Citizen scientists and astrophysicists reveal the final exoplanets spotted by NASA's Kepler space telescope, showcasing the device's remarkable, decade-long mission
Amid a near-decade-long mission, NASA’s Kepler space telescope, now decommissioned, may have yielded its last remarkable finds. A group of astrophysicists, bolstered by citizen scientists, unveiled what could be some of the final exoplanets discovered by the spacecraft.
Trio of Newfound Exoplanets between Earth and Neptune Size
The discovered exoplanets, alien worlds beyond our solar system, range in size between Earth and Neptune. Each tightly orbits its parent star. The University of Wisconsin-Madison senior, Elyse Incha, observes these are standard planets per Kepler’s measurements. Their excitement stems from the planets’ observation during Kepler’s final operational days, showcasing the spacecraft’s consistent planet-hunting prowess.
A Peek into Kepler’s Decade-Long Journey
Launched in March 2009, Kepler’s mission was to continuously monitor the Cygnus and Lyra constellations in the northern sky. This ongoing observation enabled tracking shifts in stellar brightness when planets transited across their stars. After four years, the telescope successfully identified thousands of possible exoplanets and was the first to discover an Earth-sized world within a star’s habitable zone.
Overcoming Obstacles and Continuing Discovery
Kepler experienced mechanical setbacks in 2014. However, the team behind it devised a solution that let it resume activities, which included scanning a new part of the sky every three months. The reinvigorated mission, named K2, lasted four more years, surveying over half a million stars. By its retirement in October 2018, Kepler had contributed to the confirmation of over 2,600 exoplanets.
The Final Chapter of Kepler’s Story
Kepler’s last campaign, marked 19, had a brief one-month lifespan. With diminishing attitude control fuel, the spacecraft struggled to maintain position for useful observations. Astronomers salvaged roughly seven days’ worth of high-quality data from Campaign 19.
Collaborative Effort Unearths Hidden Exoplanets
Incha’s team joined forces with the Visual Survey Group, a collaboration between professional astronomers and citizen scientists, to mine this dataset. Tom Jacobs, a member of the Visual Survey Group, emphasized the importance of human effort in discovering patterns and single objects in light curves. The group identified one transit for each of the three planet candidates in the dataset.
Calculations Reveal Potential Sizes and Orbital Periods
Using transit information, Incha’s team calculated the discovered planets’ potential sizes and orbital periods. The smallest, K2-416 b, is approximately 2.6 times the size of Earth and orbits its red dwarf star every 13 days. K2-417 b, slightly over three times Earth’s size, orbits a red dwarf star every 6.5 days. The last planet, EPIC 246251988 b, nearly four times Earth’s size, orbits a Sun-like star in around 10 days.
Kepler’s Legacy and TESS’s Ongoing Mission
Kepler’s planet-hunting legacy continues with NASA’s Transiting Exoplanet Survey Satellite (TESS), launched in April 2018. TESS uses a similar transit method, simultaneously surveying vast parts of the sky. In late 2021, TESS surveyed the region containing the three newly discovered Kepler planets, detecting two more potential transits for K2-417 b.
The Future of Planet-Hunting Missions
NASA’s Kepler and K2 missions were managed by the Ames Research Center in California’s Silicon Valley and the Jet Propulsion Laboratory in Pasadena, California. Meanwhile, TESS is a joint effort led by MIT and managed by Goddard. Kepler’s data continues to provide valuable insights for astronomers, propelling the future of planet discovery.
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