Editing Mercury (planet) (section)

==== ''MESSENGER'' ====
{{Main|MESSENGER}}
[[File:Details of MESSENGER's Impact Location.jpg|thumb|Estimated details of the impact of ''MESSENGER'' on April 30, 2015]]
A second NASA mission to Mercury, named ''MESSENGER'' (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), was launched on August 3, 2004. It made a fly-by of Earth in August 2005, and of Venus in October 2006 and June 2007 to place it onto the correct trajectory to reach an orbit around Mercury.<ref>{{cite web |year=2005 |url=http://www.spaceref.com/news/viewsr.html?pid=18956 |title=MESSENGER Engine Burn Puts Spacecraft on Track for Venus |publisher=SpaceRef.com |access-date=March 2, 2006}}</ref> A first fly-by of Mercury occurred on January 14, 2008, a second on October 6, 2008,<ref name="MessCountdown">{{cite web |url=http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=115 |title=Countdown to MESSENGER's Closest Approach with Mercury |date=January 14, 2008 |publisher=Johns Hopkins University Applied Physics Laboratory |access-date=May 30, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20130513080731/http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=115 |archive-date=May 13, 2013}}</ref> and a third on September 29, 2009.<ref>{{cite web |title=MESSENGER Gains Critical Gravity Assist for Mercury Orbital Observations |url=http://messenger.jhuapl.edu/news_room/details.php?id=136 |date=September 30, 2009 |publisher=MESSENGER Mission News |access-date=September 30, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20130510175510/http://messenger.jhuapl.edu/news_room/details.php?id=136 |archive-date=May 10, 2013}}</ref> Most of the hemisphere not imaged by {{nowrap|''Mariner 10''}} was mapped during these fly-bys. The probe successfully entered an elliptical orbit around the planet on March 18, 2011. The first orbital image of Mercury was obtained on March 29, 2011. The probe finished a one-year mapping mission,<ref name="MessCountdown" /> and then entered a one-year extended mission into 2013. In addition to continued observations and mapping of Mercury, ''MESSENGER'' observed the 2012 [[solar maximum]].<ref name="Extended2013">{{cite news | url=http://www.upi.com/Top_News/US/2011/11/15/NASA-extends-spacecrafts-Mercury-mission/UPI-55131321408343/ | title=NASA extends spacecraft's Mercury mission | work=United Press International | date=November 15, 2011 | access-date=November 16, 2011 | archive-date=May 31, 2013 | archive-url=https://web.archive.org/web/20130531103344/http://www.upi.com/Top_News/US/2011/11/15/NASA-extends-spacecrafts-Mercury-mission/UPI-55131321408343/ | url-status=live }}</ref>

[[File:MercuryTopo.png|thumb|right|Topography of Mercury based on MDIS (Mercury Dual Imaging System) data]] The mission was designed to clear up six key issues: Mercury's high density, its geological history, the nature of its magnetic field, the structure of its core, whether it has ice at its poles, and where its tenuous atmosphere comes from. To this end, the probe carried imaging devices that gathered much-higher-resolution images of much more of Mercury than {{nowrap|''Mariner 10''}}, assorted [[spectrometer]]s to determine the abundances of elements in the crust, and [[magnetometer]]s and devices to measure velocities of charged particles. Measurements of changes in the probe's orbital velocity were expected to be used to infer details of the planet's interior structure.<ref name="messenger_faq">{{cite web |url=http://messenger.jhuapl.edu/Resources/Resources/MESSENGER_FS22811_PRESS.PDF |title=MESSENGER: Fact Sheet |publisher=[[Applied Physics Laboratory]] |date=February 2011 |access-date=August 21, 2017 |archive-date=August 22, 2017 |archive-url=https://web.archive.org/web/20170822012453/http://messenger.jhuapl.edu/Resources/Resources/MESSENGER_FS22811_PRESS.PDF |url-status=live }}</ref> ''MESSENGER''{{'s}} final maneuver was on April 24, 2015, and it crashed into Mercury's surface on April 30, 2015.<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 |archive-date=April 3, 2019 |archive-url=https://web.archive.org/web/20190403102620/https://www.space.com/28948-messenger-mercury-probe-final-days.html |url-status=live }}</ref><ref name="NYT-20150427">{{cite news |last=Chang |first=Kenneth |title=NASA's Messenger Mission Is Set to Crash Into Mercury |url=https://www.nytimes.com/2015/04/28/science/nasas-messenger-mission-is-set-to-crash-into-mercury.html |archive-url=https://web.archive.org/web/20150429030725/http://www.nytimes.com/2015/04/28/science/nasas-messenger-mission-is-set-to-crash-into-mercury.html |archive-date=April 29, 2015 |url-access=subscription |url-status=live |date=April 27, 2015 |work=[[The New York Times]] |access-date=April 27, 2015}}</ref><ref name="NYT-20150430">{{cite news |last=Corum |first=Jonathan |title=Messenger's Collision Course With Mercury |url=https://www.nytimes.com/interactive/2015/04/30/science/space/messenger-collides-with-mercury.html |date=April 30, 2015 |work=[[The New York Times]] |access-date=April 30, 2015 |archive-date=March 31, 2019 |archive-url=https://web.archive.org/web/20190331205609/https://www.nytimes.com/interactive/2015/04/30/science/space/messenger-collides-with-mercury.html |url-status=live }}</ref> The spacecraft's impact with Mercury occurred at 3:26:01&nbsp;p.m. [[Eastern Time Zone|EDT]] on April 30, 2015, leaving a crater estimated to be {{convert|16|m|ft|abbr=on}} in diameter.<ref>{{cite web |date=June 3, 2015 |title=Best Determination of MESSENGER's Impact Location |url=https://messenger.jhuapl.edu/Explore/Science-Images-Database/gallery-image-1605.html |archive-url=https://web.archive.org/web/20230411141108/https://messenger.jhuapl.edu/Explore/Science-Images-Database/gallery-image-1605.html |archive-date=April 11, 2023 |access-date=October 6, 2023 |website=messenger.jhuapl.edu |publisher=[[Johns Hopkins Applied Physics Laboratory]]}}</ref>