Even after months of testing, two of the four so-called reaction wheels that were supposed to hold the telescope in position could no longer be set in motion.
Nasa celebrated the telescope’s precision work as a success despite the technical errors. "We expect to make hundreds, maybe thousands, of discoveries about new planets," said the mission’s chief scientist, william borucki. The telescope had already revolutionized knowledge about the so-called exo-planets and other astronomical relationships, it was announced in may. In its search for a "second earth," the telescope has observed between 100,000 and 150,000 stars since march 2009.
According to borucki, after further data analysis, scientists will know within a few years how common earthly celestial bodies are in space. The telescope has already shown that the galaxy is "full to the brim" of planets. But only a few of them are close enough to their stars to be home to life.
In the more than four years of its search for a "second earth," "kepler" has tracked down more than 3,500 planetary candidates, according to nasa. Already 135 exo-planets are confirmed. Last april, researchers reported two planets that are so far from their stars that liquid water is possible on them. The radius of the celestial bodies is about 1.5 times as large as that of the earth, and they are most likely boulders.
The first terrestrial planet discovered by "kepler" in a habitable zone was presented by nasa as early as 2011. But it was not clear whether it was solid, liquid or gaseous. Previously, "kepler" had discovered, among other things, several exo-planets that were about the size of the earth, but very bright.
The telescope’s first reaction wheel had already failed in july last year. The second failed in may 2013. For months, nasa specialists tried to repair the parts. Three of the four wheels are needed to steer "kepler" and point it at a smaller bundle of stars.
The program cost a total of about 600 million dollars (about 450 million euros). Because of the rough success, nasa had announced last year that it wanted to extend the mission until september 2016.
In total, international research teams have discovered more than 900 exo-planets using various techniques, and in february they even discovered one that is barely coarser than our moon.