NASA's Kepler space telescope shows that it still has life in it as its extended mission begins to bear fruit. This week, the space agency announced that the spacecraft detected a new exoplanet, demonstrating that its K2 life extension mission is working. The planet, called, HIP 116454b, is 2.5 times larger in diameter than the Earth and orbits a star 180 light years from Earth in the constellation of Pisces every nine days at a distance that makes it much too hot for it to sustain life.
When it was first launched, the Kepler space telescope hunted for exoplanets by means of the transit method. That is, it would scan a predesignated area of the sky and measure the light coming from various stars. If a planet passed between the star and Kepler, the result would be a dip in the stars brightness. By recording the curve of the light intensity and making precise calculations, it is possible to determine if a planet is indeed the cause and deduce various characteristics of it, such as orbit and size.
The only problem is that this requires extremely precise station keeping and Kepler had to point in exactly the right direction for long periods of time. In May 2013, this became impossible after two of the unmanned spacecraft's four reaction wheels failed. These wheels are used to hold the telescope steady after the manner of a gyroscope. The engineers had designed Kepler so it could continue to function with one wheel out of commission, but two was beyond its limitations.
That seemed like the end of the mission, but NASA engineers came up with a workaround. They calculated that if Kepler was set in the right angle relative to its orbit, the pressure of the Sun's light would push on it against the force of its remaining wheels and hold it steady in the same fashion as a ship's correctly trimmed sails can hold it on course by balancing the force of the wind against the ship's keel. A test phase proved to be so successful that last May Kepler began its K2 mission, which so far has involved its examination of a further 35,000 stars, several star clusters, and a number of objects inside the Solar System.
The recent find was made by graduate student Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts and was based on publicly available data from the K2 gathered last February during its test phase showing the distinct signs of an exoplanet, and was confirmed by the HARPS-North spectrograph of the Telescopio Nazionale Galileo in the Canary Islands.
"Last summer, the possibility of a scientifically productive mission for Kepler after its reaction wheel failure in its extended mission was not part of the conversation," says Paul Hertz, NASA's astrophysics division director. "Today, thanks to an innovative idea and lots of hard work by the NASA and Ball Aerospace team, Kepler may well deliver the first candidates for follow-up study by the James Webb Space Telescope to characterize the atmospheres of distant worlds and search for signatures of life."
The Kepler results will be published in The Astrophysical Journal.