, Markus; Altwegg, Kathrin; Balsiger, Hans; Berthelier, Jean-Jacques; Johan De Keyser; Fuselier, Stephen A.; Gasc, Sébastien; Gombosi, Tamas I.; Hänni, Nora; Rubin, Martin; Sémon, Thierry; Tzou, Chia-Yu; Wampfler, Susanne F. (2020). "CHO-bearing molecules in Comet 67P/Churyumov-Gerasimenko". ACS Earth and Space Chemistry. 3 (9): 1854. arXiv:2003.03967. Bibcode:2019ESC.....3.1854S. doi:10.1021/acsearthspacechem.9b00094. S2CID 201228823.
- ^ Agle, D. C.; et al. (22 January 2015). "Rosetta Comet 'Pouring' More Water Into Space". NASA. Retrieved 22 January 2015.
- ^ "Catching a Comet". Science. Special Issue. 347 (6220). 23 January 2015. Retrieved 23 January 2015.
- ^ Baldwin, Emily (18 November 2014). "Philae settles in dust-covered ice". European Space Agency. Retrieved 18 December 2014.
- ^ Bauer, Markus (14 April 2015). "Rosetta and Philae Find Comet Not Magnetised". European Space Agency. Retrieved 14 April 2015.
- ^ Schiermeier, Quirin (14 April 2015). "Rosetta's comet has no magnetic field". Nature. doi:10.1038/nature.2015.17327. S2CID 123964604.
- ^ Agle, D. C.; et al. (2 June 2015). "NASA Instrument on Rosetta Makes Comet Atmosphere Discovery". NASA. Retrieved 2 June 2015.
- ^ Feldman, Paul D.; et al. (2 June 2015). "Measurements of the near-nucleus coma of comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta" (PDF). Astronomy & Astrophysics. 583: A8. arXiv:1506.01203. Bibcode:2015A&A...583A...8F. doi:10.1051/0004-6361/201525925. S2CID 119104807.
- ^ Vincent, Jean-Baptiste; et al. (2 July 2015). "Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse" (PDF). Nature. 523 (7558): 63–66. Bibcode:2015Natur.523...63V. doi:10.1038/nature14564. PMID 26135448. S2CID 2993705.
- ^ Ritter, Malcolm (1 July 2015). . Associated Press. Archived from the original on 3 July 2015. Retrieved 2 July 2015.
- ^ Jordans, Frank (30 July 2015). "Philae probe finds evidence that comets can be cosmic labs". The Washington Post. Associated Press. Retrieved 30 July 2015.
- ^ "Science on the Surface of a Comet". European Space Agency. 30 July 2015. Retrieved 30 July 2015.
- ^ Bibring, J.-P.; et al. (31 July 2015). "Philae's First Days on the Comet – Introduction to Special Issue". Science. 349 (6247): 493. Bibcode:2015Sci...349..493B. doi:10.1126/science.aac5116. PMID 26228139.
- ^ a b Ratcliffe, Rebecca (5 July 2015). "Philae comet could be home to alien life, say scientists". The Guardian. Retrieved 6 July 2015.
- ^ "Alien Life On Philae Comet, Scientists Say". Sky News. 6 July 2015. Retrieved 6 July 2015.
- ^ Knapton, Sarah (6 July 2015). "Alien life 'unlikely' on Rosetta comet, say mission scientists". The Daily Telegraph. Archived from the original on 12 January 2022. Retrieved 6 July 2015.
- ^ Altwegg, Kathrin; et al. (27 May 2016). "Prebiotic chemicals—amino acid and phosphorus—in the coma of comet 67P/Churyumov-Gerasimenko". Science Advances. 2 (5). e1600285. Bibcode:2016SciA....2E0285A. doi:10.1126/sciadv.1600285. PMC 4928965. PMID 27386550.
- ^ Fray, Nicolas; et al. (7 September 2016). "High-molecular-weight organic matter in the particles of comet 67P/Churyumov–Gerasimenko". Nature. 538 (7623): 72–74. Bibcode:2016Natur.538...72F. doi:10.1038/nature19320. PMID 27602514. S2CID 205250295.
- ^ a b Bieler, A.; et al. (29 October 2015). "Abundant molecular oxygen in the coma of comet 67P/Churyumov–Gerasimenko" (PDF). Nature. 526 (7575): 678–681. Bibcode:2015Natur.526..678B. doi:10.1038/nature15707. PMID 26511578. S2CID 205246191.
- ^ Howell, Elizabeth (28 October 2015). "Modern Mystery: Ancient Comet Is Spewing Oxygen". Space.com. Retrieved 6 November 2015.
- ^ Yao, Y. & Giapis, K.P. (8 May 2017). "Dynamic molecular oxygen production in cometary comae". Nature Communications. 8. 15298. Bibcode:2017NatCo...815298Y. doi:10.1038/ncomms15298. PMC 5424151. PMID 28480881.
- ^ Rubin, M.; et al. (April 2015). "Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature". Science. 348 (6231): 232–235. Bibcode:2015Sci...348..232R. doi:10.1126/science.aaa6100. PMID 25791084.
- ^ Heritier, K. L.; et al. (3 July 2018). "On the origin of molecular oxygen in cometary comae". Nature Communications. 9 (1). 2580. Bibcode:2018NatCo...9.2580H. doi:10.1038/s41467-018-04972-5. PMC 6030164. PMID 29968720.
- ^ Dunning, Hayley (3 July 2018). "Molecular oxygen in comet's atmosphere not created on its surface". Imperial College London. Retrieved 4 July 2018.
- ^ Brown, Dwayne; et al. (20 December 2017). "NASA Invests in Concept Development for Missions to Comet, Saturn Moon Titan". NASA. Retrieved 25 December 2017.
- ^ Chang, Kenneth (19 December 2017). "Finalists in NASA's Spacecraft Sweepstakes: A Drone on Titan, and a Comet-Chaser". The New York Times. Retrieved 25 December 2017.
- ^ Glowatz, Elana (20 December 2017). "NASA's New Frontier Mission Will Search For Alien Life Or Reveal The Solar System's History". International Business Times. Retrieved 25 December 2017.
- ^ Brown, David W. (27 June 2019). "NASA Announces New Dragonfly Drone Mission to Explore Titan". The New York Times. Retrieved 29 June 2019.
- ^ Foust, Jeff (27 June 2019). "NASA selects Titan drone for next New Frontiers mission". SpaceNews. Retrieved 29 June 2019.
- ^ "VLT Tracks Rosetta's Comet". European Southern Observatory. 8 September 2014. Retrieved 8 September 2014.
- ^ "Astronomers Reveal Interstellar Thread of One of Life's Building Blocks - ALMA and Rosetta map the journey of phosphorus". www.eso.org. Retrieved 16 January 2020.
Further reading Edit
- Agarwal, Jessica; et al. (June 2010). "The dust trail of Comet 67P/Churyumov–Gerasimenko between 2004 and 2006". Icarus. 207 (2): 992–1012. arXiv:1001.3775. Bibcode:2010Icar..207..992A. doi:10.1016/j.icarus.2010.01.003. S2CID 118634953.
- Corum, Jonathan (30 April 2015). "Rosetta Is Tailing a Warming Comet". The New York Times.
External links Edit
- 67P/Churyumov–Gerasimenko at Cometography
- by the Instituto de Astrofísica de Canarias
- 67P/Churyumov–Gerasimenko pronunciation guide by ESA
- "Mission to Land on a Comet" by NASA
- NASA Astronomy Picture of the Day: A Dust Jet from the Surface of the Comet 67P (6 November 2017)
- Rosetta's final images on YouTube, by ESA
- Rosetta complete image archive by ESA
- OSIRIS stereo views of 67P/Churyumov–Gerasimenko by CNES
- Landing News and Comments (The New York Times; 12 November 2014)