More exoplanet news: The problems of Kepler.

The article outlines the status — both good and bad — of Kepler in its hunt for Earthlike exoplanets.

I have already reported on Kepler’s failed reaction wheel. It no longer has a backup and needs every reaction wheel it has to keep it pointed in so precise a manner. Thus, the loss of one more wheel will shut the telescope down.

However, I had not been aware that the scientists now need more than twice as much time, eight years instead of three, to do their work, because they have discovered that sunlike stars are far more variable than expected. To quote the article,

Despite the best estimates of scientists before Kepler’s launch, most of the sun-like stars in Kepler’s field-of-view show more variability than projected.

This larger variability means the scientists need more time to separate the fluctuations caused by exoplanets from the fluctuations caused by each star’s brightness changes.

This discovery, however, has a greater significance, totally separate from the search for exoplanets. While almost all the publicity surrounded Kepler has focused on its effort to find planets, one of its most important research goals has been the study of the stars themselves. With Kepler looking with great precision at a large number of G-type stars over several years, it was expected we would get a really good statistical idea about the variability and stability of those stars.

Prior to Kepler the data has suggested that our Sun was unusually constant for a G-type star. Kepler appears to be confirming this data.

What this means is that our Sun, which scientists have found to be a remarkably steady star with very little fluctuations in brightness over time, is that it is either a very unusual G-type star, or it happens in recent history to be going through an unusually calm period.

If the Sun is unusual, that suggests that it will be harder to find exoplanets and solar systems like our own where life could exist and evolve. The Sun’s steadiness has been one of the factors that made life possible here on Earth. If most G-type stars are not so steady, then the development of life on planets orbiting those stars is going to be far more difficult. In fact, it very well might not happen.

If instead the data suggests that the Sun is going through an unusual steady period, this would mean that it might in the future become far more variable than it is. If this happens it will not be good for life here on Earth. Such variability will make the fears of global warming from carbon dioxide feel like pinpricks to an elephant.