Efforts to revive NASA’s Kepler space telescope, the space based observatory now credited with identifying 3,548 possible alien planets in the Milky Way galaxy will enter a new diagnostic phase this week, according to program manager Roger Hunter.
Artist's illustration of NASA's Kepler space telescope. Image credit/NASA
The latest efforts are intended to determine whether Kepler can regain the accuracy in pointing needed to resume the search.
Kepler, launched in March 2009, was hobbled in May by troubles with a second reaction wheel. The observatory is equipped with four of the fast spinning devices that stabilize and aim Kepler with high accuracy. However, three of them must function properly if Kepler is to resume its planet search.
Both reaction wheels 2 and 4 are experiencing high friction. The May difficulties with wheel 4, prompted a safe mode response and at least a temporary end to the ultimate search for Earth-like planets circling their stars in what’s considered the habitable zone — a region temperate enough for water, if present, to exist in liquid form.
Recovery efforts so far show that both wheels 2 and 4 will spin clockwise and counter clockwise, according to a Kepler mission status report prepared by Hunter and issued Friday, Aug. 2. But the friction experienced by wheel 4 is so high it will remain inactive at least for now.
Starting Thursday, Aug. 8, NASA’s Kepler team will start a new three phase evaluation.
First, reaction wheels 1 and 3 will be commanded to spin up in an effort to achieve a sustained “coarse pointing mode,” which is equivalent to holding aim on a movie theater screen positioned inNew York City’s Central Park from San Francisco.
It’s not precise enough, however, to continue Kepler’s planet search. The search relies on measurements of a small dimming of the light emitted by a star. The dimming is attributed to the passage or “transit” of a planet across the face of the star.
Next, reaction wheel 2 will join the pointing evaluation to determine if the spinning device can operate without triggering a safe mode. In safe mode, Kepler suspends science activities in order to protect its power source and communication capabilities.
If the plan works, ground controllers will determine if Kepler has the pointing accuracy to transmit stored observational data back to Earth through NASA’s Deep Space Network, an aiming mode still not matching the precision required for science investigations.
Finally, if the evaluation is going well, Kepler will be instructed to attempt to sustain planet search accuracy using wheel 2. That requires pointing with an accuracy equivalent to holding aim on a soccer ball in New York’s Central Park from San Francisco.
The three phase evaluation is expected to take a week, followed by a couple of weeks of engineering evaluation to determine whether Kepler is cleared to resume its planet search.