{{Italic title}}{{Short description|ESA/JAXA mission to study Mercury in orbit (2018–present)}}
{{Use British English|date=January 2014}}
{{Use dmy dates|date=March 2020}}
{{Infobox spaceflight | name = ''BepiColombo'' | names_list = | image = BepiColombo spacecraft model.png | image_caption = Artist's depiction of the ''BepiColombo'' mission, with the Mercury Planetary Orbiter (left) and Mercury Magnetospheric Orbiter (right) | image_alt = Mercury Planetary Orbiter and Mercury Magnetospheric Orbiter | image_size = 300px | mission_type = Planetary science | operator = {{hlist|ESA|JAXA}} | COSPAR_ID = [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO 2018-080A] | SATCAT = 43653 | website = https://www.esa.int/Science_Exploration/Space_Science/BepiColombo | mission_duration = Cruise: 7 years (planned) 8 years (actual)<br/>Science phase: 1 year (planned)<br/> <small> {{Age in years, months and days|year=2018|month=10|day=20}} ''(in progress)''</small> | manufacturer = {{hlist|Airbus|ISAS}} | launch_mass = {{cvt|4100|kg}} <ref name="FACTS">{{cite web|url=http://www.esa.int/Our_Activities/Space_Science/BepiColombo/BepiColombo_Factsheet|title=BepiColombo Factsheet|publisher=ESA|date=6 July 2017|access-date=6 July 2017}}</ref> | dry_mass = {{cvt|2700|kg}} <ref name="FACTS"/> | BOL_mass = MPO: {{cvt|1230|kg}}<br/>''Mio'': {{cvt|255|kg}} <ref name="FACTS"/> | dimensions = MPO: {{cvt|2.4|x|2.2|x|1.7|m}}<br/>''Mio'': {{cvt|1.8|x|1.1|m}} <ref name="FACTS"/> | power = MPO: 150 watts<br/>''Mio'': 90 watts | launch_date = 20 October 2018, 01:45 UTC | launch_rocket = Ariane 5 ECA (VA245)<ref name="ariane">{{cite web|url=http://www.esa.int/spaceinimages/Images/2018/10/BepiColombo_s_first_image_from_space |title=BepiColombo's first image from space|publisher=ESA|date=10 October 2018}}</ref> | launch_site = Centre Spatial Guyanais, ELA-3<ref name="ISAS homepage">{{cite web|url=http://www.isas.jaxa.jp/en/missions/spacecraft/developing/mmo.html|title=MIO/BepiColombo |publisher=JAXA|date=2018|access-date=9 July 2018}}</ref> | launch_contractor = Arianespace | disposal_type = <!-- deorbited, decommissioned, etc --> | deactivated = <!-- when craft was decommissioned --> | destroyed = <!-- when craft was destroyed (if other than by re-entry) --> | last_contact = <!-- when last signal received if not decommissioned --> | interplanetary = {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Earth | distance = {{cvt|12677|km}} | arrival_date = 10 April 2020, 04:25 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Venus | distance = {{cvt|10720|km}} | arrival_date = 15 October 2020, 03:58 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Venus | distance = {{cvt|552|km}} | arrival_date = 10 August 2021, 13:51 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Mercury | distance = {{cvt|199|km}} | arrival_date = 1 October 2021, 23:34:41 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Mercury | distance = {{cvt|200|km|1}} | arrival_date = 23 June 2022, 09:44 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Mercury | distance = {{cvt|236|km}} | arrival_date = 19 June 2023, 19:34 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Mercury | distance = {{cvt|165|km}} | arrival_date = 4 September 2024, 21:48 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Mercury | distance = {{cvt|37626|km}} | arrival_date = 1 December 2024, 14:23 UTC }} {{Infobox spaceflight/IP | type = flyby | note = gravity assist | object = Mercury | distance = {{cvt|295|km}} | arrival_date = 8 January 2025, 05:59 UTC }} {{Infobox spaceflight/IP | type = orbiter | object = Mercury | component = Mercury Planetary Orbiter<br/>(MPO) | arrival_date = November 2026 (planned) | periapsis = {{cvt|480|km}} | apoapsis = {{cvt|1500|km}} | inclination = 90,0° | apsis = hermion }} {{Infobox spaceflight/IP | type = orbiter | object = Mercury | component = Mercury Magnetospheric Orbiter<br/>(MMO) | arrival_date = November 2026 (planned) | periapsis = {{cvt|590|km}} | apoapsis = {{cvt|11640|km}} | inclination = 90.0° | apsis = hermion }} | insignia = ESA BepiColombo.svg | insignia_caption = ESA insignia (2020s) | insignia_upright = 0.6 | programme = '''Horizon 2000 Plus''' (Science Programme) | previous_mission = LISA Pathfinder | next_mission = Cheops }}
'''''BepiColombo''''' is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury.<ref name="Amos">{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/7195374.stm|title=European probe aims for Mercury|work=BBC News|first=Jonathan|last=Amos|date=18 January 2008|access-date=21 January 2008}}</ref> The mission comprises two satellites launched together: the '''Mercury Planetary Orbiter''' ('''MPO''') and '''''Mio''''' ('''Mercury Magnetospheric Orbiter''', '''MMO''').<ref name="Miopressrelease">{{cite press release |url=http://global.jaxa.jp/press/2018/06/20180608_mmo.html|title=MIO – Mercury Magnetospheric Orbiter's New Name|publisher=JAXA|date=8 June 2018|access-date=9 June 2018}}</ref> The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure. It was launched on an Ariane 5<ref name="ariane"/> rocket on 20 October 2018, with Mercury orbit insertion planned for November 2026, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury.<ref name="FACTS"/><ref name="esa20161125">{{cite web|url=http://sci.esa.int/bepicolombo/58591-bepicolombo-launch-rescheduled-for-october-2018/|title=BepiColombo Launch Rescheduled for October 2018 |publisher=ESA|date=25 November 2016|access-date=14 December 2016}}</ref> The total cost of the mission was estimated in 2017 as US$2 billion.<ref>[https://spaceflightnow.com/2017/07/10/bepicolombo-mercury-mission-tested-for-journey-into-pizza-oven/ BepiColombo Mercury mission tested for journey into 'pizza oven'] Stephen Clarke Spaceflight Now 17 July 2017</ref>
== Names == ''BepiColombo'' is named after Giuseppe "Bepi" Colombo (1920–1984), a scientist, mathematician and engineer at the University of Padua, Italy, who first proposed the interplanetary gravity assist manoeuvre used by the 1974 ''Mariner 10'' mission, a technique now used frequently by planetary probes.
''Mio'', the name of the Mercury Magnetospheric Orbiter, was selected from thousands of suggestions by the Japanese public. In Japanese, ''Mio'' means a waterway, and according to JAXA, it symbolizes the research and development milestones reached thus far, and wishes for safe travel ahead. JAXA said the spacecraft will travel through the solar wind just like a ship traveling through the ocean.<ref name="Miopressrelease"/> In Chinese and Japanese, Mercury is known as the "water star" (水星) according to ''wǔxíng''.
== Scientific objectives == The main objectives of the mission are:<ref name="ISAS homepage" /><ref name="FACTS2">{{cite web |date=1 December 2016 |title=BepiColombo: Fact Sheet |url=http://sci.esa.int/bepicolombo/47346-fact-sheet/ |access-date=13 December 2016 |publisher=ESA}}</ref>
* Study the origin and evolution of a planet close to its parent star * Study Mercury's form, interior, structure, geology, composition and craters * Investigate Mercury's exosphere, composition and dynamics, including generation and escape * Study Mercury's magnetised envelope (magnetosphere) – structure and dynamics * Investigate the origin of Mercury's magnetic field * Test Einstein's theory of general relativity by measuring the parameters ''gamma'' and ''beta'' of the parameterized post-Newtonian formalism with high accuracy.<ref>{{cite web |date=4 July 2003 |title=BepiColombo – Testing general relativity |url=http://sci.esa.int/bepicolombo/31277-general-relativity/ |url-status=dead |archive-url=https://archive.today/20140207202758/http://sci.esa.int/bepicolombo/31277-general-relativity/ |archive-date=7 February 2014 |access-date=7 February 2014 |publisher=ESA}}</ref><ref>[https://www.sciencenews.org/article/einstein-general-relativity-mercury-orbit Einstein's general relativity reveals new quirk of Mercury's orbit] Emily Conover ''Science News'' 11 April 2018</ref> Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time, but it has a "tenuous surface-bounded exosphere"<ref>{{cite journal |last1=Domingue |first1=Deborah L. |last2=Koehn |first2=Patrick L. |last3=Killen |first3=Rosemary M. |last4=Sprague |first4=Ann L. |last5=Sarantos |first5=Menelaos |last6=Cheng |first6=Andrew F. |last7=Bradley |first7=Eric T. |last8=McClintock |first8=William E. |display-authors=2 |date=August 2007 |title=Mercury's Atmosphere: A Surface-Bounded Exosphere |journal=Space Science Reviews |volume=131 |issue=1–4 |pages=161–186 |bibcode=2007SSRv..131..161D |doi=10.1007/s11214-007-9260-9 |s2cid=121301247}}</ref> containing hydrogen, helium, oxygen, sodium, calcium, potassium and other trace elements. Its exosphere is not stable as atoms are continuously lost and replenished from a variety of sources. The mission will study the exosphere composition and dynamics, including generation and escape.
The orbiters are equipped with scientific instruments provided by various European countries and Japan. The mission will characterize the solid and liquid iron core ({{frac|3|4}} of the planet's radius) and determine the size of each.<ref>[http://sci.esa.int/jump.cfm?oid=59928 Science with BepiColombo] ESA, Accessed: 23 October 2018</ref> The mission will also complete gravitational and magnetic field mappings. Russia provided gamma ray and neutron spectrometers to verify the existence of water ice in polar craters that are permanently in shadow from the Sun's rays.
== Mission overview == The mission involves three components, which will separate into independent spacecraft upon arrival at Mercury.<ref>{{cite conference|url=http://lcpm9.jhuapl.edu/abstracts/Thursday/06_083_Hayakawa.pdf|title=BepiColombo Mercury Magnetospheric Orbiter (MMO)|conference=9th IAA Low-Cost Planetary Missions Conference. 21–23 June 2011, Laurel, Maryland|first1=Hajime|last1=Hayakawa|first2=Hironori|last2=Maejima|date=2011|access-date=15 August 2011|archive-date=23 February 2020|archive-url=https://web.archive.org/web/20200223200110/http://lcpm9.jhuapl.edu/abstracts/Thursday/06_083_Hayakawa.pdf|url-status=dead}}</ref> * Mercury Transfer Module (MTM) for propulsion, built by ESA. * Mercury Planetary Orbiter (MPO) built by ESA. * Mercury Magnetospheric Orbiter (MMO) or ''Mio'' built by JAXA.
During the launch and cruise phases, these three components are joined (with the Magnetospheric Orbiter Sunshield and Interface or MOSIF between ''Mio'' and MPO)<ref name="MOSIF"/> to form the Mercury Cruise System (MCS).<ref name="Flyby 2018"/><ref name="Arrival 2018"/>
The stacked spacecraft will take eight years to position itself to enter Mercury orbit. During this time it uses solar-electric propulsion and nine gravity assists, flying past the Earth and Moon in April 2020, Venus in 2020 and 2021, and six Mercury flybys between 2021 and 2025.<ref name="FACTS" />
Expected to arrive in Mercury orbit in November 2026, the ''Mio'' and MPO satellites will separate and observe Mercury in collaboration for one year, with a possible one-year extension.<ref name="FACTS" /> Although originally expected to enter orbit in December 2025, thruster issues discovered in September 2024 before the fourth Mercury flyby resulted in a delayed arrival of November 2026.<ref>{{cite web |title=esa-delays-bepicolombo-orbital-insertion-because-of-thruster-problem |url=https://spacenews.com/esa-delays-bepicolombo-orbital-insertion-because-of-thruster-problem/ |access-date=December 3, 2023 |website=SpaceNews |publisher=SpaceNew}}</ref>
ESA is responsible for the overall mission, the design, development assembly and test of the propulsion and MPO modules, and the launch. The two orbiters are operated by mission controllers based in Darmstadt, Germany.<ref name="launched">{{cite news |last1=Amos |first1=Jonathan |date=20 October 2018 |title=Blast-off for BepiColombo on mission to Mercury |url=https://www.bbc.co.uk/news/science-environment-45838991 |access-date=20 October 2018 |publisher=BBC News}}</ref> The spacecraft operations manager of ''BepiColombo'' was Elsa Montagnon until 2021,<ref>{{Cite web |title=Elsa Montagnon |url=https://www.esa.int/ESA_Multimedia/Images/2015/10/Elsa_Montagnon |access-date=2025-09-05 |website=www.esa.int |language=en}}</ref> and is now Ignacio Clerigo.<ref>{{Cite web |title=BepiColombo to swing by Mercury for the sixth time |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_to_swing_by_Mercury_for_the_sixth_time |access-date=2025-10-27 |website=www.esa.int |language=en}}</ref> ESA's Cebreros, Spain {{convert|35|m|adj=on}} ground station is the primary ground facility for communications during all mission phases.<ref>{{Cite web |title=BepiColombo's ground control |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_s_ground_control |website=www.esa.int}}</ref>
== Mission timeline == [[File:BepiColombo NBO 2020-04-10.webm|thumb|upright=1.0|right|''BepiColombo'', imaged at Northolt Branch Observatories, 16 hours after the Earth flyby. The bright satellite passing by is INSAT-2D.]]thumb|Mercury on 23 June 2022 during the 2nd gravity assist at the planet === Before launch === The ''BepiColombo'' mission proposal was selected by ESA in 2000. A request for proposals for the science payload was issued in 2004.<ref name="Howell">[https://www.space.com/35671-bepicolombo-facts.html BepiColombo: Joint Mission to Mercury] Elizabeth Howell ''Space.com'' 21 October 2018</ref> In 2007, Astrium (now Airbus Defence and Space) was selected as the prime contractor,<ref name="sci.esa.int">{{cite web |date=26 February 2007 |title=BepiColombo to Enter Implementation Phase |url=http://sci.esa.int/bepicolombo/40691-bepicolombo-to-enter-implementation-phase/ |publisher=ESA}}</ref> and Ariane 5 chosen as the launch vehicle.<ref name="Howell" /> The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme.<ref>{{cite web |date=5 September 2016 |title=BepiColombo Overview |url=http://www.esa.int/Our_Activities/Space_Science/BepiColombo_overview2 |access-date=13 March 2017 |publisher=ESA}}</ref> The initial target launch of July 2014 was postponed several times, mostly because of delays on the development of the solar electric propulsion system.<ref name="Howell" /> ''BepiColombo'' is the last mission of the programme to be launched.<ref name="scaling back" />
=== Launch === The two orbiters were successfully launched together on 20 October 2018.<ref name="launched" /> The launch took place on Ariane flight VA245 from Europe's Spaceport in Kourou, French Guiana.<ref>{{cite news |date=16 October 2018 |title=Watch BepiColombo launch |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Watch_BepiColombo_launch |accessdate=8 December 2021 |publisher=European Space Agency}}</ref>
=== Gravity assist maneuvers === thumb|Mercury on 5 September 2024 during the 4th gravity assist at the planetThe stacked spacecraft left Earth with a hyperbolic excess velocity of {{cvt|3.475|km/s}}. Initially, the craft was placed in a heliocentric orbit similar to that of Earth. After both the spacecraft and Earth completed one and a half orbits, it returned to Earth to perform a gravity-assist maneuver and was deflected towards Venus.<ref name="mission design">{{cite web |title=Mission Operations – Getting to Mercury |url=http://sci.esa.int/bepicolombo/48871-getting-to-mercury/ |access-date=7 February 2014 |publisher=ESA}}</ref>
Following its Earth flyby in April 2020, ''BepiColombo'' was briefly mistaken for a near-Earth asteroid, receiving the provisional designation {{mp|2020 GL|2}}.<ref name="2020GL2a">{{cite web |date=13 April 2020 |title=MPEC 2020-G96 : 2020 GL2 |url=https://minorplanetcenter.net/mpec/K20/K20G96.html |url-status=dead |archive-url=https://web.archive.org/web/20200413144547/https://minorplanetcenter.net/mpec/K20/K20G96.html |archive-date=13 April 2020 |publisher=Minor Planet Center}}</ref><ref name="2020GL2b">{{cite web |date=13 April 2020 |title=2020 GL2 |url=https://minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2020+GL2 |url-status=dead |archive-url=https://web.archive.org/web/20200413144626/https://minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2020+GL2 |archive-date=13 April 2020 |publisher=Minor Planet Center}}</ref><ref name="2020GL2c">{{cite web |date=13 April 2020 |title=MPEC 2020-G97 : DELETION OF 2020 GL2 |url=https://minorplanetcenter.net/mpec/K20/K20G97.html |access-date=14 April 2020 |publisher=Minor Planet Center}}</ref><ref>{{Cite web |date=10 April 2020 |title=BepiColombo flies by Earth |url=https://www.europlanet-society.org/bepicolombo-flies-by-earth/ |access-date=24 June 2022 |publisher=Europlanet Society |quote=The data collected for this image, even though it was submitted to the Minor Planet Center as artificial satellite 2018-080A (BepiColombo’s official designation), led to it being mistaken for a Near Earth asteroid. The “discovery”, announced by the Minor Planet Center as asteroid 2020 GL2, was retracted soon after. This was the third time a spacecraft had been mistakenly announced as a “new asteroid” during an Earth flyby, after Rosetta a.k.a. 2007 VN84 and Gaia a.k.a. 2015 HP116. Incidentally, all three of these are ESA missions.}}</ref>
Two consecutive Venus flybys reduced the perihelion near to the Sun–Mercury distance with almost no need for thrust. A sequence of six Mercury flybys lowered the relative velocity to {{cvt|1.76|km/s}}. After the fourth Mercury flyby in 2024, the spacecraft is in an orbit similar to that of Mercury and remains in the general vicinity of the planet.<ref>{{Cite web |title=ESA Science & Technology - BepiColombo's journey to Mercury |url=https://sci.esa.int/web/bepicolombo/-/59288-bepicolombo-s-journey-to-mercury |access-date=2025-09-03 |website=sci.esa.int}}</ref>
=== Science during Venus flybys === After the potential biomarker phosphine has been tentatively discovered in the Venusian atmosphere in September 2020, ESA scientists suggested that ''BepiColombo'' might be able to detect the compound during its two Venus flybys in 2020 and 2021. However, it was not clear if the spacecraft's instruments were sufficiently sensitive<ref>{{cite news |last1=O'Callaghan |first1=Jonathan |title=In A Complete Fluke, A European Spacecraft Is About To Fly Past Venus – And Could Look For Signs Of Life |url=https://www.forbes.com/sites/jonathanocallaghan/2020/09/16/in-a-complete-fluke-a-european-spacecraft-is-about-to-fly-past-venus--and-could-look-for-signs-of-life/ |access-date=16 September 2020 |work=Forbes}}</ref> and there has been no announcement of such detection since.
During the first Venus flyby in October 2020, seven science instruments and a radiation monitor onboard the Mercury Planetary Orbiter, and three instruments onboard ''Mio'', were active and gathering data. The observations were coordinated with JAXA's ''Akatsuki'', the only active spacecraft orbiting Venus at that time, as well as Earth-based observatories.<ref>{{Cite news |title=JAXA/Akatsuki - ESA/JAXA BepiColombo coordination during Venus flybys in Oct. 2020 and Aug. 2021 - EnVision: A Venus orbiter mission in partnership between ESA and NASA |url=https://sites.lesia.obspm.fr/envision/jaxa-akatsuki-esa-jaxa-bepicolombo-coordination-during-venus-flybys-in-oct-2020-and-aug-2021/ |archive-url=https://web.archive.org/web/20250322045938/https://sites.lesia.obspm.fr/envision/jaxa-akatsuki-esa-jaxa-bepicolombo-coordination-during-venus-flybys-in-oct-2020-and-aug-2021/ |archive-date=22 March 2025 |access-date=2025-11-08 |work=EnVision: A Venus orbiter mission in partnership between ESA and NASA |language=en-US |url-status=live }}</ref><ref name=":0" />
The second Venus flyby in August 2021 happened only 33 hours after another interplanetary spacecraft by ESA, ''Solar Orbiter'', completed its gravity assist at the same planet. Both spacecraft used their science instruments to study the magnetic, plasma, and particle environment around Venus during their flybys, offering unique multipoint datasets. The MPO's MERTIS instrument captured high resolution spectra of the Venus atmosphere and the Mercury Transfer Module's three monitoring cameras (M-CAM) captured a series of black-and-white images of the planet, documenting the various phases of the flyby.<ref>{{Cite web |title=Sights and sounds of a Venus flyby |url=https://www.esa.int/Science_Exploration/Space_Science/Sights_and_sounds_of_a_Venus_flyby |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref>
=== Science during Mercury flybys === During the first Mercury flyby in October 2021, the spacecraft captured its first images of the target planet using the M-CAM monitoring cameras on the Mercury Transfer Module.<ref>{{Cite web |title=BepiColombo monitoring cameras |url=https://www.esa.int/ESA_Multimedia/Images/2018/10/BepiColombo_monitoring_cameras |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref><ref>{{Cite web |title=BepiColombo's first views of Mercury |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_s_first_views_of_Mercury |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref> Some of the scientific instruments on both orbiters were also active during the flyby, exploring the magnetic and particle environment around Mercury and measuring the planet's gravity.<ref>{{Cite web |title=BepiColombo's first tastes of Mercury science |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_s_first_tastes_of_Mercury_science |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref>
During the second flyby in June 2022, the M-CAM cameras imaged, among other targets, the crater Heaney with a candidate volcano, an important target for the spacecraft's primary mission. This crater has been recently named after Seamus Heaney following a request from the M-CAM team. Some of the scientific instruments have been again active, measuring the magnetic, plasma, and particle environment around the spacecraft.<ref>{{Cite web |title=Second helpings of Mercury |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Second_helpings_of_Mercury |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref>
During the third flyby in June 2023, the MPPE suite of instruments on ''Mio'' was used to map the magnetosphere of Mercury.<ref>{{Cite web |title=Mercury's magnetic landscape mapped in 30 minutes |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Mercury_s_magnetic_landscape_mapped_in_30_minutes |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref> Based on these data, scientists described various expected features of the magnetosphere, but also made new discoveries: 1) a low latitude layer containing particles with much broader energy range than ever observed on Mercury, 2) energetic hydrogen ions trapped at low latitude and near the equator, and 3) cold plasma ions of oxygen and sodium, as well as signatures of potassium, which were probably ejected from the planet's surface by micrometeorites or the solar wind.<ref>{{Cite web |last=Caliman |first=Lucille |date=2025-03-05 |title=BepiColombo: revelations from the Mercury mission |url=https://www.polytechnique-insights.com/en/columns/space/bepicolombo-revelations-from-the-mercury-mission/ |access-date=2025-09-06 |website=Polytechnique Insights |language=en-GB}}</ref><ref>{{Cite journal |last1=Hadid |first1=Lina Z. |last2=Delcourt |first2=Dominique |last3=Harada |first3=Yuki |last4=Rojo |first4=Mathias |last5=Aizawa |first5=Sae |last6=Saito |first6=Yoshifumi |last7=André |first7=Nicolas |last8=Glass |first8=Austin N. |last9=Raines |first9=Jim M. |last10=Yokota |first10=Shoichiro |last11=Fränz |first11=Markus |last12=Katra |first12=Bruno |last13=Verdeil |first13=Christophe |last14=Fiethe |first14=Björn |last15=Leblanc |first15=Francois |date=2024-10-03 |title=Mercury's plasma environment after BepiColombo's third flyby |url=https://www.nature.com/articles/s42005-024-01766-8 |journal=Communications Physics |language=en |volume=7 |issue=1 |pages=316 |doi=10.1038/s42005-024-01766-8 |bibcode=2024CmPhy...7..316H |issn=2399-3650}}</ref> ''Mio''<nowiki/>'s observations during this flyby also identified the chirping-like discrete whistler-mode emission waves previously observed in Earth's magnetosphere but so far unknown from Mercury.<ref>{{Cite web|title=The Magnetic "Birdsong" of the Smallest Planet|url=https://www.universetoday.com/articles/the-magnetic-birdsong-of-the-smallest-planet|website=Universe Today|date=2026-01-28|access-date=2026-01-30|language=en|first=Andy|last=Tomaswick}}</ref><ref>{{Cite journal|title=Nonlinear spatiotemporal signatures of whistler-mode wave activity around Mercury during six flybys of BepiColombo mission|url=https://www.nature.com/articles/s41467-025-66968-2|journal=Nature Communications|date=2025-12-01|issn=2041-1723|pages=266|volume=17|issue=1|doi=10.1038/s41467-025-66968-2|language=en|first=Mitsunori|last=Ozaki|first2=Satoshi|last2=Yagitani|first3=Yasumasa|last3=Kasaba|first4=Yoshiya|last4=Kasahara|first5=Shoya|last5=Matsuda|first6=Yoshiharu|last6=Omura|first7=Mitsuru|last7=Hikishima|first8=Fouad|last8=Sahraoui|first9=Laurent|last9=Mirioni|first10=Gérard|last10=Chanteur|first11=Go|last11=Murakami|doi-access=free}}</ref>
In May 2024, computers on ''BepiColombo'' (as well as on another ESA mission, ''Mars Express'') reported a sharp increase in the number of memory errors, coinciding with a massive solar flare from the active region AR3664, at that time facing away from Earth. The event was also observed in detail by ESA's ''Solar Orbiter''.<ref>{{Cite web |title=Can't stop won't stop: Solar Orbiter shows the Sun raging on |url=https://www.esa.int/Science_Exploration/Space_Science/Solar_Orbiter/Can_t_stop_won_t_stop_Solar_Orbiter_shows_the_Sun_raging_on |access-date=2025-05-18 |website=www.esa.int |language=en}}</ref>
During the fourth flyby in September 2024, the spacecraft had, for the first time, a clear view of Mercury's south pole. The M-CAM 2 and 3 cameras provided images of the polar region, as well as the Vivaldi crater and a crater newly named Stoddart after Margaret Olrog Stoddart following a request from the M-CAM team.<ref>{{Cite web |title=BepiColombo's best images yet highlight fourth Mercury flyby |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_s_best_images_yet_highlight_fourth_Mercury_flyby |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref>
During the fifth flyby in December 2024, using the MERTIS instrument, ''BepiColombo'' became the first spacecraft ever to observe Mercury in mid-infrared light.<ref>{{Cite web |title=BepiColombo reveals Mercury in a new light |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_reveals_Mercury_in_a_new_light |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref> During the sixth and final Mercury flyby in January 2025, the M-CAM 1 camera imaged the permanently shadowed craters Prokofiev, Kandinsky, Tolkien, and Gordimer near the planet's north pole.<ref>{{Cite web |title=Top three images from BepiColombo's sixth Mercury flyby |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Top_three_images_from_BepiColombo_s_sixth_Mercury_flyby |access-date=2025-09-03 |website=www.esa.int |language=en}}</ref>
=== Thruster issues === On 15 May 2024, ESA reported an issue preventing the spacecraft's thrusters from operating at full power during a scheduled manoeuvre on 26 April 2024.<ref name="x457">{{cite web |date=15 May 2024 |title=Glitch on BepiColombo: work ongoing to restore spacecraft to full thrust |url=https://www.esa.int/Enabling_Support/Operations/Glitch_on_BepiColombo_work_ongoing_to_restore_spacecraft_to_full_thrust |access-date=29 May 2024 |website=ESA}}</ref> On 2 September 2024, ESA reported that to compensate for the reduced available thrust, a revised trajectory had been developed that would add 11 months to the cruise, delaying the expected arrival date from 5 December 2025 to November 2026.<ref>{{cite web |date=2 September 2024 |title=Fourth Mercury flyby begins BepiColombo's new trajectory |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Fourth_Mercury_flyby_begins_BepiColombo_s_new_trajectory |access-date=2 September 2024 |work=ESA}}</ref>
=== Future === Four final thrust arcs will reduce the relative velocity to the point where Mercury will "weakly" capture the spacecraft in November 2026 into polar orbit. Only a small maneuver is needed to bring the craft into an orbit around Mercury with an apocentre of {{convert|178,000|km}}. The orbiters then separate and will adjust their orbits using chemical thrusters.<ref name="Data Center">{{cite web |date=26 August 2014 |title=BepiColombo |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO |access-date=6 April 2015 |work=National Space Science Data Center |publisher=NASA |archive-date=21 October 2021 |archive-url=https://web.archive.org/web/20211021043935/https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO |url-status=dead }} {{PD-notice}}</ref><ref name="mission design" />
== Trajectory == {{asof|January 2025}}, the mission schedule is:<ref>{{cite web |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_factsheet|title=BepiColombo factsheet|website=ESA|access-date=2025-01-07}}</ref>{{Clear}} {| class="wikitable" ! Date ! Event ! Comment
|- bgcolor=#ccffcc | 20 October 2018, 01:45 UTC | Launch |
|- bgcolor=#ccffcc | 10 April 2020,<br/>04:25 UTC | Earth flyby | 1.5 years after launch
|- bgcolor=#ccffcc | 15 October 2020, 03:58 UTC | First Venus flyby | On 15 October 2020, the ESA reported the flyby was a success. Closest approach at a distance of about 10 720 km from the planet's surface.<ref name=":0">{{cite web |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_flies_by_Venus_en_route_to_Mercury|title=BepiColombo flies by Venus en route to Mercury|publisher=ESA|quote="The flyby itself was very successful", confirms Elsa. "The only difference to normal cruise phase operations is that near to Venus we have to temporarily close the shutter of any of the star trackers that are expected to be blinded by the planet, similar to closing your eyes to avoid looking at the Sun"|date=15 October 2020|access-date=15 October 2020}}</ref>
|- bgcolor=#ccffcc | 10 August 2021,<br/>13:51 UTC | Second Venus flyby | 1.35 Venus years after first Venus flyby. Flyby was a success, and saw BepiColombo come within {{convert|552|km}} of Venus's surface.<ref>{{cite web|url=https://www.esa.int/ESA_Multimedia/Images/2021/08/BepiColombo_s_second_Venus_flyby_in_images|title=BepiColombo's second Venus flyby in images|publisher=European Space Agency|accessdate=8 December 2021}}</ref><ref>{{cite news|url=https://www.space.com/bepicolombo-spacecraft-venus-flyby-selfie-photo|title=Mercury-bound spacecraft snaps selfie with Venus in close flyby (photo)|first=Tereza|last=Pultarova |publisher=Space.com|date=August 11, 2021|access-date=December 8, 2021}}</ref>
|- bgcolor=#ccffcc | 1 October 2021,<br/>23:34:41 UTC | First Mercury flyby | Passed {{convert|199|km}} from Mercury's surface.<ref>{{Cite tweet |number=1444250895114555395 |title=At 01:34:41 CEST this morning, BepiColombo passed just {{convert|199|km}} from the hot, rocky, innermost planet|user=esaoperations |author=ESA Operations |date=2 Oct 2021 |link=no }}</ref> Occurred on the 101st anniversary of Giuseppe Colombo’s birth.
|- bgcolor=#ccffcc | 23 June 2022,<br/>09:44 UTC | Second Mercury flyby | ~2 orbits (3 Mercury years) after 1st Mercury flyby. Closest approach of about {{convert|200|km}} altitude.<ref>{{cite web|url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Second_helpings_of_Mercury|title=Second helpings of Mercury|publisher=European Space Agency|date=24 June 2022|access-date=24 June 2022}}</ref>
|- bgcolor=#ccffcc | 19 June 2023,<br/>19:34 UTC | Third Mercury flyby | ~3 orbits (4.1 Mercury years) after 2nd Mercury flyby. Closest approach of about {{convert|236|km}} altitude.<ref>{{cite web|url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_braces_for_third_Mercury_flyby|title=BepiColombo braces for third Mercury flyby|publisher=European Space Agency|date=14 June 2023|access-date=16 June 2023}}</ref><ref>{{Cite news |title=BepiColombo |url=https://twitter.com/BepiColombo/status/1671041136423493633 |access-date=2023-06-20|date=20 June 2023 |work=Twitter/BepiColombo|quote=Our #BepiColombo @esaoperations team confirm all went well with our #MercuryFlyby last night! Now we wait and see what images & data our instrument teams collected|language=en}}</ref> |- bgcolor=#ccffcc | {{nowrap|4 September 2024}}, 21:48 UTC | Fourth Mercury flyby | ~4 orbits (5.0 Mercury years) after 3rd Mercury flyby. Closest approach of about {{convert|165|km}} altitude.<ref>{{Cite web |title=BepiColombo's best images yet highlight fourth Mercury flyby |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_s_best_images_yet_highlight_fourth_Mercury_flyby |access-date=2024-09-06 |website=www.esa.int |language=en}}</ref>
|- bgcolor=#ccffcc | 1 December 2024, 14:23 UTC | Fifth Mercury flyby | 1 orbit (1.0 Mercury year) after 4th Mercury flyby. Closest approach about {{convert|37626|km}} altitude.<ref>{{cite web |date=9 December 2024 |access-date=8 January 2025 |title=BepiColombo reveals Mercury in a new light |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_reveals_Mercury_in_a_new_light}}</ref>
|- bgcolor=#ccffcc | 8 January 2025, 05:58:52 UTC | Sixth Mercury flyby | ~0.4 orbits (0.4 Mercury years) after 5th Mercury flyby. Closest approach about {{convert|295|km}} altitude.<ref>{{cite web |access-date=8 January 2025 |date=6 January 2025|title=BepiColombo to swing by Mercury for the sixth time |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/BepiColombo_to_swing_by_Mercury_for_the_sixth_time}}</ref><ref>{{cite web |date=8 January 2025 |access-date=8 January 2025 |title=@BepiColombo (on X.com). Post "BepiColombo is reaching its closest approach to Mercury now (...) |work=X (formerly Twitter) |url=https://x.com/BepiColombo/status/1876871164791750849 }}</ref>
|- | November 2026 | Mercury orbit insertion | 7.8 Mercury years after 6th Mercury flyby. 60-hour orbital period
|- | December 2026 | {{nowrap|MMO reaches science orbit}}, detaches from MPO | 9.3-hour orbital period
|- | Early 2027 | {{nowrap|MPO reaches science orbit}} | 2.36-hour orbital period
|- | April 2028 | End of nominal mission |
|- | April 2029 | End of planned extended mission | |}
thumb|Timeline of ''BepiColombo'' from 20 October 2018 to 2 November 2025. Red circle indicates flybys.|left|850x850px<gallery mode=packed heights=180> File:Animation of BepiColombo trajectory.gif|Animation of ''BepiColombo''{{'s}} trajectory from 20 October 2018 to 2 November 2025<br/>{{legend2|magenta| BepiColombo}}{{·}}{{legend2|RoyalBlue|Earth}}{{·}}{{legend2|Cyan|Venus}}{{·}}{{legend2|Lime|Mercury}}{{·}}{{legend2|Yellow|Sun}}<br/>For more detailed animation, see this video File:Animation of BepiColombo trajectory around Mercury.gif|Animation of ''BepiColombo''{{'}}s trajectory around Mercury File:MMO&MPO-Orbits.svg|Planned orbits for ''Mio'' and MPO, the two probes of the ''BepiColombo'' mission </gallery> {{-}}
== Mission components ==
=== Mercury Transfer Module === {| class="wikitable floatright" |- ! QinetiQ T6 !! Performance <ref>[http://erps.spacegrant.org/uploads/images/2015Presentations/IEPC-2015-132_ISTS-2015-b-132.pdf Qualification of the T6 Thruster for BepiColombo] {{Webarchive |url=https://web.archive.org/web/20160812075030/http://erps.spacegrant.org/uploads/images/2015Presentations/IEPC-2015-132_ISTS-2015-b-132.pdf|date=12 August 2016}} R. A. Lewis, J. Pérez Luna, N. Coombs. 30th International Symposium on Space Technology and Science 34th International Electric Propulsion Conference and 6th Nano-satellite Symposium, Hyogo-Kobe, Japan, 4–10 July 2015</ref><ref>[http://erps.spacegrant.org/uploads/images/2015Presentations/IEPC-2015-131_ISTS-2015-b-131.pdf QinetiQ's T6 and T5 Ion Thruster Electric Propulsion System Architectures and Performances] {{Webarchive|url=https://web.archive.org/web/20171215162142/http://erps.spacegrant.org/uploads/images/2015Presentations/IEPC-2015-131_ISTS-2015-b-131.pdf |date=15 December 2017 }} Mark Hutchins, Huw Simpson. 30th International Symposium on Space Technology and Science 34th International Electric Propulsion Conference and 6th Nano-satellite Symposium, Hyogo-Kobe, Japan, 4–10 July 2015</ref> |- | Type || Kaufman Ion Engine |- | Units on board || 4 <ref>{{cite web|url=http://www.esa.int/spaceinimages/Images/2016/04/T6_ion_thruster_firing|title=T6 ion thruster firing|publisher=ESA|date=27 April 2016|access-date=7 August 2019}}</ref><ref>{{cite web|url=http://www.esa.int/spaceinimages/Images/2016/04/T6_ion_thrusters_installed_on_BepiColombo|title=T6 ion thrusters installed on BepiColombo|publisher=ESA|date=26 April 2016|access-date=7 August 2019}}</ref> |- | Diameter || {{cvt|22|cm}} |- | Max. thrust || 145 mN each |- | Specific impulse<br/>(I<sub>sp</sub>) || 4300 seconds |- | Propellant || Xenon |- | Total power || 4628 W |}
The Mercury Transfer Module (MTM) has a mass of {{cvt|2615|kg}}, including {{cvt|1400|kg}} of xenon propellant, and is located at the base of the stack. Its role is to carry the two science orbiters to Mercury and to support them during the cruise.
The MTM is equipped with a solar electric propulsion system as the main spacecraft propulsion. Its four QinetiQ-T6 ion thrusters operate singly or in pairs for a maximum combined thrust of 290 mN,<ref>{{cite conference|url=http://www.iepc2013.org/get?id=133|archive-url=https://web.archive.org/web/20161220114057/http://www.iepc2013.org/get?id=133|url-status=dead|archive-date=2016-12-20|title=BepiColombo Electric Propulsion Thruster and High Power Electronics Coupling Test Performances|conference=33rd International Electric Propulsion Conference 6–10 October 2013 Washington, D.C.|first1=Stephen D.|last1=Clark |first2=Mark S.|last2=Hutchins|first3=Ismat|last3=Rudwan|first4=Neil C.|last4=Wallace|first5=Javier|last5=Palencia|first6=Howard|last6=Gray|display-authors=2|date=2013|id=IEPC-2013-133}}</ref> making it the most powerful ion engine array ever operated in space. The MTM supplies electrical power for the two hibernating orbiters as well as for its solar electric propulsion system thanks to two {{convert|14|m||adj=mid|-long}} solar panels.<ref name="MPO page">{{cite web|url=http://sci.esa.int/bepicolombo/48872-spacecraft/|title=Mercury Planetary Orbiter – Spacecraft|publisher=ESA|date=16 August 2018|access-date=7 August 2019}}</ref> Depending on the probe's distance to the Sun, the generated power will range between 7 and 14 kW, each T6 requiring between 2.5 and 4.5 kW according to the desired thrust level.
The solar electric propulsion system has typically very high specific impulse and low thrust. This leads to a flight profile with months-long continuous low-thrust braking phases, interrupted by planetary gravity assists, to gradually reduce the velocity of the spacecraft. Moments before Mercury orbit insertion, the MTM will be jettisoned from the spacecraft stack. After separation from the MTM, the MPO will provide ''Mio'' all necessary power and data resources until ''Mio'' is delivered to its mission orbit.<ref>{{Cite web |title=ESA Science & Technology - Mercury Planetary Orbiter - spacecraft |url=https://sci.esa.int/web/bepicolombo/-/48872-spacecraft |access-date=2025-11-14 |website=sci.esa.int}}</ref> Separation of ''Mio'' from MPO will be accomplished by spin-ejection.<ref>{{Cite journal |last1=STEIGER |first1=Christoph |last2=ALTAY |first2=Alkan |last3=MONTAGNON |first3=Elsa |last4=BUDNIK |first4=Frank |last5=CASASCO |first5=Massimo |last6=ESPEILLAC |first6=Pascal |last7=FUGGER |first7=Susanne |last8=STRANDBERG |first8=Tommy |date=2019 |title=GNC Operations for the BepiColombo Mission to Mercury: First In-flight Experience |url=https://www.eucass.eu/doi/EUCASS2019-0218.pdf |journal=8th European Conference for Aeronautics and Space Sciences (Eucass) |pages=16 pages |doi=10.13009/EUCASS2019-218}}</ref>
<gallery mode="packed" heights="100"> File:Mercury Transfer Module in space simulator ESA387743.jpg|MTM in space simulator File:BepiColombo Mercury Transfer Module solar wing deployment.jpg|MTM solar wing deployment File:BepiColombo MTM ESTEC.jpg|MTM at ESTEC File:Mercury Transfer Module thruster detail(1).jpg|MTM thruster detail </gallery>
=== Mercury Planetary Orbiter === The Mercury Planetary Orbiter (MPO) has a mass of {{cvt|1150|kg}} and uses a single-sided solar array capable of providing up to 1000 watts and featuring Optical Solar Reflectors to keep its temperature below {{cvt|200|C}}. The solar array requires continuous rotation keeping the Sun at a low incidence angle in order to generate adequate power while at the same time limiting the temperature.<ref name="MPO page"/>
The MPO carries a payload of 11 instruments, comprising cameras, spectrometers (IR, UV, X-ray, γ-ray, neutron), a radiometer, a laser altimeter, a magnetometer, particle analysers, a Ka-band transponder, and an accelerometer. The payload components are mounted on the nadir side of the spacecraft to achieve low detector temperatures, apart from the MERTIS and PHEBUS spectrometers located directly at the main radiator to provide a better field of view.<ref name="MPO page"/>
A high-temperature-resistant {{cvt|1.0|m}} diameter high-gain antenna is mounted on a short boom on the zenith side of the spacecraft. Communications will be on the X-band and Ka-band with an average bit rate of 50 kbit/s and a total data volume of 1550 Gbit/year. ESA's Cebreros, Spain {{convert|35|m|adj=on}} ground station is planned to be the primary ground facility for communications during all mission phases.<ref name="MPO page"/>
<gallery mode="packed" heights="120"> File:BepiColombo MPO being placed in Phenix thermal vacuum test facility ESA287633.jpg|MPO being placed in Phenix thermal vacuum test facility File:Radio testing of BepiColombo orbiter ESA353568.jpg|Radio testing of MPO File:Mercury Planetary Orbiter radiator panel and instruments(1).jpg|MPO radiator panel and instruments File:BepiColombo MPO ESTEC.jpg|MPO at ESTEC before stacking </gallery>
==== Science payload of MPO ==== thumb|MPO's science instruments The science payload of the Mercury Planetary Orbiter consists of eleven instruments:<ref name="MMO objectives"/><ref name="MPO Instruments 2008">{{cite web|url=http://sci.esa.int/bepicolombo/38831-instruments/ |title=Mercury Planetary Orbiter – Instruments|publisher=ESA|date=15 January 2008|access-date=6 February 2014}}</ref>
* BepiColombo Laser Altimeter (BELA), developed by DLR in cooperation with the University of Bern, the Max Planck Institute for Solar System Research (MPS) and the Instituto de Astrofísica de Andalucía.<ref name="www2.mps.mpg.de">{{Cite web|url=https://www2.mps.mpg.de/en/projekte/bepicolombo/serena/|title = MPS: BepiColombo – SERENA}}</ref> * Italian Spring Accelerometer (ISA), developed by Italy * Mercury Magnetometer (MPO-MAG, MERMAG), developed by Germany and United Kingdom<ref name="MPO page"/> * Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS), developed by Germany * Mercury Gamma-ray and Neutron Spectrometer (MGNS), developed by Russia * Mercury Imaging X-ray Spectrometer (MIXS), developed and built by the University of Leicester, the Max Planck Institute for Solar System Research (MPS) and the Max Planck Institute for Extraterrestrial Physics (MPE).<ref>{{Cite web|url=https://www2.mps.mpg.de/en/projekte/bepicolombo/mixs/|title = MPS: MIXS on BepiColombo}}</ref><ref name="FraserCarpenter2010">{{cite journal|last1=Fraser|first1=G.W.|last2=Carpenter |first2=J.D.|last3=Rothery|first3=D.A.|last4=Pearson|first4=J.F.|last5=Martindale|first5=A.|last6=Huovelin|first6=J.|last7=Treis|first7=J.|last8=Anand|first8=M.|last9=Anttila|first9=M.|last10=Ashcroft|first10=M.|last11=Benkoff|first11=J.|last12=Bland|first12=P.|last13=Bowyer|first13=A.|last14=Bradley|first14=A.|last15=Bridges|first15=J.|last16=Brown|first16=C.|last17=Bulloch|first17=C.|last18=Bunce|first18=E.J.|last19=Christensen|first19=U.|last20=Evans|first20=M.|last21=Fairbend|first21=R.|last22=Feasey|first22=M.|last23=Giannini|first23=F.|last24=Hermann|first24=S.|last25=Hesse|first25=M.|last26=Hilchenbach|first26=M.|last27=Jorden|first27=T.|last28=Joy|first28=K.|author-link28=Katherine Joy|last29=Kaipiainen|first29=M.|last30=Kitchingman|first30=I.|last31=Lechner|first31=P.|last32=Lutz|first32=G.|last33=Malkki|first33=A. |last34=Muinonen|first34=K.|last35=Näränen|first35=J.|last36=Portin|first36=P.|last37=Prydderch|first37=M.|last38=Juan|first38=J. San|last39=Sclater|first39=E.|last40=Schyns|first40=E.|last41=Stevenson |first41=T.J.|last42=Strüder|first42=L.|last43=Syrjasuo|first43=M.|last44=Talboys|first44=D.|last45=Thomas|first45=P.|last46=Whitford|first46=C.|last47=Whitehead|first47=S.|title=The mercury imaging X-ray spectrometer (MIXS) on bepicolombo|journal=Planetary and Space Science|volume=58|issue=1–2|year=2010|pages=79–95|issn=0032-0633|doi=10.1016/j.pss.2009.05.004|bibcode=2010P&SS...58...79F |url=http://oro.open.ac.uk/16347/}}</ref> * Mercury Orbiter Radio-science Experiment (MORE), developed by Italy and the United States * Probing of Hermean Exosphere by Ultraviolet Spectroscopy (PHEBUS), developed by France and Russia * Search for Exosphere Refilling and Emitted Neutral Abundances (SERENA),<ref>{{cite web|url=https://www.cosmos.esa.int/web/bepicolombo/serena|title=SERENA|publisher=ESA|access-date=7 August 2019}}</ref> made up of 2 neutral and 2 ionised particle analysers: **ELENA (Emitted Low-Energy Neutral Atoms) developed by Italy; **STROFIO (STart from a ROtating Field mass spectrOmeter) developed by United States;<ref>{{cite web |url=https://discovery.nasa.gov/strofio.cfml|title=Strofio|series=Discovery Program|publisher=NASA|access-date=7 January 2017|url-status=dead|archive-url=https://web.archive.org/web/20170108093835/https://discovery.nasa.gov/strofio.cfml|archive-date=8 January 2017}} {{PD-notice}}</ref> **MIPA (Miniature Ion Precipitation Analyser) developed by Sweden; **PICAM (Planetary Ion CAMera) developed by the Space Research Institute (Institut für Weltraumforschung, IWF), Russian Space Research Institute (IKI), Institut de recherche en sciences de l'environnement (CETP/IPSL), European Space Research and Technology Centre (ESTEC), Research Institute for Particle and Nuclear Physics (KFKI-RMKI) and the Max Planck Institute for Solar System Research (MPS).<ref name="www2.mps.mpg.de"/> * Spectrometers and Imagers for MPO BepiColombo Integrated Observatory System (SIMBIO-SYS), high resolution stereo cameras and a visual and near infrared spectrometer, developed by Italy, France and Switzerland * Solar Intensity X-ray and Particle Spectrometer (SIXS), developed by Finland and United Kingdom.
=== ''Mio'' (Mercury Magnetospheric Orbiter) === ''Mio'', or the Mercury Magnetospheric Orbiter (MMO), developed and built mostly by Japan, has the shape of a short octagonal prism, {{cvt|180|cm}} long from face to face and {{cvt|90|cm}} high.<ref name='ISAS homepage'/><ref>{{cite journal|title=Current status of the BepiColombo/MMO spacecraft design|journal=Advances in Space Research|first1=Hiroshi|last1=Yamakawa|first2=Hiroyuki|last2=Ogawa |first3=Yasumasa|last3=Kasaba|first4=Hajime|last4=Hayakawa|first5=Toshifumi|last5=Mukai|first6=Masaki|last6=Adachi|display-authors=2|volume=33|issue=12|pages=2133–2141|date=January 2004|doi=10.1016/S0273-1177(03)00437-X|bibcode=2004AdSpR..33.2133Y}}</ref> It has a mass of {{cvt|285|kg}}, including a {{cvt|45|kg}} scientific payload consisting of 5 instrument groups, 4 for plasma and dust measuring run by investigators from Japan, and one magnetometer from Austria.<ref name='ISAS homepage'/><ref name="MMO brochure 2015">{{cite web|url=http://global.jaxa.jp/activity/pr/brochure/files/sat27.pdf |title=Mercury Exploration Project "BepiColombo"|publisher=JAXA|date=2014|access-date=6 April 2015}}</ref><ref>{{cite web|title=A pair of planetary Explorers at Mercury|url=http://sci.esa.int/bepicolombo/59934-spacecraft-duo/|website=esa.int|access-date=21 October 2018}}</ref>
''Mio'' will be spin stabilized at 15 rpm with the spin axis perpendicular to the equator of Mercury. It will enter a polar orbit at an altitude of {{cvt|590|xx|11640|km}}, outside of MPO's orbit.<ref name="MMO brochure 2015"/> The top and bottom of the octagon act as radiators with louvers for active temperature control. The sides are covered with solar cells which provide 90 watts. Communications with Earth will be through a {{cvt|0.8|m}} diameter X-band phased array high-gain antenna and two medium-gain antennas operating in the X-band. Telemetry will return 160 Gb/year, about 5 kbit/s over the lifetime of the spacecraft, which is expected to be greater than one year. The reaction and control system is based on cold gas thrusters. After its release in Mercury orbit, ''Mio'' will be operated by Sagamihara Space Operation Center using Usuda Deep Space Center{{'s}} {{cvt|64|m}} antenna located in Nagano, Japan.<ref name="MMO objectives">{{cite web|url=http://www.stp.isas.jaxa.jp/mercury/p_mmo.html|title=MMO (Mercury Magnetospheric Orbiter): Objectives|publisher=JAXA|date=2011|access-date=7 February 2014}}</ref>
<gallery mode=packed heights=150> File:BepiColombo MMO ESTEC.jpg|''Mio'' at ESTEC before stacking File:BepiColombo MMO'mio' Supended.jpg|''Mio'' being lifted from the container by a crane File:Mercury Magnetospheric Orbiter on top of Mercury Planetary Orbiter.jpg|''Mio'' on top of MPO (without sunshield) </gallery>
==== Science payload of ''Mio'' ==== ''Mio'' carries five groups of science instruments with a total mass of {{cvt|45|kg}}:<ref name='ISAS homepage'/><ref name='MMO objectives'/> * Mercury Plasma Particle Experiment (MPPE), studies the plasma and neutral particles from the planet, its magnetosphere, and the solar wind. It will employ these instruments: ** Mercury Electron Analyzers (MEA1 and MEA2) ** Mercury Ion Analyzer (MIA) ** Mass Spectrum Analyzer (MSA), developed by Laboratory of Plasma Physics (LPP), Max Planck Institute for Solar System Research (MPS), IDA of Technical University of Braunschweig and Institute of Space and Astronautical Science (ISAS) <ref>{{Cite web|url=https://www.mps.mpg.de/planetenforschung/bepi-colombo-mppe|title = MPPE}}</ref> ** High-Energy Particle instrument for electrons (HEP-ele) ** High-Energy Particle instrument for Ions (HEP-ion) ** Energetic Neutrals Analyzer (ENA) * Mercury Magnetometer (MMO-MGF), studies Mercury's magnetic field, magnetosphere, and interplanetary solar wind * Plasma Wave Investigation (PWI), studies the electric field, electromagnetic waves, and radio waves from the magnetosphere and solar wind * Mercury Sodium Atmosphere Spectral Imager (MSASI), studies the thin sodium atmosphere of Mercury * Mercury Dust Monitor (MDM), studies dust from the planet and interplanetary space
=== Magnetospheric Orbiter Sunshield and Interface === thumb|upright=0.8|Full stack with sunshield on top The ''Mio'' orbiter requires additional thermal control on the cruise to Mercury, in addition to umbilicals to the MPO. The European Space Agency thus provided the Magnetospheric Orbiter Sunshield and Interface (MOSIF), a white shroud that is shaped like a conical frustrum to provide clearance, as ''Mio'' is spun up during its separation in 2026, before being ejected from the MPO.<ref name="MOSIF">{{cite web | title=Magnetospheric Orbiter Sunshield and Interface Shaker Test | website=ESA Science & Technology | date=29 September 2011 | url= https://sci.esa.int/web/bepicolombo/-/49501-magnetospheric-orbiter-sunshield-and-interface-structure-mosif-shaker-test | access-date=4 January 2025}}</ref><ref name="Flyby 2018">{{cite web | title=BepiColombo Flyby | website=BepiColombo Flyby | date=October 20, 2018 | url=https://www.cosmos.esa.int/web/bepicolombo-flyby | access-date=January 4, 2025}}</ref><ref name="Arrival 2018">{{cite web | title=BepiColombo arrival at Mercury timeline | website=ESA | url=https://www.esa.int/ESA_Multimedia/Images/2018/10/BepiColombo_arrival_at_Mercury_timeline | access-date=4 January 2025}}</ref>
=== Mercury Surface Element (cancelled) === The Mercury Surface Element (MSE) was cancelled in 2003 due to budgetary constraints.<ref name="scaling back">{{cite press release |url=http://www.esa.int/For_Media/Press_Releases/Critical_decisions_on_Cosmic_Vision|title=Critical Decisions on Cosmic Vision|publisher=ESA|date=7 November 2003|access-date=14 December 2016|id=No. 75-2003}}</ref> At the time of cancellation, MSE was meant to be a small, {{cvt|44|kg}}, lander designed to operate for about one week on the surface of Mercury.<ref name="Data Center"/> Shaped as a {{cvt|0.9|m}} diameter disc, it was designed to land at a latitude of 85° near the terminator region. Braking manoeuvres would bring the lander to zero velocity at an altitude of {{cvt|120|m}} at which point the propulsion unit would be ejected, airbags inflated, and the module would fall to the surface with a maximum impact velocity of {{cvt|30|m/s}}. Scientific data would be stored onboard and relayed via a cross-dipole UHF antenna to either the MPO or ''Mio''. The MSE would have carried a {{cvt|7|kg}} payload consisting of an imaging system (a descent camera and a surface camera), a heat flow and physical properties package, an alpha particle X-ray spectrometer, a magnetometer, a seismometer, a soil penetrating device (mole), and a micro-rover.<ref>{{cite web |url=http://www.esa.int/spaceinimages/Images/2001/11/BepiColombo_s_lander|title=BepiColombo's lander|publisher=ESA|date=20 February 2002|access-date=7 February 2014}}</ref>
== See also == * List of European Space Agency programmes and missions * Exploration of Mercury * ''MESSENGER'' – the first spacecraft to orbit Mercury
== References == {{Reflist}}
== External links == {{Commons}} * [https://www.esa.int/Science_Exploration/Space_Science/BepiColombo ''BepiColombo'' website] by the European Space Agency * [http://www.esa.int/Our_Activities/Operations/BepiColombo_operations ''BepiColombo'' Operations website] by the European Space Agency * [https://global.jaxa.jp/projects/sas/bepi ''BepiColombo'' website] by JAXA * [http://www.isas.jaxa.jp/en/missions/spacecraft/developing/mmo.html ''BepiColombo'' website] by JAXA's Institute of Space and Astronautical Science * [https://solarsystem.nasa.gov/missions/bepicolombo/in-depth/ ''BepiColombo'' website] by NASA's Solar System Exploration * [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO ''BepiColombo'' website] {{Webarchive|url=https://web.archive.org/web/20211021043935/https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO |date=21 October 2021 }} by the National Space Science Data Center * [https://link.springer.com/journal/11214/topicalCollection/AC_76aacd1766d3980239c6d84531056577/page/1 The BepiColombo mission to Mercury], edited by Johannes Benkhoff, Go Murakami and Ayako Matsuoka. ''Space Science Reviews''. '''216–217''' (2020–2021) * [https://www.eoportal.org/satellite-missions/bepicolombo BepiColombo article on eoPortal by ESA]
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