The team behind NASA's Kepler spacecraft did not give up when the probe's planet-seeking mission appeared to have been doomed because of equipment malfunction in 2013. With their efforts, the spacecraft is back and discovering extraterrestrial worlds again.
On Dec. 18, the U.S. space agency announced that Kepler has made a comeback with the discovery of a planet 12 times as massive as the Earth. The new find was made after a team of astronomers and engineers came up with a workaround after data collection during the spacecraft's prime mission ended in May 2013 when two of the four reaction wheels that stabilized the spacecraft malfunctioned.
Kepler uses a so-called transit method when looking for planets, and this involves watching for the dimming of a distant star caused when a planet transits across its face. Smaller planets cause weaker dimming, so measuring the brightness needs to be accurate. Precise pointing is required for this, but Kepler lost its ability when half of its orientation-maintaining reaction wheels broke down.
What the scientists and engineers did was to use a virtual reaction wheel in the form of pressure from sunlight to stabilize the spacecraft. The new strategy worked; with Kepler's new K2 mission came the discovery of an exoplanet called HIP 116454b.
"Like a phoenix rising from the ashes, Kepler has been reborn and is continuing to make discoveries. Even better, the planet it found is ripe for follow-up studies," said Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics (CfA) who looked at the data collected by Kepler during a K2 test earlier this year.
HIP 116454b, which is located 180 light-years away, has a diameter of 20,000 miles, which is 2.5 times greater than the Earth's. The HARPS-North spectrograph installed at the Telescopio Nazionale Galileo telescope in Canary Islands, which also confirmed the discovery, shows that the exoplanet weighs nearly 12 times as our planet, making HIP 116454b a super-Earth.
The exoplanet likewise circles its host star, a type K orange dwarf smaller and cooler than the solar system's sun, every 9.1 days at 8.4 million miles, making HIP 116454b too hot to sustain life, albeit its density suggests it could also be a water world like ours, made up of three-fourths water and one-fourth rock, or be a mini-Neptune.
"K2 is uniquely positioned to dramatically refine our understanding of these alien worlds and further define the boundary between rocky worlds like Earth and ice giants like Neptune," said Kepler/K2 project scientist Steve Howell.