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NASA's Kepler Spacecraft Detects First Far-off World on its New K2 Mission

Amy Tyndall, News reporter
Dec 24, 2014, 21:06 UTC

Sen—After some inventive engineering to get Kepler stabilised again after a second reaction wheel failure last year, the first exoplanet has been detected by the NASA spacecraft on its new K2 mission.

The exoplanet, designated HIP 116454b, was found using Kepler test data taken in February 2014. It is on a nine-day orbit around a star some 180 light-years away, and is around 2.5 times the size of Earth.

Its detection was confirmed using observations taken by the HARPS-North spectrograph mounted on the Telescopio Nazionale Galileo in La Palma, Canary Islands.

Because of its close proximity to its sun, the planet is too hot to have any chance of supporting life. But being able to add HIP 116454b to the ever-increasing catalogue of known exoplanets is not the only success story to come out of this discovery.

Originally planned to have a mission length of 3.5 years, Kepler has now been in operation for almost six years, meaning that this incredible spacecraft has already exceeded expectations and that problems were perhaps inevitable.

Kepler relies on four 'reaction wheels' to help keep it stable and pointing in the right direction when performing crucial observations, and the first of these failed back in July 2012. It was believed that the original mission could continue as long as the other three reaction wheels remained fully operative, but unfortunately, in May 2013, a second wheel failed, jeopardising the future of both the spacecraft and the mission.

As a back-up, a call for proposals on what science could be done with only two wheels was announced, whilst simultaneously behind the scenes, scientists and engineers were working hard to come up with a solution.

They succeeded. A force is generated by the photons within sunlight hitting Kepler's solar panels, allowing a 'virtual' reaction wheel to be created. This application of pressure in the correct place gave the spacecraft back its three-wheel abilities and subsequently some of the stability that the spacecraft needs in order to continue operations.

The end result was the K2 mission, that will fill in the gaps between the original Kepler mission and the future launches of both the Transiting Exoplanet Survey Satellite and the James Webb Space Telecope with its four, 83-day observing campaigns.


Illustration to show how pressure from sunlight can be used to help re-stabilise the Kepler spacecraft. Image credit: NASA Ames/W. Stenzel

HIP 116454b was discovered using the 'transit' method, where the presence of an exoplanet is inferred by detecting a dip in the brightness of its parent star as it passes in front of it, temporarily blocking some of the sunlight.

However, due to the sensitivity of such observations, it is imperative that the spacecraft or telescope be extremely steady so as not to create a false 'wobble' that may end up with the results being misinterpreted. Without the newly stable K2 mission, HIP 116454b would most likely have remained undiscovered for a few more years.