A Spacecraft's Second Life: Our K2 mission
A critical failure that ended one mission has borne an unexpected and an exciting new science opportunity. The Kepler spacecraft, known for finding thousands of planets orbiting other stars, has a new job as the K2 mission.
Like its predecessor, K2 detects the tiny, telltale dips in the brightness of a star as an object passes or transits it, to possibly reveal the presence of a planet. Searching close neighboring stars for near-Earth-sized planets, K2 is finding planets ripe for follow-up studies on their atmospheres and to see what the planet is made of. A step up from its predecessor, K2 is revealing new info on comets, asteroids, dwarf planets, ice giants and moons. It will also provide new insight into areas as diverse as the birth of new stars, how stars explode into spectacular supernovae, and even the evolution of black holes.
K2 is expanding the planet-hunting legacy and has ushered in entirely new opportunities in astrophysics research, yet this is only the beginning.
Searching Nearby for Signs of Life
Image credit: ESO/L. Calçada
Scientists are excited about nearby multi-planet system known as K2-3. This planetary system, discovered by K2, is made of three super-Earth-sized planets orbiting a cool M-star (or red dwarf) 135 light-years away, which is relatively close in astronomical terms. To put that distance into perspective, if the Milky Way galaxy was scaled down to the size of the continental U.S. it would be the equivalent of walking the three-mile long Golden Gate Park in San Francisco, California. At this distance, our other powerful space-investigators – the Hubble Space Telescope and the forthcoming James Webb Space Telescope (JWST) – could study the atmospheres of these worlds in search of chemical fingerprints that could be indicative of life. K2 expects to find a few hundred of these close-by, near-Earth-sized neighbors.
K2 won’t be alone in searching for nearby planets outside our solar system. Revving up for launch around 2017-2018, our Transiting Exoplanet Survey Satellite (TESS) plans to monitor 200,000 close stars for planets, with a focus on finding Earth and Super-Earth-sized planets.
The above image is an artist rendering of Gliese 581, a planetary system representative of K2-3.
Neptune’s Moon Dance
Movie credit: NASA Ames/SETI Institute/J. Rowe
Spying on our neighbors in our own solar system, K2 caught Neptune in a dance with its moons Triton and Nereid. On day 15 (day counter located in the top right-hand corner of the green frame) of the sped-up movie, Neptune appears, followed by its moon Triton, which looks small and faint. Keen-eyed observers can also spot Neptune’s tiny moon Nereid at day 24. Neptune is not moving backward but appears to do so because of the changing position of the Kepler spacecraft as it orbits around the sun. A few fast-moving asteroids make cameo appearances in the movie, showing up as streaks across the K2 field of view. The red dots are a few of the stars K2 examines in its search for transiting planets outside of our solar system. An international team of astronomers is using these data to track Neptune’s weather and probe the planet’s internal structure by studying subtle brightness fluctuations that can only be observed with K2.
Dead Star Devours Planet
Image credit: CfA/Mark A. Garlick
K2 also caught a white dwarf – the dead core of an exploded star –vaporizing a nearby tiny rocky planet. Slowly the planet will disintegrate, leaving a dusting of metals on the surface of the star. This trail of debris blocks a tiny fraction of starlight from the vantage point of the spacecraft producing an unusual, but vaguely familiar pattern in the data. Recognizing the pattern, scientists further investigated the dwarf’s atmosphere to confirm their find. This discovery has helped validate a long-held theory that white dwarfs are capable of cannibalizing possible remnant planets that have survived within its solar system.
Searching for Far Out Worlds
In April, spaced-based K2 and ground-based observatories on five continents will participate in a global experiment in exoplanet observation and simultaneously monitor the same region of sky towards the center of our galaxy to search for small planets, such as the size of Earth, orbiting very far from their host star or, in some cases, orbiting no star at all. For this experiment, scientists will use gravitational microlensing – the phenomenon that occurs when the gravity of a foreground object focuses and magnifies the light from a distant background star.
The animation demonstrates the principles of microlensing. The observer on Earth sees the source (distant) star when the lens (closer) star and planet pass through the center of the image. The inset shows what may be seen through a ground-based telescope. The image brightens twice, indicating when the star and planet pass through the observatory’s line of sight to the distant star.
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9 Mar, 2016
A Spacecraft's Second Life: Our K2 mission
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