MESSENGER

This article is about the NASA space mission. For otheruses, see Messenger.

MESSENGER (an acronym of MErcury Surface,Space ENvironment, GEochemistry, and Ranging,and a reference to the mythological Mercury being themessenger of the gods) was a robotic NASA spacecraftorbiting the planet Mercury.[7] The 485-kilogram (1,069lb) spacecraft was launched aboard a Delta II rocket inAugust 2004 to study Mercury’s chemical composition,geology, and magnetic field.MESSENGER became the second mission after Mariner10's 1975 flyby to reach Mercury when it made a flybyin January 2008, followed by a second flyby in October2008,[8] and a third flyby in September 2009, prior to en-tering Mercury’s orbit in March 2011.[9][10] It was the firstspacecraft to orbit Mercury.[7]

The instruments carried by MESSENGER were used on acomplex series of flybys – the spacecraft flew by Earthonce, Venus twice, and Mercury itself three times, al-lowing it to decelerate relative to Mercury using mini-mal fuel. MESSENGER entered orbit around Mercuryon March 18, 2011, and reactivated its science instru-ments on March 24, returning the first photo from Mer-cury orbit on March 29. MESSENGER successfully com-pleted its primary mission in 2012.[2] Following two mis-sion extensions, theMESSENGERmission ended on April30, 2015,[11][12][13] after the spacecraft used the last ofits maneuvering propellant and suffered orbital decay,which ultimately led to an impact onto the surface ofMercury.[14][15]

1 Mission timeline

MESSENGER's formal data collection mission began onApril 4, 2011. The primary mission was completedon March 17, 2012, having collected close to 100,000images.[16] MESSENGER achieved 100% mapping ofMercury on March 6, 2013, and completed its first year-long extended mission on March 17, 2013.[2] Its secondextended mission concluded in 30 April 2015.[17][18] AsMESSENGER ' s low orbit has degraded, it has requiredreboosts to avoid impact. It conducted its final reboostburns on October 24, 2014, and January 21, 2015, be-fore crashing into Mercury on April 30, 2015.[14]

During its stay in Mercury orbit, MESSENGER's instru-ments have yielded significant data, including a charac-

terization of Mercury’s magnetic field[19] and the discov-ery of water ice at the planet’s north pole,[20][21] whichhad long been suspected on the basis of Earth-based radardata.[22]

2 Mission background

2.1 Previous missions

In 1973, Mariner 10 was launched to make multiple flybyencounters of Venus and Mercury. Mariner 10 providedthe first detailed data of Mercury, mapping 40-45% ofthe surface.[23] The final flyby of Mercury by Mariner 10occurred on March 16, 1975. No subsequent close-rangeobservations of the planet would take place for more than30 years.

2.2 Proposals for the mission

In 1998, a study detailed a proposed mission to sendan orbiting spacecraft to Mercury, as the planet was atthat point the least-explored of the inner planets. In theyears following the Mariner 10 mission, subsequent mis-sion proposals to revisit Mercury had appeared too costly,requiring large quantities of propellant and a heavy liftlaunch vehicle. Moreover, inserting a spacecraft intoorbit around Mercury is difficult, because a probe ap-proaching on a direct path from Earth would be acceler-ated by the Sun's gravity and pass Mercury far too quicklyto orbit it. However, using a trajectory designed by Chen-wan Yen in 1985, the study showed it was possible toseek a Discovery-class mission by using multiple, con-secutive gravity assist, 'swingby' maneuvers around Venusand Mercury, in combination with minor propulsive tra-jectory corrections, to gradually slow the spacecraft andthereby minimize propellant needs.[24]

2.3 Objectives

The MESSENGER mission was designed to study thecharacteristics and environment of Mercury from or-bit. Specifically, the scientific objectives of the missionwere:[25][26]

• to characterize the chemical composition of Mer-cury’s surface.

1

2 2 MISSION BACKGROUND

Higher-resolution swaths of Mercury’s surface

• to study the planet’s geologic history.

• to elucidate the nature of the global magnetic field(magnetosphere).

• to determine the size and state of the core.

• to determine the volatile inventory at the poles.

• to study the nature of Mercury’s exosphere.

2.4 Spacecraft design

The spacecraft was designed and built at the Johns Hop-kins University Applied Physics Laboratory. Scienceoperations, managed by Sean Solomon as principal in-vestigator, and mission operations are also conducted atJHU/APL.[27] The MESSENGER bus measures 1.85 me-ters (73 in) tall, 1.42 m (56 in) wide, and 1.27 m (50in) deep. The bus was primarily constructed with fourgraphite fiber / cyanate ester composite panels that sup-port the propellant tanks, the large velocity adjust (LVA)thruster, attitude monitors and correction thrusters, theantennas, the instrument pallet, and a large ceramic-clothsunshade, measuring 2.5 m (8.2 ft) tall and 2 m (6.6 ft)wide, for passive thermal control.[27] MESSENGER's totalmission cost, including the cost of the spacecraft’s con-struction, was estimated at under US$450 million.[28]

2.4.1 Attitude control and propulsion

Main propulsion was via the 645 N, 317 sec.Ibipropellant (hydrazine and nitrogen tetroxide) large ve-locity assist (LVA) thruster. The model used wasthe LEROS 1b, developed and manufactured at AM-PAC‐ISP’s Westcott facility, in the United Kingdom. Thespacecraft was designed to carry 607.8 kilograms (1,340lb) of propellant and pressurizer (helium).[27]

Four 22 N (4.9 lb ) monopropellant thrusters providedspacecraft steering during main thruster burns, and twelve4.4 N (1.0 lb ) monopropellant thrusters were used forattitude control. For precision attitude control, a reactionwheel attitude control system was also included.[27] Infor-mation for attitude control was provided by star trackers,an inertial measurement unit and six sun sensors.[27]

2.4.2 Communications

Images from Messenger

The probe included two small deep space transpondersfor communications with the Deep Space Network andthree kinds of antennas: a high gain phased array whosemain beam can be electronically steered in one plane, amedium-gain “fan-beam” antenna and a low gain hornwith a broad pattern. The high gain antenna was used astransmit-only at 8.4 GHz, the medium-gain and low gainantennas transmit at 8.4 GHz and receive at 7.2 GHz, andall three antennas operate with right-hand circularly po-larized (RHCP) radiation. One of each of these antennaswas mounted on the front of the probe facing the Sun, andone of each was mounted to the back of the probe facingaway from the Sun.[29]

2.4.3 Power

The space probe was powered by a two-panel, galliumarsenide/germanium (GaAs/Ge) solar array providing anaverage of 450 watts at Mercury. Each panel was rotat-able and included optical solar reflectors to balance the

3.2 Earth flyby 3

temperature of the array. Power was stored in a common-pressure-vessel, 23-ampere-hour nickel–hydrogen bat-tery, with 11 vessels and two cells per vessel.[27]

2.4.4 Computer and software

The spacecraft’s onboard computer system was containedin an Integrated Electronics Module (IEM), a device thatcombines core avionics into a single box. The computerfeatures two radiation-hardened IBM RAD6000s, a 25megahertz main processor, and a 10 MHz fault protec-tion processor. For redundancy, the spacecraft carried apair of identical IEMs. For data storage, the spacecraftcarried two solid-state recorders able to store up to onegigabyte each. The IBM RAD6000 main processor col-lected, compresses, and stored data from MESSENGER'sinstruments for later playback to Earth.[27]

MESSENGER used a software suite called SciBox to sim-ulate its orbit and instruments, in order to “choreographthe complicated process of maximizing the scientific re-turn from the mission and minimizing conflicts betweeninstrument observations, while at the same time meet-ing all spacecraft constraints on pointing, data downlinkrates, and onboard data storage capacity.”[30]

2.4.5 Scientific instruments

3 Mission profile

3.1 Launch and trajectory

TheMESSENGER probe was launched on August 3, 2004at 06:15:56 UTC by NASA from Space Launch Complex17B at the Cape Canaveral Air Force Station in Florida,aboard a Delta II 7925 launch vehicle. The complete burnsequence lasted 57 minutes bringing the spacecraft intoa heliocentric orbit, with a final velocity of 10.68 km/s(6.64 miles/s) and sending the probe into a 7.9 billion-kilometer trajectory that took 6 years, 7 months and 16days before its orbital insertion on March 18, 2011.[27]

Traveling to Mercury requires an extremely large veloc-ity change (see delta-v) because Mercury’s orbit is deepin the Sun’s gravity well. On a direct course from Earthto Mercury, a spacecraft is constantly accelerated as itfalls toward the Sun, and will arrive at Mercury with avelocity too high to achieve orbit without excessive useof fuel. For planets with an atmosphere, such as Venusand Mars, spacecraft can minimize their fuel consump-tion upon arrival by using friction with the atmosphere toenter orbit (aerocapture), or can briefly fire their rocketengines to enter into orbit followed by a reduction of theorbit by aerobraking. However, the tenuous atmosphereof Mercury is far too thin for these maneuvers. Instead,MESSENGER extensively used gravity assist maneuvers atEarth, Venus, and Mercury to reduce the speed relative

to Mercury, then used its large rocket engine to enter intoan elliptical orbit around the planet. The multi-flyby pro-cess greatly reduced the amount of propellant necessaryto slow the spacecraft, but at the cost of prolonging thetrip by many years and to a total distance of 4.9 billionmiles. To further minimize the amount of necessary pro-pellant, the spacecraft orbital insertion targeted a highlyelliptical orbit around Mercury.The elongated orbit had two other benefits: It allowed thespacecraft time to cool after the times it was between thehot surface of Mercury and the Sun, and also it allowedthe spacecraft to measure the effects of solar wind andthe magnetic fields of the planet at various distances whilestill allowing close-up measurements and photographs ofthe surface and exosphere.

3.2 Earth flyby

Main article: Earth observation satellite

MESSENGER performed an Earth flyby one year afterlaunch, on August 2, 2005, with the closest approachat 19:13 UTC at an altitude of 2,347 kilometers (1,458statute miles) over central Mongolia. On December 12,2005, a 524-second-long burn (Deep-Space Maneuver orDSM-1) of the large thruster adjusted the trajectory forthe upcoming Venus flyby.[52]

During the Earth flyby, the MESSENGER team imagedthe Earth and Moon using MDIS and checked the statusof several other instruments observing the atmosphericand surface compositions and testing the magnetosphereand determining that all instruments tested were workingas expected. This calibration period was intended to en-sure accurate interpretation of data when the spacecraftentered orbit around Mercury.[53]

3.3 Two Venus flybys

Main article: Exploration of Venus

On October 24, 2006 at 08:34 UTC, MESSENGER en-countered Venus at an altitude of 2,992 kilometers (1,859mi). During the encounter, MESSENGER passed behindVenus and entered superior conjunction, a period whenEarth was on the exact opposite side of the Solar System,with the Sun inhibiting radio contact. For this reason, noscientific observations were conducted during the flyby.Communication with the spacecraft was reestablished inlate November and performed a deep space maneuveron December 12, to correct the trajectory to encounterVenus in a second flyby.[54]

On June 5, 2007, at 23:08 UTC,MESSENGER performeda second flyby of Venus at an altitude of 338 km (210 mi),for the greatest velocity reduction of the mission. Dur-ing the encounter, all instruments were used to observe

4 4 PRIMARY SCIENCE

Venus and prepare for the following Mercury encounters.The encounter provided visible and near-infrared imag-ing data of the upper atmosphere of Venus. Ultravioletand X-ray spectrometry of the upper atmosphere werealso recorded, to characterize the composition. TheESA's Venus Express was also orbiting during the en-counter, providing the first opportunity for simultaneousmeasurement of particle-and-field characteristics of theplanet.[55]

3.4 Three Mercury flybys

Main article: Exploration of Mercury

MESSENGER made a flyby of Mercury on January 14,2008 (making its closest approach of 200 km above thesurface of Mercury at 19:04:39 UTC), followed by asecond flyby on October 6, 2008.[8] MESSENGER exe-cuted a final flyby on September 29, 2009, further slow-ing down the spacecraft.[9][10] Sometime during the clos-est approach of the last flyby, the spacecraft entered safemode. Although this had no effect on the trajectory nec-essary for later orbit insertion, it resulted in the loss ofscience data and images that were planned for the out-bound leg of the fly-by. The spacecraft had fully recov-ered by about seven hours later.[56] One last deep spacemaneuver, DSM-5, was executed on November 24, 2009,at 22:45 UTC to provide the required velocity changefor the scheduled Mercury orbit insertion on March 18,2011, marking the beginning of the orbital mission.[57]

3.5 Orbital insertion

The thruster maneuver to insert the probe into Mercury’sorbit began at 00:45 AM (UTC) on March 18, 2011. Themaneuver lasted about 15 minutes, with confirmation thatthe craft was in Mercury orbit received at 1:10 AM (UTC)on March 18 (9:10 PM, March 17 EDT).[51] Mission leadengineer Eric Finnegan indicated that the spacecraft hadachieved a near-perfect orbit.[58]

MESSENGER's orbit was highly elliptical, taking it within200 kilometers (120 mi) of Mercury’s surface and then15,000 km (9,300 mi) away from it every twelve hours.This orbit was chosen to shield the probe from the heatradiated by Mercury’s hot surface. Only a small portionof each orbit was at a low altitude, where the spacecraftwas subjected to radiative heating from the hot side of theplanet.[59]

4 Primary science

After MESSENGER's orbital insertion, an eighteen-daycommissioning phase took place. The supervising per-sonnel switched on and tested the craft’s science in-

struments to ensure they had completed the journeywithout damage.[60] The commissioning phase “demon-strated that the spacecraft and payload [were] all oper-ating nominally, notwithstanding Mercury’s challengingenvironment.”[30]

The primary mission began as planned on April 4, 2011,with MESSENGER orbiting Mercury once every twelvehours for an intended duration of twelve Earth months,the equivalent of two solar days on Mercury.[30] Princi-pal Investigator Sean Solomon, then of the Carnegie In-stitution of Washington, said: “With the beginning to-day of the primary science phase of the mission, wewill be making nearly continuous observations that willallow us to gain the first global perspective on the in-nermost planet. Moreover, as solar activity steadily in-creases, we will have a front-row seat on the most dy-namic magnetosphere–atmosphere system in the SolarSystem.”[30]

On October 5, 2011, the scientific results obtained byMESSENGER during its first six terrestrial months in Mer-cury’s orbit were presented in a series of papers at the Eu-ropean Planetary Science Congress in Nantes, France.[19]

Among the discoveries presented were the unexpectedlyhigh concentrations of magnesium and calcium found onMercury’s nightside, and the fact that Mercury’s magneticfield is offset far to the north of the planet’s center.[19]

4.1 Extended mission

In November 2011, NASA announced that the MESSEN-GER mission would be extended by one year, allowingthe spacecraft to observe the 2012 solar maximum.[1] Itsextended mission began on March 17, 2012, and contin-ued until March 17, 2013. Between April 16 and April20, 2012, MESSENGER carried out a series of thrustermanoeuvres, placing it in an eight-hour orbit to conductfurther scans of Mercury.[61]

In November 2012, NASA reported that MESSEN-GER had discovered both water ice and organic com-pounds in permanently shadowed craters in Mercury’snorth pole.[20][62] In February 2013, NASA publishedthe most detailed and accurate 3D map of Mercuryto date, assembled from thousands of images taken byMESSENGER.[63][64] MESSENGER completed its first ex-tended mission on March 17, 2013,[2] and its secondlasted until April 2015.[18] In November 2013, MESSEN-GER was among the numerous space assets that imagedComet Encke (2P/Encke) and Comet ISON (C/2012S1).[65][66][67] As its orbit began to decay in early 2015,MESSENGER was able to take highly detailed close-upphotographs of ice-filled craters and other landforms atMercury’s north pole.[68]

5

4.2 Discovery of water, organic com-pounds and volcanism

On July 3, 2008, MESSENGER team member ThomasZurbuchen announced that the probe had discoveredlarge amounts of water present in Mercury’s exosphere,which was an unexpected finding.[72] In the later years ofits mission, MESSENGER also provided visual evidenceof past volcanic activity on the surface of Mercury,[73]

as well as evidence for a liquid iron planetary core.[72]

The probe also constructed the most detailed and ac-curate maps of Mercury to date, and furthermore dis-covered carbon-containing organic compounds and waterice inside permanently shadowed craters near the northpole.[11]

5 End of mission

After running out of propellant for course adjustments,MESSENGER entered a terminal phase of orbital decayin late 2014. The spacecraft’s operation was extendedby several weeks by exploiting the remaining supply ofhelium gas, which was used to pressurize the propel-lant tanks, as reaction mass.[15] MESSENGER continuedstudying Mercury during its decay period.[3] The space-craft crashed into the surface of Mercury on 30 April2015 3:26 p.m.EDT (1926 GMT) at 14,080 km/h (8,750mph).[17][74] probably creating a crater in the ground ap-proximately 52 feet (16 m) wide. The spacecraft was es-timated to have impacted at 54.4° N, 149.9° W, near thecrater Janáček.[75] The crash occurred on the side of theplanet not visible from Earth, so it was not detected byany observers or instruments. NASA confirmed MES-SENGER’s end of mission at 3:40 p.m. EDT (1940 GMT)after the time when MESSENGER would have emergedfrom behind Mercury had it remained in orbit. NASA’sDeep Space Network failed to detect a signal from thespacecraft’s beacon, confirming its demise.[74]

MESSENGER - images: first (March 29, 2011) to last (April 30,2015).

6 Solar System portrait

Main article: Family Portrait (MESSENGER)

On February 18, 2011, a portrait of the Solar System waspublished on the MESSENGER website. The mosaic con-tained 34 images, acquired by the MDIS instrument dur-ing November 2010. All the planets were visible with theexception of Uranus and Neptune, due to their vast dis-tances from the Sun. The MESSENGER “family portrait”was intended to be complementary to the Voyager familyportrait, which was acquired from the outer Solar Systemby Voyager 1 on February 14, 1990.[76]

MESSENGER captured a near-complete portrait of the SolarSystem during November 2010.

7 See also

• BepiColombo, a planned European-Japanese Mer-cury mission

• List of active Solar System probes

• Mariner program

• Stamatios Krimigis, a NASA physicist and keycontributor to the mission

8 References[1] “NASA extends spacecraft’s Mercury mission”. UPI.

November 15, 2011. Retrieved December 20, 2012.

[2] “MESSENGER Completes Its First Extended Mission atMercury”. JHU – APL. March 18, 2013. Retrieved July8, 2013.

[3] Wu, Brian (April 3, 2015). “NASA Set to Extend Mer-cury Mission for Another Month”. John’s Hopkins Univer-sity APL (The Science Times). Retrieved April 4, 2015.

[4] “MESSENGER’s Operations at Mercury Extended”.John’s Hopkins University APL (SpaceRef.com). April 3,2015. Retrieved April 4, 2015.

[5] Domingue, D.L.; Russell, C.T.; Domingue, editors ; fore-word by D.L.; Russell, C.T. (2007). Messenger mission toMercury (1st ed. ed.). New York: Springer. p. 225–245.ISBN 9780387772141.

6 8 REFERENCES

[6] Lee, Jimmy; Galuska, Mike (March 18, 2011). “NASAChats - MESSENGER Prepares to Orbit Mercury”.NASA. Archived from the original on June 7, 2011. Re-trieved March 18, 2011.

[7] “NASA Spacecraft Circling Mercury”. New York Times.March 17, 2011. Retrieved July 9, 2013.

[8] “Countdown to MESSENGER’s Closest Approach withMercury” (Press release). Johns Hopkins University. Jan-uary 14, 2008. Retrieved May 1, 2009.

[9] “Critical Deep-Space Maneuver Targets MESSENGERfor Its Second Mercury Encounter” (Press release). JohnsHopkins University. March 19, 2008. Retrieved April 20,2010.

[10] “Deep-Space Maneuver Positions MESSENGER forThird Mercury Encounter” (Press release). Johns Hop-kins University. December 4, 2008. Retrieved April 20,2010.

[11] Wall, Mike (March 29, 2015). “NASA Mercury ProbeTrying to Survive for Another Month”. Space.com. Re-trieved April 4, 2015.

[12] Chang, Kenneth (April 27, 2015). “NASA’s MessengerMission Is Set to Crash Into Mercury”. New York Times.Retrieved April 27, 2015.

[13] Corum, Jonathan (April 30, 2015). “Messenger’s Colli-sion Course With Mercury”. New York Times. RetrievedApril 30, 2015.

[14] “From Mercury orbit, MESSENGER watches a lunareclipse”. Planetary Society. October 10, 2014. RetrievedJanuary 23, 2015.

[15] “Innovative use of pressurant extends MESSENGER’sMercury mission”. Astronomy.com. December 29, 2014.Retrieved January 22, 2015.

[16] “MESSENGER Provides New Look at Mercury’s Land-scape, Metallic Core, and Polar Shadows” (Press release).Johns Hopkins University. March 21, 2012. RetrievedMarch 22, 2012.

[17] Messenger’s Mercury trip ends with a bang, and silence.Jonathan Webb, BBC News. April 30, 2015.

[18] “MESSENGER Surpasses 200,000 Orbital Images ofMercury”. JHU – APL. February 6, 2014. RetrievedApril 14, 2014.

[19] “MESSENGER Team Presents New Mercury Findings atPlanetary Conference”. Johns Hopkins University Ap-plied Physics Laboratory. October 5, 2011. RetrievedNovember 23, 2011.

[20] “NASA probe reveals organics, ice on Mercury”. Reuters.November 29, 2012. Retrieved November 29, 2012.

[21] Rincon, Paul (October 16, 2014). “Mercury’s hiddenwater-ice revealed”. BBC News. Retrieved October 17,2014.

[22] Harmon, J. K.; Slade, M. A.; Vélez, R. A.; Cre-spo, A.; Dryer, M. J.; Johnson, J. M. (1994).“Radar mapping of Mercury’s polar anomalies”. Nature369 (6477): 213–215. Bibcode:1994Natur.369..213H.doi:10.1038/369213a0. ISSN 0028-0836.

[23] Malik, Tariq (August 16, 2004). “MESSENGER to testtheory of shrinking Mercury”. USA Today. RetrievedMay 23, 2012.

[24] McAdams, J. V.; J. L. Horsewood; C. L. Yen (August10–12, 1998). “1998 Astrodynamics Specialist Confer-ence” (PDF). Boston, MA: American Institute of Aero-nautics and Astronautics/American Astronautical Society.pp. 109–115. AIAA-98-4283. |chapter= ignored (help)

[25] “MESSENGER - Mission description”. NASA. Re-trieved July 8, 2013.

[26] “Discovery Program: MESSENGER”. NASA. RetrievedJuly 8, 2013.

[27] “MESSENGER NASA’s Mission to Mercury LaunchPress Kit” (PDF) (Press release). NASA / JHUAPL. Au-gust 2004. Archived from the original (PDF) on 2007-08-24. Retrieved 2011-02-19.

[28] “MESSENGER Completes Primary Mission at Mercury,Settles in for Another Year” (Press release). Johns Hop-kins University. March 19, 2012. Retrieved 2012-04-10.

[29] “The Medium-gain Antenna of the MESSENGER Space-craft”. Microwave Journal. October 1, 2005. Retrieved2011-03-19.

[30] “MESSENGER Kicks Off Yearlong Campaign of Mer-cury Science”. JHU – APL. April 4, 2011. RetrievedNovember 23, 2011.

[31] Hawkins, S. Edward; John D. Boldt; Edward H. Dar-lington; Raymond Espiritu; Robert E. Gold; BruceGotwols; Matthew P. Grey; Christopher D. Hash;John R. Hayes; Steven E. Jaskulek et al. (Au-gust 1, 2007). “The Mercury Dual Imaging Systemon the MESSENGER spacecraft”. Space Science Re-views 131: 247–338. Bibcode:2007SSRv..131..247H.doi:10.1007/s11214-007-9266-3.

[32] “Mercury Dual Imaging System (MDIS)".NASA/National Space Science Data Center. RetrievedFebruary 19, 2011.

[33] Hash, Christopher; Raymond Espiritu; Erick Malaret;Louise Prockter; Scott Murchie; Alan Mick; JenniferWard (2007). “MESSENGER Mercury Dual ImagingSystem (MDIS) Experimental Data Record (EDR) Soft-ware Interface Specification (SIS)" (PDF).

[34] Goldsten, John O.; Edgar A. Rhodes; William V.Boynton; William C. Feldman; David J. Lawrence;Jacob I. Trombka; David M. Smith; Larry G. Evans;Jack White; Norman W. Madden et al. (November 8,2007). “The MESSENGER Gamma-Ray and NeutronSpectrometer”. Space Science Reviews 131: 339–391.Bibcode:2007SSRv..131..339G. doi:10.1007/s11214-007-9262-7.

7

[35] “Gamma-Ray and Neutron Spectrometer (GRNS)".NASA / National Space Science Data Center. Retrieved2011-02-19.

[36] Schlemm, Charles; Richard D. Starr; George C. Ho;Kathryn E. Bechtold; Sarah A. Hamilton; John D. Boldt;William V. Boynton; Walter Bradley; Martin E. Fraeman;Robert E. Gold et al. (2007). “The X-Ray Spectrome-ter on the MESSENGER Spacecraft”. Space Science Re-views 131 (1): 393–415. Bibcode:2007SSRv..131..393S.doi:10.1007/s11214-007-9248-5.

[37] “X-ray Spectrometer (XRS)". NASA / National SpaceScience Data Center. Retrieved 2011-02-19.

[38] Anderson, Brian J.; Mario H. Acuña; David A.Lohr; John Scheifele; Asseem Raval; Haje Korth &James A. Slavin (2007). “The Magnetometer In-strument on MESSENGER”. Space Science Reviews131 (1): 417–450. Bibcode:2007SSRv..131..417A.doi:10.1007/s11214-007-9246-7.

[39] “Magnetometer (MAG)". NASA / National Space Sci-ence Data Center. Retrieved 2011-02-19.

[40] Cavanaugh, John F.; James C. Smith; Xiaoli Sun; ArlinE. Bartels; Luis Ramos-Izquierdo; Danny J. Krebs; JanF. McGarry; Raymond Trunzo; Anne Marie Novo-Gradac; Jamie L. Britt et al. (2007). “The MercuryLaser Altimeter Instrument for the MESSENGERMission”. Space Science Reviews 131 (1): 451–479.Bibcode:2007SSRv..131..451C. doi:10.1007/s11214-007-9273-4.

[41] “Mercury Laser Altimeter (MLA)". NASA / NationalSpace Science Data Center. Retrieved 2011-02-19.

[42] McClintock, William; Mark Lankton (2007). “The Mer-cury Atmospheric and Surface Composition Spectrometerfor the MESSENGER Mission”. Space Science Reviews131 (1): 481–521. Bibcode:2007SSRv..131..481M.doi:10.1007/s11214-007-9264-5.

[43] “Mercury Atmospheric and Surface Composition Spec-trometer (MASCS)". NASA / National Space ScienceData Center. Retrieved 2011-02-19.

[44] Andrews, G. Bruce; Thomas H. Zurbuchen; BarryH. Mauk; Horace Malcom; Lennard A. Fisk; GeorgeGloeckler; George C. Ho; Jeffrey S. Kelley; Patrick L.Koehn; Thomas W. LeFevere et al. (2007). “The En-ergetic Particle and Plasma Spectrometer Instrument onthe MESSENGER Spacecraft”. Space Science Reviews131 (1): 523–556. Bibcode:2007SSRv..131..523A.doi:10.1007/s11214-007-9272-5.

[45] “Energetic Particle and Plasma Spectrometer (EPPS)".NASA / National Space Science Data Center. Retrieved2011-02-19.

[46] Srinivasan, Dipak K.; Mark E. Perry; Karl B. Fiel-hauer; David E. Smith; Maria T. Zuber (2007). “TheRadio Frequency Subsystem and Radio Science onthe MESSENGER Mission”. Space Science Reviews131 (1): 557–571. Bibcode:2007SSRv..131..557S.doi:10.1007/s11214-007-9270-7.

[47] “Earth Flyby Timeline”. JHU/APL. August 2, 2005. Re-trieved January 24, 2011.

[48] “Mercury Flyby 1” (PDF) (Press release). JHU/APL. Jan-uary 14, 2008. Retrieved January 24, 2011.

[49] “Mercury Flyby 2” (PDF) (Press release). JHU/APL. Oc-tober 6, 2008. Retrieved January 24, 2011.

[50] “Mercury Flyby 3” (PDF) (Press release). JHU/APL.September 29, 2009. Retrieved January 24, 2011.

[51] “MESSENGER Begins Historic Orbit around Mercury”(Press release). NASA/APL. March 17, 2011. RetrievedMarch 18, 2011.

[52] “MESSENGER Engine Burn Puts Spacecraft on Trackfor Venus” (Press release). Johns Hopkins University.December 12, 2005. Retrieved May 1, 2009.

[53] “MESSENGER Status Report” (Press release).NASA/APL. August 26, 2005. Retrieved March17, 2011.

[54] “MESSENGER Completes Venus Flyby” (Press release).NASA/APL. October 24, 2006. Retrieved 2011-03-17.

[55] “Critical Deep-Space Maneuver Targets MESSENGERfor Its First Mercury Encounter” (Press release). JohnsHopkins University. October 17, 2007. Retrieved 2009-05-01.

[56] “MESSENGER Gains Critical Gravity Assist for MercuryOrbital Observations”. MESSENGER Mission News.September 30, 2009. Retrieved September 30, 2009.

[57] “Deep-Space Maneuver Positions MESSENGER forMercury Orbit Insertion” (Press release). Johns HopkinsUniversity. November 24, 2009. Retrieved April 20,2010.

[58] Roylance, Frank (March 17, 2011). “Messenger success-fully goes into orbit around Mercury”. Baltimore Sun. Re-trieved March 18, 2011.

[59] Cowen, Ron (March 17, 2011). “MESSENGER easesinto Mercury’s orbit”. Science News. Retrieved March 18,2011.

[60] “MESSENGER Mercury Orbit Insertion” (PDF) (Pressrelease). NASA/APL. March 18, 2011. Retrieved March17, 2011.

[61] “Messenger settles into new orbit to probe Mercury”.Wired UK. April 24, 2012. Retrieved April 29, 2012.

[62] “Mercury’s water ice at north pole finally proven”. BBC.November 30, 2012. Retrieved November 30, 2012.

[63] “New Nasa Photos Show Off Mercury In Brilliant 3D Map(VIDEO)". Huffington Post. February 16, 2013. Re-trieved February 16, 2013.

[64] “Mercury shows off its colourful side”. BBC. February16, 2013. Retrieved February 16, 2013.

[65] “MESSENGER Detects Comets ISON and Encke, Pre-pares for Closer Encounters”. USRA.edu. November 15,2013. Retrieved January 23, 2015.

8 9 EXTERNAL LINKS

[66] Staff (December 6, 2013). “How NASA Space AssetsObserved Comet ISON”. NASA. Retrieved May 11,2014.

[67] Sekanina, Zdenek; Kracht, Rainer (May 8, 2014).“Disintegration of Comet C/2012 S1 (ISON) Shortly Be-fore Perihelion: Evidence From Independent Data Sets”(PDF). arXiv. Retrieved May 11, 2014.

[68] “Best views yet of Mercury’s ice-filled craters”. BBCNews. March 17, 2015. Retrieved March 18, 2015.

[69] “High-resolution Hollows”. MESSENGER Featured Im-ages. JHU - APL. 2014-03-12. Archived from the origi-nal on 2014-03-14.

[70] Lakdawalla, E. (2014-02-18). “What are Mercury’s hol-lows?". Planetary Society. Retrieved 2015-05-01.

[71] “High-resolution Hollows”. MESSENGER Featured Im-ages. JHU - APL. 2014-03-12. Archived from the origi-nal on 2014-03-14.

[72] Lakdawalla, Emily (July 3, 2008). “MESSENGER Scien-tists 'Astonished' to Find Water in Mercury’s Thin Atmo-sphere”. The Planetary Society. Retrieved May 1, 2009.

[73] Head, James W.; Chapman, Clark R.; Strom, RobertG.; Fassett1,, Caleb I.; Denevi, Brett W. (30 Septem-ber 2011). “Flood Volcanism in the Northern High Lati-tudes of Mercury Revealed by MESSENGER”. Science33 (6051): 1853–1856. doi:10.1126/science.1211997.Retrieved April 4, 2015.

[74] space.com 2015-04-30 04:35pm ET Farewell, MESSEN-GER! NASA Probe Crashes Into Mercury

[75] [http://www.universetoday.com/120043/mercury-messenger-mission-concludes-with-a-smashing-finale/Mercury Messenger Mission Ends with a Smashing Fi-nale[, Universe Today

[76] “A Solar System Family Portrait, from the Inside Out”(Press release). APL. February 18, 2011. RetrievedFebruary 18, 2011.

9 External links• JHUAPL homepage – official site at Johns Hopkins

University Applied Physics Laboratory

• MESSENGER Mission Page – official informationregarding the mission on the nasa.gov website

• MESSENGER Mission Profile by NASA’s SolarSystem Exploration

• Mercury Flyby 1 Visualization Tool and MercuryFlyby 1 Actuals – comparison between simulatedviews of Mercury to the images actually acquiredby MESSENGER during flyby 1

• Mercury Flyby 2 Visualization Tool and MercuryFlyby 2 Actuals – comparison between simulatedviews of Mercury to the images actually acquiredby MESSENGER during flyby 2

• MESSENGER Image Gallery

• NSSDC Master Catalog entry

• Video from MESSENGER as it departs Earth

• Mercury data collected by both Mariner 10 andMESSENGER

9

10 Text and image sources, contributors, and licenses

10.1 Text• MESSENGER Source: http://en.wikipedia.org/wiki/MESSENGER?oldid=660195433 Contributors: The Epopt, Bryan Derksen, An-

dre Engels, Rmhermen, Heron, Patrick, Iluvcapra, Jniemenmaa, Andres, Conti, Stone, Malcohol, Doradus, Timc, Tempshill, Wernher,Raul654, AnonMoos, Chrisjj, Pigsonthewing, Enceladus, PedroPVZ, Alexwcovington, Jpo, Gtrmp, Awolf002, Sthneed, Lethe, Karn,Wwoods, Curps, JamesHoadley, Yekrats, DX, Matt Crypto, Python eggs, Joseph Dwayne, Andycjp, Keith Edkins, Alexf, Beland, Felin-eAvenger, Kaldari, Icairns, Neutrality, Urhixidur, Peter bertok, Lostchicken, N328KF, O'Dea, Jkl, Jørgen Friis Bak, LuckyStarr, Arnol-dReinhold, IlyaHaykinson, Ponder, JPX7, Bender235, El C, Huntster, Ganesha, Mdf, Remember, Devil Master, PatrikR, Che090572,Elipongo, Jojit fb, Miranche, Philip Cross, Kfitzgib, Ruleke, VladimirKorablin, SidP, Gdavidp, Evil Monkey, Gene Nygaard, John-tex, Kitch, BerserkerBen, Brookie, Stephen, Zntrip, Gmaxwell, Thryduulf, Reinoutr, Bushytails, Ylem, Bkkbrad, BillC, Bricktop, MiG,BlaiseFEgan, Eyreland, Studio34, Emerson7, David Levy, Jcmo, Drbogdan, Rjwilmsi, Tim!, Mike s, Ligulem, Bubba73, Matt Deres,FlaBot, SchuminWeb, G Clark, Gparker, Goudzovski, Chobot, Ahpook, RussBot, Chaser, Hellbus, Brian A Schmidt, RadioFan, Archelon,Eleassar, Gcapp1959, Marcus Cyron, NawlinWiki, FFLaguna, Ravedave, Mysid, Gadget850, Bota47, Jessemerriman, Ms2ger, Ageek-gal, Vicarious, Hurricane Devon, Philip Stevens, GrinBot~enwiki, Sardanaphalus, Attilios, SmackBot, Zazaban, Cdogsimmons, Nickst,Kintetsubuffalo, Man with two legs, Galloglass, Skizzik, Jordan.Kreiger, Hibernian, Sbharris, Colonies Chris, WDGraham, OrphanBot,LouScheffer, Andy120290, Flyguy649, Lostart, Algr, CFLeon, ArglebargleIV, John, Pomakis, Onlim, JorisvS, RandomCritic, AndrésD., Pappubahry, Slakr, Rock4arolla, Xiaphias, Akitstika, Novangelis, Xionbox, Masem, Myopic Bookworm, Joseph Solis in Australia,Earnric, Courcelles, George100, SkyWalker, Surasaman, Olaf Davis, Drinibot, ThreeBlindMice, Ruslik0, N2e, Necessary Evil, Cydebot,Kanags, Reywas92, Gogo Dodo, Jaerik, Msebast~enwiki, Davidelit, Headbomb, WillMak050389, Bobblehead, Saeid.aghaei, Escarbot,Luna Santin, Ricnun, QuiteUnusual, Poshzombie, JAnDbot, MER-C, Planetary, IanOsgood, Andonic, Rothorpe, WolfmanSF, VoABotII, Usien6, Jatkins, BatteryIncluded, BilCat, Stephenchou0722, Ebellii, R'n'B, AlexiusHoratius, Pdeitiker, Mikek999, Tinwelint, TomSTDotO, Aqwis, Rod57, Nwbeeson, Rosenknospe, Ohms law, ACBest, Lord Jubjub, Laager, VolkovBot, TreasuryTag, Jeff G., Aesopos,Sdsds, Yovinedelcielo, Jacknye, Broadbot, Entropy1963, SpikeZOM, Truthanado, Vinhtantran, AlleborgoBot, SieBot, Calliopejen1, Portal-ian, BotMultichill, Sakkura, KGyST, Crash Underride, Toddst1, Oxymoron83, Lightmouse, Murlough23, Nipsonanomhmata, Randy Kryn,ImageRemovalBot, MBK004, ClueBot, Trojancowboy, Avenged Eightfold, GorillaWarfare, Anonymous799, Gits (Neo), EoGuy, Rilak,Wwheaton, Jezza333, Fleem, Av0id3r, Piledhigheranddeeper, Ktr101, Naleh, PixelBot, Njardarlogar, Chaosdruid, MATRIX, BWH76,Infidelis, SuddenFrost, Jmsmcnll, Alaypj, Rolandscholten, Poobrain765, Addbot, Mortense, Roentgenium111, Fluffernutter, Download,84user, David Asher, Lightbot, HerculeBot, Luckas-bot, Aldebaran66, Цуканов Кирилл, AnomieBOT, DemocraticLuntz, Empg98, Ma-terialscientist, RadioBroadcast, Citation bot, ArthurBot, LilHelpa, Xqbot, Sketchmoose, Nrpf22pr, Fishhawkg, GrouchoBot, Alan.A.Mick,Fotaun, FrescoBot, Originalwana, 117Avenue, Tom.Reding, RedBot, Beao, Burke3934, Jirka.h23, IVAN3MAN, Belchman, Tbhotch,RjwilmsiBot, Ripchip Bot, WikitanvirBot, Tinss, GoingBatty, JustinTime55, Black Yoshi, Wikipelli, ZéroBot, Traxs7, Rppeabody, Pipposkaio, SporkBot, Music Sorter, Adamjaviv, Jguy, Whoop whoop pull up, Alcazar84, ClueBot NG, Michaelmas1957, रामा, SarasotaDreams,Sleddog116, Xession, A wild Rattata, Frietjes, Danim, Mrmalloy, Ballztoyou:), Bibcode Bot, Arielwaldman, BG19bot, SpaceChimp1992,Rodrigolopes, Ninney, Arlin Bartels, Vesna Wylde, Darrman, Jjjliu, BattyBot, Dplcrnj, Jcardazzi, Hilarmont, I am One of Many, Geoboy09,Tjraptis20, JeanLucMargot, Artman maine, Lolannaicker, Monkbot, LeFagget, Tauwe1, Tetra quark, EternalNomad and Anonymous: 198

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10 10 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:Hypergolic_Fuel_for_MESSENGER.jpg Source: http://upload.wikimedia.org/wikipedia/commons/2/2a/Hypergolic_Fuel_for_MESSENGER.jpg License: Public domain Contributors: http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=23320 Original artist:NASA

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• File:MESSENGER_-_EPPS.jpg Source: http://upload.wikimedia.org/wikipedia/commons/2/29/MESSENGER_-_EPPS.jpg License:Public domain Contributors: http://messenger.jhuapl.edu/instruments/EPPS.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_GRS_-_GRNS.jpg Source: http://upload.wikimedia.org/wikipedia/commons/b/b7/MESSENGER_-_GRS_-_GRNS.jpg License: Public domain Contributors: http://messenger.jhuapl.edu/instruments/GRNS.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_MAG.jpg Source: http://upload.wikimedia.org/wikipedia/commons/c/c1/MESSENGER_-_MAG.jpg License:Public domain Contributors: http://messenger.jhuapl.edu/instruments/MAG.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_MASCS.jpg Source: http://upload.wikimedia.org/wikipedia/commons/9/9e/MESSENGER_-_MASCS.jpg Li-cense: Public domain Contributors: http://messenger.jhuapl.edu/instruments/MASCS.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_MDIS.jpg Source: http://upload.wikimedia.org/wikipedia/commons/b/b8/MESSENGER_-_MDIS.jpg License:Public domain Contributors: http://messenger.jhuapl.edu/instruments/MDIS.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_NS.jpg Source: http://upload.wikimedia.org/wikipedia/commons/1/19/MESSENGER_-_NS.jpg License: Publicdomain Contributors: http://messenger.jhuapl.edu/instruments/GRNS.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_Sonda.png Source: http://upload.wikimedia.org/wikipedia/commons/2/28/MESSENGER_-_Sonda.png License:Public domain Contributors: ? Original artist: ?

• File:MESSENGER_-_Venus2_departure_seq.jpg Source: http://upload.wikimedia.org/wikipedia/commons/1/16/MESSENGER_-_Venus2_departure_seq.jpg License: Public domain Contributors: http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=87 Original artist: NASA / JHU/APL

• File:MESSENGER_-_Venus_630_nm_stretch.jpg Source: http://upload.wikimedia.org/wikipedia/commons/3/3b/MESSENGER_-_Venus_630_nm_stretch.jpgLicense: Public domainContributors: http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=327 Original artist: NASA / JHU/APL

• File:MESSENGER_-_XRS.jpg Source: http://upload.wikimedia.org/wikipedia/commons/c/c2/MESSENGER_-_XRS.jpg License:Public domain Contributors: http://messenger.jhuapl.edu/instruments/XRS.html Original artist: NASA / JHU/APL

• File:MESSENGER_-_exploded_launch_vehicle_diagram.png Source: http://upload.wikimedia.org/wikipedia/commons/2/2c/MESSENGER_-_exploded_launch_vehicle_diagram.png License: Public domain Contributors: MESSENGER NASA’s Mission toMercury Launch Press Kit pg. 14 Original artist: NASA / JHU/APL

• File:MESSENGER_-_installation_of_solar_panels.jpg Source: http://upload.wikimedia.org/wikipedia/commons/2/2a/MESSENGER_-_installation_of_solar_panels.jpg License: Public domain Contributors: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2664 Original artist: NASA

• File:MESSENGER_04pd1465.jpg Source: http://upload.wikimedia.org/wikipedia/commons/1/11/MESSENGER_04pd1465.jpg Li-cense: Public domain Contributors: http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=23310 Original artist: NASA

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• File:MESSENGER_EN0108828359M.png Source: http://upload.wikimedia.org/wikipedia/commons/7/72/MESSENGER_EN0108828359M.png License: Public domain Contributors: http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0108828359M.png Original artist: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

• File:MESSENGER_Solar_System_Family_Portrait.jpg Source: http://upload.wikimedia.org/wikipedia/commons/6/65/MESSENGER_Solar_System_Family_Portrait.jpg License: Public domain Contributors: NASA Image of the Day Original artist:NASA, Johns Hopkins University Applied Physics Laboratory, Carnegie Institution of Washington

• File:MESSENGER_launch_on_Delta_7925_rocket.jpg Source: http://upload.wikimedia.org/wikipedia/commons/d/dd/MESSENGER_launch_on_Delta_7925_rocket.jpg License: Public domain Contributors: http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=23529 (image link) Original artist: NASA/KSC

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• File:MESSENGERannouncement.jpg Source: http://upload.wikimedia.org/wikipedia/commons/9/98/MESSENGERannouncement.jpg License: Public domain Contributors: MESSENGER Website Original artist: NASA, Jet Propulsion Laboratory, Applied PhysicsLaboratory

• File:MESSENGERearth.jpg Source: http://upload.wikimedia.org/wikipedia/commons/6/67/MESSENGERearth.jpg License: Publicdomain Contributors: MESSENGER Website Original artist: NASA, Jet Propulsion Laboratory, Applied Physics Laboratory

• File:MESSENGERmercurylimb.PNG Source: http://upload.wikimedia.org/wikipedia/commons/f/fc/MESSENGERmercurylimb.PNG License: Public domain Contributors: ? Original artist: NASA, JPL, APL (Jet Propulsion Laboratory)

10.2 Images 11

• File:MESSENGERridges.png Source: http://upload.wikimedia.org/wikipedia/commons/9/95/MESSENGERridges.png License: Publicdomain Contributors: MESSENGER Website Original artist: NASA, Jet Propulsion Laboratory, Applied Physics Laboratory

• File:MESSENGERsouthpole.png Source: http://upload.wikimedia.org/wikipedia/commons/a/a8/MESSENGERsouthpole.png License:Public domain Contributors: MESSENGER Website Original artist: NASA, Jet Propulsion Laboratory, Applied Physics Laboratory

• File:MESSENGERvenus1approach.jpg Source: http://upload.wikimedia.org/wikipedia/commons/3/3e/MESSENGERvenus1approach.jpg License: Public domain Contributors: MESSENGER Website Original artist: NASA, Jet PropulsionLaboratory, Applied Physics Laboratory

• File:Maat_Mons_on_Venus.jpg Source: http://upload.wikimedia.org/wikipedia/commons/1/16/Maat_Mons_on_Venus.jpg License:Public domain Contributors: ? Original artist: ?

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• File:Mercury.jpg Source: http://upload.wikimedia.org/wikipedia/commons/c/c5/Mercury.jpg License: Public domain Contributors: ?Original artist: ?

• File:MercuryOrbitInsertionDirectionofSunFull.jpg Source: http://upload.wikimedia.org/wikipedia/commons/0/05/MercuryOrbitInsertionDirectionofSunFull.jpg License: Public domain Contributors: MESSENGER Website Original artist: NASA, JetPropulsion Laboratory, Applied Physics Laboratory

• File:Mercury_in_color_-_Prockter07_centered.jpg Source: http://upload.wikimedia.org/wikipedia/commons/3/30/Mercury_in_color_-_Prockter07_centered.jpg License: Public domain Contributors: NASA/JPL [1] Original artist: NASA/Johns Hopkins UniversityApplied Physics Laboratory/Carnegie Institution of Washington. Edited version of Image:Mercury in color - Prockter07.jpg by Papa LimaWhiskey.

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• File:Mercurymessengerstrips.jpg Source: http://upload.wikimedia.org/wikipedia/commons/b/b2/Mercurymessengerstrips.jpg License:Public domain Contributors: Transferred from en.wikipedia to Commons.

(Original text : from http://messenger.jhuapl.edu/images/rotatePics/File3a.jpgOriginal artist: ?

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• File:PIA19285-Mercury-GravityAnomalies-Messenger-20150415.jpg Source: http://upload.wikimedia.org/wikipedia/commons/0/03/PIA19285-Mercury-GravityAnomalies-Messenger-20150415.jpg License: Public domain Contributors: http://photojournal.jpl.nasa.gov/jpeg/PIA19285.jpg Original artist: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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• File:PIA19449-PlanetMercury-MESSENGER-Images-First-20110329-Last-20150430.jpg Source: http://upload.wikimedia.org/wikipedia/commons/7/75/PIA19449-PlanetMercury-MESSENGER-Images-First-20110329-Last-20150430.jpg License: Public do-main Contributors: http://photojournal.jpl.nasa.gov/jpeg/PIA19449.jpg Original artist: NASA/Johns Hopkins University Applied PhysicsLaboratory/Carnegie Institution of Washington

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• File:Venus_2_Approach_Image.jpg Source: http://upload.wikimedia.org/wikipedia/commons/b/b2/Venus_2_Approach_Image.jpg Li-cense: Public domain Contributors: ? Original artist: ?

12 10 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:View_of_Earth_from_MESSENGER.jpg Source: http://upload.wikimedia.org/wikipedia/commons/a/a2/View_of_Earth_from_MESSENGER.jpg License: Public domain Contributors: NASA Earth Observatory Original artist: Image courtesy NASA, Johns HopkinsUniversity Applied Physics Laboratory, and Carnegie Institution of Washington.

• File:Vénus_télescope.jpg Source: http://upload.wikimedia.org/wikipedia/commons/c/cc/V%C3%A9nus_t%C3%A9lescope.jpg Li-cense: GFDL Contributors: http://astrosurf.com/lecleire/2007/venuscolor_100907_05h22.jpg Original artist: Marc Lecleire

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