On 6 August 2014, the spacecraft reached the comet and performed a series of manoeuvers to eventuallyorbit the comet at distances of 30 to 10 kilometres (19 to 6 mi).[14] On 12 November, its lander modulePhilae performed the first successful landing on a comet,[15] though its battery power ran out two days later.[16] Communications withPhilae were briefly restored in June and July 2015, but due to diminishing solar power,Rosetta's communications module with the lander was turned off on 27 July 2016.[17] On 30 September 2016, theRosetta spacecraft ended its mission by hard-landing on the comet in its Ma'at region.[18][19]
The probe was named after theRosetta Stone, astele ofEgyptian origin featuring adecree in three scripts. The lander was named after thePhilae obelisk, which bears a bilingual Greek and Egyptian hieroglyphic inscription.
Rosetta was launched on 2 March 2004 from theGuiana Space Centre inKourou,French Guiana, on anAriane 5 rocket and reached Comet Churyumov–Gerasimenko on 7 May 2014.[20] It performed a series of manoeuvres to enter orbit between then and 6 August 2014,[21] when it became the first spacecraft to orbit a comet.[22][20][23] (Previous missions had conducted successful flybys of seven other comets.)[24] It was one of ESA'sHorizon 2000 cornerstone missions.[25] The spacecraft consisted of theRosetta orbiter, which featured 12 instruments, and thePhilae lander, with nine additional instruments.[26] TheRosetta mission orbited Comet Churyumov–Gerasimenko for 17 months and was designed to complete the most detailed study of a comet ever attempted. The spacecraft was controlled from theEuropean Space Operations Centre (ESOC), inDarmstadt, Germany.[27] The planning for the operation of the scientific payload, together with the data retrieval, calibration, archiving and distribution, was performed from theEuropean Space Astronomy Centre (ESAC), inVillanueva de la Cañada, nearMadrid, Spain.[28] It has been estimated that in the decade preceding 2014, some 2,000 people assisted in the mission in some capacity.[29]
In 2007,Rosetta made a Marsgravity assist (flyby) on its way to Comet Churyumov–Gerasimenko.[30] The spacecraft also performed twoasteroid flybys.[31] The craft completed its flyby of asteroid2867 Šteins in September 2008 and of21 Lutetia in July 2010.[32] Later, on 20 January 2014,Rosetta was taken out of a 31-monthhibernation mode as it approached Comet Churyumov–Gerasimenko.[33][34]
Rosetta'sPhilae lander successfully made the first soft landing on acomet nucleus when it touched down on Comet Churyumov–Gerasimenko on 12 November 2014.[35][36][37] On 5 September 2016, ESA announced that the lander was discovered by the narrow-angle camera aboardRosetta as the orbiter made a low, 2.7 km (1.7 mi) pass over the comet. The lander sits on its side wedged into a dark crevice of the comet, explaining the lack of electrical power to establish proper communication with the orbiter.[38]
During the 1986 approach ofHalley's Comet, international space probes were sent to explore the comet, most prominent among them beingESA'sGiotto.[39] 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.[40]
Both ESA andNASA started cooperatively developing new probes. The NASA project was theComet Rendezvous Asteroid Flyby (CRAF) mission.[41] The ESA project was the follow-on Comet Nucleus Sample Return (CNSR) mission.[42] Both missions were to share theMariner 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.[43] 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.[43] After the spacecraft launch,Gerhard Schwehm was named mission manager; he retired in March 2014.[29]
TheRosetta 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.[14]
The probe was named after theRosetta Stone,[44] astele ofEgyptian origin featuring adecree in three scripts. The lander was named after thePhilae 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 earlySolar System.[45][46] In a more direct analogy to its namesake, theRosetta spacecraft also carried a micro-etched pure nickel prototype of theRosetta disc donated by theLong Now Foundation. The disc was inscribed with 6,500 pages of language translations.[47][48]
TheRosetta mission achieved many historic firsts.[49]
On its way to comet 67P,Rosetta passed through the mainasteroid belt, and made the firstEuropean close encounter with several of these primitive objects.Rosetta was the first spacecraft to fly close toJupiter's orbit using solar cells as its main power source.[50]
Rosetta was the first spacecraft to orbit acomet nucleus,[51] and was the first spacecraft to fly alongside a comet as it headed towards theinner Solar System. It became the first spacecraft to examine at close proximity the activity of a frozen comet as it is warmed by theSun. Shortly after its arrival at 67P, theRosetta orbiter dispatched thePhilae 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 firstin situ analysis of its composition.
TheRosettabus was a 2.8 × 2.1 × 2.0 m (9.2 × 6.9 × 6.6 ft) central frame and aluminium honeycomb platform. Its total mass was approximately 3,000 kg (6,600 lb), which included the 100 kg (220 lb)Philae lander and 165 kg (364 lb) of science instruments.[52] 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 2.2 m (7.2 ft) steerable high-gain parabolic dish antenna, a 0.8 m (2.6 ft) fixed-position medium-gain antenna, and two omnidirectional low-gain antennas.[53]
Electrical power for the spacecraft came from two solar arrays totalling 64 square metres (690 sq ft).[54] Each solar array was subdivided into five solar panels, with each panel being 2.25 × 2.736 m (7.38 × 8.98 ft). The individual solar cells were made of silicon, 200 μm thick, and 61.95 × 37.75 mm (2.44 × 1.49 in).[55] The solar arrays generated a maximum of approximately 1,500 watts atperihelion,[55] a minimum of 400 watts in hibernation mode at 5.2 AU, and 850 watts when comet operations begin at 3.4 AU.[53] Spacecraft power was controlled by a redundantTerma power module also used in theMars Express spacecraft,[56][57] and was stored in four 10-A·h [Li-ion] batteries supplying 28 volts to the bus.[53]
Main propulsion comprised 24 paired bipropellant 10 N thrusters,[54] with four pairs of thrusters being used fordelta-v burns. The spacecraft carried 1,719.1 kg (3,790 lb) of propellant at launch: 659.6 kg (1,454 lb) ofmonomethylhydrazine fuel and 1,059.5 kg (2,336 lb) ofdinitrogen tetroxide oxidiser, contained in two 1,108-litre (244 imp gal; 293 US gal)grade 5 titanium alloy tanks and providing delta-v of at least 2,300 metres per second (7,500 ft/s) over the course of the mission. Propellant pressurisation was provided by two 68-litre (15 imp gal; 18 US gal) high-pressure helium tanks.[58]
Rosetta was built in aclean room according toCOSPAR rules, but "sterilisation [was] generally not crucial since comets are usually regarded as objects where you can findprebioticmolecules, that is, molecules that are precursors of life, but not livingmicroorganisms", according to Gerhard Schwehm,Rosetta's project scientist.[59] The total cost of the mission was about €1.3 billion (US$1.8 billion).[60]
Rosetta was set to be launched on 12 January 2003 to rendezvous with the comet46P/Wirtanen in 2011.[40] This plan was abandoned after the failure of anAriane 5 ECA carrier rocket duringHot Bird 7's launch on 11 December 2002, grounding it until the cause of the failure could be determined.[61] 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.[62][63] The larger mass and the resulting increased impact velocity made modification of the landing gear necessary.[64]
After two scrubbed launch attempts,Rosetta was launched on 2 March 2004 at 07:17 UTC from theGuiana Space Centre in French Guiana, usingAriane 5 G+ carrier rocket.[3] Aside from the changes made to launch time and target, the mission profile remained almost identical. Both co-discoverers of the comet,Klim Churyumov andSvetlana Gerasimenko, were present at the spaceport during the launch.[65][66]
To achieve the required velocity to rendezvous with 67P,Rosetta usedgravity assist manoeuvres to accelerate throughout the inner Solar System.[14] The comet's orbit was known beforeRosetta's launch, from ground-based measurements, to an accuracy of approximately 100 km (62 mi). Information gathered by the onboard cameras beginning at a distance of 24 million kilometres (15,000,000 mi) were processed at ESA's Operation Centre to refine the position of the comet in its orbit to a few kilometres.[citation needed]
On 25 February 2007, the craft was scheduled for a low-altitude flyby ofMars, to correct the trajectory. This was not without risk, as the estimated altitude of the flyby was a mere 250 kilometres (160 mi).[68] 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.[69] This Mars manoeuvre was therefore nicknamed "The Billion Euro Gamble".[70] The flyby was successful, withRosetta even returning detailed images of the surface and atmosphere of the planet, and the mission continued as planned.[11][30]
The second Earth flyby was on 13 November 2007 at a distance of 5,700 km (3,500 mi).[71][72] In observations made on 7 and 8 November,Rosetta was briefly mistaken for anear-Earth asteroid about 20 m (66 ft) in diameter by an astronomer of theCatalina Sky Survey and was given theprovisional designation2007 VN84.[73] Calculations showed that it would pass very close to Earth, which led to speculation that it could impact Earth.[74] However, astronomerDenis Denisenko recognised that the trajectory matched that ofRosetta, which theMinor Planet Center confirmed in an editorial release on 9 November.[75][76]
The spacecraft performed a close flyby of asteroid2867 Šteins on 5 September 2008. Its onboard cameras were used to fine-tune the trajectory, achieving a minimum separation of less than 800 km (500 mi). Onboard instruments measured the asteroid from 4 August to 10 September. Maximum relative speed between the two objects during the flyby was 8.6 km/s (19,000 mph; 31,000 km/h).[77]
Rosetta's third and final flyby of Earth happened on 12 November 2009 at a distance of 2,481 km (1,542 mi).[78]
On 10 July 2010,Rosetta flew by21 Lutetia, a largemain-beltasteroid, at a minimum distance of3,168±7.5 km (1,969±4.7 mi) at a velocity of 15 kilometres per second (9.3 mi/s).[13] The flyby provided images of up to 60 metres (200 ft) per pixel resolution and covered about 50% of the surface, mostly in the northern hemisphere.[32][79] The 462 images were obtained in 21 narrow- and broad-band filters extending from 0.24 to 1 μm.[32] 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.[32][79]
Rosetta's signal received atESOC inDarmstadt, Germany, on 20 January 2014Earth fromRosetta 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 775 to 7.9 m/s (2,543 to 26 ft/s).[21]
In 2006,Rosetta suffered a leak in itsreaction control system (RCS).[14] The system, which consists of 24bipropellant 10-newton thrusters,[21] was responsible for fine tuning the trajectory ofRosetta 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.[80]
Prior toRosetta's deep space hibernation period, two of the spacecraft's fourreaction wheels began exhibiting increased levels of "bearing friction noise". Increased friction levels in Reaction Wheel Assembly (RWA) 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 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 C's performance stabilising.[81]
During the spacecraft's Deep Space Hibernation flight phase, engineers performed ground testing on a flight spare RWA at theEuropean Space Operations Centre. AfterRosetta 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 rpm. After these fixes, the RWAs showed nearly identical performance data.[81] Three RWAs were kept operational, while one of the malfunctioning RWAs was held in reserve. Additionally, new on-board software was developed to allowRosetta to operate with only two active RWAs if necessary.[14][82] These changes allowed the four RWAs to operate throughoutRosetta's mission at 67P/Churyumov–Gerasimenko despite occasional anomalies in their friction plots and a heavy workload imposed by numerous orbital changes.[81]
Animation ofRosetta's trajectory around 67P from 1 August 2014 to 31 March 2015 Rosetta·67P
In August 2014,Rosetta rendezvoused with the comet67P/Churyumov–Gerasimenko (67P) and commenced a series of manoeuvres that took it on two successive triangular paths, averaging 100 and 50 kilometres (62 and 31 mi) from the nucleus, whose segments arehyperbolic escape trajectories alternating with thruster burns.[22][20] After closing to within about 30 km (19 mi) from the comet on 10 September, the spacecraft entered actualorbit about it.[22][20][23][needs update]
The surface layout of 67P was unknown beforeRosetta's arrival. The orbiter mapped the comet in anticipation of detaching its lander.[83] By 25 August 2014, five potential landing sites had been determined.[84] On 15 September 2014, ESA announced Site J, namedAgilkia in honour ofAgilkia Island by an ESA public contest and located on the "head" of the comet,[85] as the lander's destination.[86]
Philae detached fromRosetta on 12 November 2014 at 08:35 UTC, and approached 67P at a relative speed of about 1 m/s (3.6 km/h; 2.2 mph).[87] It initially landed on 67P at 15:33 UTC, but bounced twice, coming to rest at 17:33 UTC.[15][88] Confirmation of contact with 67P reached Earth at 16:03 UTC.[89]
On contact with the surface, twoharpoons were to be fired into the comet to prevent the lander from bouncing off, as the comet's escape velocity is only around 1 m/s (3.6 km/h; 2.2 mph).[90] Analysis of telemetry indicated that the surface at the initial touchdown site is relatively soft, covered with a layer of granular material about 0.82 feet (0.25 meters) deep,[91] 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 acidenantiomers[92]
Study of comet activities and developments over time
After bouncing,Philae settled in the shadow of a cliff,[38] canted at an angle of around 30 degrees. This made it unable to adequately collect solar power, and it lost contact withRosetta when its batteries ran out after three days, well before much of the planned science objectives could be attempted.[38][16] 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,[93] and the transmitter to communicate withPhilae was switched off in July 2016 to reduce power consumption of the probe.[17] The precise location of the lander was discovered in September 2016 whenRosetta came closer to the comet and took high-resolution pictures of its surface.[38] Knowing its exact location provides information needed to put Philae's two days of science into proper context.[38]
The comet in January 2015 as seen byRosetta'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 40–50millihertz. A German composer and sound designer created an artistic rendition from the measured data to make it audible.[94] Although it is a natural phenomenon, it has been described as a "song"[95] and has been compared toContinuum for harpsichord byGyörgy Ligeti.[96] However, results fromPhilae's landing show that the comet's nucleus has no magnetic field, and that the field originally detected byRosetta is likely caused by thesolar wind.[97][98]
Theisotopic signature of water vapour from comet 67P, as determined by theRosetta spacecraft, is substantially different from that found on Earth. That is, the ratio ofdeuterium tohydrogen 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.[99][100][101] 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.[102]
On 2 June 2015, NASA reported that theAlice spectrograph onRosetta determined thatelectrons within 1 km (0.6 mi) above the comet nucleus — produced from photoionization of watermolecules, and not directphotons from the Sun as thought earlier — are responsible for the degradation of water andcarbon dioxide molecules released from the comet nucleus into itscoma.[103][104]
As the orbit of comet 67P took it farther from the Sun, the amount of sunlight reachingRosetta's solar panels decreased. While it would have been possible to putRosetta 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 guideRosetta down to the comet's surface and end the mission on impact, gathering photographs and instrument readings along the way.[105] 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.[106]
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. —Sylvain Lodiot,Rosetta Spacecraft Operations Manager,European Space Operations Centre[107]
Rosetta began a 19 km (12 mi) descent with a 208-second thruster burn executed on 29 September 2016 at approximately 20:50 UTC.[108][109][107] Its trajectory targeted a site in the Ma'at region near an area of dust- and gas-producing active pits.[110]
Impact on the comet's surface occurred 14.5 hours after its descent manoeuvre; the final data packet fromRosetta was transmitted at 10:39:28.895 UTC (SCET) by the OSIRIS instrument and was received at theEuropean Space Operations Centre in Darmstadt, Germany, at 11:19:36.541 UTC.[108][109][111] The spacecraft's estimated speed at the time of impact was 3.2 km/h (2.0 mph; 89 cm/s),[19] and its touchdown location, namedSais by the operations team after the Rosetta Stone's original temple home, is believed to be only 40 m (130 ft) off-target.[110] The final complete image transmitted by the spacecraft of the comet was taken by its OSIRIS instrument at an altitude of 23.3–26.2 m (76–86 ft) about 10 seconds before impact, showing an area 0.96 m (3.1 ft) across.[110][112]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 withInternational Telecommunication Union rules.[107]
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 17.9–21.0 m (58.7–68.9 ft), and representsRosetta's closest image of the surface.[112][113]
Alice (an ultraviolet imaging spectrograph). Theultravioletspectrograph searched for and quantified thenoble gas content in the comet nucleus, from which the temperature during the comet creation could be estimated. The detection was done by an array ofpotassium bromide andcaesium iodidephotocathodes. The 3.1 kg (6.8 lb) instrument used 2.9 watts, with an improved version onboardNew Horizons. It operated in the extreme and far ultraviolet spectrum, from 700–2,050 Å (70–205 nm).[114][115] ALICE was built and operated by theSouthwest Research Institute for NASA's Jet Propulsion Laboratory.[116]
VIRTIS (Visible and Infrared Thermal Imaging Spectrometer). The Visible andIR spectrometer was able to make pictures of the nucleus in the IR and also search for IR spectra of molecules in thecoma. The detection was done by a mercury cadmium telluride array for IR and with a CCD chip for thevisible wavelength range. The instrument was produced in Italy, and improved versions were used forDawn andVenus Express.[118]
MIRO (Microwave Instrument for the Rosetta Orbiter). The abundance and temperature of volatile substances like water, ammonia and carbon dioxide could be detected by MIRO via theirmicrowave emissions. The 30 cm (12 in) radio antenna along with the rest of the 18.5 kg (41 lb) instrument was built by NASA's Jet Propulsion Laboratory with international contributions by the Max Planck Institute for Solar System Research (MPS), among others.[119]
CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission). The CONSERT experiment provided information about the deep interior of the comet usingradar. The radar performedtomography of the nucleus by measuring electromagnetic wave propagation between thePhilae lander and theRosetta orbiter through the comet nucleus. This allowed it to determine the comet's internal structure and deduce information on its composition. The electronics were developed by France and both antennas were constructed in Germany. Development was led by the Laboratoire de Planétologie de Grenoble with contributions by the Ruhr-Universität Boch and the Max Planck Institute for Solar System Research (MPS).[120][121]
RSI (Radio Science Investigation). RSI made use of the probe's communication system for physical investigation of the nucleus and the innercoma of the comet.[122]
ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis). The instrument consisted of a double-focusmagnetic mass spectrometer (DFMS) and areflectron typetime of flight mass spectrometer (RTOF). The DFMS had a high resolution (could resolveN2 fromCO) for molecules up to300 Da. The RTOF was highly sensitive for neutral molecules and for ions. The Max Planck Institute for Solar System Research (MPS) has contributed to the development and construction of the instrument.[123] ROSINA was developed at the University of Bern in Switzerland.
MIDAS (Micro-Imaging Dust Analysis System). The high-resolutionatomic force microscope investigated several physical aspects of the dust particles which are deposited on a silicon plate.[124]
COSIMA (Cometary Secondary Ion Mass Analyser). COSIMA analysed the composition of dust particles bysecondary ion mass spectrometry, usingindium ions. It could detect ions up to a mass of 6500 amu. COSIMA was built by the Max Planck Institute for Extraterrestrial Physics (MPE, Germany) with international contributions. The COSIMA team is led by the Max Planck Institute for Solar System Research (MPS, Germany).[125]
GIADA (Grain Impact Analyser and Dust Accumulator). GIADA analysed the dust environment of thecomet coma by measuring the optical cross section, momentum, speed and mass of each grain entering inside the instrument.[126][127]
Previous observations have shown that comets contain complexorganic compounds.[14][130][131][132] These are the elements that make upnucleic acids andamino acids, essential ingredients for life as we know it. Comets are thought to have delivered a vast quantity of water to Earth, and they may have also seeded Earth withorganic molecules.[133]Rosetta andPhilae also searched for organic molecules, nucleic acids (the building blocks ofDNA andRNA) and amino acids (the building blocks of proteins) by sampling and analysing the comet's nucleus and coma cloud of gas and dust,[133] helping assess the contribution comets made to thebeginnings of life on Earth.[14] Before succumbing to falling power levels,Philae's COSAC instrument was able to detect organic molecules in the comet's atmosphere.[134]
Twoenantiomers of a genericamino acid. The mission will study why onechirality of some amino acids seems to be dominant in the universe.
Amino acids
Upon landing on the comet,Philae should have also tested some hypotheses as to whyessential amino acids are almost all "left-handed", which refers to how the atoms arrange in orientation in relation to the carbon core of the molecule.[135] Most asymmetrical molecules are oriented in approximately equal numbers of left- and right-handed configurations (chirality), and the primarily left-handed structure of essential amino acids used by living organisms is unique. One hypothesis that will be tested was proposed in 1983 by William A. Bonner andEdward Rubenstein,Stanford University professors emeritus of chemistry and medicine respectively. They conjectured that when spiralling radiation is generated from asupernova, the circular polarisation of that radiation could then destroy one type of "handed" molecules. The supernova could wipe out one type of molecules while also flinging the other surviving molecules into space, where they could eventually end up on a planet.[136]
The mission has yielded a significant science return, collecting a wealth of data from the nucleus and its environment at various levels of cometary activity.[137] The VIRTISspectrometer on board theRosetta spacecraft has provided evidence of nonvolatile organic macromolecular compounds everywhere on the surface of comet 67P with little to no water ice visible.[138] Preliminary analyses strongly suggest the carbon is present aspolyaromatic organic solids mixed withsulfides and iron-nickel alloys.[139][140]
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 those found incarbonaceous chondrite meteorites.[141] However, no hydrated minerals were detected, suggesting no link with carbonaceous chondrites.[140]
In turn, thePhilae lander's COSAC instrument detected organic molecules in the comet's atmosphere as it descended to its surface.[142][143] Measurements by the COSAC and Ptolemy instruments on thePhilae's lander revealed sixteenorganic compounds, four of which were seen for the first time on a comet, includingacetamide,acetone,methyl isocyanate andpropionaldehyde.[144][145][146] The only amino acid detected thus far on the comet isglycine, along with the precursor moleculesmethylamine andethylamine.[147]
One of the most outstanding discoveries of the mission was the detection of large amounts of free molecularoxygen (O2) gas surrounding the comet.[148][149] A local abundance ofoxygen was reported to be in range from 1% to 10% relative to H2O.[148]
2 March –Rosetta was successfully launched at 07:17UTC (04:17 local time) fromKourou, French Guiana.
2005
4 March –Rosetta executed its first planned close swing-by (gravity assist passage) of Earth. The Moon and the Earth's magnetic field were used to test and calibrate the instruments on board of the spacecraft. The minimum altitude above the Earth's surface was 1,954.7 km (1,214.6 mi).[67]
4 July – Imaging instruments on board observed the collision between the cometTempel 1 and the impactor of theDeep Impact mission.[150]
8 November –Catalina Sky Survey briefly misidentified theRosetta spacecraft, approaching for its second Earth flyby, as a newly discovered asteroid.
13 November – Second Earth swing-by at a minimum altitude of 5,295 km (3,290 mi), travelling at 45,000 km/h (28,000 mph).[152]
Enhanced image of asteroid Šteins byRosetta
2008
5 September – Flyby of asteroid2867 Šteins. The spacecraft passed themain-belt asteroid at a distance of 800 km (500 mi) and the relatively slow speed of 8.6 km/s (31,000 km/h; 19,000 mph).[153]
2009
13 November – Third and final swing-by of Earth at 48,024 km/h (29,841 mph).[154][155]
2010
16 March – Observation of the dust tail of asteroidP/2010 A2. Together with observations byHubble Space Telescope it could be confirmed that P/2010 A2 is not a comet, but an asteroid, and that the tail most likely consists of particles from an impact by a smaller asteroid.[156]
10 July – Flew by and photographed the asteroid21 Lutetia.[157]
Comet 67P seen from 10 km (6 mi)
2014
May to July – Starting on 7 May,Rosetta began orbital correction manoeuvres to bring itself into orbit around 67P. At the time of the first deceleration burnRosetta was approximately 2,000,000 km (1,200,000 mi) away from 67P and had a relative velocity of +775 m/s (2,540 ft/s); by the end of the last burn, which occurred on 23 July, the distance had been reduced to just over 4,000 km (2,500 mi) with a relative velocity of +7.9 m/s (18 mph).[21][158] In total eight burns were used to align the trajectories ofRosetta 67P with the majority of the deceleration occurring during three burns:Delta-v's of 291 m/s (650 mph) on 21 May, 271 m/s (610 mph) on 4 June, and 91 m/s (200 mph) on 18 June.[21]
14 July – The OSIRIS on-board imaging system returned images of comet 67P which confirmed the irregular shape of the comet.[159][160]
6 August –Rosetta arrives at 67P, approaching to 100 km (62 mi) and carrying out a thruster burn that reduces its relative velocity to 1 m/s (3.3 ft/s).[161][162][163] Commences comet mapping and characterisation to determine a stable orbit and viable landing location forPhilae.[164]
4 September – The first science data fromRosetta's Alice instrument was reported, showing that the comet is unusually dark inultraviolet wavelengths,hydrogen andoxygen are present in thecoma, and no significant areas of water-ice have been found on the comet's surface. Water-ice was expected to be found as the comet is too far from the Sun to turn water into vapour.[165]
10 September 2014 –Rosetta enters the Global Mapping Phase, orbiting 67P at an altitude of 29 km (18 mi).[6]
12 November 2014 –Philae lands on the surface of 67P.[15]
10 December 2014 – Data from the ROSINA mass spectrometers show that the ratio ofheavy water to normal water on comet 67P is more than three times that on Earth. The ratio is regarded as a distinctive signature, and the discovery means that Earth's water is unlikely to have originated from comets like 67P.[99][100][101]
Comet 67P with a tail of gas and dust, seen from 162 km (101 mi)
2015
14 April 2015 – Scientists report that the comet's nucleus has no magnetic field of its own.[97]
2 July 2015 – Scientists report that active pits, related tosinkhole collapses and possibly associated with outbursts, have been found on the comet.[166][167]
November 2014 to December 2015 –Rosetta escorted the comet around the Sun and performed riskier investigations.[106]
2016
27 July 2016 – ESA switched off the Electrical Support System Processor Unit (ESS) aboardRosetta, disabling any possibility of further communications with thePhilae lander.[17]
2 September 2016 –Rosetta photographs thePhilae lander for the first time after its landing, finding it wedged against a large overhang.[170]
30 September 2016 – Mission ended in an attempt to slow land on the comet's surface near a 130 m (425 ft) wide pit called Deir el-Medina. The walls of the pit contain 0.91 m (3 ft) wide so-called "goose bumps", believed to represent the building blocks of the comet.[18][19][171] AlthoughPhilae sent back some data during its descent,Rosetta has more powerful and more varied sensors and instruments, offering the opportunity to get some very close-in science to complement the more distant remote sensing it has been doing. The orbiter descended more slowly thanPhilae did.[172][173]
Cartoon versions ofRosetta andPhilae as they appear in the ESA'sOnce upon a time... series
As part of the European Space Agency's media campaign in support of theRosetta mission, both theRosetta andPhilae spacecraft were givenanthropomorphic personalities in ananimatedweb series titledOnce upon a time.... The series depicts various stages in theRosetta mission, involving the personifiedRosetta andPhilae on "a classic road trip story into the depths of our universe", complemented with variousvisual gags presented in an educational context.[174] Produced by animation studio Design & Data GmbH, the series was initially conceived by the ESA as a four-partfantasy-like series with aSleeping Beauty theme that promoted community involvement inRosetta's wake up from hibernation in January 2014. After the success of the series, however, the ESA commissioned the studio to continue producing new episodes in the series throughout the course of the mission.[174] A total of twelve videos in the series were produced from 2013 to 2016, with a 25-minute compilation of the series released in December 2016, after the end of the mission.[175] In 2019, Design & Data adapted the series into a 26-minuteplanetarium show that was commissioned by theSwiss Museum of Transport, and solicited to eighteen planetariums across Europe, with an aim "to inspire the young generation to explore the universe."[176]
TheRosetta andPhilae characters featured inOnce upon a time..., designed by ESA employee and cartoonist Carlo Palazzari, became a central part of public image of theRosetta mission, appearing in promotional material for the mission such as posters and merchandise,[177] and often credited as a major factor in the popularity of the mission among the public.[174][178] ESA employees alsorole-played as the characters onTwitter throughout the course of the mission.[177][179] The characters were inspired by theJAXA's "kawaii" characters, who portrayed a number of their spacecraft, such asHayabusa2 andAkatsuki, with distinctanime-like personalities.[180] The script for each episode of the series is written by science communicators at theEuropean Space Research and Technology Centre, who kept close with mission operators and the producers at Design & Data.[180] Canonically,Rosetta andPhilae are depicted as siblings, withRosetta being the older sister, inspired by the spacecraft's feminine name, ofPhilae, her younger brother. TheGiotto spacecraft is also depicted as the duo's grandfather, whereas others in theHalley Armada as well asNASA'sDeep Impact andStardust spacecraft are depicted as their cousins.[180]
To promote the spacecraft's arrival at comet 67P/Churyumov–Gerasimenko and the landing ofPhilae in 2014, ashort film was produced by the European Space Agency with Polishvisual effects production companyPlatige Image. TitledAmbition, the film, shot inIceland, stars Irish actorAidan Gillen, known for his roles inGame of Thrones andThe Wire, and Irish actressAisling Franciosi, also ofGame of Thrones fame, and was directed byOscar-nominated Polish directorTomasz Bagiński.[181][182] Set in the far future,Ambition centers around a discussion between a master, played by Gillen, discussing the importance ofambition with his apprentice, played by Franciosi, using theRosetta mission as an example of such.[183][184]Ambition was premiered at theBritish Film Institute'sSci-Fi: Days of Fear and Wonderfilm festival inLondon on 24 October 2014, three weeks before the landing ofPhilae on 67P/Churyumov–Gerasimenko.[185] Britishscience fiction author and former ESA employeeAlastair Reynolds spoke about the film's message at the premiere, stating to the audience that "our distant descendants may look back to Rosetta with the same sense of admiration that we reserve for, say,Columbus orMagellan."[181] The film's conception was the result of the BFI's inquiry to the ESA for a contribution to their celebration of science fiction, with the ESA taking the opportunity to promote theRosetta mission through the festival.[181][186]
Critical reception of the film upon its premiere was mostly positive. Tim Reyes ofUniverse Today complimented the titular theme of ambition in the film, stating that it "shows us the forces at work in and around ESA", and that it "might accomplish more in 7 minutes thanGravity did in 90."[183] Ryan Wallace ofThe Science Times also gave praise to the film, writing, "whether you're a sci-fi fanatic, or simply an interested humble astronomer, the short clip will undoubtedly give you a new view of our solar system, and the research out there in space today."[187]
The entire mission was featured heavily in social media, with a Facebook account for the mission and both the satellite and the lander having an official Twitter account portraying apersonification of both spacecraft. Thehashtag "#CometLanding" gained widespread traction. Alive stream of the control centres was set up, as were multiple official and unofficial events around the world to followPhilae's landing on 67P.[188][189] On 23 September 2016,Vangelis released the studio albumRosetta in honour of the mission,[190][191] which was used on 30 September in the "Rosetta's final hour" streaming video of the ESA Livestream event "Rosetta Grand Finale".[192]
^Agle, D. C.; Cook, Jia-Rui; Brown, Dwayne; Bauer, Markus (17 January 2014). Agle, DC; Cook, Jia-Rui; Bauer, Markus (eds.)."Rosetta: To Chase a Comet".NASA /JPL. 2014-015.Archived from the original on 4 October 2024. Retrieved18 January 2014.
^Glassmeier, Karl-Heinz; Boehnhardt, Hermann; Koschny, Detlef; Kührt, Ekkehard; Richter, Ingo (February 2007). "The Rosetta Mission: Flying Towards the Origin of the Solar System".Space Science Reviews.128 (1–4):1–21.Bibcode:2007SSRv..128....1G.doi:10.1007/s11214-006-9140-8.S2CID119512857.
^abD'Accolti, G.; Beltrame, G.; Ferrando, E.; Brambilla, L.; Contini, R.; et al. (2002).The Solar Array Photovoltaic Assembly for the ROSETTA Orbiter and Lander Spacecraft's. 6th European Space Power Conference. 6–10 May 2002. Porto, Portugal.Bibcode:2002ESASP.502..445D.
^Jensen, Hans; Laursen, Johnny (2002).Power Conditioning Unit for Rosetta/Mars Express. 6th European Space Power Conference. 6–10 May 2002. Porto, Portugal.Bibcode:2002ESASP.502..249J.
^Stramaccioni, D. (2004).The Rosetta Propulsion System. 4th International Spacecraft Propulsion Conference. 2–9 June 2004. Sardinia, Italy.Bibcode:2004ESASP.555E...3S.
^Ulamec, S.; Espinasse, S.; Feuerbacher, B.; Hilchenbach, M.; Moura, D.; et al. (April 2006). "Rosetta Lander—Philae: Implications of an alternative mission".Acta Astronautica.58 (8):435–441.Bibcode:2006AcAau..58..435U.doi:10.1016/j.actaastro.2005.12.009.
^Coradini, A.; Capaccioni, F.; Capria, M. T.; Cerroni, P.; de Sanctis, M. C.; et al. (July 1995).VIRTIS, visible infrared thermal imaging spectrometer for the ROSETTA mission. 1995 International Geoscience and Remote Sensing Symposium, IGARSS '95. Quantitative Remote Sensing for Science and Applications. Vol. 27. Firenze, Italy:IEEE. p. 253.Bibcode:1996LPI....27..253C.doi:10.1109/igarss.1995.521822.ISBN978-0-7803-2567-8.S2CID119978931.
^Kofman, W.; Herique, A.; Goutail, J.-P.; Hagfors, T.; Williams, I. P.; et al. (February 2007). "The Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT): A Short Description of the Instrument and of the Commissioning Stages".Space Science Reviews.128 (1–4):414–432.Bibcode:2007SSRv..128..413K.doi:10.1007/s11214-006-9034-9.S2CID122123636.
^Riedler, W.; Torkar, K.; Rüdenauer, F.; Fehringer, M.; Schmidt, R.; et al. (1998). "The MIDAS experiment for the Rosetta mission".Advances in Space Research.21 (11):1547–1556.Bibcode:1998AdSpR..21.1547R.doi:10.1016/S0273-1177(97)00947-2.
^Engrand, Cecile; Kissel, Jochen; Krueger, Franz R.; Martin, Philippe; Silén, Johan; et al. (April 2006). "Chemometric evaluation of time-of-flight secondary ion mass spectrometry data of minerals in the frame of futurein situ analyses of cometary material by COSIMA onboard ROSETTA".Rapid Communications in Mass Spectrometry.20 (8):1361–1368.Bibcode:2006RCMS...20.1361E.doi:10.1002/rcm.2448.PMID16555371.
^Colangeli, L.; Lopez-Moreno, J. J.; Palumbo, P.; Rodriguez, J.; Cosi, M.; et al. (February 2007). "The Grain Impact Analyser and Dust Accumulator (GIADA) experiment for the Rosetta mission: design, performances and first results".Space Science Reviews.128 (1–4):803–821.Bibcode:2007SSRv..128..803C.doi:10.1007/s11214-006-9038-5.S2CID123232721.
^Trotignon, J. G.; Boström, R.; Burch, J. L.; Glassmeier, K.-H.; Lundin, R.; et al. (January 1999). "The Rosetta plasma consortium: Technical realization and scientific aims".Advances in Space Research.24 (9):1149–1158.Bibcode:1999AdSpR..24.1149T.doi:10.1016/S0273-1177(99)80208-7.
^Glassmeier, Karl-Heinz; Richter, Ingo; Diedrich, Andrea; Musmann, Günter; Auster, Uli; et al. (February 2007). "RPC-MAG The Fluxgate Magnetometer in the ROSETTA Plasma Consortium".Space Science Reviews.128 (1–4):649–670.Bibcode:2007SSRv..128..649G.doi:10.1007/s11214-006-9114-x.S2CID121047896.
^Tate, Karl (17 January 2014)."How the Rosetta Spacecraft Will Land on a Comet". Space.com. Retrieved9 August 2014.A previous sample-return mission to a different comet found particles of organic matter that are the building blocks of life.
^abcMarcu, Sebastian D.; Laird, Ryan J. M. (March 2016)."Captivating hearts and minds".Room, The Space Journal. Aerospace International Research Center. Retrieved28 December 2016.
^"Launching the Planetarium Show "The Adventures of Rosetta & Philae"". Design & Data GmbH. 26 April 2019.Archived from the original on 30 April 2019.Production was initiated by the Verkehrshaus der Schweiz (Museum of Transport Planetarium) and brought to full dome with the support of the Swiss Space Office. The project involves 18 other planetaria (Berlin, Baikonur, Bochum, Chemnitz, ESO Supernova Garching, Kiel, Klagenfurt, Münster, Nuremberg, Prague, Shanghai, Singapore, Vienna and others) from seven countries. The aim of the project is to inspire the young generation to explore the universe.
Missions are ordered by launch date. Sign† indicates failure en route or before intended mission data returned.‡ indicates use of the planet as agravity assist en route to another destination.
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).
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