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Freitag, 7. Juli 2017 - 21:10 Uhr

Raumfahrt - Merkur Mission BepiColombo 2017 - Update-1

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7.04.2015

Artist’s concept of the BepiColombo mission, showing the European-built Mercury Planetary Orbiter (top) and the Japanese Mercury Magnetospheric Orbiter (bottom). Credit: ESA
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The launch of a nearly $2 billion joint mission robotic mission to Mercury by Europe and Japan will be delayed from next year to early 2017 to account for late deliveries of critical components and scientific instrumentation, according to the European Space Agency.
The BepiColombo mission, comprising two main spacecraft built in Europe and Japan, will still reach Mercury in January 2024.
The new launch window — determined by the positions of the planets — opens on Jan. 27, 2017, and extends for one month, ESA announced March 30. The launch was previously set for July 2016.
Mission managers completed BepiColombo’s critical design review March 25 and decided to put off the launch for six months.
“As the result of delays in the procurement of critical units and the availability of some payloads, a decision was taken to opt for a later launch opportunity in order to minimize the operational risk to this ambitious dual mission,” ESA said in a statement.
Another launch opportunity is available in mid-2017 to allow BepiColombo to still get to Mercury in 2024.
BepiColombo will launch on an Ariane 5 rocket from the Guiana Space Center in South America to kick off a seven-year cruise through the inner solar system. The European and Japanese components will blast off with a carrier spacecraft called the Mercury Transfer Module, which will carry ion engines to guide the mission on the journey to Mercury.
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A mock-up of the BepiColombo composite spacecraft in launch configuration undergoes shaker testing in July 2012. Credit: ESA
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When packaged inside the Ariane 5’s payload fairing, the three-part spacecraft stack will measure about the size of a moving van.
The spacecraft will return to the vicinity of Earth in July 2018 for a gravity boost to slingshot the probe closer to the sun. BepiColombo will spiral toward Mercury with two flybys of Venus in September 2019 and May 2020, followed by five Mercury encounters between 2020 and 2023.
BepiColombo’s transit module will be jettisoned just before it steers into orbit around Mercury on Jan. 1, 2024. The mission’s Japanese and European components — each fully functioning spacecraft — will separate and fly into different orbits for at least one year of observations, looking at the planet’s cratered surface, investigating its origin, probing its interior, examining its tenuous atmosphere, studying its magnetic field, and timing Mercury’s orbit around the sun to test Albert Einstein’s theory of general relativity.
Mercury will fly around the sun four times during BepiColombo’s one-year prime mission. The orbiters should have enough fuel for a one-year extension.
BepiColombo’s Japanese section — known as the Mercury Magnetospheric Orbiter — is about the size of a compact car. It will probe Mercury’s magnetic field and atmosphere from a highly elliptical orbit.
ESA’s Mercury Planetary Orbiter will fly closer to the planet’s surface, measuring Mercury’s terrain and composition.
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BepiColombo’s Mercury Planetary Orbiter is seen inside a clean room at ESA’s test center in Noordwijk, the Netherlands. Credit: ESA – A. Le Floc’h
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BepiColombo will be the first mission to Mercury by Europe and Japan, and the second to orbit the fleet-footed planet after NASA’s Messenger spacecraft.
First proposed to ESA in the 1990s, BepiColombo is one of the most difficult space missions ever attempted by Europe and the most ambitious probe ever sent to Mercury. Powered by ion engines and shielded to withstand scorching temperatures of nearly 700 degrees Fahrenheit at Mercury, BepiColombo has endured redesigns, upgrades and delays that have sent the mission’s cost more than 50 percent higher than original estimates.
ESA officials intended BepiColombo to launch on a medium-class Soyuz rocket, but the spacecraft outgrew the capacity of the Soyuz, forcing it to lift off on the more expensive Ariane 5.
Technicians in February mated BepiColombo’s European orbiter and transfer module for the first time at ESA’s test center in the Netherlands. Japan’s magnetospheric probe is due to arrive at ESA in April for final tests.
Quelle: SN
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Update: 21.04.2015
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The BepiColombo probe to examine Mercury, the largely unexplored planet closest to the Sun
The mission comprises a composite of two orbiters and two supporting modules which are launched in a four-module stack configuration. The orbiters are the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The supporting modules are the Mercury Transfer Module (MTM) and the MMO Sunshade and Interface Structure (MOSIF). The prime contractor for the mission is Airbus Defence and Space.  ESA is providing the MPO, MTM and MOSIF. JAXA will supply the MMO. The mission is slated for launch in 2017. On arrival at Mercury in 2024 it will gather data for at least one year.
Quelle: Airbus DEFENCE&SPACE
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Update: 22.07.2015
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BEPICOLOMBO ANTENNA IN LSS

The antenna that will connect Europe’s BepiColombo with Earth is being tested for the extreme conditions it must endure orbiting Mercury.
The trial is taking place over 10 days inside ESA’s Large Space Simulator, which, at 15 m high and 10 m across, is cavernous enough to accommodate an upended double decker bus.
The 1.5 m-diameter high-gain antenna, plus its boom and support structure, are subjected to a shaft of intense sunlight in vacuum conditions, while gradually rotated through 90º.
The antenna will be part of ESA’s Mercury Planetary Orbiter, one of two main components of the January 2017 BepiColombo mission – the other being Japan’s Mercury Magnetospheric Orbiter.
The two will be launched together in a stack, carried by the Mercury Transfer Module for their seven-year journey towards the Solar System’s innermost world.
The Simulator is part of the largest spacecraft testing facility in Europe, at ESA’s ESTEC technical centre in Noordwijk, the Netherlands.
The mammoth chamber’s high-performance pumps create a vacuum a billion times lower than standard sea-level atmosphere, while the chamber’s black interior walls are lined with tubes pumped full of –190°C liquid nitrogen to mimic the extreme cold of deep space.
At the same time, the hexagonal mirrors seen at the top of the picture reflect simulated sunlight onto the satellite from a set of 25 kW bulbs more typically employed to project IMAX movies.
In this case, the alignment of the 121 mirrors was adjusted to tighten the focus of their light beam, reproducing the intensity of sunlight experienced in Mercury orbit – around 10 times more intense than terrestrial illumination.
Quelle: ESA
Siehe auch: http://www.hjkc.de/_blog/2013/03/11/raumfahrt---bepicolombo-mercury-transfer-module-im-sonnen-test/
 
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Update: 28.12.2015
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MERCURY PLANETARY ORBITER
The Mercury Planetary Orbiter (MPO) is a three-axis stabilised spacecraft which will orbit Mercury in an inertial polar orbit of 2.3h period. It accommodates 11 instruments or instrument suites and has a box-like shape of 3.9 x 2.2 x 1.7 m.
 
The radiator, on the -Y side, will always face away from the Sun (the MPO will flip by 180º at perihelion and aphelion, meaning both -X and +X sides will face in the ram direction), and most of the instruments are on the -Z side, which will nominally always face towards Mercury (i.e. nadir). The altitude range is expected to be 480 km to 1500 km, with the latitude of the periherm varying between 16ºN to 16ºS over the course of the nominal science phase (i.e. the first full Earth year).
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As can be seen in the orbit figure below, at perihelion, the MPO's apoherm is on the dayside - this configuration minimises the thermal load, both from the Sun and from Mercury's albedo. The perihelion is an important time for the exospheric instruments; at perihelion the planet's spin speed is slightly overtaken by the orbit speed, and from the surface the Sun would appear to slow down, stop, go in the other direction for ~4 (Earth) days, then slow, stop and continue in the ‘correct' direction - the dawn and dusk effectively swap. 
 
The aphelion time is the most important for the cameras and surface scanning instruments, while the periherm is in the dayside, i.e. the surface is lit and close so that the cameras can get good resolution.
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Diagram describing schematically how the periherm and apoherm vary throughout the Mercury year.
 
THE SPACECRAFT
STAR TRACKERS, THRUSTERS AND REACTION WHEELS
Four redundant 22N thrusters in the nadir face to be used in orbital manoeuvres until final orbit acquisition, after which they will be deactivated. The control of the attitude is provided by a set of four reaction wheels and four 10N thrusters for momentum wheel de-saturation; these thrusters are mounted on the radiator. Three star trackers, also mounted on the radiator side, sun sensors and a high precision gyroscope package are employed as sensors for attitude control, the combination of which provides precise attitude determination required by several of the instruments.
 
RADIATOR
The only side of the spacecraft not to see the Sun is the radiator; highly reflective fins (polished and geometrically reflecting outwards) have been mounted to it at an appropriate angle, to minimize absorption of heat radiated from Mercury, and to allow radiation towards deep space. 
 
SOLAR ARRAY
Because of the intense heat, the three-panel solar array is a 70-30% mixture of solar cells and Optical Surface Reflectors (OSR, i.e. mirrors) to keep its temperature below 200°C. This is supported by choosing sun incident angles up to 80° that generate enough power, but do not unnecessarily heat up the solar array. There is a battery and heaters that operate in the freezing dark during eclipse.
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MERCURY MAGNETOSPHERE ORBITER
The Mercury Magnetospheric Orbiter (MMO) is a spin-axis stabilised spacecraft with a rotation rate of 15 rpm or spin period of 4s; the spin axis will be nearly perpendicular to Mercury's equator. Altitude range is currently expected to be from 590 km to 11639 km – the apoherm is nearly 6 planetary radii from planet's centre.
STRUCTURE OF THE SPACECRAFT
The main body of the spacecraft is octagonal and would fit inside a circle of 1.8 m diameter. The height of side panel is 0.9 m; the upper portion is 50% solar cells and 50% optical solar reflectors (OSRs). There are two decks (upper and lower)separated by 40 cm that hold the instruments, a central cylinder (thrust tube) and four bulkheads.
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MMO structure (side view) (after Fig. 4, Yamakawa et al., 2008).
 
The spacecraft attitude will be determined by a pair of sun sensors on the side panel and a star scanner attached to the bottom surface. The attitude is controlled by the propulsion system with a cold gas jet. A nutation dumper installed inside the central cylinder is used for passive nutation dumping.
 
OVERVIEW OF THE INSTRUMENTS
The MMO carries as payload:
MDM - Mercury Dust Monitor
MGF - Magnetometer
MPPE - Mercury Plasma Particle Experiment
MSASI - Mercury Sodium Atmospheric Spectral Imager
PWI - Plasma Wave Investigation
 
The figure below shows how the sensors and electronics/receivers fit together. All of the inputs to DPU1 are from the MPPE suite, and inputs from the other four suites/instruments are routed to DPU2.
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External view of the MMO spacecraft and PWI sensors (after Fig 3., Kasaba et al.,
2010).
 
The labelled mast is referred to as MAST-SC and the unlabelled mast is termed MAST-MGF and holds the MGF dual-sensor instrument. The antennas are PWI's WPT and MEFISTO (electric-field sensors), which measure 32 m tip-to-tip, or 15 m each from the s/c.
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Detailed view of the extendable mast system (after Fig. 25, Kasaba et al., 2010).
 
One mast (MAST-MGF) holds MMO/MGF (dual fluxgate magnetometer; MGF-O at the tip and MGF-I 1.6 m from the tip) and the other mast (MAST-SC) holds both PWI's LF-SC (Low-Frequency Search Coils) and DB-SC (Dual-Band Search Coils) at the tip. Extension of the masts will be performed in the initial phase of the MMO operation just after the separation of the MMO from the MCS (Mercury Composite Spacecraft) at the Mercury orbit.
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The trajectory of the MMO spacecraft. MSASI observations may be performed
during an interval of 3h 25m between periapsis and apoapsis (the red arc) (after
Fig. 1., Yoshikawa et al., 2010).
 
As the spin axis is in the same direction as the spin axis of Mercury, the spacecraft will remain ‘upright' throughout the orbit around Mercury; the bottom of the lower deck (radiator and second surface mirror (SSM)) and the top of the upper deck (MLI) will be able to ‘see' Mercury above the northern hemisphere and southern hemisphere, respectively. An HGA of 80cm diameter is used for the high speed X-band. The average bit rate is 16 kbps, which in turn translates into ~40 Mbyte/day assuming a 6 h consecutive pass on average. 2.0 GByte volume is assumed for the data recorder for the storage of MMO housekeeping and science data before the transmission to the Earth.
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MMO Sunshield and Interface Structure (MOSIF) surrounding the MMO and with closure MLI to MPO (after Fig 9., Benkhoff et al,. 2010).
 
As the MMO is a spinning spacecraft, it needs to be thermally protected during the interplanetary cruise phase - this is done by the MOSIF (figure above).
 
Taken from:
Benkoff, J., van Casteren, J. & Hayakawa, H. BepiColombo—Comprehensive exploration of Mercury: Mission overview and science goals. Planetary and Space Science 58, 2–20 (2010).
Kasaba, Y. et al. The Plasma Wave Investigation (PWI) onboard the BepiColombo/MMO: First measurement of electric fields, electromagnetic waves, and radio waves around Mercury. Planetary and Space Science 58, 238–278 (2010).
Mukai, T., Yamakawa, H., Hayakawa, H., Kasaba, Y. & Ogawa, H. Present status of the BepiColombo/Mercury magnetospheric orbiter. Advances in Space Research 38, 578–582 (2006).
Yamakawa, H., Ogawa, H., Sone, Y. & Hayakawa, H. BepiColombo Mercury magnetospheric orbiter design. Acta Astronautica (2008). doi:10.1016/j.actaastro.2008.01.040
Yoshikawa, I. et al. The Mercury sodium atmospheric spectral imager for the MMO spacecraft of Bepi-Colombo. Planetary and Space Science 58, 224–237 (2010).
Quelle: ESA
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Update: 27.01.2016 
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RADIO TESTING OF BEPICOLOMBO ORBITER

If ESA’s Mercury orbiter of the BepiColombo mission seems to stand at an unusual angle above its test chamber floor, that’s because it does – intentionally so.
The orbiter underwent ‘electromagnetic compatibility, radiated emission and susceptibility’ testing last month inside the Maxwell chamber of ESA’s ESTEC Test Centre in Noordwijk, the Netherlands.
Maxwell’s shielded metal walls and doors form a ‘Faraday cage’ to block unwanted external electromagnetic radiation, while its internal walls are cover with ‘anechoic’ radio-absorbing foam pyramids to mimic boundless space.
“We are performing two types of compatibility testing,” explained Marco Gaido, assembly, integration and test manager for BepiColombo.
“First, we are checking the craft is electrically compatible with the electrical field generated by the Ariane 5 launcher that will deliver it into orbit, with no possibility of interference with BepiColombo’s receivers.
“Secondly, we are testing if there is any risk of incompatibility between the different subsystems of the spacecraft itself when it orbits Mercury. In particular, we want to check that its trio of antennas on top can communicate properly with Earth.
“Accordingly, it was deliberately oriented to simulate a worst-case scenario for test purposes.”
The orbiter was positioned to allow deployment of its medium-gain antenna in terrestrial gravity. The high-gain antenna reflector meanwhile was deployed in a worst-case position, supported by a dedicated fixture.
The spacecraft was tilted by means of a large platform while the high-gain antenna was supported by a tower made of wood, transparent to radio waves. All test cables used were shielded to reduce potential interference.
ESA’s Mercury Planetary Orbiter will be launched to Mercury together with Japan’s Mercury Magnetospheric Orbiter aboard an ESA-built carrier spacecraft, the Mercury Transfer Module. This entire three-module BepiColombo stack will undergo similar testing at ESTEC.
Quelle: ESA
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Update: 17.04.2017
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BepiColombo at Mercury
 

MEET THE FLEET

 
New artist's views of the BepiColombo spacecraft that will be launched to Mercury in 2018
Quelle: ESA
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Update: 5.07.2017
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bepicolombo-a-1
Quelle: ESA
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Update: 6.07.2017
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BepiColombo: Joint Mercury mission ready for 'pizza oven'

Stack on show
Image captionFully fuelled at launch, the 6.4m-high flight stack will weigh over four tonnes

The two satellites that make up the BepiColombo mission to Mercury were presented to the media on Thursday. 

This joint European-Japanese venture has been in development for nearly two decades, but should finally get to the launch pad in 15 months' time.

The two spacecraft will travel together to the baking world but separate on arrival to conduct their own studies.

Thursday's event in the Netherlands was the last chance for journalists to view the so-called "flight stack".

This is the edifice that goes on top of the rocket and comprises Europe's Mercury Planetary Orbiter (MPO) and Japan's Mercury Magnetospheric Orbiter (MMO), as well as the propulsion module to control their path towards the world that circles closest to the Sun.

As a single item, the stack has just finished a series of important tests, but it will shortly be taken apart so that the individual components can continue with their own preparations. The structure will not be reassembled until all equipment reaches the Kourou spaceport in French Guiana. 

The double mission is due to blast away from Earth on an Ariane rocket in October 2018. Everyone will have to be patient, however. It is going to take seven years for the satellite duo to get to their destination. 

The gravity of the Sun pulls hard on any spacecraft travelling into the inner Solar System, and Bepi will have to fire thrusters in the direction of travel to ensure it does not overshoot Mercury. 

"Mercury is the least explored of the rocky planets, but not because it is uninteresting," said Prof Alvaro Giménez Cañete, the director of science at the European Space Agency (Esa). 

"It's because it's difficult. It's difficult to get there; it's even more difficult to work there." 

Temperatures on the surface of the diminutive world go well above 400C - hot enough to melt some metals, such as tin, zinc and lead.


How to build a mission to Mercury

StackImage copyrightESA
Image captionEurope's Airbus company led production of the MTM, MPO and the sun shield for MMO
  • MTM is a propulsion module to control the cruise to Mercury
  • Europe's Mercury Planetary Orbiter carries 11 instruments
  • For the cruise phase, a sun shield protects the MMO
  • At Mercury, Japan's orbiter dispenses with the shield 
  • It will simply spin to prevent its surfaces from overheating
  • MMO and MPO will go into different polar orbits at Mercury

The MPO and MMO will be looking to deepen and extend the knowledge gained at Mercury by the US space agency’s recent Messenger mission. 

The American probe, which ceased operations in 2015, took some 270,000 images of the planet's surface and acquired 10 terabytes of other scientific measurements. 

It provided remarkable new insights on the composition and structure of the smallest terrestrial planet, and it made the amazing discovery that, despite those high temperatures, there are shadowed craters where it is still cold enough to support water-ice. 

Esa and the Japanese space agency (Jaxa) hope that the more advanced, higher-resolution technology on their satellites will be able to answer questions that Messenger could not. 

Esa's BepiColombo project scientist, Johannes Benkhoff, said: "We need to come up with new ideas. And for that reason we need to have good instrumentation and we need to do very close monitoring of the planet; and we can do that with our spacecraft that we're sending to Mercury."


The oddball close to the Sun

Media captionEmma Bunce: "Bepi will allow us to make a step change in our understanding"
  • Past Mercury visitors were Nasa missions: Mariner 10 and Messenger
  • The planet's diameter is 4,880km - about one-third that of the Earth
  • It is the second densest planet in the Solar System: 5.4 grams/cu cm
  • The Caloris Basin is the largest surface feature (1,550km across)
  • It is an extreme place: surface temps swing between 425C and -180C
  • There is water-ice in the planet's permanently shadowed craters
  • Mercury's huge iron core takes up more than 60% of the planet's mass
  • Apart from Earth, it is the only inner planet with a global magnetic field

The key conundrum is why the planet contains an outsized iron core and only a thin veneer of silicate rocks. 

A favoured theory before Messenger was that Mercury at some point in its history was stripped of its outer layers, either by a big collision with another body or by the erosive effects of being so close to the Sun. 

But the American probe observed large abundances of volatile substances. "They shouldn't be there had those events happened in Mercury's past; the sulphur and potassium volatiles on the surface just shouldn't be there," insisted Prof Emma Bunce, a principal investigating scientist from Leicester University, UK. 

"And the other mystery about the surface is that there isn't much iron on it, seemingly; and so that needs to be looked into in more detail and that's something we'll be able to do with our imaging X-ray spectrometer, MIXS."

Europe's MPO will have a total of 11 instruments onboard. It will fly in a near-circular polar orbit around the planet, mapping the terrain, generating height profiles, sensing the interior, and collecting data on surface composition and the wispy "atmosphere". 

Japan's MMO will have five instruments and will investigate the planet's magnetic field. 

Mercury is the only terrestrial planet - apart from Earth - to have a global magnetic field. But it is an odd one. The field is roughly three times stronger in the northern hemisphere than it is in the south. 

Media captionMessenger compiled this exaggerated colour map of Mercury during its first year in orbit

Both Esa and Jaxa are delighted to at last be approaching launch. 

The development of the mission, particularly on the European side, has been a torrid learning curve. 

The launch date was repeatedly put back as engineers struggled to find equipment that could cope with the intense heat and radiation experienced just a few tens of millions of km from the Sun. The development of solar cells in particular proved extremely problematic. 

"We're flying into a pizza oven," quipped Esa project manager Ulrich Reininghaus. "We had to test materials at different, very high temperature regimes, sometimes with very unwanted results." 

When Esa's Science Programme Committee originally green-lit BepiColombo in 2000, it had in mind a launch in 2009. Even when the industrial contract to build the MPO was finally signed in 2008, a launch was thought possible in 2013. 

Esa says the mission is costing roughly €1.65bn (£1.45bn; $1.85bn). This includes all European and Japanese costs.

One fascinating aside. That SPC meeting in 2000 also approved Esa participation in the successor space telescope to Hubble, which is called the James Webb Space Telescope. Its development schedule has also been heavily delayed and is itself now booked for launch on an Ariane in October 2018.

But it is not possible to put both missions up at the same time, so one will have to stand aside. A decision on whether it is Bepi or JWST that goes first is likely to be made this September.

Hollows
Image copyrightNASA/JHU-APL/CIW
Image captionMessenger found hollowed out surface features that indicated the presence of volatiles

Quelle: BBC

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Update: 7.07.2017

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BepiColombo stack
 

PREPARING FOR MERCURY: BEPICOLOMBO STACK COMPLETES TESTING 

ESA’s Mercury spacecraft has passed its final test in launch configuration, the last time it will be stacked like this before being reassembled at the launch site next year.

BepiColombo’s two orbiters, Japan’s Mercury Magnetospheric Orbiter and ESA’s Mercury Planetary Orbiter, will be carried together by the Mercury Transport Module. The carrier will use a combination of electric propulsion and multiple gravity-assists at Earth, Venus and Mercury to complete the 7.2 year journey to the Solar System’s mysterious innermost planet

 
 
 
 
BepiColombo’s journey to Mercury

Once at Mercury, the orbiters will separate and move into their own orbits to make complementary measurements of Mercury’s interior, surface, exosphere and magnetosphere. The information will tell us more about the origin and evolution of a planet close to its parent star, providing a better understanding of the overall evolution of our own Solar System.

To prepare for the harsh conditions close to the Sun, the spacecraft have undergone extensive testing both as separate units, and in the 6 m-high launch and cruise configuration.

One set of tests carried out earlier this year at ESA’s technical centre in the Netherlands focused on deploying the solar wings, and the mechanisms that lock each panel in place. The 7.5 m-long array of the Mercury Planetary Orbiter and the two 12 m-long array of the Mercury Transport Module will be folded while inside the Ariane 5 rocket.

 
 
 
 
BepiColombo vibration test

Last month, the full spacecraft stack was tested inside the acoustic chamber, where the walls are fitted with powerful speakers that reproduce the noise of launch.

Just last week, tests mimicked the intense vibrations experienced by a satellite during launch. The complete stack was shaken at a range of frequencies, both in up-down and side-to-side motions.

These were the final tests to be completed with BepiColombo in mechanical launch configuration, before it is reassembled again at the launch site.

Mercury Transfer Module solar wing deployment

In the coming weeks the assembly will be dismantled to prepare the transfer module for its last test in the thermal–vacuum chamber. This will check it will withstand the extremes of temperatures en route to Mercury.

The final ‘qualification and acceptance review’ of the mission is foreseen for early March. Then BepiColombo will be flown to Europe’s Spaceport in Kourou, French Guiana, in preparation for the October 2018 departure window. The date will be confirmed later this year.

“This week was the last opportunity to see the spacecraft in its stacked launch configuration before it leaves Europe. The next time will be when we are at the launch site already fueled,” says Ulrich Reininghaus, ESA’s BepiColombo Project Manager. “This is quite a milestone for the project team. We are looking forward to completing the final tests this year, and shipping to Kourou on schedule.”

Quelle: ESA

 

Tags: Raumfahrt ESA Merkur Mission BepiColombo 

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