The Beginning is the End is the Beginning
Image credit: NASA/NASA Ames/Kepler Team
There has been much talk about Kepler’s reaction wheels over the past year, when in July 2012 one of Kepler’s four spinning reaction wheels (wheel 2) failed. Kepler uses these wheels to precisely point the spacecraft so that the stars it is monitoring stay nearly at the same positions on Kepler’s imaging plane in order to achieve the ~30 ppm photometric precision required to detect Earth-sized planets transiting Sun-like stars. Kepler’s thrusters used for coarse adjustments are unable to provide that kind of sensitive nudging.
Kepler only needs 3 reaction wheels to successfully keep pointing for the exoplanet observations, so with 1 out of 4 wheels non-functional, observations could continue. It was known at that point that another reaction wheel (wheel 4) was already acting up in similar ways to the failed wheel 2. It was unknown at that point how long the wheel would last. It could be days or months or years, and NASA was investigating ways and implementing strategies in attempts to prolong the lifetime of Kepler’s remaining working reaction wheels.
In May of this year, after 4 years of light curves, Wheel 4 failed halting the exoplanet observations in the beginning of Quarter 17. (Read Chris’ take on Wheel 4’s failure). Kepler was placed in a configuration to preserve fuel while NASA explored ways of reviving one of the 2 broken wheels. After engineering tests, NASA announced two weeks ago that the failed reaction wheels are unrecoverable. The spacecraft is in an Earth-trailing orbit, not reachable for an astronaut servicing mission. This means the end of Kepler’s exoplanet transit observations, and NASA is exploring alternative observations that Kepler could be used for (like looking for Near Earth Asteroids).
This is the end of the Kepler’s exoplanet transit observations, but this in many ways just the beginning of the mission’s next phase as the focus shifts solely to analysis of the data that has been collected and thinking of new ways of processing the existing observations to find smaller and smaller planets. The mission is far from over. Although there will be no more light curves coming from Kepler, there are still many discoveries yet to be made and science to do. There are still ~ 2 years of worth of Kepler observations already on the ground that the Kepler team and the astronomical community have yet to fully analyze. To fully search and analyze all the Kepler data will take at least another several years, keeping astronomers and citizen scientists busy until the launch of TESS. Kepler has revolutionized the field of exoplanets and will continue to do so for a long time to come.
What does the news about Kepler mean specifically for Planet Hunters? At Planet Hunters, we have only searched a small fraction of the Kepler quarters. In addition new and better data reduction techniques have been implemented by the Kepler team to improve the quality of the Kepler light curves and help reveal planets that may been invisible previously. We plan to search all four years of the newly reprocessed light curves with Planet Hunters. We need your help more than ever. We’ll be serving light curves (with previously unknown planet transits likely lurking in the dataset) needing classifications for a long time to come!
So join us today, as one phase of the Kepler era ends and the next one begins. Help continue the exoplanet search today at http://www.planethunters.org
A mysterious object no more
This post is by Tabby Boyajian, one of the Planet Hunters science team at Yale
As you all know, planethunter volunteers use archive data taken with the Kepler space telescope to classify lightcurves and identify transiting planets. Since the launch of the Planethunters citizen science program, we have contributed five scientific publications reporting on the discovery of dozens of candidate and confirmed exoplanetary systems – otherwise undiscovered by the Kepler team.
The design of the project is expanding with the opportunity for Planethunter volunteers to support astronomers interested in using Kepler data for scientific research unrelated to the main exoplanet goals of the Kepler mission. We have dubbed this as our own ‘Guest Scientist’ program. The idea is that guest scientists participate in Planethunters Talk forum and make requests for the public to collect particular light curves, such as signatures of moons or rings, pulsators, variable stars, flare stars, cataclysmic variables, or microlensing events.
This schematic, by Planet Hunter Daryll LaCourse, shows off our new discovery. (Click to make larger)
We are delighted to announce that the first paper presenting results associated with the Planethunters Guest Scientist program has been accepted for publication in the Astrophysical Journal! In this paper, the lead scientists Doug Gies and Zhao Guo from Georgia State University and Steve Howell and Martin Still from NASA AMES follow up on a mysterious object in the Kepler field identified by Planethunters, later confirming it to be an unusual type of cataclysmic variable. They perform an in-depth analysis on the Kepler lightcurve as well as observations made at the Kitt Peak National Observatory 4-m Mayall telescope and RC spectrograph. The result is a newly published paper, so take a momtent to read ‘KIC 9406652: An Unusual Cataclysmic Variable in the Kepler Field of View’ or to check out the planethunters talk thread where the object was first discovered and discussed:
Thanks you all for your enthusiasm and contributions to the scientific community. We have several other projects underway so keep an eye out for updates in the future!
More from Protostars and Planets
Last month, many of the Planet Hunters science team attended the Protostars & Planets VI conference in Heidelberg, Germany. The conference happens every few years and serves to summarize the state of the field from stars to exoplanets and everything in between. I presented a poster on the preliminary results from our TCE review and Yale graduate student Joey Schmitt presented a poster on the current status of the Planet Hunters planet candidate effort . Most of the posters from the conference have been posted online. You can find my poster here and Joey’s poster here. The talks from the conference are also online (including a talk on Exoplanet Detection by Planet Hunters PI Debra Fischer).
Planet Hunters 