Arianespace’s Soyuz launcher has begun its sixth flight from the Spaceport, carrying Europe’s Gaia star-mapper spacecraft for an ambitious mission to chart the Milky Way.
With an on-time liftoff from French Guiana at 6:12 a.m., the Soyuz is to deploy its payload at the completion of a nearly 42-minute flight.
Gaia has an estimated liftoff mass of 2,034 kg. and was produced by Astrium for a mission developed and operated by the European Space Agency. Gaia will monitor each of its one billion target stars approximately 70 times during a five-year period, precisely charting their positions, distances, movements and changes in brightness.
It is the 25th scientific satellite to be launched by Arianespace.
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Quelle: arianespace
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Arianespace successfully launches the Gaia scientific satellite
Kourou, December 19, 2013
On Thursday, December 19, 2013 at 6:12 am, local time in French Guiana, Arianespace successfully carried out the sixth Soyuz launch from the Guiana Space Center (CSG), orbiting the Gaia scientific satellite for the European Space Agency (ESA).
Today's mission was the second successful Soyuz launch from CSG in 2013, and was the launcher’s sixth successful mission overall from CSG. Also in 2013, Arianespace used a Soyuz rocket to orbit the first four satellites for the O3b constellation in June.
An Arianespace launch at the service of science
Arianespace has always supported the world's leading scientific missions, enabling humankind to better understand our Universe. Gaia is the 25th scientific satellite to be launched by Arianespace, bringing a real breakthrough in understanding our galaxy, and create a 3D map of the Milky Way.
The launch of Gaia continues a long-standing and steady cooperation between Arianespace and ESA: it also is the 40th payload sent into orbit for the space agency, 28 years after the launch of Giotto – ESA's first scientific satellite in July 1985 on an Ariane 1 (Flight 14).
In 2013, Arianespace carried out four Ariane 5 launches, orbiting the ATV Albert Einstein with supplies for the International Space Station and six telecommunications satellites, as well as the second Vega launch with satellites dedicated to sustainable development (Proba-V, VNREDSat-1 and ESTCube-1).
The "Soyuz at CSG" program that brought Soyuz to French Guiana carries on the long-standing space collaboration between Europe and Russia, and gives Europe a medium-lift launcher that perfectly complements its heavy Ariane 5 and light Vega launchers. Arianespace and its Starsem subsidiary also performed a Soyuz launch from the Baikonur Cosmodrome (Kazakhstan) in February 2013, orbiting six satellites in the Globalstar constellation.
With these three launchers now fully operational, Arianespace is the world’s only launch services company capable of lofting all types of payloads to all orbits, including communications, scientific and Earth observation satellites; constellations; cargo missions to the International Space Station, and more.
Just a few minutes after the announcement that Gaia had been injected into orbit, Arianespace Chairman and CEO Stéphane Israël said: "We are very proud of our third mission for ESA this year, following the successful launches of Proba-V and the ATV Albert Einstein. With our 3 operational launchers at CSG, we are especially proud of our ongoing role in guaranteeing independent access to space for Europe, and for the entire European scientific community in particular. I would like to thank ESA – Arianespace's long-standing partner – for continuing to place their trust in us. My congratulations also go to Astrium and the 50 other companies in Europe that were involved in the construction of Gaia. And of course congratulations to our Russian partners within the Roscosmos agency for the remarkable reliability of the Soyuz launcher."
The VS06/Soyuz ST-B/Gaia launch at a glance
The Soyuz ST-B launcher lifted off from the Soyuz Launch Complex (ELS) at the Guiana Space Center (CSG) in French Guiana. Liftoff was on Thursday, December 19 at 6:12:19 am local time in French Guiana (4:12:19 am in Washington, D.C., 09:12:19 UTC, 10:12:19 am in Paris, and 1:12:19 pm in Moscow).
Gaia satellite
Over its 5-year lifetime, Gaia will produce an astronomical catalog of a billion stars, with extremely precise information on the stars' distance and positions, their movement and their magnitudes in different bandwidths. Through Gaia, scientists hope to clarify the structure, formation and evolution of our galaxy – the Milky Way – as well as making significant contributions to the knowledge of extrasolar planets, the solar system, other galaxies and fundamental physics. Gaia will generate a catalog 50 times larger than that provided by its predecessor, Hipparcos, launched by Arianespace for ESA in 1989.
Gaia features two telescopes for observations in two different directions. Three major scientific instruments, which share a focal plane, analyze the light collected by these telescopes: an astrometric instrument to measure the angular position of stars; a spectrophotometer to determine their spectrum; and a high-resolution spectrometer to measure their radial velocity.
Designed and built by Astrium for the European Space Agency, Gaia will be located at one of the five Lagrange points in the Sun-Earth system, at the L2 point. Lagrange points are located at points of gravitational equilibrium in our Solar System, where a body such as a satellite orbits around the Sun at the same angular velocity as the Earth, and therefore remains in a fixed position in relation to the Sun-Earth axis.
Quelle:arianespace
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Update: 20.12.2013
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World's most powerful satellite launched to map billions of stars
The world's most powerful satellite was successfully launched into space this morning. Over the next five years GAIA will create a 3D map of a billion stars in the Milky Way.
Much of the technology on board was designed and built by Astium in Stevenage. The satellite has the most advanced camera ever sent into space. With one billion mega pixels it is able to measure things 40,000 times more feint than the human eye can see.
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Quelle: itv
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Update: 20.12.2013
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Soyuz VS06, carrying the Gaia space observatory, lifted off from Europe's Spaceport, French Guiana, on 19 December 2013. Credit: ESA
BON VOYAGE, GAIA: On Dec. 19th, the European Space Agency launched one of the most ambitious astronomy missions ever: GAIA, an observatory that will survey more than one billion stars in the Milky Way. By the time GAIA's five year mission is over, astronomers will be able to build the first accurate three-dimensional map of celestial objects in our home galaxy. GAIA will do its work from the L2 Lagrange point approximately 1.5 million km from Earth. On Dec. 20th, amateur astronomer Dave Eagle of Higham Ferrers UK observed the spacecraft hurtling toward that distant station:
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"It was great to see the spacecraft in the exact position predicted, near the shield of Orion," says Eagle. "After watching the launch live on the Web in the morning, I was glad to be able to track it down and wish it well in its coming mission. It was much brighter than I expected, so its newly deployed Sun shield is doing a great job." Once it reaches its L2 parking orbit and begins observing, GAIA will log the position, brightness and color of every star 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 star GAIA sees, chart variations in their brightness, and determine whether they have nearby companions. This kind of detailed information about the Milky Way is unprecedented and may lead to important new discoveries about the evolution and structure of our galaxy.
Quelle: Spaceweather
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Update: 8.01.2014
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Gaia ist jetzt in seiner operativen Umlaufbahn L2
ESA’s billion-star surveyor Gaia is now in its operational orbit around a gravitationally stable virtual point in space called ‘L2’, 1.5 million km from Earth.
Gaia has been travelling towards L2 since 19 December, when, just before dawn local time, it was spectacularly launched from ESA’s Spaceport in Kourou, French Guiana.
A day later, Gaia performed an important thruster burn to set course to its destination. Last night, a critical manoeuvre boosted Gaia into its 263 000 x 707 000 x 370 000 km, 180 day-long orbit around L2. A small course correction will be made next week to complete the manoeuvre.
“Entering orbit around L2 is a rather complex endeavour, achieved by firing Gaia’s thrusters in such a way as to push the spacecraft in the desired direction whilst keeping the Sun away from the delicate science instruments,” describes David Milligan, Gaia spacecraft operations manager.
“After a beautiful launch from Kourou last month, we are very happy to now have reached our destination, and we are looking forward to starting our science operations in the coming months,” says Giuseppe Sarri, ESA’s Gaia project manager.
Once the spacecraft instruments have been fully tested and calibrated – an activity that started en route to L2 and will continue for another four months – Gaia will be ready to enter a five-year operational phase.
Gaia will make very accurate observations of one billion stars, charting their precise positions and motions, as well as their temperatures, luminosities and compositions.
This enormous census will result in the most accurate 3D map yet of the Milky Way and allow astronomers to determine the origin and the evolution of our galaxy.
To achieve its goal, Gaia will spin slowly, sweeping its two telescopes across the entire sky and focusing their light simultaneously onto a single digital camera – the largest ever flown in space with nearly a billion pixels.
Gaia will observe each star an average of 70 times over the five-year mission, after which the data archive will exceed one million Gigabytes, equivalent to about 200 000 DVDs’ worth of data.
The task of processing and analysing this colossal treasure trove of data will fall to the Gaia Data Processing and Analysis Consortium, comprising more than 400 individuals at scientific institutes across Europe.
“Our Gaia discovery machine will keep us busy throughout the mission, with the final results coming only after the five years of data have been analysed. But it will be well worth the wait, ultimately giving us a new view of our cosmic neighbourhood and its history,” says Timo Prusti, ESA’s Gaia project scientist.
Quelle: ESA
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Update: 15.01.2014
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THE EXPERTS BEHINDGAIA´S ARRIVAL AT NOTHINGNESS
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With a final, modest, thruster burn yesterday afternoon, ESA’s billion-star surveyor finalised its entry into orbit around ‘L2’, a virtual point far out in space. But how do you orbit nothing? And who can show you how to get there, anyway?
Just after 15:30 GMT (16:30 CET) yesterday, Gaia made a short thruster burn, nudging the galactic survey craft onto its planned scientific orbit. The job had been mostly completed last week, after an almost two-hour firing took Gaia into a squiggly path about the L2 Lagrange point, 1.5 million km from Earth.
But this apparently simple manoeuvre belies an astonishing fact: the L2 point consists of precisely nothing. It’s simply a point in space.
Nothing there
“Lagrange points are special – it’s true there’s nothing there,” says Markus Landgraf, a mission analyst at ESOC, ESA’s operations centre in Darmstadt, Germany.
“They are points where the gravitational forces between two masses, like the Sun and Earth, add up to compensate for the centrifugal force of Earth’s motion around the Sun, and they provide uniquely advantageous observation opportunities for studying the Sun or our Galaxy.”
As seen from this Lagrange point (there are a total of five such points in the Sun–Earth system), the Sun, Earth and Moon will always be close together in the sky, so Gaia can use its sunshield to protect its instruments from the light and heat from these three celestial bodies simultaneously.
This also helps the satellite to stay cool and enjoy a clear view of the Universe from the other side.
L2 provides a moderate radiation environment, which helps extend the life of the instrument detectors in space.
However, orbits around L2 are fundamentally unstable.
“We'll have to conduct stationkeeping burns every month to keep Gaia around L2, otherwise perturbations would cause it to ‘fall off’ the point,” says Gaia Operations Manager David Milligan.
For those used to seeing images of the International Space Station orbiting Earth, or Mars Express orbiting the Red Planet, it seems intuitive that spacecraft have to orbit something. How do you get a spacecraft to orbit around a point of nothingness?
ESA flight dynamics experts
To maintain this orbit for Gaia’s planned 5-year mission requires extremely careful work by ESA’s flight dynamics team – the experts who determine and predict trajectories, prepare orbit manoeuvres and determine satellite attitudes.
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"In terms of the math, the thruster burns in January 2014 are moving Gaia onto what's known as a 'stable manifold' – a pathway in space that will lead the spacecraft to orbit around L2," says Mathias Lauer, one of the flight dynamics specialists at ESOC working on the Gaia mission. “Gaia is now moving in a so-called Lissajous orbit around L2, once every 180 days.”
The name Lissajous refers to the shape of the path traced out by the orbit as seen from Earth, which will rise then fall above and below the ecliptic plane (the plane of Earth's orbit around the Sun) while sometimes leading and sometimes lagging the Earth.
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The flight dynamics experts use a range of software tools, developed and refined during decades of support to missions around Earth and across the Solar System.
To plan the orbit, the team applies mathematical models to generate an initial guess for the target orbit and how to get there. This guess must account for the requirements and constraints of the launcher and the needed telecommunications links.
Next, those initial guesses are fed into simulation software to see if the results would violate any of the constraints. Often, no solution is possible.
“That is where expertise and experience are indispensable to reconsider the assumptions and then start all over,” says Frank Dreger, Head of Flight Dynamics.
“There's no commercial source for this sort of software or expertise – it’s been built up over many years at ESOC and represents a capability that is rare in the world and unique in Europe.”
Quelle: ESA
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Update: 30.07.2014
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Gaia, ist bereit, seine Wissenschaftsmission zu beginnen.
Gaia BP/RP data for seven bright stars. Credits: ESA/Gaia/DPAC/Airbus DS
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Following extensive in-orbit commissioning and several unexpected challenges, ESA’s billion-star surveyor, Gaia, is now ready to begin its science mission.
The satellite was launched on 19 December 2013, and is orbiting a virtual location in space 1.5 million kilometres from Earth.
Gaia’s goal is to create the most accurate map yet of the Milky Way. It will make extremely accurate measurements of the positions and motions of about 1% of the total population of roughly 100 billion stars in our home Galaxy to help answer questions about its origin and evolution.
Repeatedly scanning the sky, Gaia will observe each of its billion stars an average of 70 times each over five years. Small apparent motions in the positions of the stars will allow astronomers to determine their distances and movements through the Milky Way.
In addition, Gaia will also measure key physical properties of each star, including its brightness, temperature and chemical composition.
Gaia spins slowly once every six hours, sweeping its two telescopes across the sky and focusing the light from their separate fields simultaneously onto a single focal plane – the largest digital camera ever flown in space, with nearly a billion pixels.
As the stars drift across the camera, the relative positions of all detected stars are measured and downlinked to Earth. Over time, a complete network of positions of stars covering the whole sky is built up, before being analysed to yield a highly accurate 3D map.
The accuracy required is astonishing: Gaia must be able to measure positions to a level equivalent to the width of a human hair seen at 2000 km. In turn, these measurements demand a very rigorous calibration of the satellite and its instruments, a painstaking procedure that has taken the first part of the year to complete.
Gaia is now ready to begin its five-year science phase, but the commissioning also uncovered some unexpected anomalies.
One problem detected early in the commissioning was associated with water freezing on some parts of the optics, causing a temporary reduction in transmission of the telescopes.
This water was likely trapped in the spacecraft before launch and emerged once it was in a vacuum. Heating the affected optics to remove the ice has now largely solved this problem, but it is likely that one or two more ‘decontamination’ cycles will be required during the mission to keep it in check.
Another problem is associated with ‘stray light’ reaching Gaia’s focal plane at a level higher than predicted before launch. This appears to be a mixture of light from the Sun finding its way past Gaia’s 10 m-diameter sunshield and light from other astronomical objects, both making their way to the focal plane as a diffuse background.
Quelle: ESA
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Update: 12.09.2014
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GAIA ENTDECKT SEINE ERSTE SUPERNOVA
While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy far, far away.
This powerful event, now named Gaia14aaa, took place in a distant galaxy some 500 million light-years away, and was revealed via a sudden rise in the galaxy’s brightness between two Gaia observations separated by one month.
Gaia, which began its scientific work on 25 July, repeatedly scans the entire sky, so that each of the roughly one billion stars in the final catalogue will be examined an average of 70 times over the next five years.
“This kind of repeated survey comes in handy for studying the changeable nature of the sky,” comments Simon Hodgkin from the Institute of Astronomy in Cambridge, UK.
Many astronomical sources are variable: some exhibit a regular pattern, with a periodically rising and declining brightness, while others may undergo sudden and dramatic changes.
“As Gaia goes back to each patch of the sky over and over, we have a chance to spot thousands of ‘guest stars’ on the celestial tapestry,” notes Dr Hodgkin. “These transient sources can be signposts to some of the most powerful phenomena in the Universe, like this supernova.”
Dr Hodgkin is part of Gaia’s Science Alert Team, which includes astronomers from the Universities of Cambridge, UK, and Warsaw, Poland, who are combing through the scans in search of unexpected changes.
It did not take long until they found the first ‘anomaly’ in the form of a sudden spike in the light coming from a distant galaxy, detected on 30 August. The same galaxy appeared much dimmer when Gaia first looked at it just a month before.
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Light curve of galaxy SDSS J132102.26+453223.8 obtained with Gaia. It shows the evolution in time of the galaxy’s brightness. The brightness is indicated on the vertical axis; smaller magnitude values indicate a brighter source.
The light curve shows how the galaxy significantly brightened up between the two consecutive Gaia observations because of a stellar explosion, or supernova, which was named Gaia14aaa. This is the first supernova discovered with Gaia.
The data points and error bars at the lower left corner are from the first observation, performed on 31 July 2014, and they are in line with previous observations of the same galaxy performed with other telescopes. The data points at the upper right corner are from the second observation, performed on 30 August 2014, and reveal a sudden rise in brightness of almost two magnitudes (roughly a factor of 6).
Using data from Gaia and other telescopes, astronomers confirmed that Gaia14aaa is a Type Ia supernova, the explosion of a white dwarf caused by the accretion of matter from a companion star in a binary system.
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“We immediately thought it might be a supernova, but needed more clues to back up our claim,” explains Łukasz Wyrzykowski from the Warsaw University Astronomical Observatory, Poland.
Other powerful cosmic events may resemble a supernova in a distant galaxy, such as outbursts caused by the mass-devouring supermassive black hole at the galaxy centre.
However, in Gaia14aaa, the position of the bright spot of light was slightly offset from the galaxy’s core, suggesting that it was unlikely to be related to a central black hole.
So, the astronomers looked for more information in the light of this new source. Besides recording the position and brightness of stars and galaxies, Gaia also splits their light to create a spectrum. In fact, Gaia uses two prisms spanning red and blue wavelength regions to produce a low-resolution spectrum that allows astronomers to seek signatures of the various chemical elements present in the source of that light.
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This image shows the supernova named Gaia14aaa as seen on 10 September 2014 with the robotic Liverpool Telescope on La Palma, in the Canary Islands, Spain. This is a Type Ia supernova – the explosion of a white dwarf locked in a binary system with a companion star – and it was discovered in the data collected with ESA’s Gaia satellite on 30 August.
In the left panel, the image from the Liverpool Telescope shows both Gaia14aaa and its host galaxy, named SDSS J132102.26+453223.8, which is about 500 million light-years away. In this image, the supernova is slightly offset from the galaxy’s core.
The central panel shows an image of the same galaxy, taken as part of the Sloan Digital Sky Survey, several years before the explosion of Gaia14aaa could be observed from Earth.
The right panel was obtained by subtracting the second image, which contains the light emitted by the galaxy, from the first one, which depicts both the galaxy and the supernova. The difference between the two images clearly shows the appearance of Gaia14aaa.
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Low-resolution spectrum obtained with the photometric instrument on Gaia of a stellar explosion, or supernova.
Astronomers using Gaia discovered that a source had significantly brightened up between two consecutive observations, performed on 31 July 2014 and 30 August 2014, respectively. The boost in brightness was caused by a supernova, which was named Gaia14aaa. This is the first supernova discovered with Gaia.
The photometric instrument splits the light of an astronomical source to create a spectrum. In fact, Gaia uses two prisms spanning red and blue wavelength regions to produce a low-resolution spectrum that allows astronomers to seek signatures of the various chemical elements present in the source of that light.
Light from the blue photometer is shown in the left half of the graph, and that from the red photometer in the right half. On the horizontal axis, the position of pixels in each of the two photometers is indicated. The pixel position provides a rough indication of the wavelength, with the blue photometer receiving light with shorter wavelengths (330–680 nanometres), and the red photometer with longer wavelengths (640–1050 nanometres). On the vertical axis, the intensity of light registered at each pixel is indicated. The gap at the centre of the graph is an instrumental effect.
This low-resolution spectrum contains hints about the nature of this transient source. The blue part of the spectrum appears significantly brighter than the red one, as expected from a supernova of Type Ia – the explosion of a white dwarf caused by the accretion of matter from a companion star in a binary system. The presence of absorption lines from iron, sulphur, oxygen and calcium (indicated in the graph) is also in line with the elements expected from a Type Ia supernova.
The astronomers followed up this source with the Isaac Newton Telescope on La Palma, in the Canary Islands, Spain, obtaining a high-resolution spectrum. This not only confirmed that the explosion corresponds to a Type Ia supernova, but also provided an estimate of its distance, proving that it actually happened in the galaxy where it was observed.
