Issue 14 - October 2014

The Kepler-K2 (K2) mission is an amazing story of perseverance and engineering ingenuity in the face of seemingly insurmountable obstacles. It is aptly named after the second highest mountain on Earth, which is generally considered harder to climb than Mount Everest.

Looking back, it is hard to believe that only a little more than a year has passed since we were faced with the fact that a second reaction wheel had stopped working on Kepler, no longer allowing us to control the fine attitude of the spacecraft. The science data collection for the hugely successful Kepler mission had come to a sudden end. Today the K2 mission has completed its first science campaign, not only continuing the search for exoplanets, but contributing to a large variety of astrophysics topics.

When the idea was floated to continue a different mission with the remaining two reaction wheels, my initial reaction was: “We will never be able to make this work and if we can, we won’t be able to afford it.” But fortunately, the Kepler team proved me wrong.

The spacecraft had to relearn all of its basic functions. Procedures and software that normally take years to develop on the ground before launch had to be redone in only a few months, while at the same time keeping the damaged spacecraft healthy and safe. How do we move without spending too much fuel? Can we point accurately and remain stable enough to communicate to the ground? Can we save the spacecraft when it is in trouble while avoiding pointing at the Sun? We can’t hear the spacecraft in its science attitude, how can we make it work autonomously for several months without being able to intervene? The list went on and on and the clock was ticking, as every day without optimized pointing we were losing precious fuel we would need to execute the new mission.

The engineers at NASA’s Ames Research Center and Ball Aerospace kept at it, solving one problem after another to get the spacecraft to balance the solar pressure on the ridge of its sunshield, compensating for the seasonal variations as Kepler revolves along its orbit around the Sun.

At the same time, the science community responded with overwhelming support through a flurry of white papers making the all-important science case to continue the mission, and NASA Headquarters gave the team the opportunity to submit K2 mission through the Senior Review process which in April recommended continuation of K2 for two years (through the end of FY16).