View source for BepiColombo

{{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|[[European Space Agency|ESA]]|[[JAXA]]}}
| COSPAR_ID          = [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO 2018-080A]
| SATCAT             = 43653
| website            = 
| mission_duration   = Cruise: 7 years (planned)<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]]|[[Institute of Space and Astronautical Science|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 [[watt]]s<br/>''Mio'': 90 watts
| launch_date        = 20 October 2018, 01:45 [[Coordinated Universal Time|UTC]]
| launch_rocket      = [[Ariane 5|Ariane 5 ECA]] [[Ariane flight VA245|(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        = [[Guiana Space Centre|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 (planet)|Mercury]]
  | distance        = {{cvt|199|km}}
  | arrival_date    = 1 October 2021, 23:34:41 UTC
 }}
{{Infobox spaceflight/IP
  | type            = flyby
  | note            = gravity assist
  | object          = [[Mercury (planet)|Mercury]]
  | distance        = {{cvt|200|km|1}}
  | arrival_date    = 23 June 2022, 09:44 UTC
 }}
 {{Infobox spaceflight/IP
  | type            = flyby
  | note            = gravity assist
  | object          = [[Mercury (planet)|Mercury]]
  | distance        = {{cvt|236|km}}
  | arrival_date    = 19 June 2023, 19:34 UTC
 }}
 {{Infobox spaceflight/IP
  | type            = orbiter
  | object          = [[Mercury (planet)|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 (planet)|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           = BepiColombo Insignia.png
| insignia_caption   = ''BepiColombo'' insignia
| insignia_alt       = BepiColombo mission insignia
| insignia_size      = 250px
| programme          = [[European Space Agency Science Programme|Horizon 2000 Plus]]
| previous_mission   = [[LISA Pathfinder]]
| next_mission       = [[CHEOPS]]
}}

'''BepiColombo''' is a joint mission of the [[European Space Agency]] (ESA) and the [[JAXA|Japan Aerospace Exploration Agency]] (JAXA) to the planet [[Mercury (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 at 01:45 [[Coordinated Universal Time|UTC]], with an arrival at Mercury 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 mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's [[List of European Space Agency programmes and missions|Horizon 2000+]] programme;<ref>{{cite web|url=http://www.esa.int/Our_Activities/Space_Science/BepiColombo_overview2|title=BepiColombo Overview|publisher=ESA|date=5 September 2016|access-date=13 March 2017}}</ref> it is the last mission of the programme to be launched.<ref name="scaling back"/>

On 15 May 2024, ESA reported that a "glitch" prevented the spacecraft's thrusters from operating at full power during a scheduled manoeuvre on 26 April.<ref name="x457">{{cite web |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 |website=ESA |date=15 May 2024 | access-date=29 May 2024}}</ref> On 2 September, 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 |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Fourth_Mercury_flyby_begins_BepiColombo_s_new_trajectory |title=Fourth Mercury flyby begins BepiColombo’s new trajectory |work=[[ESA]] |date=2 September 2024 |access-date=2 September 2024}}</ref>

== Names ==
''BepiColombo'' is named after [[Giuseppe Colombo|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 ''[[Wuxing (Chinese philosophy)|wǔxíng]]''.

Following its [[Earth]] flyby in April 2020, ''BepiColombo'' was briefly mistaken for a [[near-Earth asteroid]], receiving the [[Provisional designation in astronomy|provisional designation]] {{mp|2020 GL|2}}.<ref name="2020GL2a">{{cite web|url=https://minorplanetcenter.net/mpec/K20/K20G96.html|title=MPEC 2020-G96 : 2020 GL2|date=13 April 2020|publisher=Minor Planet Center|archive-url=https://web.archive.org/web/20200413144547/https://minorplanetcenter.net/mpec/K20/K20G96.html|archive-date=13 April 2020|url-status=dead}}</ref><ref name="2020GL2b">{{cite web |url=https://minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2020+GL2|title=2020 GL2|date=13 April 2020|publisher=Minor Planet Center|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|url-status=dead}}</ref><ref name="2020GL2c">{{cite web|url=https://minorplanetcenter.net/mpec/K20/K20G97.html|title=MPEC 2020-G97 : DELETION OF 2020 GL2|date=13 April 2020|publisher=Minor Planet Center|access-date=14 April 2020}}</ref><ref>{{Cite web|url=https://www.europlanet-society.org/bepicolombo-flies-by-earth/|title=BepiColombo flies by Earth|publisher=Europlanet Society|date=10 April 2020|access-date=24 June 2022|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 (spacecraft)|Rosetta]] a.k.a. 2007 VN84 and [[Gaia (spacecraft)|Gaia]] a.k.a. 2015 HP116. Incidentally, all three of these are [[European Space Agency|ESA]] missions.}}</ref>

== Mission ==
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 together to form the Mercury Cruise System (MCS).

The [[General contractor|prime contractor]] for [[European Space Agency|ESA]] is [[Airbus Defence and Space]].<ref name="sci.esa.int">{{cite web|url=http://sci.esa.int/bepicolombo/40691-bepicolombo-to-enter-implementation-phase/ |title=BepiColombo to Enter Implementation Phase|publisher=ESA|date=26 February 2007}}</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, which are operated by mission controllers based in Darmstadt, Germany, were successfully launched together on 20 October 2018.<ref name=launched>{{cite news|last1=Amos|first1=Jonathan|title=Blast-off for BepiColombo on mission to Mercury |date=20 October 2018|url=https://www.bbc.co.uk/news/science-environment-45838991|publisher=BBC News|access-date=20 October 2018}}</ref> The launch took place on [[Ariane flight VA245]] from Europe’s Spaceport in Kourou, French Guiana.<ref>{{cite news|url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Watch_BepiColombo_launch|title=Watch BepiColombo launch|publisher=European Space Agency|date=16 October 2018|accessdate=8 December 2021}}</ref> The spacecraft will have a seven-year interplanetary cruise to Mercury using solar-electric propulsion ([[ion thruster]]s) and [[gravity assist]]s from Earth, [[Venus]] and eventual gravity capture at [[Mercury (planet)|Mercury]].<ref name="FACTS"/> ESA's [[Cebreros Station|Cebreros, Spain]] {{convert|35|m|adj=on}} ground station is planned to be the primary ground facility for communications during all mission phases.

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"/> The orbiters are equipped with scientific instruments provided by various European countries and Japan. The mission will characterize the solid and liquid iron [[Planetary core|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 field|gravitational]] and [[magnetic field]] mappings. Russia provided [[Gamma-ray spectrometer|gamma ray]] and [[Neutron spectroscopy|neutron spectrometers]] to verify the existence of water ice in polar craters that are permanently in shadow from the Sun's rays.

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 [[Atmosphere of Mercury|exosphere]]"<ref>{{cite journal |title=Mercury's Atmosphere: A Surface-Bounded Exosphere|journal=Space Science Reviews|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|volume=131|issue=1–4|pages=161–186|date=August 2007 |doi=10.1007/s11214-007-9260-9|bibcode=2007SSRv..131..161D|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.

=== Objectives ===
The main objectives of the mission are:<ref name="ISAS homepage"/><ref name="FACTS2">{{cite web|url=http://sci.esa.int/bepicolombo/47346-fact-sheet/|title=BepiColombo: Fact Sheet|publisher=ESA|date=1 December 2016|access-date=13 December 2016}}</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 [[Atmosphere of Mercury|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]]
* Verify 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 |url=http://sci.esa.int/bepicolombo/31277-general-relativity/|archive-url=https://archive.today/20140207202758/http://sci.esa.int/bepicolombo/31277-general-relativity/|url-status=dead|archive-date=7 February 2014|title=BepiColombo – Testing general relativity|publisher=ESA|date=4 July 2003|access-date=7 February 2014}}</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>

=== Design ===
[[File:MMO&MPO-Orbits.svg|thumb|upright=1.0|left|Planned orbits for ''Mio'' and MPO satellites, the two probes of the ''BepiColombo'' mission]]

The stacked spacecraft will take eight years to position itself to enter Mercury orbit. During this time it will use [[Ion thruster|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"/>

The stacked spacecraft left Earth with a [[Hyperbola|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 is deflected towards Venus. Two consecutive Venus flybys reduce the perihelion near to the Sun–Mercury distance with almost no need for thrust. A sequence of six Mercury flybys will lower the relative velocity to {{cvt|1.76|km/s}}. After the fourth Mercury flyby, the craft will be in an orbit similar to that of Mercury and will remain in the general vicinity of Mercury (see [http://sci.esa.int/bepicolombo/59288-bepicolombo-s-journey-to-mercury/video]). Four final thrust arcs 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|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=BEPICLMBO |title=BepiColombo|work=National Space Science Data Center|publisher=NASA|date=26 August 2014|access-date=6 April 2015}} {{PD-notice}}</ref><ref name="mission design">{{cite web |url=http://sci.esa.int/bepicolombo/48871-getting-to-mercury/|title=Mission Operations – Getting to Mercury|publisher=ESA|access-date=7 February 2014}}</ref>

=== History ===
The ''BepiColombo'' mission proposal was selected by [[European Space Agency|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]] was selected as the prime contractor, and [[Ariane 5]] chosen as the [[launch vehicle]].<ref name='Howell'/> 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'/> 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>

=== Schedule ===
[[File:Animation of BepiColombo trajectory.gif|thumb|upright=1.0|right|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 (planet)|Mercury]]}}{{·}}{{legend2|Yellow|[[Sun]]}}<br/>For more detailed animation, see [[:File:Animation of BepiColombo trajectory.webm|this video]]]]
[[File:BepiColombo%E2%80%99s_second_Mercury_flyby.webm|thumb|upright=1.0|right|start=11|thumbtime=36|Sequence of images taken during the second Mercury flyby]]
[[File:Animation of BepiColombo trajectory around Mercury.gif|thumb|upright=1.0|right|Animation of BepiColombo's trajectory around Mercury]]
{{asof|2021}}, the mission schedule is:<ref name="FACTS"/>
{| 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
| According to Johannes Benkhoff of [[ESA]], the probe may possibly be capable of detecting phosphine – [[Life on Venus#Potential biomarkers|the chemical allegedly discovered in the Venusian atmosphere in September 2020]] – during this and the following flyby. He stated that "we do not know if our instrument is sensitive enough".<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/|work=Forbes|access-date=16 September 2020}}</ref> On 15 October 2020, the ESA reported the flyby was a success.<ref>{{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' 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 (planet)|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 what would have been the 101st birthday of [[Giuseppe Colombo]]. 

|- bgcolor=#ccffcc
| 23 June 2022,<br/>09:44 UTC
| Second Mercury flyby
| 2 orbits (3.00 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 (4.12 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 (5.04 Mercury years) after 3rd Mercury flyby. Closest approach of about 165 kilometres (103mi) 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>

|-
| 1 December 2024
| Fifth Mercury flyby
| 1 orbit (1.00 Mercury year) after 4th Mercury flyby

|-
| 8 January 2025
| Sixth Mercury flyby
| ~0.43 orbits (0.43 Mercury years) after 5th Mercury flyby

|-
| November 2026
| Mercury orbit insertion
| Spacecraft separation; ~7 Mercury years after 6th Mercury flyby

|-
| 2027
| {{nowrap|MPO in final science orbit}}
| 1.13 Mercury years after orbit insertion?

|-
| April 2028
| End of nominal mission
| 5.82 Mercury years after orbit insertion

|-
| April 2029
| End of extended mission
| 9.98 Mercury years after orbit insertion
|}
[[File:Timeline of BepiColombo.svg|thumb|800px|center|Timeline of ''BepiColombo'' from 20 October 2018 to 2 November 2025. Red circle indicates flybys.]]


== Components ==
=== Mercury Transfer Module ===
[[File:BepiColombo_Earth_Flyby_10_april_2020.gif|thumb|upright=1.0|right|Earth flyby on 10 April 2020]]
[[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]], a defunct [[geostationary satellite]].]]

{| class="wikitable floatright"
|-
! [[Qinetiq|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&nbsp;mN each
|-
| [[Specific impulse]]<br/>(I<sub>sp</sub>)  || 4300 seconds
|-
| Propellant || [[Xenon]]
|-
| Total power || 4628 [[Watt|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&nbsp;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 on spacecraft|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&nbsp;kW, each T6 requiring between 2.5 and 4.5&nbsp;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 assist]]s, to gradually reduce the velocity of the spacecraft. Moments before Mercury orbit insertion, the MTM will be jettisoned from the spacecraft stack.<ref name='MPO page'/> After separation from the MTM, the MPO will provide ''Mio'' all necessary power and data resources until ''Mio'' is delivered to its mission orbit; separation of ''Mio'' from MPO will be accomplished by spin-ejection.

=== Mercury Planetary Orbiter ===
[[Image:BepiColombo MPO ESTEC.jpg|thumb|upright=1.0|right|Mercury Planetary Orbiter in ESTEC before stacking]]
[[File:Radio testing of BepiColombo orbiter ESA353568.jpg|thumb|upright=1.0|right|Radio testing of ''BepiColombo'' 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 [[watt]]s 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 will carry a payload of 11 instruments, comprising cameras, spectrometers ([[Infrared|IR]], [[Ultraviolet|UV]], [[X-ray]], [[Gamma 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|X-band]] and [[Ka band|Ka-band]] with an average bit rate of 50 [[kbit/s]] and a total data volume of 1550 [[Gigabit|Gbit]]/year. ESA's [[Cebreros Station|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"/>

==== Science payload ====
[[File:MPO’s science instruments ESA17050215.jpeg|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 [[Lidar|Laser Altimeter]] (BELA), developed by [[German Aerospace Center|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 spectroscopy|Thermal Infrared Spectrometer]] (MERTIS), developed by Germany
* Mercury [[Gamma-ray spectrometer|Gamma-ray and Neutron Spectrometer]] (MGNS), developed by [[Russia]]
* Mercury [[Phase-contrast X-ray imaging|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 [[Outline of radio science|Radio-science]] Experiment (MORE), developed by Italy and the [[United States]]
* Probing of Hermean [[Exosphere]] by [[Ultraviolet–visible spectroscopy|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 [[Infrared spectroscopy|near infrared spectrometer]], developed by Italy, France and [[Switzerland]]
* Solar Intensity [[Alpha particle X-ray spectrometer|X-ray and Particle Spectrometer]] (SIXS), developed by [[Finland]] and United Kingdom.

=== ''Mio'' (Mercury Magnetospheric Orbiter) ===
[[Image:BepiColombo MMO ESTEC.jpg|thumb|upright=1.0|right|''Mio'' in ESTEC before stacking]]

''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 [[Revolutions per minute|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 cell]]s which provide 90 watts. Communications with Earth will be through a {{cvt|0.8|m}} diameter [[X band|X-band]] phased array [[high-gain antenna]] and two medium-gain antennas operating in the X-band. Telemetry will return 160 [[Gigabit|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 thruster]]s. After its release in Mercury orbit, ''Mio'' will be operated by [[Sagamihara Campus|Sagamihara Space Operation Center]] using [[Usuda Deep Space Center]]{{'s}} {{cvt|64|m}} antenna located in [[Nagano Prefecture|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>

==== Science payload ====
[[File:The search for volcanoes (annotated) ESA24328694.png|thumb|Photo captured on 23 June 2022 as the spacecraft flew past the planet for its second of six gravity assist manoeuvres at Mercury. This image was taken by the Mercury Transfer Module’s Monitoring Camera 3, when the spacecraft was 1406 km from the surface of Mercury.]]
''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 (physics)|plasma]] and [[neutral particle]]s 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

=== 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 [[Ultra high frequency|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 (space exploration)|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 ==
* [[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] 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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