Monday, August 27, 2012
A billion pixels for a billion stars
E2v has worked for more than five years to produce all of the Gaia CCD. I doubt those going to buy a can of paint to store hardware chain Homebase has in the English town of Chelmsford think too much about what happens in the factory adjoining art. It is the headquarters of e2v; a company that gained fame after World War II manufactured lamps for television industry but now produces camera sensors for some of the most important space missions.
The latest images of Mars, Mercury and the Sun, and the extraordinary views from the Hubble telescope have been taken by the charge-coupled devices (CCDs, for its acronym in English) manufactured by e2v in eastern England. Explained in a simple manner, the CCD converts light reflected by the surface into an electrical signal. In a telescope like Hubble, which orbits about 560 miles of the surface of our planet, the electrical signal is processed and transmitted to the ground, where it can easily be transformed back into an image on a computer screen.
But while the Hubble's main instrument, the Wide Field Camera 3, incorporates two CCD manufactured by e2v, the sensor system just ended the company includes 106 CCD. This huge system (about 1,000 million pixels) will be installed on the Gaia satellite that the European Space Agency (ESA, for its acronym in English) launched in June 2013.
Gaia will be sent to 1.5 million kilometers from Earth, where you will observe the universe.
The Gaia telescope
The Gaia telescope draws an accurate map in three dimensions of the Milky Way. It is the successor European Hipparcos satellite, which recorded almost 100,000 stars. The 1,000 million stars that register the Gaia represent only 1% of the Milky Way. The quality of the new research discoveries will go beyond the stars themselves. Gaia will search for new asteroids, failed stars and will perform tests of physical theories.
It will be launched by the Soyuz in 2013 and is located 1.5 million kilometers from Earth. They need a supercomputer to prepare the final catalog, which is expected to be ready by 2020. In a period of five years, the system created by e2v, along with two telescopes and other sophisticated instrumentation includes an atomic clock; draw a map of the Milky Way in 3D without precedent.
Gaia will detail the position, distance, movement and precise composition of the brightest stars in galaxies as far away as the Andromeda. It expects this new information on the structure, origin and evolution of our galaxy. And as Gaia will capture anything that passes in front of its CCD, is likely to register many hitherto unknown objects, like asteroids or planets that lie beyond our solar system or stars that never saw the light. Their measurements even allow scientists to perform tests of the Theory of Relativity by Albert Einstein.
E2v is involved in the early work of Gaia in the late '90s. At that time they wanted to build a large satellite teleport two camera systems that incorporate some 500 CCD. The company has worked for more than five years to produce all leading Gaia CCD. The sensitive area of the CCD detector each measured 45.0 millimeters by 59.0 millimeters, covering 1966 pixels by 4500 pixels.
Small devices are arranged in rows on a supporting structure made of silicon carbide, a very light and resistant materials not curved or twisted when extreme temperatures experienced in space. In total, the system has an area of just under half a square meter.
The idea is that the two Gaia telescopes focalized the stars in the CCD system, which records the positions and individual properties of these celestial objects. Although for the final mission it took 106 CCD, different development and test programs that were delivered were many more of these devices to Astrium, a manufacturer who is riding the Gaia at its facilities in Toulouse, France.
The CCD transforms the light which is reflected at its surface into an electrical signal that can be easily transmitted. These devices, whose inventors received the Nobel in 2009, are essential in modern space missions e2v CCD produced 174 for the Gaia project. Four of them can be seen in the image above.
The biggest CCD system is in the NASA Kepler telescope.
"The total number of flight models and flight spare was 130, which is a significant number when you consider that for most of our space programs speak five or six flight devices at most ten," explains Roy Steward, e2v project manager. "And of course there were engineering models and other, 44 of them. So we are talking about a total of 174 CCD".
Gaia is certainly a long-term project. Since its adoption until its launch 13 years have passed. Collect and process all the data from its catalog of stars will take another seven or eight years. "The data that will be collected will have a size of 100 terabytes and when they are processed will be talking about one petabyte (1,000,000,000,000,000 bytes" explains Giuseppe Sarri, project manager of the ESA Gaia telescope. "For analysis will require a supercomputer," said Sarri.
Bring all the information required Gaia-Earth transfer capability impressive: about 5 Mb / s in their daily shipments, similar to many home broadband connections, but at a distance of 1.5 million kilometers.
The draft for the Gaia e2v, valued at 20 million Euros ($ 27 million), has been more than an interesting challenge. The required investment in the company premises in Chelmsford to produce all CCD has made the firm is currently in an excellent position to compete for other business space. "Gaia made us to increase in pace and put us ahead," said Jon Kemp, Marketing and e2v applications.
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