Mission

The BEPICOLOMBO mission consists in sending two probes, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio). The launch will take place in October 2018 by an Ariane 5 rocket, which will lead to an orbit injection around Mercury in late 2025, the end of the nominal mission in spring 2026, and the end of the extended mission in late 2027.

Mission profile

• For the cruise, a spacecraft composite constituted of the 4 following elements will be assembled:
   
• Mio
• MOSIF: Mio Sunshield & Interface Structure
• MPO
• MTM: Mercury Transfer Module used during the cruise phase
   
• The launcher is an Ariane 5 rocket.
   
• The cruise will last 7 years and wil use gravity assists around the Earth (1), Venus (2) and Mercury (6).
   
• At the arrival near Mercury, MTM will be jettisoned. Then Mio will be injected in orbit around Mercury, MOSIF will be jettisoned, then MPO will be injected in orbit around Mercury.
   
• Mio will have an elliptical polar orbit with a periherm at 600 km altitude and apoherm at 11800 km. The Mio orbital period will have an approximate duration of 9.2 hours. Mio periherm is designed to be at proximity of Mercury's subsolar point (the closest point to the Sun at any given instant) near the apohelion and around midnight near perihelion. This orbit was selected to minimize the effects of the infrared radiations emitted by Mercury's surface.
• MPO will have a slightly elliptical low polar orbit with a periherm at 480 km altitude and apoherm at 1500 km. The MPO orbital period will have an approximate duration of 2.3 hours. The polar orbit has been chosen to facilitate the global observation and to optimize the spatial resolution.

Scientific Objectives

BepiColombo is the first mission in total collaboration between ESA(European Space Agency) and JAXA(Japan Space Agency), for the interdisciplinary study of Mercury. Mercury, the closest planet to the Sun, is known since antiquity, but direct observation of Mercury was only performed by the Mariner 10 probe in 1974-75 and by the American probe Messenger launched in August 2004 whose mission is ending.

Mercury has a unique structure i.e. a very big core (3/4 of the planet's radius. This could be linked to its intrinsic magnetic field). Detailed observations of its interior and surface reveal that the planet formed in the region nearer to the Sun.

Mercury will provide the first opportunity to compare the planetary magnetic field structure of a telluric planet to the Earth's one.

The only telluric planets with an intrinsic magnetic field are the Earth and Mercury. The detailed observation of Mercury's magnetic field and its magnetosphere will lead to the first comparative studies with the Earth and will increase our knowledge in these domains.

Thanks to the BepiColombo mission, Mercury's interior, surface, exosphere, magnetosphere, and environment will be thoroughly studied and a new frontier to solar system science will be open. This mission is constituted of two probes: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio).

MPO probe is dedicated to the study of the surface and the interior of Mercury (surface geology, geomorphology, geophysics, volcanism, global tectonics, age of the surface, composition of Mercury's surface) as well as its exosphere.

The Mio probe's instruments will enable to mainly study the magnetic field, the magnetosphere, the inner interplanetary space, the radiations and particles in Mercury's environment and the exosphere. The comparison of the magnetic field and the magnetosphere to those of the Earth will supply a new vision of the magnetosphere's dynamics and physical processes.

Thanks to the MPO instruments coupled with the Mio instruments, coordinated measurements of the planetary magnetic field will be conducted.