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Raumfahrt - BepiColombo Mercury Transfer Module "im Sonnen-Test"

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BepiColombo module in space simulator

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The engineering model of the BepiColombo Mercury Transfer Module has completed a 12-day Sun-simulation test inside the Large Space Simulator at ESA’s test centre in the Netherlands, where it received a taste of the extreme solar heating it will experience when it enters orbit around the Solar System’s innermost planet in 2022.
The image was taken during a dry run on 20 February, during which the facility’s motion system replicated the different orientations of the simulated solar beam and the positions of the test table. 
The real test, in vacuum, began on 26 February and continued non-stop for 12 days. During this time the module was subjected to ten times the solar heating experienced by satellites circling Earth.
Some of the 121 hexagonal mirror segments that direct the simulated solar radiation onto the spacecraft are visible towards the top of the image. The aperture through which the ‘sunlight’ travels from the nineteen 25 kW lamps can be seen just to the left of the mirror segments.
The Mercury Transfer Module will carry the mission’s two scientific satellites – Japan’s Mercury Magnetospheric Orbiter and Europe’s Mercury Planetary Orbiter – into orbit around Mercury. The spacecraft will use electric propulsion to reach its destination.
In this view, one of four ion propulsion engines has already been installed (the grey cylinder close to the centre of the unit), while part of the solar array drive protrudes from the right side of the module.
Earlier this month, the mission’s Mercury Planetary Orbiter Mechanical and Propulsion Bus Proto-Flight Model completed a ‘bake out’ in the Phenix thermal vacuum facility at ESA’s ESTEC test facility. This heated the unit to 60°C in a vacuum for 23 days to remove any contaminants that would outgas in space.
BepiColombo is an international mission between ESA and the Japan’s JAXA space agency. It is scheduled for launch in 2015 and will arrive at Mercury in 2022, where it will study the planet’s composition, geophysics, atmosphere, magnetosphere and geological history.

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This artist’s impression provides a view of the two BepiColombo spacecraft, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO), in their elliptical polar orbits around Mercury.
The MPO will circle the planet along an orbit ranging between 400 and 1500 kilometres above the surface. The MMO orbit ranges between 400 and 12 000 kilometres above the surface. The inclination and the eccentricity of these orbits are optimised for the study of the planet and of its magnetosphere in the very high temperature environment around Mercury.
The MPO will circle the planet along an orbit ranging between 400 and 1500 kilometres distance from the surface. The MMO orbit ranges between 400 and 12000 kilometres from the surface. The inclination and the eccentricity of these orbits are optimised for the study of the planet and of its magnetosphere in the very-high-temperature environment around Mercury.
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This exploded view shows BepiColombo in its cruise configuration. Visible from the bottom are: the BepiColombo transfer module, the Mercury Planetary Orbit (MPO), the sun shield and the Mercury Magnetospheric Orbiter (MMO).
The transfer module is provided with solar-electric propulsion and chemical propulsion units. The former will be used during the cruise to destination; the latter will be used after launch to boost up the orbit to the Moon's altitude for the planned lunar gravity-assist.
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Objective:
One of ESA’s cornerstone missions, it will study and understand the composition, geophysics, atmosphere, magnetosphere and history of Mercury, the least explored planet in the inner Solar System.
Mission:
BepiColombo will provide the best understanding of Mercury to date. It consists of two individual orbiters: the Mercury Planetary Orbiter (MPO) to map the planet, and the Mercury Magnetospheric Orbiter (MMO) to investigate its magnetosphere.
What’s special?
Most of ESA's previous interplanetary missions have been to relatively cold parts of the Solar System. BepiColombo will be the Agency's first experience of sending a planetary probe close to the Sun.
BepiColombo’s mission is especially challenging because Mercury's orbit is so close to our star. The planet is hard to observe from a distance, because the Sun is so bright. Furthermore, it is difficult to reach because a spacecraft must lose a lot of energy to ‘fall’ towards the planet from the Earth. The Sun’s enormous gravity presents a challenge in placing a spacecraft into a stable orbit around Mercury.
Only NASA's Mariner 10 and Messenger have visited Mercury so far. Mariner 10 provided the first-ever close-up images of the planet when it flew past three times in 1974-1975. En route to its final destination in orbit around Mercury in 18 March 2011, Messenger flew past the planet 3 times (14 January 2008, 6 October 2008, and 29 September 2009), providing new data and images. Once BepiColombo arrives in 2022, it will help reveal information on the composition and history of Mercury. It should discover more about the formation and the history of the inner planets in general, including Earth.
Spacecraft
The BepiColombo mission is based on two spacecraft:
a Mercury Planetary Orbiter (MPO); and
a Mercury Magnetospheric Orbiter (MMO)
Among several investigations, BepiColombo will make a complete map of Mercury at different wavelengths. It will chart the planet's mineralogy and elemental composition, determine whether the interior of the planet is molten or not, and investigate the extent and origin of Mercury’s magnetic field.
Journey
Several launch methods have been extensively studied. In the selected scenario, BepiColombo will use the gravity of the Earth, Venus and Mercury in combination with the thrust provided by solar-electric propulsion (SEP). During the voyage to Mercury, the two orbiters and a transfer module, consisting of electric propulsion and traditional chemical rocket units, will form one single composite spacecraft.
When approaching Mercury in 2022, the transfer module will be separated and the composite spacecraft will use rocket engines and a technique called 'weak stability boundary capture’ to bring it into polar orbit around the planet. When the MMO orbit is reached, the MPO will separate and lower its altitude to its own operational orbit. Observations from orbit will be taken for at least one Earth year with the possibility of an extension.
History
As the nearest planet to the Sun, Mercury has an important role in showing us how planets form. Mercury, Venus, Earth and Mars make up the family of terrestrial planets; each one carrying essential information to trace the history of the whole group.
The knowledge of how they originated and evolved is key to understanding how conditions supporting life arose in the Solar System, and possibly elsewhere. As long as Earth-like planets orbiting other stars remain inaccessible to astronomers, the Solar System is the only laboratory where scientists can test models applicable to other planetary systems.
Exploring Mercury is therefore fundamental to answering important astrophysical and philosophical questions such as 'Are Earth-like planets common in the Galaxy?'
A European mission to Mercury was first proposed in May 1993. Although an assessment showed it to be too costly for a medium-size mission, ESA made a Mercury orbiter one of its three new cornerstone missions when the Horizon 2000 science programme was extended in 1994. Gaia competed with BepiColombo for the fifth cornerstone mission. In October 2000, ESA approved a package of missions for 2008–2013 and both BepiColombo and Gaia were approved.
In February 2007, the mission was approved as part of the Cosmic Vision programme. Following an unavoidable increase in the mission’s mass during 2008, the launch vehicle was changed from Soyuz-Fregat to Ariane 5. Final approval for the redesigned mission was given by ESA’s Science Programme Committee in November 2009.
BepiColombo represents the first time ESA and JAXA have joined forces for the implementation of a major space science mission.
Partnerships
BepiColombo is a joint mission between ESA and the Japanese Aerospace Exploration Agency (JAXA), executed under ESA leadership.
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Quelle: ESA
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