BepiColombo is a joint mission of the

European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...

(ESA) and the

Japan Aerospace Exploration Agency The is the Japanese national Aeronautics, air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satell ...

(JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and ''Mio'' (Mercury Magnetospheric Orbiter, MMO). The mission will perform a comprehensive study of Mercury, including characterization of its

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

, and both interior and surface structure. It was launched on an

Ariane 5 Ariane 5 is a retired European heavy-lift space launch vehicle operated by Arianespace for the European Space Agency (ESA). It was launched from the Guiana Space Centre (CSG) in French Guiana. It was used to deliver payloads into geostationar ...

rocket on 20 October 2018 at 01:45

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

, with an arrival at Mercury planned for November 2026, after a flyby of

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

, and two flybys of

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

. It will complete six flybys of Mercury. The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme; it is the last mission of the programme to be launched. 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. 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.

Names

''BepiColombo'' is named after Giuseppe "Bepi" Colombo (1920–1984), a

scientist A scientist is a person who Scientific method, researches to advance knowledge in an Branches of science, area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engag ...

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

and

engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while ...

at the

University of Padua The University of Padua (, UNIPD) is an Italian public research university in Padua, Italy. It was founded in 1222 by a group of students and teachers from the University of Bologna, who previously settled in Vicenza; thus, it is the second-oldest ...

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

, who first proposed the interplanetary

gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...

manoeuvre used by the 1974 ''

Mariner 10 ''Mariner 10'' was an American Robotic spacecraft, robotic space probe launched by NASA on 3 November 1973, to fly by the planets Mercury (planet), Mercury and Venus. It was the first spacecraft to perform flybys of multiple planets. ''Marin ...

'' 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 The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

just like a ship traveling through the ocean. In Chinese and Japanese, Mercury is known as the "water star" (水星) according to '' wǔxíng''. Following its

flyby in April 2020, ''BepiColombo'' was briefly mistaken for a

near-Earth asteroid A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit aro ...

, receiving the

provisional designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

Mission

The mission involves three components, which will separate into independent spacecraft upon arrival at Mercury. * 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 (with the Magnetospheric Orbiter Sunshield and Interface or MOSIF between ''Mio'' and MPO) to form the Mercury Cruise System (MCS). The

prime contractor Prime contractor may refer to: * Prime contractor (US Government), a specific term in the US law for contractors that work directly with the US government * Prime contractor, a synonym of general contractor A contractor (North American English) or ...

for

ESA The European Space Agency (ESA) is a 23-member international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 in the context of European ...

Airbus Defence and Space Airbus Defence and Space is a division of Airbus SE. Formed in 2014 in the restructuring of European Aeronautic Defence and Space (EADS), Airbus SE comprises the former Airbus Military, Astrium, and divisions. Contributing 21% of Airbus reven ...

. 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. The launch took place on

Ariane flight VA245 Ariane Flight VA245 is the Ariane 5 space launch of ''BepiColombo'' that took place on 20 October 2018 at 01:45:28UTC from the Guiana Space Centre. It was the launch of Ariane 5 (the in 2018), and the Arianespace mission (the in 2018). Pay ...

from Europe’s Spaceport in Kourou, French Guiana. The spacecraft will have an eight-year interplanetary cruise to Mercury using solar-electric propulsion (

ion thruster An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. An ion thruster creates a cloud of positive ions from a neutral gas by ionizing it to extract some electrons from its atoms. The i ...

s) and

s from Earth,

and eventual gravity capture at Mercury. ESA's Cebreros, Spain 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. Although originally expected to enter orbit in December 2025, thruster issues discovered in September 2024 before its 4th flyby resulted in a delayed arrival of November 2026. The orbiters are equipped with scientific instruments provided by various European countries and Japan. The mission will characterize the solid and liquid iron

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...

( of the planet's radius) and determine the size of each. The mission will also complete

gravitational In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force be ...

and

mappings. Russia provided

gamma ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

and 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

exosphere The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision-less. In the case of ...

" containing

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

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: * 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 (

) – structure and dynamics * Investigate the origin of Mercury's magnetic field * Verify Einstein's theory of

general relativity General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...

by measuring the parameters ''gamma'' and ''beta'' of the

parameterized post-Newtonian formalism In physics, precisely in the study of the theory of general relativity and many alternatives to it, the post-Newtonian formalism is a calculational tool that expresses Einstein's (nonlinear) equations of gravity in terms of the lowest-order de ...

with high accuracy.

Design

The stacked spacecraft will take eight years to position itself to enter Mercury orbit. During this time it will use 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. The stacked spacecraft left Earth with a

hyperbolic Hyperbolic may refer to: * of or pertaining to a hyperbola, a type of smooth curve lying in a plane in mathematics ** Hyperbolic geometry, a non-Euclidean geometry ** Hyperbolic functions, analogues of ordinary trigonometric functions, defined u ...

excess velocity of . Initially, the craft was placed in a

heliocentric orbit A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun ...

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 . 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 (se

. Four final thrust arcs reduce the relative velocity to the point where Mercury will "weakly" capture the spacecraft in November 2026 into

polar orbit A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) on each revolution. It has an inclination of abo ...

. Only a small maneuver is needed to bring the craft into an orbit around Mercury with an apocentre of . The orbiters then separate and will adjust their orbits using chemical thrusters.

History

The ''BepiColombo'' mission proposal was selected by

in 2000. A request for proposals for the science payload was issued in 2004. In 2007,

Astrium Astrium was a European aerospace company and subsidiary of the European Aeronautic Defence and Space Company (EADS), headquartered in Paris. It designed, developed and manufactured civil and military space systems and provided related services ...

was selected as the prime contractor, and

chosen as the

launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...

. The initial target launch of July 2014 was postponed several times, mostly because of delays on the development of the

solar electric propulsion Solar electric propulsion (SEP) is the combination of solar cells and electric thrusters to propel a spacecraft through outer space. This technology has been exploited in a variety of spacecraft designs by the European Space Agency (ESA), ...

system. The total cost of the mission was estimated in 2017 as US$2 billion.

Schedule

Animation of BepiColombo trajectory around Mercury

, the mission schedule is: Timeline of BepiColombo

Components

Mercury Transfer Module

The Mercury Transfer Module (MTM) has a mass of , including 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

system as the main spacecraft propulsion. Its four

QinetiQ QinetiQ ( as in '' kinetic'') is a British defence technology company headquartered in Farnborough, Hampshire. It operates primarily in the defence, security and critical national infrastructure markets and run testing and evaluation capabili ...

-T6

ion thrusters An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. An ion thruster creates a cloud of positive ions from a neutral gas by ionizing it to extract some electrons from its atoms. The io ...

operate singly or in pairs for a maximum combined thrust of 290 mN, 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

solar panels A solar panel is a device that converts sunlight into electricity by using photovoltaic (PV) cells. PV cells are made of materials that produce excited electrons when exposed to light. These electrons flow through a circuit and produce direct ...

. Depending on the probe's distance to the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, 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

system has typically very high

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...

and low

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

. This leads to a flight profile with months-long continuous low-thrust braking phases, interrupted by planetary

s, 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; separation of ''Mio'' from MPO will be accomplished by spin-ejection.

Mercury Planetary Orbiter

Radio testing of BepiColombo orbiter ESA353568

The Mercury Planetary Orbiter (MPO) has a mass of and uses a single-sided solar array capable of providing up to 1000

watt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...

s and featuring Optical Solar Reflectors to keep its temperature below . The solar array requires continuous rotation keeping the

at a low incidence angle in order to generate adequate power while at the same time limiting the temperature. The MPO will carry a payload of 11 instruments, comprising cameras, spectrometers ( IR, UV,

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

γ-ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

), 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. A high-temperature-resistant diameter

high-gain antenna A directional antenna or beam antenna is an antenna that radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in a certain direction ...

is mounted on a short boom on the zenith side of the spacecraft. Communications will be on the

X-band The X band is the designation for a band of frequency, frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is set at approximately 7.0� ...

and

Ka-band The Ka band (pronounced as either "kay-ay band" or "ka band") is a portion of the microwave part of the electromagnetic spectrum. The designation "Ka-band" is from Kurz-above, which stems from the German word ''kurz,'' meaning "short". There ...

with an average bit rate of 50

kbit/s In telecommunications, data transfer rate is the average number of bits ( bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mu ...

and a total data volume of 1550

Gbit The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...

/year. ESA's Cebreros, Spain ground station is planned to be the primary ground facility for communications during all mission phases.

Science payload

The science payload of the Mercury Planetary Orbiter consists of eleven instruments: * BepiColombo

Laser Altimeter A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

(BELA), developed by DLR in cooperation with the

University of Bern The University of Bern (, , ) is a public university, public research university in the Switzerland, Swiss capital of Bern. It was founded in 1834. It is regulated and financed by the canton of Bern. It is a comprehensive university offering a br ...

, the

Max Planck Institute for Solar System Research The Max Planck Institute for Solar System Research (abbreviation: MPS; ) is a research institute in astronomy and astrophysics located in Göttingen, Germany, where it relocated in February 2014 from the nearby village of Lindau (Katlenburg-Lindau ...

(MPS) and the

Instituto de Astrofísica de Andalucía The Institute of Astrophysics of Andalusia (, IAA-CSIC) is a research institute funded by the High Council of Scientific Research of the Spanish government Consejo Superior de Investigaciones Científicas (CSIC), and is located in Granada, And ...

. * Italian Spring

Accelerometer An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change (mathematics), rate of change of velocity) of the object relative to an observer who is in free fall (tha ...

(ISA), developed by

* Mercury

Magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...

(MPO-MAG, MERMAG), developed by

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

* Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS), developed by Germany * Mercury Gamma-ray and Neutron Spectrometer (MGNS), developed by

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

* Mercury Imaging X-ray Spectrometer (MIXS), developed and built by the

University of Leicester The University of Leicester ( ) is a public university, public research university based in Leicester, England. The main campus is south of the city centre, adjacent to Victoria Park, Leicester, Victoria Park. The university's predecessor, Univ ...

, the

(MPS) and the

Max Planck Institute for Extraterrestrial Physics The Max Planck Institute for Extraterrestrial Physics is part of the Max Planck Society, located in Garching, near Munich, Germany. In 1991 the Max Planck Institute for Physics and Astrophysics split up into the Max Planck Institute for Extraterr ...

(MPE). * Mercury Orbiter Radio-science Experiment (MORE), developed by Italy and the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

* Probing of Hermean

Exosphere The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision-less. In the case of ...

Ultraviolet Spectroscopy Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

(PHEBUS), developed by

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

and Russia * Search for Exosphere Refilling and Emitted Neutral Abundances (SERENA), 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; **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 The European Space Research and Technology Centre (ESTEC) is the European Space Agency's main technology development and test centre for spacecraft and space technology. It is situated in Noordwijk, South Holland, in the western Netherlands, alth ...

(ESTEC), Research Institute for Particle and Nuclear Physics (KFKI-RMKI) and the

(MPS). * 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 Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

* Solar Intensity X-ray and Particle Spectrometer (SIXS), developed by

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

and United Kingdom.

''Mio'' (Mercury Magnetospheric Orbiter)

''Mio'', or the Mercury Magnetospheric Orbiter (MMO), developed and built mostly by

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, has the shape of a short octagonal prism, long from face to face and high. It has a mass of , including a scientific payload consisting of 5 instrument groups, 4 for plasma and dust measuring run by investigators from Japan, and one

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...

from

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

. ''Mio'' will be spin stabilized at 15

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

with the spin axis perpendicular to the equator of Mercury. It will enter a polar orbit at an altitude of , outside of MPO's orbit. The top and bottom of the octagon act as radiators with louvers for active temperature control. The sides are covered with

solar cell A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect.

s which provide 90 watts. Communications with Earth will be through a diameter

phased array

and two medium-gain antennas operating in the X-band. Telemetry will return 160 Gb/year, about 5

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 A cold gas thruster (or a cold gas propulsion system) is a type of rocket engine which uses the expansion of a (typically inert) pressurized gas to generate thrust. As opposed to traditional rocket engines, a cold gas thruster does not house any co ...

s. After its release in Mercury orbit, ''Mio'' will be operated by

Sagamihara Space Operation Center is a city in Kanagawa Prefecture, Japan. , the city has an estimated population of 723,470, with 334,812 households, and a population density of 1,220 persons per km2. The total area of the city is . Sagamihara is the third-most-populous city ...

using

Usuda Deep Space Center is a facility of the Japan Aerospace Exploration Agency. It is a spacecraft tracking station in Saku, Nagano (formerly in Usuda, Nagano; Usuda merged into Saku in 2005), opened in October, 1984. The main features of the station are two large be ...

antenna located in Nagano, Japan.

Science payload

''Mio'' carries five groups of science instruments with a total mass of : * Mercury Plasma Particle Experiment (MPPE), studies the plasma and

neutral particle In physics, a neutral particle is a particle without an electric charge, such as a neutron. Stable or long-lived neutral particles Long-lived neutral particles provide a challenge in the construction of particle detectors, because they do not int ...

s from the planet, its

, and the

. 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),

(MPS), IDA of

Technical University of Braunschweig TU Braunschweig (, unofficially ''University of Braunschweig – Institute of Technology'') is the oldest ' (comparable to an institute of technology in the American system) in Germany. It was founded in 1745 as Collegium Carolinum and is a membe ...

and

Institute of Space and Astronautical Science , or ISAS, is a Japanese national research organization of astrophysics using rockets, astronomical satellites and interplanetary probes which played a major role in Japan's space development. Established as part of the University of Tokyo ...

(ISAS) ** High-Energy Particle instrument for electrons (HEP-ele) ** High-Energy Particle instrument for Ions (HEP-ion) ** Energetic Neutrals Analyzer (ENA) * Mercury

(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 (planet), Mercury, being the closest to the Sun, with a weak magnetic field and the smallest mass of the IAU definition of planet, recognized terrestrial planets, has a very tenuous and highly variable atmosphere (surface-bound exosphere) ...

* Mercury Dust Monitor (MDM), studies dust from the planet and interplanetary space

Magnetospheric Orbiter Sunshield and Interface

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.

Mercury Surface Element (cancelled)

The Mercury Surface Element (MSE) was cancelled in 2003 due to budgetary constraints. At the time of cancellation, MSE was meant to be a small, , lander designed to operate for about one week on the surface of Mercury. Shaped as a 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 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 . Scientific data would be stored onboard and relayed via a cross-dipole

UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter ...

antenna to either the MPO or ''Mio''. The MSE would have carried a 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 :''APXS is also an abbreviation for APache eXtenSion tool, an extension for Apache web servers.'' An alpha particle X-ray spectrometer (APXS) is a spectrometer that analyses the chemical element composition of a sample from scattered alpha parti ...

, a

seismometer A seismometer is an instrument that responds to ground displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The out ...

, a soil penetrating device (mole), and a micro-

rover Rover may refer to: People Name * Constance Rover (1910–2005), English historian * Jolanda de Rover (born 1963), Dutch swimmer * Rover Thomas (c. 1920–1998), Indigenous Australian artist Stage name * Rover (musician), French singer-songw ...

References

External links

''BepiColombo'' website
by the

''BepiColombo'' Operations website
by the European Space Agency
''BepiColombo'' website
by

JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into o ...

''BepiColombo'' website
by JAXA's

''BepiColombo'' website
by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

's Solar System Exploration
''BepiColombo'' website
by the

National Space Science Data Center The NASA Space Science Data Coordinated Archive (NSSDCA) serves as the permanent archive for NASA space science mission data. "Space science" includes astronomy Astronomy is a natural science that studies celestial objects and the phenome ...

The BepiColombo mission to Mercury
edited by Johannes Benkhoff, Go Murakami and Ayako Matsuoka. ''Space Science Reviews''. 216–217 (2020–2021)
BepiColombo article on eoPortal by ESA
{{2018 in space Missions to Mercury European Space Agency space probes Japanese space probes Orbiters (space probe) Space probes launched in 2018 Spacecraft launched by Ariane rockets 2018 in French Guiana

Names

Mission

Objectives

Design

History

Schedule

Components

Mercury Transfer Module

Mercury Planetary Orbiter

Science payload

''Mio'' (Mercury Magnetospheric Orbiter)

Science payload

Magnetospheric Orbiter Sunshield and Interface

Mercury Surface Element (cancelled)

See also

References

External links