Kepler monitors 145,000 Sun-like stars for signs of planets passing in front of them, searching for periodic dips in star brightness that might indicate planet orbital activity around its host star. Astronomers look out for patterns suggesting planet presence by tracking periodic brightness dips that might signal their passage.
Kepler had been operating successfully until one of its steering devices malfunctioned in 2012, three years into its mission. Engineers devised a plan called K2 to extend it until Kepler finally ran out of fuel in 2018.
What is kepler?
Kepler was a planet-hunting telescope designed to detect any diminution in star brightness when an exoplanet transited in front of it; thus yielding thousands of planets over three years.
The only scientific instrument onboard this spacecraft is a photometer, which precisely measures star brightness while searching for potential variations caused by passing planets. A telescope was directed toward an area located between Cygnus and Lyra constellations.
Kepler studied most stars located between 600 to 3,000 light years away from its orbit around Earth-trailing heliocentric orbit around Sun. This orbit enables Kepler to avoid encountering heat from passing stars while keeping its photometer cool; scientists employed thermal blankets and special finishes on solar panels to minimize heat transfer into photometer.
Kepler was conceptualized and implemented by NASA scientist William Borucki. He advocated within NASA for a spacecraft capable of searching for exoplanets by monitoring transits – when planets pass in front of their parent star and dim its brightness enough for detection by telescopes.
Kepler’s mission was extended far beyond its initial term and ran smoothly until May 2013, when one of three reaction wheels (gyroscopes) malfunctioned – these devices allow precise pointing by keeping track of rotational speeds of their reaction wheels (reactoscopes).
The Kepler photometer observes a field of 100,000 main-sequence stars and searches for any indication that any have planets transiting them. The field can be found near Cygnus, Lyra and Draco constellations far enough from Earth to prevent sunlight from penetrating into its photometer.
The spacecraft consists of a low-profile hexagonal box topped by three decks enclosing the photometer, each deck housing battery, power distribution system, reaction control system and radio equipment. Six shear panels serve as structural supports for the spacecraft.
Kepler utilized a photometer to assess the brightness of stars. Its wide field of view allowed him to detect dimming caused by planets passing in front of their host stars and cause further investigation of planet transits.
The photometer’s focal plane contains 25 individual modules that serve a specific function. Precision photometry is essential to the mission’s success as it can detect variations as small as fractions of one percent in star light variations.
Kepler is not only used to find planets; its 42 CCD detectors also gather statistics on various kinds of stars whose properties determine planet sizes and orbits. Such observations provide key insights into understanding what determines planet formation.
The spacecraft was able to extend its mission well past its original specifications until 2012 when one of four reaction wheels (gyroscopes) failed. A further wheel failed in 2013, bringing its service life down to just 83 days at a time.
Kepler suffered its third reaction wheel failure in May 2013. To save its operation, engineers devised a plan which involved shifting Kepler’s field of view every three months – an action known as “campaigning.”
Engineers also modified how the spacecraft pointed at stars in Cygnus and Lyra. Instead of relying on sunlight’s force (which doesn’t exert gravity-like pull) for keeping its telescope pointed towards one patch of sky, they relied instead on starlight itself as the force to do this job.
Kepler has produced an extraordinary treasure trove of data about new worlds to study since its initial launch and has set an incredible standard for future missions. Kepler data will ultimately further scientific understanding about stars and planets that orbit them, expanding scientists’ understanding of both themselves.