ExoplanetDiscoveries-Histogram-20140226By now every single one of you should know what the Kepler is and what it has accomplished over the last five years. For the ones that do not, here is a quick rundown on a very important space observatory, which actually maintains an orbit around the sun. The most important measurement device in the Kepler is the photometer. This instrument continuously measures the amount of light from a target star, when a planet passes in front of the star it cause a shift in brightness of the star which is picked up by the photometer on Kepler. This information is then sent down to Earth so that scientists can analyze the data and determine first if the anomaly was caused by a planet, and second, figure out the orbital distant from the host star as well as the size of the planet.

The Kepler was launched in 2009 with a three year mission, which turned into five, to find extrasolar planets, specifically Earth like planets in the “Goldilocks zone”. Just this past April it was announced that Kepler-186f was discovered. This is the first planet discovered that is nearly the size of Earth and in the habitable zone in orbit around a red dwarf. In all Kepler has confirmed almost 1000 exoplanets in 76 stellar systems, but there are also almost 3,000 unconfirmed planets as well. Astronomers have surmised from the Kepler date that there could be up to 40 billion Earth-sized planets that maintain an orbit in the habitable zone of their host star. It is estimated that up to 11 billion of these planets orbit sun-like stars, with the closest being only 12 light-years from Earth. Maybe that’s where the Tribbles live.

Unfortunately, there a four devices in the Kepler that are called reaction wheels, in a spacecraft these wheels are used for attitude control without using any sort of fuel based rocket since they are electrically driven. Basically the reaction wheels are what allow the Kepler to focus on a certain part of space and remain stable enough to measure the shift in light from a target star. Well, in July of 2012 one of these wheels failed, and then in May of 2013 a second wheel failed. Testing of failed wheels was carried out, and it was determined by August of 2013 that the Kepler could no longer carry out its primary mission because it needs at least three reaction wheels to stay stable and aim at targets. It looked as if Kepler was done, but scientists do not rest on their laurels!

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A new mission has been proposed for the aging Kepler craft, called Second Light, or K2. The craft is going to be repurposed to search out and study supernova explosions, star formation, comets, asteroids and even more exoplanets. The crazy thing is how they are going to do it.  They are going to stabilize the craft with the remaining wheels, and also use photons from the sun. Yup, they are going to balance a spacecraft with photons from the sun, let that set in. Photons exert pressure when they strike an object in space so in turn you can balance an object with equal opposite force. With this new program Kepler will have 83 days to study target areas of the sky, it will have 4.5 viewing periods per year. This mission proposal was approved on May 16, 2014. So here we are, new life for one of the greatest scientific instruments that Humanity has put into space. Next time you look up in the sky try to understand that we have a scientific instrument out there that is being held up by the sun, sort of changes things.

image source: [Delta II] [Exoplanets] [Second Light]