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Raumfahrt - ESA´s GAIA Ready for launch Soyuz Flight VS06! Teil-1

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Gaia is a global space astrometry mission. It will make the largest, most precise three-dimensional map of our Galaxy by surveying more than a thousand million stars.

In this blog we'll cover the activities from Kourou from once the spacecraft has left the clean room in Toulouse until launch.

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The main goal of the Gaia mission is to make the largest, most precise three-dimensional map of our Galaxy by surveying an unprecedented one per cent of its population of 100 billion stars.

 

During the mapping, Gaia will detect and very accurately measure the motion of each star in its orbit around the centre of the Galaxy. Much of this motion was imparted upon each star during its birth and studying it allows astronomers to peer back in time, to when the Galaxy was first forming. By constructing a detailed map of the stars, Gaia will provide a crucial tool to study the formation of our Galaxy, the Milky Way.

While surveying the sky, Gaia is bound to make many other discoveries. During its anticipated lifetime of five years, Gaia will observe each of its one billion sources about  70 times, resulting in a record of the brightness and position of each source over time. Together with the unprecedented accuracy of the astrometric measurements, this will lead to the discovery of: planets around other stars, asteroids in our Solar System, icy bodies in the outer Solar System, brown dwarfs, and far-distant supernovae and quasars. The list of Gaia's potential discoveries makes the mission unique in scope and scientific return.

Huge databases of information will be compiled from the Gaia data, allowing astronomers to trawl the archives looking for similar celestial objects or events and other correlations that might just provide the clue necessary to solve their particular, seemingly intractable, scientific puzzle.

The Spacecraft

The Gaia spacecraft is comprised of a payload module, a mechanical service module and an electrical service module and has a launch mass of around 2 tonnes. The payload module is built around the hexagonal optical bench (~3m diameter) which provides the structural support for the single integrated instrument that comprises three functions: astrometry, photometry and spectrometry. It further contains all necessary electronics for managing the instrument operation and processing the raw data.

The mechanical service module comprises all mechanical, structural and thermal elements supporting the instrument and the spacecraft electronics. It also includes the micro-propulsion system, deployable sunshield, payload thermal tent, solar arrays and harness.

The electrical service module offers support functions to the Gaia payload and spacecraft for pointing, electrical power control and distribution, central data management and radio communications with the Earth.

The L2 Orbit

Gaia will be placed in an orbit around the Sun, at the second Lagrange point L2, which is named after its discoverer, Joseph Louis Lagrange (1736-1813).  For the Sun-Earth system, the L2 point lies at a distance of 1.5 million kilometres from the Earth in the anti-Sun direction and co-rotates with the Earth in it's 1-year orbit around the Sun.

One of the principal advantages of an L2 orbit is that it offers uninterrupted observations, since the Earth, Moon and Sun all lay within the orbit of the L2 point. From L2 the entire celestial sphere can be observed during the course of one year. To ensure Gaia stays at L2, the spacecraft must perform small manoeuvres every month.

Gaia will not be the only ESA mission going to L2.  Herschel and Planck have operated from there and currents plans call for  JWST to be placed there, too.

The Hipparcos Mission

Gaia is not the first space mission to chart the heavens. In 1989, ESA launched Hipparcos. Sounding like the name of Hipparchus, the Greek astronomer, its different spelling reflects that the name was also an acronym for High Precision Parallax Collecting Satellite.

This entirely European mission was the first satellite to chart the positions of stars and produced a primary catalogue of about 118 000 stars, and a secondary catalogue, called Tycho, of over 2 million stars whose positions were determined to slightly less precision. The data is now widely used by the entire community of professional astronomers.

Among other results, Hipparcos' data contributed to the prediction of when comet Shoemaker-Levy 9 would collide with Jupiter. The data showed that many billions of years ago, the Galaxy swallowed a large group of stars. Hipparcos also helped astronomers to refine the age of the Universe.

The Challenge of Gaia

Gaia will significantly improve on Hipparcos for a number of different reasons. For example, the collecting area of the primary mirrors means that Gaia will collect more than 30 times the light of its predecessor, allowing for more sensitive and accurate measurements.

Gaia will be able to measure a star's position and motion 200 times more accurately than Hipparcos. Changes in a star's position and motion are registered as tiny angles. As a comparison, if Hipparcos could measure the angle that corresponds to the height of an astronaut standing on the Moon, Gaia will be able to measure his thumbnail!

Highly efficient cameras, CCDs, will be used to record the images, so wide-angle images of many celestial objects can be obtained at the same time. Devices known as photocathodes were used on Hipparcos, which meant that the satellite could only record information from a single celestial object at a time.

Astronomers will have the challenge of dealing with a flood of data when Gaia begins its work in 2013. Even after being compressed by software, the data produced by the five-year mission will fill over 30 000 CD ROMs. This data will be transmitted 'raw' and will need processing on Earth to turn it into a calibrated set of measurements that can be freely used by the astronomical community.

So, not only must ESA design and build the spacecraft itself, they must also develop new computer software that will ensure the data can be processed efficiently once it is back on Earth.

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The primary objective of the Gaia mission is to survey more than one billion stars in our Galaxy and beyond. Data from this astronomical census will allow astronomers to answer some fundamental questions about the formation and evolution of our Galaxy, and will provide insight into many other topical areas of astronomy. Some of these are briefly mentioned below.

 

Main Objectives

Gaia is designed with a single, primary goal in mind: to investigate the origin and subsequent evolution of our Galaxy, the Milky Way. To do this, it will conduct an astronomical census of 1 billion stars, allowing astronomers to build the most accurate three-dimensional map to date of the celestial objects in our Galaxy.

Gaia's mission is scheduled to last for five years. During that time, it will log the position, brightness and colour of every visible celestial object that falls within its field of view. By repeating these observations throughout its mission, astronomers will be able to calculate the distance, speed and direction of motion of each of the celestial objects, chart variations in their brightness, and determine whether they have nearby companions.

This kind of data is the lifeblood of astronomy, and Gaia will gather it with unprecedented accuracy. It will allow astronomers to painstakingly piece together the history of our Galaxy, since each celestial object preserves something of the era during which it was born.

The History of the Milky Way

Our Galaxy is the product of the stars it contains. Just like a city, the Milky Way is split into different locales and surrounded by suburbs. Each of these different areas has their own characteristics that show up in the stars' orbits and chemical composition. Gaia's observations will enable astronomers to identify these regions one from another.

As stars condense out of celestial clouds of gas, they naturally incorporate the chemicals found in space. The stars then process this material in their hearts and expel it at the end of their lives. This enriches the galaxy with new, heavier chemical elements that are incorporated into the next generation of stars. Gaia will be able to discriminate between these different generations and so build up a picture of the way the Galaxy was born and subsequently evolved.

Planet Detection

For stars within a distance of approximately 150 light-years from the Sun, Gaia is expected to find every Jupiter-sized planet with an orbital period of 1.5 - 9 years. It will do this by watching out for tiny wobbles in the star's position. This behaviour is caused when a star is tugged by the gravitational pull of a planet in orbit around it. In our own Solar System Jupiter, and to a lesser extent all the other planets, do this to the Sun, making it wobble. Estimates suggest that Gaia will detect between 10 000 and 50 000 planets beyond our Solar System.

The Brown Dwarf Desert

A brown dwarf is a failed star, which fell short of accumulating enough mass to ignite nuclear fusion in its heart. Vast numbers of brown dwarfs are thought to drift, as vagabonds, across interstellar space. Astronomers also expect to find them in orbit around stars, but observations from telescopes on the Earth are not finding this particular type of brown dwarf in their expected quantities. The paucity of brown dwarfs orbiting other stars has been dubbed 'The Brown Dwarf desert'.

Gaia will detect tens of thousands of brown dwarfs, both drifting through space and in orbit around other stars, if they are there. The data is vital for astronomers to investigate how stars form, as the brown dwarfs represent the ones that did not make it. The more gas there is locked inside brown dwarfs, the less there is to make real stars.

Asteroids and Solar System Discoveries

Closer to home, there is currently great scientific and public interest in detecting our Solar System's inventory of asteroids and comets. Gaia will contribute to this search because of its unprecedented sensitivity to faint, moving objects. It is expected that the spacecraft will detect tens of thousands of minor planets. Some of them will be near-Earth objects (NEOs), others will live in the 'main-belt' of asteroids between Mars and Jupiter, yet more will be located in the icy realms of the outer Solar System known as the Kuiper Belt.

It is also possible that Gaia will discover 'Planet X' - if such an object exists. Ever since Pluto was discovered in 1930, a number of astronomers have believed in the existence of a tenth planet, out beyond Pluto. The hypothetical planet has been searched for many times but, obviously, not yet found.

Exploding Stars

During Gaia's five-year lifetime, calculations suggest that the spacecraft will detect some 100 000 exploding stars (supernovae) in distant galaxies, before they reach their maximum brightness. This will provide an early warning system for astronomers on Earth who wish to study them and use them to gauge distances to the host galaxies.

It is essential to observe such supernovae as they are still climbing in brightness. This is because the peak brightness they reach is the essential measurement for calculating their distance. Far out in space, Gaia will be in a prime location to make such observations.

Testing Einstein's General Relativity

Gaia's scientific harvest will allow Einstein's theory of General Relativity to be tested as never before. This is because the accuracy to which the spacecraft can measure positions is so great that usually negligible gravitational effects will show up in the data.

One such distortion is the bending of light by massive objects. As light passes by the Sun, or a planet in our Solar System, it is deflected slightly by that object's gravitational field. This means that the star's position will appear to move slightly. Gaia will detect this shift and allow the most precise measurement of this effect ever.

Another consequence of General Relativity is its prediction that the fabric of space, the so-called space-time continuum, can 'ripple'. These movements, called gravitational waves, cause distortions that will alter the apparent position of a star. As yet, gravitational waves remain undiscovered but Gaia's precision observations will allow astronomers to calculate upper limits on their strength. This will help to pin down the accuracy that gravitational wave 'telescopes' will need to achieve if they are to detect these elusive ripples.

Another tantalising possibility is that the strength of gravity is changing slightly every year. Whilst this can only be a minuscule variation even during a human lifetime, it could mount up into something significant over billions of years. Gaia will pinpoint white dwarfs, the cooling remains of dead stars. These give out heat for billions of years according to their pull of gravity. The amount of heat they give out determines how brightly they shine. If the strength of their gravity has decreased, then the white dwarfs will be dimmer than expected. So Gaia's census of white dwarfs will afford astronomers an insight into the amount of any decrease in gravity that has taken place.

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Gaia spacecraft at Astrium, packed in its high-tech case. Credit: Astrium SAS

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With the final tests and the Mission Flight Acceptance Review successfully concluded, Gaia is now ready for launch and has been assigned a launch window from 17 November to 5 December 2013. Meanwhile Gaia has been ‘switched off' and packed, and will be shipped to Kourou in the second half of August in order to prepare for its launch. Ready to go at last!

The Gaia spacecraft is seen here at the Astrium premises, being packed in its high-tech case in preparation for shipping to Kourou.

The shipment of Gaia will take place in two steps:

The spacecraft will leave Toulouse on 22 August at 20:00, landing in the early morning of 23 August at Cayenne.
The deployable sunshield together with its umbrella-like mechanism will be dispatched in a separate shipment on 28 August.
Both transports will be flown by an Antonov 124 - one of the largest aircraft in the world.

The team in Kourou
The ‘early team’ will leave a couple of days ahead of the first Antonov and will welcome the spacecraft in Cayenne, taking care of the initial phases of the launch campaign, including  transport by road from the airport to the clean rooms of the launch site, unpacking and initial inspections. Ared, Joe and David will be in the early team, and Giuseppe will fly with the spacecraft on the first Antonov. He will tell us afterwards if it is more comfortable than the regular Air France.

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Gaia shipment to Kourou in Antonov airplane

Yesterday, Gaia was transported in a special convoy from the Astrium premises to Toulouse-Blagnac airport from where it departed for the launch site in Kourou in an Antonov plane.

The plane was already waiting at the runway when the container with Gaia arrived: An Antonov 124-100, the second largest plane in the world (after A380), capable to carry up to 150 tonnes.

After closing the nose of the plane and the back, the aircraft is ready to take off.

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ESA’s billion-star surveyor, Gaia, departed yesterday evening from Toulouse and arrived early this morning in French Guiana. Gaia will be launched later this year from Europe’s Spaceport in Kourou on a five-year mission to map the stars of the Milky Way with unprecedented precision.

Built by Astrium in Toulouse, the Gaia spacecraft took off on board an Antonov 124 heavy-lift aircraft at 20.00 yesterday from Toulouse airport with the destination of Cayenne, the capital of French Guiana. The spacecraft will now be transported by truck to Europe’s Spaceport in Kourou, 64 km from Cayenne.

“This is a very exciting day for the Gaia mission and all the teams involved, who have worked for years to get to where we are today,” says Giuseppe Sarri, ESA’s Gaia project manager. “Arriving in Kourou and starting the launch campaign is a great achievement.”

Gaia’s main goal is to create a highly accurate 3D map of our galaxy, the Milky Way, by repeatedly observing a billion stars to determine their precise positions in space and their motions through it.

A billion stars is roughly 1% of all the stars spread across the Milky Way, providing a representative sample from which the properties of the whole galaxy can be measured. Gaia will measure these stars from an orbit around the Sun, near a location known as the L2 Lagrangian point, some 1.5 million km beyond Earth’s orbit.

Other measurements will assess the vital physical properties of each star, including its temperature, luminosity and composition.

The resulting census will allow astronomers to determine the origin and the evolution of our galaxy.

Gaia will also uncover tens of thousands of previously unseen objects, including asteroids in our Solar System, planets around nearby stars, and exploding stars – supernovae – in other galaxies.

Sarri, who also flew on the Antonov aircraft with Gaia, said that the flight from Europe to South America went smoothly. “We are now looking forward to the coming weeks of final preparation, which we will undertake with the same care and determination that the teams have shown so far when building the spacecraft.”

On 28 August, a second Antonov 124 aircraft will carry Gaia’s sunshield and most of the ground support equipment from Toulouse to Cayenne. At that point, all the spacecraft parts and equipment will have arrived in French Guiana, leading towards the launch later this year.

Quelle: ESA

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Update: 24.08.2013

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The eye of Gaia

The largest digital camera ever built for a space mission has been painstakingly mosaicked together from 106 separate electronic detectors. The resulting ‘billion-pixel array’ will serve as the super-sensitive ‘eye’ of the European Space Agency (ESA) galaxy-mapping Gaia mission.

At its Toulouse site, Astrium is making final adjustments to the scientific instruments for the Gaia satellite, which from 2013 will start mapping more than a billion stars in the Milky Way. As well as drawing up a 3D map of our galaxy, this mission will also verify Einstein’s general theory of relativity with greater precision than ever before.

In mid-September, Vincent Poinsignon witnessed the culmination of years of work. He had before him the largest digital camera ever built, with a total of a billion pixels. Vincent, who heads up the Gaia project at Astrium, maintains that from the Earth this camera could have measured a freckle on Neil Armstrong’s face as he took his first steps on the moon. The camera has now been integrated in the payload module of the Gaia satellite, built by Astrium for ESA, and is being tested in Astrium’s cleanroom facility in Toulouse. In late 2013, it will be launched from the European Spaceport in French Guiana and placed in orbit to assume its role as the most powerful ‘eye’ ever to observe the Milky Way.“In astrometric terms, Gaia will have a precision 100 to 1,000 times greater than its predecessor Hipparcos,” explains Vincent. When ESA launched Hipparcos in August 1989 it was the first satellite devoted to astrometry, a branch of astronomy involving measurement of the position and movements of celestial bodies as well as their distance from the Earth. Up until its ‘retirement’ in 1993, it amassed a catalogue of 120,000 stars with a precision 200 times greater than any other previous measurements. Now, Gaia’s eagle eye makes Hipparcos seem as blind as a bat. Once in orbit around the sun, the new satellite will begin to precisely measure the characteristics of a billion stars which will then be used to generate a 3D chart of our galaxy. This sensitivity will enable it to detect more than 250,000 objects in our solar system (mostly asteroids), 15,000 extrasolar planets, 50,000 brown dwarfs and around 20,000 supernovae.

A diamond in space

Gaia’s exceptional capabilities have come about through years of work by a team of over 500 people at Astrium, explains Vincent Poinsignon, who was previously project manager for Mars Express, the first European mission to the Red Planet. Gaia contains two telescopes which in combination are powerful enough to detect stars 400,000 times fainter than the human eye can see. The weak light of these celestial bodies is captured on a focal plane the two telescopes share, which consists of 106 charge-coupled devices (CCDs), an advanced version of the chips in standard digital cameras.

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A key feature of the CCD support structure and the rest of the satellite is the use of silicon carbide, a material with ceramic properties originally developed as a diamond substitute which is incredibly light and resistant to deforming under temperature changes.

Astrium has already used this material on other satellites, including the Herschel space observatory launched in 2009. The 3.5-metre mirror of Herschel’s large telescope, made entirely of silicon carbide, weighs a mere 270 kilograms compared to the 1,500 kilograms it would have weighed using standard technology. Now the use of silicon carbide will enable Gaia to function at temperatures of -110°C to increase the sensitivity of its sensors. A deployable sunshield with a length of around 10 metres will keep its instruments in the shade at all times to protect them from the sun’s heat. “Gaia’s innovations include the micropropulsion system and the antenna, along with the generalised use of silicon carbide not only for the telescope mirrors but also for many parts of the payload module,” highlights Timo Prusti, Gaia Project Scientist at ESA.

As Timo indicates, the antenna plays a vital role. The satellite will detect and measure the characteristics of hundreds of stars per second practically uninterrupted during its five-year mission. Each star will be monitored around 70 times with a precision “that could divide the moon into 180 million slices from the Earth”, he says. Every day, Gaia’s antenna will need to send 50 gigabytes of data to the Earth over a distance of 1.5 million kilometres. At the end of the mission, scientists will have gathered one petabyte of data, equivalent to the information stored on 200,000 DVDs.

Relativity takes centre stage

The Gaia mission was proposed in 1993 by Swedish astronomer Lennart Lindegren of Lund University. His idea will take to the skies 20 years after it took shape in his mind. Lennart, one of the world’s foremost astrometry experts, points out that Gaia will also verify with greater precision than ever Einstein’s general theory of relativity, which states that mass causes spacetime to curve. Even light rays are bent when they pass near a massive object such as the sun. “Gaia will measure this effect a few orders of magnitude more precisely than ever before and will also observe the deflection of light rays caused by Jupiter, the Earth and other planets,” says Lennart. “We expect all these measurements to be in line with the general theory of relativity and accordingly to confirm our current understanding of the structure of spacetime. However, it is part of scientific method to constantly test accepted theories in the most rigorous manner possible and Gaia will be a hard taskmaster in this sense,” he continues.In the early 17th century, the Florentine astronomer Galileo Galilei tried to convince the cardinals of the Inquisition that the universe is “written in the language of mathematics, and its characters are triangles, circles and other geometric figures, without which it is humanly impossible to understand a single word of it”. According to Galileo, without these characters “one is wandering around in a dark labyrinth”. Four centuries later, Gaia is preparing to shed light on this labyrinth with the ‘luminous’ mathematics of astrometry – although there is still much to be done. The one billion stars to be mapped by Gaia make up barely one percent of the stars in our galaxy. The remaining 99% will have to wait for Hipparcos’ and Gaia’s successors …

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Gaia: recording over a billion stars for an extraordinary 3-D map of the galaxy

Gaia is a global space astrometry mission, and a successor to the ESA Hipparcos mission. Part of ESA’s long-term scientific programme, Gaia is being built by Astrium and is expected to be launched in 2013 on a Soyuz vehicle.

It will conduct a census of a billion stars in our galaxy, monitoring each of its target stars about 100 times over a five-year period, precisely charting their distances, movements, and changes in brightness. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and failed stars called brown dwarfs. Within our own solar system, Gaia should also identify tens of thousands of asteroids.

Additional scientific benefits include detection and characterisation of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our solar system, through galaxies in the nearby Universe, to about 10 million galaxies and 500,000 distant quasars. It will also provide stringent new tests of general relativity.

The spacecraft will use the global astronomy concept successfully demonstrated on Hipparcos, also built by Astrium, which successfully mapped 100,000 stars in 1989. Gaia will be equipped with a latest-generation payload integrating the most sensitive telescope ever made. This cutting-edge technology draws on Astrium’s extensive experience particularly on silicon carbide (SiC) telescopes, used on the Herschel telescope and Aladin instrument as well as on three Earth observation satellites (Formosat, Theos and Alsat 2). Gaia’s measurement accuracy is so great that if it were on the Moon, it could measure the thumbnail of a person on Earth!

Gaia will be placed in orbit around the Sun, at a distance of 1.5 million kilometres further out than Earth, at the L2 Lagrangian point of the Sun–Earth system.

Quelle: Astrium

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Update: 25.08.2013

Arianespace to “reach for the stars” with its Soyuz launch of Europe’s Gaia space surveyor spacecraft

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Shown in its protective shipping container, Europe’s Gaia is unloaded from the cargo jetliner that transported this advanced “star-mapper” spacecraft from Toulouse, France – where it was built by Astrium – to French Guiana.

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Soyuz Flight VS07

Europe’s Gaia “star-mapper” has arrived in French Guiana for an Arianespace Soyuz launch later this year on a mission to chart the locations and motions of a billion stars, while also opening opportunities in discovering new celestial objects in the hundreds of thousands.

Gaia was delivered today aboard a chartered Antonov An-124 cargo jetliner at Félix Eboué International Airport near the capital city of Cayenne – clearing the way for its transfer via road to the Spaceport.

With a liftoff mass of 2,030 kg. – which includes the spacecraft’s two optical telescopes, three science instruments, as well as a 10-meter deployable “skirt” as a sunshield and a power generator – Gaia will observe one billion stars approximately 70 times each over five years.

A truly impressive space charting mission

Many aspects of this mission – organized by the European Space Agency – are impressive. The spacecraft carries one of the largest digital cameras to be placed in space (with nearly one billion pixels), and is designed to detect celestial objects that are a million times fainter than the unaided human eye can see.

Built by Astrium at its Toulouse, France facility, Gaia will be operated by the European Space Agency to provide a representative sample from which the properties of the entire galaxy can be measured, ultimately allowing astronomers to determine its origin and evolution.

Gaia’s two optical telescopes will determine star locations and velocities, splitting their light into a spectrum for analysis. The spacecraft will operate from an orbit around the Sun, at the L2 Lagrangian point located some 1.5 million kilometers beyond Earth’s orbit.

Discoveries numbering in the hundreds of thousands also anticipated

During its operation, Gaia also is expected to find hundreds of thousands of new celestial objects – including asteroids, comets, extra-solar planets, brown dwarf “failed stars,” supernovae and quasars.

When completed, the mission’s data archive should exceed 1 petabyte (1 million gigabytes), which is equivalent to about 200,000 DVDs worth of data.

Gaia arrived today in French Guiana with a portion of its ground support equipment. A second air cargo flight later this month is to bring Gaia’s sunshield and the remaining ground support equipment.

A mission follow-up to Hipparcos, also launched by Arianespace

The star-mapper has its roots in the European Space Agency’s Hipparcos space astrometry platform, lofted by Arianespace on an Ariane-series vehicle in 1989. The Soyuz mission with Gaia is designated VS07 in Arianespace’s launcher family numbering system, representing this medium-lift workhorse’s seventh flight from French Guiana.

It will follow two other Arianespace launches currently in preparation at the Spaceport: Flight VA215, scheduled for August 29 with an Ariane 5 to orbit the EUTELSAT 25B/Es’hail 1 and GSAT-7 relay satellites; and VS06, targeted in late September with a Soyuz to deploy four connectivity spacecraft for O3b Networks.

Quelle: arianespace

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Update: 20.09.2013

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A special sunshield is readied for Arianespace's Soyuz mission with the Gaia star-mapper
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Gaia’s deployable sunshield framework is readied in the Spaceport’s S1C clean room facility after removal from its shipping container.
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The deployable sunshield framework for Europe’s Gaia billion-star surveyor has been unpacked at the Spaceport, marking a new milestone in preparations for Arianespace’s next mission with its medium-lift Soyuz launcher.
This skirt-type structure will be just over 10 meters in diameter when opened in space, serving as a sunshade to permanently protect Gaia’s telescopes and allow their temperatures to drop to below –100 degrees Celsius, while also acting as a power generator for the spacecraft. The shield’s underside will be partially covered with solar panels and always is to face the Sun, generating electricity to operate the spacecraft and its instruments.
Gaia was developed by the European Space Agency and produced by Astrium for an ambitious mission to chart a three-dimensional map of the Milky Way.  In the process, it will reveal the galaxy’s composition, formation and evolution.
The launch is planned for November 20. With a liftoff mass of 2,030 kg., Gaia is to be placed by the Soyuz launcher on a trajectory to an orbit around the Sun at a location known as the L2 Lagrangian point.
Arianespace’s mission with Gaia will be the Spaceport’s second liftoff with the Russian workhorse launcher in 2013.  It is now designated Flight VS06, taking the numbering previously assigned to an upcoming Soyuz launch with four O3b Network satellites – which has been delayed at the customer’s request.
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Successful system test

 

 

Few people realize how complicated a launch actually is. Gaia is launched with a Russian-built Soyuz rocket, which has three stages. In fact, it ignites the first and second stage at the same time and the third stage is ignited before the second stage is burned out. The three main stages take the payload (spacecraft) into orbit around Earth. Then the Fregat upper stage takes over. The Fregat stage is also Russian-built. With some complicated manoeuvres, it brings the satellite on course to its final destination, the L2 point. Once the Fregat has done its job, it separates from the satellite, and the satellite starts working autonomously from then on.

 

When the satellite detects the separation from the Fregat, the first thing it will do is switch on its communication system, so the ground station can see the telemetry (data coming from the spacecraft to Earth), which is then used to judge the health of the satellite and to follow its trajectory. One of the most important next steps is to deploy the sunshield (an animation of the deployment has already been posted in this blog on August 29th). However, to do so, the satellite first needs to face the Sun with its sun shield side, so the optical instrument is in the shade. The instrument is designed to measure the very weak light coming from very faint stars, so an abundant flood of direct sunlight will damage the instrument.
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Orientating the spacecraft is done with the CPS, the Chemical Propulsion System. There are in total 16 thrusters on board, which are then used individually or in combination with each other. However, before they can be used, they need to be "primed", meaning leftover air from Earth's atmosphere needs to be vented from the pipework, fuel tanks needs to be pressurized, and the propellant needs to be guided to the individual thrusters in a safe way. Only then, when the CPS is ready, will the on board computer re-orientate the satellite, with the aid of its on board sun sensors and gyroscopes.
All this, from lift off until deployment, is done automatically. It is all pre-programmed and no manual intervention is possible or needed. The launcher (Soyuz and Fregat) is delivered with its own flight program, under responsibility of the Russian authorities. The Gaia project team is responsible for all the autonomous operations that the satellite has to do. Since this is such a critical phase for the whole mission, this is one of the most important tests to do on ground before launch, the so-called LAM test (Launch & initial Acquisition Mode). This test was successfully run last Saturday morning. Although part was simulated (e.g. the sunshield is not mounted yet), it was proven that all the steps are programmed correctly and executed at the right time in the right order. We're again one step closer to launch!
Quelle: arianespace

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Update: 7.10.2013 

The Milky Way-mapping Gaia spacecraft receives its sunshield in preparation for Arianespace's next Soyuz launch

Team members from SENER and Astrium oversee the installation of Gaia’s sunshield framework on the hexagonal/conical-shaped spacecraft at the Spaceport in French Guiana.

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A high-tech sunshield to protect the Gaia spacecraft during its deep space mission is now being installed at the Spaceport as preparations continue for Arianespace’s Flight VS06 Soyuz launch of the billion-star mapper from French Guiana.
In activity at the Spaceport’s S1B clean room facility, the carbon-fiber reinforced composite framework for this deployable skirt-like system has been positioned around Gaia. It clears the way for integration of the sunshield’s two parallel multi-layer insulation blankets over the next several days.
Gaia’s sunshield performs an essential role: keeping the spacecraft in shadow, and thereby maintaining its scientific instruments at a constant temperature of approximately –110°C.
This will enable Gaia to perform its ambitious mission of making the largest, most precise three-dimensional map of the Milky Way by surveying an unprecedented one percent of its 100 billion stars. Also expected are discoveries of hundreds of thousands of unknown celestial objects, including extra-solar planets and failed stars known as brown dwarfs.
With a deployed sunshield size of some 10 meters across and an area of approximately 75 square meters, the system is composed of a dozen folding panels that will rotate outward from the hexagonal/conical-shaped Gaia to their opened position after the Soyuz launch.
The sunshield was produced by Spain’s SENER, while the spacecraft’s designer and builder is Astrium – all operating under contract to the European Space Agency, which is responsible for the Gaia mission’s development and operation.
After Gaia’s launch by Arianespace, the spacecraft will be placed in an orbit around the Sun at the second Lagrange point (L2) – a distance of 1.5 million kilometers from the Earth.
Flight VS06 is Arianespace’s sixth Soyuz launch at the Spaceport – and the medium-lift launcher’s first deep-space mission from French Guiana. Liftoff is scheduled for November 20. 
Quelle: arianespace

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Update: 12.10.2013

Continued sunshield preparations bring Gaia closer to its deep-space Arianespace Soyuz launch

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Soyuz Flight VS06

Payload preparations for Arianespace’s next Soyuz launch are progressing well at the Spaceport in French Guiana, where the Gaia billion-star surveyor is receiving its sunshield for in-orbit telescope protection as well as power generation.

This sunshield is one of the final elements in completing the European Space Agency’s Gaia, the installation of which has been performed by the assembly, integration and testing team of prime contractor Astrium – with support from Spain’s SENER, which produced the sunshield.

The latest activities involved placement of the inner thermal blankets for Gaia’s multi-layer sunshield insulation, as well as incorporation of solar array panels that will provide energy to power all on-board electronics. Both elements are positioned on the sunshield’s carbon-fiber reinforced composite framework, which also was integrated at the Spaceport.

When the sunshield’s 12 folding frames are opened in orbit after launch by Arianespace’s Soyuz, the fully-insulated sunshield will form a flat disc at the base of Gaia – shading its telescope from the sun and maintaining the spacecraft’s scientific instruments at a constant temperature of approximately -100 degrees Celsius. This will allow Gaia to perform its ambitious mission of making the largest, most precise three-dimensional map of the Milky Way by surveying an unprecedented one percent of its 100 billion stars.

Solar array panels for spacecraft power

The solar array panels fixed to the sunshield will provide approximately 1,850 Watts of electrical power, to be used by Gaia for powering the data processing computers, along with the communications, navigation and thermal control systems.

A massive amount of data will be collected over Gaia’s planned five-year mission, with its full archive to exceed 1 petabyte in size – providing enough information to answer questions related to the origin, structure and evolutionary history of the galaxy. 

Gaia will be orbited on Arianespace’s Flight VS06, which is scheduled for liftoff on November 20 from the Spaceport.  As indicated by the company’s launcher family numbering designation, this will be the Spaceport’s sixth liftoff with medium-lift vehicle since its introduction at French Guiana in October 2011 by Arianespace.

After being deployed by Soyuz, the 2,030-kg. hexagonal/conical-shaped spacecraft will follow a flight path to an orbit around the Sun at the second Lagrange point (L2) – a distance of 1.5 million kilometers from Earth.  This makes Gaia the first deep space payload launched by Arianespace with Soyuz from the Spaceport.

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The 12 frames of Gaia’s sunshield are hinged on the spacecraft at its base, and they open 90 degrees. When all thermal blankets are integrated on the framework, the sunshield will form a flat disc at the base of the spacecraft, with a diameter of just over 10 meters.

Quelle: arianespace

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Update: 17.10.2013 

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Gaia “opens up” at the Spaceport in preparation for Arianespace’s next Soyuz launch

Soyuz Flight VS06

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Arianespace’s payload for the Soyuz VS06 mission in November is now ready to take in some sun on its upcoming deep-space trip, as the completed sunshield for Europe’s billion-star surveyor – Gaia – has been opened and validated for the final time at the Spaceport in French Guiana.
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During activity in the Spaceport’s S1B clean room facility (pictured at right, from top to bottom), Gaia’s completed sunshield – which is composed of a carbon-fiber reinforced composite framework with thermal blankets covering the structural skeleton – was lowered around the spacecraft’s base, forming a flat disc more than 10 meters across.
Once deployed in space, this disc will shade Gaia from the Sun, maintaining a -110°C approximate temperature for its scientific instruments. In addition, the sunshield is equipped with solar array panels to power all onboard electronics, including data processing computers, as well as the communications, navigation and thermal control systems.
Operating under contract to the European Space Agency, the sunshield’s installation was performed by prime contractor Astrium’s assembly, integration and testing team – with support from Spain’s SENER, which is responsible for the sunshield’s design and manufacture.
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With a liftoff mass of approximately 2,030 kg. for its Arianespace Soyuz launch, Gaia is tasked with the ambitious mission of measuring the position and velocity of approximately one billion stars, as well as determining their brightness, temperature, composition and motion through space, while creating a three-dimensional map of the Milky Way Galaxy.
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This spacecraft’s scientific instruments can detect objects one million times fainter than the unaided human eye can see. For objects 4,000 times dimmer than human viewing limits, Gaia will measure to an accuracy of 24 microarcseconds – comparable to observing the diameter of one strand of human hair at a distance of 1,000 km. 
As the first deep-space passenger on an Arianespace Soyuz flight from French Guiana, Gaia will operate from the second Lagrange point (L2) in its orbit around the Sun, which keeps it on pace with Earth, while allowing for a more stable viewpoint some 1.5 million kilometers away.
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Designated VS06 in Arianespace’s numbering system, this flight – scheduled for a November 20 liftoff – represents the sixth mission of the medium-lift Russian workhorse from French Guiana since its initial launch from the Spaceport in 2011. 
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Quelle: arianespace

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Update: 23.10.2013

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GAIA: Start verschoben
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Aufgrund kürzlich entdeckter technischer Probleme hat die ESA beschlossen, zusätzliche Überprüfungen von Satellit Gaia durchzuführen, und deshalb gefordert, dass Arianespace den Start von Gaia verschiebt, der derzeit für 20 November geplant war.
 
Ein neuer Starttermin wird, sobald die Verfügbarkeit des Satelliten bestätigt wird bekannt gegeben.
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Quelle: ESA

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Update: 23.30 MESZ

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Yesterday, the decision was taken to postpone the launch of ESA’s Gaia mission after a technical issue was identified in another satellite already in orbit.
Gaia shares some of the components involved in this technical issue and prompt notification of this problem has allowed engineers working on the final preparations for Gaia’s launch to take additional precautionary measures.
The issue concerns components used in two transponders on Gaia that generate ‘timing signals’ for downlinking the science telemetry. To avoid potential problems, they will be replaced.
The transponders will be removed from Gaia at Kourou and returned to Europe, where the potentially faulty components will be replaced and verified. After the replacements have been made, the transponders will be refitted to Gaia and a final verification test made.
As a consequence of these precautionary measures, it will not be possible to launch Gaia within the window that includes the previously targeted launch date of 20 November.
The next available launch window is 17 December to 5 January 2014.
More details will be given as soon as they are available. The new launch date will be announced when the timeline for completing the additional work has been confirmed and the overall launch manifest of Arianespace has been established. 
Gaia is ESA’s billion-star surveyor, designed to provide a precise 3D map of our Milky Way galaxy in order to understand its composition, formation and evolution.
Quelle: ESA

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Update: 29.10.2013

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Gaia Mission Control Teams absolvieren ein intensives Simulationstraining

Seit Monaten absolvieren die etwa 60 Ingenieure des Gaia Mission Control Teams ein intensives Simulationstraining, das jeden Aspekt der ersten Mission der Raumsonde zum 1,5 Millionen Kilometer von der Erde entfernten Lagrange-Punkt L2 umfasst.
Das Training, das oft 12 Stunden am Stück dauert, findet im Hauptkontrollraum des Europäischen Satellitenkontrollzentrums (ESOC) in Darmstadt statt.
In Simulationen bedienen die Ingenieure das tatsächliche Missionskontrollsystem, um eine realitätsgetreue Software-Replikation der echten Gaia zu steuern und zu fliegen. Diese Replikation reagiert genau so auf die Befehle wie die echte Software.
„Es sieht vielleicht wie ein riesiges Videospiel aus, aber das Training ist viel komplexer und anspruchsvoller – und so soll es auch sein. Wir wollen sichergehen, dass die Teams schnell auf jedwede Eventualitäten reagieren können", sagt Michael Gabel von der ESA, der Verantwortliche für das Training am ESOC. 
Das Training wird von einem wenig bekannten Team aus ESA- und Branchenspezialisten überwacht, das in einem zugangsbeschränkten Simulationsraum unter dem Hauptkontrollraum arbeitet.
Während der Trainingsreihe speisen die Trainer eine gezielt strukturierte Reihe von Störungen, Fehlern und Ausfällen in die Raumsonde bzw. die Software und die Systeme ein, die Gaia fliegen sollen.
Unter der Aufsicht des Flugleiters (Flight Director) über ihnen müssen die Missionscontroller an den Geräten das Problem erkennen, bewerten und daraufhin den entsprechenden Notfallplan anwenden. In früheren Phasen der Trainingsreihe waren Fehler einfacherer Art eingestreut worden.
„Nun, da der Zeitpunkt des Starts immer näher rückt, simulieren wir die Ankunft Gaias am L2. Neben der LEOP-Phase ist dies wahrscheinlich die risikoreichste und sicherlich die kritischste Phase bei jeder Mission. „Wir setzen multiple, komplexe Störungen ein. Wir versuchen wirklich, das Kontrollteam unter Druck zu setzen, um zu testen, ob sie wissen, was sie tun. Um Lösungen zu finden, müssen sie als Team zusammenarbeiten“, so Joe Bush von Telespazio VEGA Deutschland, der für die Gaia-Simulationen verantwortlich ist.
LEOP umfasst die Trennung vom Startgerät, das Ausrichten der Solarmodule und das Empfangen der ersten Signale des Satelliten.
„Wenn bei einer Mission etwas schiefläuft, dann wahrscheinlich während der LEOP oder einem Manöver wie bei der Ankunft am L2. In dieser Phase können die Folgen der Störung durchaus kritisch sein. Es ist unsere Aufgabe, die Missionscontroller auf alle Eventualitäten vorzubereiten“ erläutert Michael Gabel
Der Start von Gaia ist in naher Zukunft geplant. Der Satellit wird den Lagrange-Punkt 2 nach 21 Tagen Flugzeit erreichen.
Quelle: ESA

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Arianespace launches VA216 and VS06 scheduled respectively for December 6 and 20, 2013

 

To allow the Gaia program to carry out additional checks on its satellite, Arianespace has switched the order of its two upcoming launches, with full agreement of its customers, moving the Ariane 5 ECA mission for SES and Hispasat ahead of the Soyuz launch for ESA.

 

Arianespace is now able to announce the planned dates of its next two launches, thanks to the combined efforts of the teams in charge of preparing the Gaia, ASTRA 5B and AMAZONAS 4A satellites, the teams in charge of the Ariane 5 and Soyuz launchers and the staff at the Guiana Space Center, CNES in particular, responsible for optimizing launch preparations:

 

VA216 – Ariane 5 ECA – Astra 5B and Amazonas 4A – December 6

 

VS06 – Soyuz – Gaia – December 20
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Quelle: arianespace

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Update: 22.11.2013

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Arianespace Flight VS06 Soyuz ST-B - Gaia
Launch set for Thursday, December 19, 2013

Evry, November 22, 2013.  The checks on the Gaia satellite are proceeding nominally, enabling Arianespace in agreement with ESA to announce the launch date.

Liftoff of the Soyuz ST-B launcher is set for Thursday, December 19, at precisely:

09:12:18 am (UTC)
06:12:18 am (local time in French Guiana)
10:12:18 am (Paris)
04:12:18 am (Washington, D.C.)
12:12:18 pm (Moscow)

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Quelle: arianespace

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Update: 27.11.2013 

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Quelle: arianespace

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Update: 2.12.2013

 

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Quelle: ESA

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Update: 9.12.2013 

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Gaia ready for fuelling

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Towards the end of November, the first part of the Gaia launch preparation was complete: the satellite was 90% ready, with its tanks pressurised. The second part begins with filling the tanks with the appropriate propellants. This phase is particularly dangerous because the propellants are toxic, and there is also a risk of explosion, so it is carried out in a dedicated building. That’s why Gaia had to move from building S1B in the payload preparation complex (EPCU), where it has been since the start of the campaign, to the S5 building to be fuelled.

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Three months before the start of the launch campaign we had to define the logo to be put on the launcher fairing, to ensure it would be ready for launch. Earlier this year we had already put in place the main characteristics of the Gaia logo: stars, Earth, spacecraft, the Gaia goddess and Gaia name. But one of the main themes we wanted to represent is humankind’s curiosity towards the Universe. Quickly, different options were ready. Christophe, our graphic designer at ESTEC, came up with a very nice representation of the Milky Way. Elizabeth, from Toulouse, suggested that the girl staring at the sky should be trying to reach it. However, the presentation of the girl, the Gaia goddess linking Earth with the sky and stars, was difficult. Several options were proposed but it was difficult to get everyone to agree.

Having recently seen the final work of Joël Schopfer (the nephew of Ared) finishing graphic art studies in Switzerland, we informed him of this issue. Joël is a fan of all sorts of things related to space and was very enthusiastic to contribute his ideas. When he presented his proposal it was clear that this was the one we would go for.
After scrutiny and agreement inside ESA, here we are in the space centre at Kourou, soon ready for launch with a superb logo for our fairing, measuring 3.5m x 3.5m! We also have smaller sizes and it even appears on flags at the entrance of the base and next to the building where Gaia is located. Last week it also appeared on T-shirts.
Thanks to all those who helped to solve one of the numerous issues that Gaia encountered during its life on Earth.
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Soyuz’ Block I third stage is mated to the Russian launcher in the Spaceport’s MIK integration building for Arianespace’s Gaia mission.
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The Soyuz launcher for an ambitious mission of developing the Milky Way’s most precise three-dimensional map is completing its basic build-up following mating of the vehicle’s Block I third stage in French Guiana.
This step occurred in the Spaceport’s MIK Launcher Integration Building, enabling checkout of the integrated Soyuz prior to its upcoming transfer to the launch pad – where the European Space Agency’s Gaia star-mapper satellite and Fregat upper stage will be installed.
Scheduled for liftoff on December 19, the mission – designated Soyuz Flight VS06 – will be Arianespace’s sixth with the workhorse Russian-built launcher from French Guiana since its service entry at the Spaceport in October 2011.
Gaia will make the largest three-dimensional map of the Milky Way by surveying an unprecedented one percent of its 100 billion stars. The Astrium-built spacecraft also is expected to discover hundreds of thousands of unknown celestial objects, including extra-solar planets and failed stars known as brown dwarfs. 
Quelle: arianespace

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Update: 11.12.2013

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Quelle: arianespace

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Update: 13.12.2013

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Gaia is positioned for its star-mapping launch on an Arianespace Soyuz

In this photo sequence in the Spaceport’s S3B facility, the Gaia star-mapper is lowered into position atop the Fregat upper stage for Soyuz.
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Soyuz Flight VS06
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The payload “stack” is now taking shape for this month’s Arianespace launch of Gaia – Europe’s billion-star mapper satellite, which is to be lofted by a Soyuz vehicle on December 19 from French Guiana.
As the latest milestone in a now well-established processing flow for Arianespace’s medium-lift Soyuz, Gaia was positioned atop the launcher’s Fregat upper stage during activity in the Spaceport’s S3B preparation building.  Fregat is an autonomous, highly flexible upper stage that will perform two separate burns in sending Gaia on its way to an orbit around the Sun at the L2 Lagrangian point.
The next processing step is to encapsulate the Gaia/Fregat combination in a two-piece payload fairing, readying the unit for mating to Soyuz after the vehicle’s rollout from its separate MIK integration building – where the Russian-built launcher was assembled.
Gaia is designed to observe one billion stars in the Milky Way approximately 70 times each during a mission design life of 5.5 years, and has a liftoff mass of 2,030 kg.
Built by Astrium at its Toulouse, France facility, Gaia will be operated by the European Space Agency to provide a representative sample from which properties of the entire galaxy can be measured, ultimately allowing astronomers to determine its origin and evolution.
Gaia will be launched on Arianespace’s sixth Soyuz flight performed from the Spaceport since 2011, where this workhorse launcher is operational alongside the company’s heavy-lift Ariane 5 and lightweight Vega vehicles.
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Quelle: arainespace

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Update:

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GAIA SECURED INSIDE FAIRING 

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ESA’s billion-star surveyor Gaia, less than a week from launch, is now tucked up inside the fairing that will protect it during the first few minutes of ascent into space.
Last week, Gaia was loaded with the propellants it will need to journey to its ‘L2’ destination, a gravitationally stable location 1.5 million km aw
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