The mood was already solved, as the space telescope “Gaia” was still on the ground. It was finally mounted on a Russian Soyuz rocket. These start since 2011, from the European spaceport in Kourou, French Guiana, and are considered highly reliable. The weather left to be desired too little left. Light of the full moon shone through the expiring tropical night, when the jungle northwest of Kourou on Thursday at 6.12 clock early local time was enlightened by the start engines and the Soyuz along with the two-ton instrument in its tip flew thundering into the sunrise.
Even the separation of the four auxiliary engines was to follow with the naked eye. As glistening dots they moved away from the rocket before these moments later left the atmosphere. A picture-perfect launch. Nevertheless, relief turned to the employees of the European Space Agency ESA, the rocket company Arianespace and satellite manufacturer Astrium engineers of only 43 minutes later. As the last step was separated and finally sent the precious cargo on the trip.
The dynamics of the Milky Way to explore
goal is an orbit around the Sun, 1.5 million kilometers from Earth. From there, in the shadow of a ten-meter-wide parasol, Gaia is five years looking at the stars under the best observing conditions. Especially in the stars. Because unlike, say, the Hubble Space Telescope is Gaia is not there, also scan glowing gas clouds and the spiral nebulae galaxies. The purpose is, rather, the exact structure to explore the dynamics of our own galaxy, the Milky Way. From which we know though, that it has a spiral shape. But already on the number of spiral arms are conflicting opinions of astronomers. With Gaia will not only clarify this issue, but ultimately find out how it came to the creation of our cosmic home -. In which one looks at her star to determine as many as precisely as possible the positions and velocities of
a billion stars, it will be – and thus a star for every euro, which the company will cost all in all. While this is slightly less than one percent of all stars in the Milky Way, but it’s enough to make a precise three-dimensional map of this side of the center of the Milky Way, because at up to ten million stars in addition to the position in the sky, the distance is measured. A star that Gaia has scanned, the instrument appears half a year later under a slightly different angle, because in the meantime the instrument has indeed moved on its path around the sun one web diameter, slightly more than 300 million kilometers. However, this so-called parallax is tiny even for nearby stars. It was not until 1838, it was possible to detect this shift with only a ten light-years distant star. And even today the location and distance, so the 3D position, only a few hundred nearby stars as accurately known as Gaia will measure – despite Hubble, despite the ground-based extremely large telescopes that are built today, and in spite of Gaia’s predecessor mission Hipparcos, the between In 1989 and 1993 mapped almost 118000 stars from space.
Gaia 3D star map will therefore be millions of times larger and extend over tens of thousands of light years. For the instrument the largest digital camera ever was installed. About a half square meters in this gigapixel instrument and thanks to its mirror optics can determine stellar positions to less than one hundred-thousandth of a degree of angle exactly – which corresponds to the angle at which we would appear from Earth a euro coin on the moon. “So on the eve of a revolution in our understanding, we are of the Milky Way,” said Stephane Israël Arianespace after launch.
13 years work have gone into Gaia
This accuracy is due in addition to the special train is engaged in construction, have tinkered on the astronomers and engineers 13 years. “The precision was the hardest,” says Wolfgang Pitz EADS Astrium in Friedrichshafen. The company has therefore made not only the levels but also the backbone of the satellites of silicon carbide, a ceramic substance that almost does not expand with temperature changes. “This is the largest structure of this material, which has been sent into space,” says Pitz. “And the problem is that the stuff is extremely brittle. It breaks very easily. You have to treat it like a raw egg. “
Now is the raw egg on top, but the cliffhanger is not over yet. One month will be to their observation posts on the way Gaia. “We’ve got a few steps ahead of us,” said Alvaro Gimenez, Director of Science Esa. For it is only when the first star light has fallen into the mirror of the instrument and the data is returned to Earth as planned, will be established that there really will be the great 3D image of the Milky Way.