Editing MESSENGER (section)

==Primary science==
After ''MESSENGER'''s orbital insertion, an eighteen-day commissioning phase took place. The supervising personnel switched on and tested the craft's science instruments to ensure they had completed the journey without damage.<ref name="OrbitInsertionPressKit">{{cite press release| publisher=NASA/APL| date=March 18, 2011| title=MESSENGER Mercury Orbit Insertion| url=http://messenger.jhuapl.edu/news_room/Mercury_PK_TST_Rev7_Web.pdf| access-date=March 17, 2011| url-status=dead| archive-url=https://web.archive.org/web/20130513075203/http://messenger.jhuapl.edu/news_room/Mercury_PK_TST_Rev7_Web.pdf| archive-date=May 13, 2013}}</ref> The commissioning phase "demonstrated that the spacecraft and payload [were] all operating nominally, notwithstanding Mercury's challenging environment."<ref name="jhuapl"/>

The primary mission began as planned on April 4, 2011, with ''MESSENGER'' orbiting Mercury once every twelve hours for an intended duration of twelve Earth months, the equivalent of two [[solar day]]s on Mercury.<ref name="jhuapl">[http://messenger.jhuapl.edu/news_room/details.php?id=166 "MESSENGER Kicks Off Yearlong Campaign of Mercury Science"] {{webarchive|url=https://web.archive.org/web/20130412074056/http://messenger.jhuapl.edu/news_room/details.php?id=166 |date=April 12, 2013 }}. JHU – APL. April 4, 2011. Retrieved November 23, 2011.</ref> Principal Investigator Sean Solomon, then of the [[Carnegie Institution of Washington]], said: "With the beginning today of the primary science phase of the mission, we will be making nearly continuous observations that will allow us to gain the first global perspective on the innermost planet. Moreover, as solar activity steadily increases, we will have a front-row seat on the most dynamic magnetosphere–atmosphere system in the Solar System."<ref name="jhuapl"/>

On October 5, 2011, the scientific results obtained by ''MESSENGER'' during its first six terrestrial months in Mercury's orbit were presented in a series of papers at the European Planetary Science Congress in [[Nantes]], France. Among the discoveries presented were the unexpectedly high concentrations of [[magnesium]] and [[calcium]] found in the [[Exosphere#The Exosphere of Mercury|atmosphere]] of Mercury's nightside, and the fact that Mercury's [[magnetic field]] is offset far to the north of the planet's center.<ref name = Nantes5>{{Cite web |date=October 5, 2011 |title=MESSENGER Team Presents New Mercury Findings at Planetary Conference |url=http://messenger.jhuapl.edu/news_room/details.php?id=185 |archive-url=https://web.archive.org/web/20130513075758/http://messenger.jhuapl.edu/news_room/details.php?id=185 |archive-date=May 13, 2013 |access-date= |website=Johns Hopkins University Applied Physics Laboratory}}</ref>

<gallery class="center" widths="175" heights="135" style="font-size:95%; line-height:130%">
File:MESSENGERmercurylimb.PNG|alt=A Monochrome view of Mercury from MESSENGER|A [[monochrome]] image of Mercury from ''MESSENGER'', with [[Warhol (crater)|Warhol]] at center.
File:Stevenson crater (MESSENGER).png|alt=Crater Stevenson, with [[crater chain]]s forming an 'x' across its surface|[[Stevenson (crater)|Stevenson]] crater, with two perpendicular [[Secondary crater|secondary]] [[crater chain]]s running through its center.
File:MESSENGERsouthpole.png|alt=A South Polar Projection of Mercury|A south [[polar projection]] of Mercury.
File:MESSENGERridges.png|alt=A close snapshot of Ridges near the South Pole|A close snapshot of ridges near Mercury's south pole.
File:Tectonically Active Planet Mercury.jpg|A [[False color#False_color|false-color]] ''MESSENGER'' composite image of Mercury shows previously undetected fault scarps— cliff-like landforms resembling stairs that are small enough that scientists believe they are geologically young. This shows that Mercury is still contracting, and that Earth is not the only tectonically active Solar System planet.
</gallery>

===Extended mission===
[[File:MercuryTopo.png|thumb|right|Topography of Mercury based on MDIS (Mercury Dual Imaging System) data]]
In November 2011, NASA announced that the ''MESSENGER'' mission would be extended by one year, allowing the spacecraft to observe the 2012 [[solar maximum]].<ref name=Extended2013/> Its extended mission began on March 17, 2012, and continued until March 17, 2013. Between April 16 and 20, 2012, ''MESSENGER'' carried out a series of thruster manoeuvres, placing it in an eight-hour orbit to conduct further scans of Mercury.<ref>[https://www.wired.co.uk/news/archive/2012-04/24/messenger-settles-into-new-orbit-to-probe-mercury "Messenger settles into new orbit to probe Mercury"] {{webarchive|url=https://web.archive.org/web/20120426223523/http://www.wired.co.uk/news/archive/2012-04/24/messenger-settles-into-new-orbit-to-probe-mercury |date=April 26, 2012 }}. ''[[Wired (magazine)|Wired UK]]''. April 24, 2012. Retrieved April 29, 2012.</ref>

In November 2012, NASA reported that ''MESSENGER'' had discovered a possibility of both [[ice|water ice]] and organic compounds in permanently shadowed craters in Mercury's north pole.<ref name="IceonMercury">{{cite news |date=November 29, 2012 |title=NASA probe reveals organics, ice on Mercury |url=https://reuters.com/article/us-space-mercury-idUKBRE8AS17F20121129 |access-date=November 29, 2012 |work=Reuters}}</ref><ref>{{cite web|url=https://www.bbc.co.uk/news/science-environment-20553879|title=Mercury's water ice at north pole finally proven|publisher=BBC|date=November 30, 2012|access-date=November 30, 2012}}</ref><ref>{{Cite web |date=2019-08-02 |title=The Moon and Mercury May Have Thick Ice Deposits - NASA |url=https://www.nasa.gov/solar-system/the-moon-and-mercury-may-have-thick-ice-deposits/ |access-date=2024-11-19 |language=en-US}}</ref> In February 2013, NASA published the most detailed and accurate 3D map of Mercury to date, assembled from thousands of images taken by ''MESSENGER''.<ref>{{cite web|url=http://www.huffingtonpost.co.uk/2013/02/16/nasa-mercury-3d-map_n_2700218.html|title=New Nasa Photos Show Off Mercury In Brilliant 3D Map (VIDEO)|work=Huffington Post|date=February 16, 2013|access-date=February 16, 2013}}</ref><ref>{{cite web|url=https://www.bbc.co.uk/news/science-environment-21468172|title=Mercury shows off its colourful side|publisher=BBC|date=February 16, 2013|access-date=February 16, 2013}}</ref> ''MESSENGER'' completed its first extended mission on March 17, 2013,<ref name=ExMissionCompleted2013/> and its second lasted until April 2015.<ref name=200,000ImagesSurpassed/> In November 2013, ''MESSENGER'' was among the numerous space assets that imaged [[Comet Encke]] (2P/Encke) and [[Comet ISON]] (C/2012 S1).<ref>[http://www.lpi.usra.edu/planetary_news/2013/11/15/messenger-detects-comets-ison-and-encke-prepares-for-closer-encounters/ "MESSENGER Detects Comets ISON and Encke, Prepares for Closer Encounters"]. USRA.edu. November 15, 2013. Retrieved January 23, 2015.</ref><ref name="NASA-20131206">{{cite web |author=Staff |title=How NASA Space Assets Observed Comet ISON |url=https://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=17405 |archive-url=https://web.archive.org/web/20140202100625/https://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=17405 |url-status=dead |archive-date=February 2, 2014 |date=December 6, 2013 |publisher=[[NASA]] |access-date=May 11, 2014 }}</ref><ref name="ARXIV-20140508">{{cite arXiv |last1=Sekanina |first1=Zdenek |last2=Kracht |first2=Rainer |title=Disintegration of Comet C/2012 S1 (ISON) Shortly Before Perihelion: Evidence From Independent Data Sets |eprint=1404.5968|date=May 8, 2014  |class=astro-ph.EP }}</ref> As its orbit began to decay in early 2015, ''MESSENGER'' was able to take highly detailed close-up photographs of ice-filled craters and other landforms at Mercury's north pole.<ref name=DyingGifts>{{cite news|url=https://www.bbc.co.uk/news/science-environment-31917308|title=Best views yet of Mercury's ice-filled craters|work=BBC News|date=March 17, 2015|access-date=March 18, 2015}}</ref>  After the mission was completed, review of the radio ranging data provided the first measurement of the rate of mass loss from the Sun.<ref>{{cite journal |title=Solar system expansion and strong equivalence principle as seen by the NASA MESSENGER mission |author1=Antonio Genova|author2=Erwan Mazarico|author3=Sander Goossens|author4=Frank G. Lemoine|author5=Gregory A. Neumann|author6=David E. Smith|author7=Maria T. Zuber |journal=Nature Communications |volume=9 |issue=289 |date=January 18, 2018 |page=289 |doi=10.1038/s41467-017-02558-1|pmid=29348613 |pmc=5773540 |bibcode=2018NatCo...9..289G |doi-access=free }}</ref>
<gallery class="center" widths="175" heights="135" style="font-size:95%; line-height:130%">
File:PIA19247-Mercury-NPolarRegion-Messenger20150316.jpg|False-color map showing maximum temperatures of north polar region.
File:Crater Apollodor and Pantheon Fossae.jpg|Crater [[Apollodorus (crater)|Apollodorus]], with the [[Pantheon Fossae]] radiating from it.
File:EW1026656707Gnomap.png|[[Ray system|Crater rays]] streaking across the planet's southern hemisphere.
File:Hollows in Sholem Aleichem.jpg|[[Hollows (Mercury)|Hollows]] in the wall of crater [[Sholem Aleichem (crater)|Sholem Aleichem]].<ref>{{cite web|url=http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1349|title=High-resolution Hollows|work=MESSENGER Featured Images|date=March 12, 2014|publisher=JHU - APL|archive-url=https://web.archive.org/web/20140314010953/http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1349|archive-date=March 14, 2014|url-status=dead}}</ref><ref name = "Lakdawalla2014.02.18">{{cite web|last = Lakdawalla|first = E.|author-link = Emily Lakdawalla|title = What are Mercury's hollows?|publisher = [[Planetary Society]]|date = February 18, 2014|url = http://www.planetary.org/blogs/emily-lakdawalla/2014/02171332-what-are-mercurys-hollows.html|access-date = May 1, 2015 }}</ref>
File:PIA19450-PlanetMercury-CalorisBasin-20150501.jpg|Perspective view of [[Caloris Basin]] – high (red); low (blue).
</gallery>

===Discovery of water, organic compounds and volcanism===
On July 3, 2008, the ''MESSENGER'' team announced that the probe had discovered large amounts of water present in Mercury's [[exosphere]], which was an unexpected finding.<ref name="planetary society">{{cite news|first=Emily |last=Lakdawalla |title=MESSENGER Scientists 'Astonished' to Find Water in Mercury's Thin Atmosphere |url=http://www.planetary.org/news/2008/0703_MESSENGER_Scientists_Astonished_to.html |date=July 3, 2008 |work=The Planetary Society |access-date=May 1, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20080707035106/http://www.planetary.org/news/2008/0703_MESSENGER_Scientists_Astonished_to.html |archive-date=July 7, 2008 }}</ref> In the later years of its mission, ''MESSENGER'' also provided visual evidence of past volcanic activity on the surface of Mercury,<ref name="Volcanism 2011">{{cite journal |title=Flood Volcanism in the Northern High Latitudes of Mercury Revealed by MESSENGER |journal=Science |date=September 30, 2011 |last1=Head |first1=James W. |last2=Chapman |first2=Clark R. |last3=Strom |first3=Robert G. |last4=Fassett1 |first4=Caleb I. |last5=Denevi |first5=Brett W. |volume= 333|issue=6051 |pages=1853–1856 |doi=10.1126/science.1211997 |pmid=21960625|bibcode=2011Sci...333.1853H |s2cid=7651992 |url=https://authors.library.caltech.edu/72395/2/Head.SOM.pdf }}</ref> as well as evidence for a liquid iron [[planetary core]].<ref name="planetary society"/> The probe also constructed the most detailed and accurate maps of Mercury to date, and furthermore discovered carbon-containing [[organic compound]]s and water ice inside permanently shadowed craters near the north pole.<ref name="results 2015">{{cite news |last=Wall |first=Mike |url=http://www.space.com/28948-messenger-mercury-probe-final-days.html |title=NASA Mercury Probe Trying to Survive for Another Month |work=Space.com |date=March 29, 2015 |access-date=April 4, 2015 }}</ref>
<gallery class="center" widths="200" heights="200" style="font-size:95%; line-height:130%">
File:Gravity Anomalies on Mercury.jpg|[[Mass concentration (astronomy)|Mass concentrations]] (red; [[Caloris Basin]] at center, [[Sobkou Planitia]] at right), detected via gravity anomalies, provide evidence for subsurface structure and evolution.
File:PIA19420-Mercury-NorthHem-Topography-MLA-Messenger-20150416.jpg|Northern hemisphere topography from [[MESSENGER#Scientific instruments|MLA]] data shows a 10&nbsp;km vertical range: high (red); low (purple).
File:Unmasking the Secrets of Mercury.jpg|[[MESSENGER#Scientific instruments|MASCS]] spectral scan of Mercury's surface.
File:PIA19411-Mercury-WaterIce-Radar-MDIS-Messenger-20150416.jpg|[[Geology of Mercury#High-albedo polar patches and possible presence of ice|Water ice]] (yellow) in [[Crater of eternal darkness|permanently shaded craters]] of Mercury's north polar region
<!---File:EN1036539529M.nomap web.jpg|Surface hollows on Mercury imaged by ''MESSENGER'' during its final descent.<ref>{{cite web|url=http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1349|title=High-resolution Hollows|work=MESSENGER Featured Images|date=March 12, 2014|publisher=JHU – APL|archive-url=https://web.archive.org/web/20140314010953/http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1349|archive-date=March 14, 2014|url-status=live }}</ref>--->
</gallery>

===Solar System portrait===
{{main|Family Portrait (MESSENGER)}}
On February 18, 2011, a portrait of the Solar System was published on the ''MESSENGER'' website.  The mosaic contained 34 images, acquired by the MDIS instrument during November 2010.  All the planets were visible with the exception of [[Uranus]] and [[Neptune]], due to their vast distances from the Sun. The ''MESSENGER'' "family portrait" was intended to be complementary to the [[Family Portrait (Voyager)|Voyager family portrait]], which was acquired from the outer Solar System by ''[[Voyager 1]]'' on February 14, 1990.<ref name="APLPortrait">{{cite press release| publisher=APL| date=February 18, 2011| title=A Solar System Family Portrait, from the Inside Out| url=http://messenger.jhuapl.edu/news_room/details.php?id=155| access-date=February 18, 2011| url-status=dead| archive-url=https://web.archive.org/web/20130512035442/http://messenger.jhuapl.edu/news_room/details.php?id=155| archive-date=May 12, 2013}}</ref>
[[File:MESSENGER Solar System Family Portrait.jpg|thumb|center|800px|{{center|''MESSENGER'' captured a near-complete portrait of the [[Solar System]] during November 2010.}}]]
<!---
{{wide image|MESSENGER Solar System Family Portrait.jpg|1080px|alt=MESSENGER'' near-complete portrait of the [[Solar System]].|align-cap=center|''MESSENGER'' captured a near-complete portrait of the [[Solar System]] during November 2010.}}
--->

===View of a total lunar eclipse===
{{main|October 2014 lunar eclipse}}
[[File:MESSENGER views 2014-10-08 lunar eclipse from Mercury orbit.gif|thumb|right|A lunar eclipse as viewed from Mercury, captured from the ''MESSENGER'' spacecraft. The [[Moon]] can be seen falling into the shadow of Earth.]]
On October 8, 2014 from 9:18 UTC to 10:18 UTC, ''MESSENGER'' took 31 images, taken two minutes apart, of the Earth and the Moon, as the Moon underwent a [[total lunar eclipse]]. MESSENGER was 107 million kilometers (66 million miles) from the Earth at the time of the lunar eclipse. The Earth is about 5 pixels across and the Moon is just over 1 pixel across in the field of view of the NAC, with about 40 pixels distance between them. The images are zoomed by a factor of two and the Moon's brightness has been increased by a factor of about 25 to show its disappearance more clearly. This was the first observation of a [[lunar eclipse]], of Earth's Moon, in history to be viewed from another planet.<ref>{{cite web |title=Lunar Eclipse From Mercury |url=https://science.nasa.gov/resource/lunar-eclipse-from-mercury/ |publisher=NASA |access-date=20 April 2024}}{{source-attribution}}</ref><ref name=EclipseReboost/>