Earlier this year, NASA’s Kepler spacecraft lost its second gyroscope wheel. Although there are a total of four wheels, three operational ones are necessary to allow Kepler to position itself to point at the right patch of sky. With two of these wheels down, Kepler's search for habitable exoplanets came to an end. Since then, it’s just been floating out there in space, although NASA never gave up on using it for something. NASA, along with a team of engineers from Ball Aerospace, have figured out a way to recover the ability to position Kepler, by using the Sun. In other words, the Kepler search for habitable planets is back in business.
The Sun, which provides energy to Kepler's solar panels, moves the spacecraft around as photons hit the spacecraft. NASA believes they can use the solar pressure by distributing it evenly across the spacecraft, giving it some of the stability which was lost with the failing of the gyroscope wheels. However, Kepler will need to be in an exact position in relation to the sun.
NASA is currently testing this idea, and so far, the results have been positive. Last month, the telescope captured a full frame image of its field of view. The image quality was within a mere 5 percent of previous images it captured when it had all four gyroscope wheels working. More testing is currently underway.
Kepler discovers planets by looking at a specific part of the sky, and then measuring the variations of brightness of stars every 30 minutes. It looks for occasional dimming of each star’s brightness to determine when planets “transit” (or come in front of) a star. So, if a star goes slightly darker, there’s a good chance it has a planet orbiting in front of it. With Kepler’s mission being on again, we can now collect even more data about planets out there, many of them potentially habitable.