NASA's Kepler Telescope finds first exoplanet of its new K2 mission

The Kepler Space Telescope's new 'K2' mission fields of view across the galaxy. Credit: NASA Ames/JPL-Caltech/T Pyle

Friday, December 19, 2014, 11:38 AM - NASA's ingenious workaround for its Kepler Space Telescope has paid off, as the team reports spotting the very first confirmed exoplanet of its new mission.

According to experts at NASA's Jet Propulsion Laboratory (JPL), this newly-confirmed extra-solar planet, named HIP 116454b, is located roughly 180 light years away, orbiting a small dwarf star in the constellation Pisces. A 'super Earth' world, roughly 2.5 times bigger than Earth, HIP 116454b orbits around its star so closely that it completes one of its years in just 9 Earth days. As such, the planet is far too hot for any life - as we know it - to survive there, but this discovery is very important for a different reason. It shows that despite suffering a mechanical failure, the Kepler Space Telescope is still able to continue its original mission, just in a slightly different form.

When Kepler was launched into space in 2009, on a mission to search out planets orbiting around other stars, it was an incredible success. Staring with an unblinking eye down the spiral arm of our galaxy, just off from the constellation Cygnus, the telescope kept a nearly continuous watch over around 150,000 stars.

Credit: NASA/Kepler/Carl Roberts

It's goal? To spot telltale dips in brightness that indicate the presence of a planet orbiting around that star, as shown in the illustration to the right. In the first three years of its mission, the telescope gathered enough data to find nearly 1,000 confirmed exoplanets, with more than four times that number still waiting as 'candidates' to be confirmed by other telescopes.

To accomplished this, Kepler used four 'reaction wheels' - small flywheels that allow it to keep its mirror and instruments ultra-steady, even as photons from the Sun buffeted the telescope and exerted a small amount of radiation pressure. However, Kepler's observations have to be so precise that even that relatively tiny amount of pressure is capable of blurring its view and spoiling the mission.

Starting in mid-2012, the telescope ran into troubles as one of these reaction wheels failed. Kepler can work with only three wheels functioning, but the mission was really in jeopardy when a second wheel began to stick and ultimately failed about a year later. While several other uses were proposed for the telescope (as it was otherwise functional), the loss of these reaction wheels would have rendered it incapable of searching for distant exoplanets, if it wasn't for an ingenious plan to get around the problem.

Rather than use the reaction wheels to resist the effects of pressure from solar photons, the Kepler team are now using that very pressure, balanced against the telescope's symmetrically-shaped solar panels, to keep it steady to keep on with its original mission.

Credit: NASA

As the diagram above shows, there's a few tricks to this new rebooted 'K2' mission, though. In addition to the careful balance Kepler must maintain with this solar radiation pressure, it also must strike a balance between how long it can look at a particular part of space and keeping the Sun's light from shining onto its photoreceptors. Therefore, as it follows Earth around the Sun, it will watch a particular field of stars for roughly 83 days, then shift to another field for the next 83 days, and so on. To see the planned fields of view, click here.

Credit: ESO/S. Brunier/NASA Kepler Mission/Wendy Stenzel.

While this new mission plan will make it harder to spot planets with longer orbits, it will actually open up the mission to finding planets over a much broader range of the galaxy.

"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," Paul Hertz, the director of NASA's astrophysics division, said in a JPL press release. "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."