The wildly successful Kepler mission, launched in 2009 and which, to date, has found nearly 3000 extrasolar planet candidates, suffered the loss of a second reaction wheel this past spring. Beginning a couple weeks ago, engineers, working very closely with Ball Aerospace, began testing Kepler to see if they could bring it back.
Discovery News reports that engineers are, “cautiously optimistic” on NASA’s attempts to bring Kepler back off life support. Engineers tasked with the problem were able to get the two reaction wheels to move, and one of them moved in both directions.
Reaction wheels are critical to any space component, as they are responsible for the spacecraft’s ability to point and remain stationary. Without reaction wheels, it is like being in the middle of nowhere without maps or a GPS system to tell you where you are. In space, reaction wheels are needed for the three degrees of freedom of motion, not just the two degrees of freedom we tend to think of here on Earth. Each spacecraft must possess the ability to move up and down, front and back, and side to side. The reaction wheels provide this, as well as station keeping. Station keeping is the ability of a spacecraft to remain, relatively, in one place, with respect to some references. The references used in space are stars, and acquiring a position with reference to three fixed stars provides the spacecraft with the stability needed to make very long observations, of the type required for finding extrasolar planets. The reaction wheels maintain the spacecraft’s position, so that the transit method employed by Kepler can, then, be utilized to locate prospective extrasolar planets.
Kepler’s reaction wheels have suffered excessive friction, causing them to wear out before their time.
Keep your fingers crossed that NASA Engineers will succeed in getting the extrasolar planet hunter Kepler mission out of the ER and back to finding where ET lives.by