Kepler, the NASA spacecraft that has introduced us to other Earth-like planets in our neighborhood of the universe, may be done spotting distant worlds floating in their respective suns' habitable zones.
In May, Kepler saw the second of its four gyroscope-like reaction wheels fail. Among the spacecraft's few moving parts, the wheel allows it to point precisely at its observation targets. The first wheel failed last year, and NASA says at least three operational wheels are required for Kepler to maintain the precise aim needed to observe the transit of smaller planets.
In a conference call Thursday, NASA announced that after unsuccessful tests, it was giving up on attempts to restore at least one of the two failed wheels and get Kepler back into full working order.
Paul Hertz, astrophysics director at NASA headquarters, said that an engineering study will be conducted over the next several weeks to determine what kind of operations and observations might be possible with two out of four functional wheels. Although the precision pointing ability that Kepler was originally designed for appears to be gone, William Borucki, Kepler science principal investigator at NASA's Ames Research Center, speculated that it could possibly continue to look for asteroids, comets, supernovae, and perhaps even some planets.
Kepler launched in 2009 for a primary mission that ended in 2012, when an extended mission began. In the past four years, Kepler data has confirmed 135 exoplanets and identified more than 3,500 candidates. Borucki stressed that there is still much more data from Kepler's observations that needs to be fully analyzed.
When asked if he was sad about the state of Kepler, Borucki responded:
"I am delighted with what we've accomplished... it's like standing at the bottom of the ocean and just being covered with this ocean of data (from Kepler's observations)."
And the planet-hunting doesn't end with Kepler. NASA is readying a follow-up mission, the Transiting Exoplanet Survey Satellite (TESS), planned for launch in 2017 or 2018 with the goal of surveying transiting exoplanets closer to Earth.