Kepler telescope

I don't have a wife or kids but I do have a brother, Peter M. Shearer . He contributes the following:

Let’s hope that tomorrow’s planned launch of NASA’s Kepler Telescope to search for Earth-sized planets is more successful than the crash of their CO2 sensing satellite last month. The Kepler mission will continuously monitor the brightness of over 100,000 stars to detect subtle dimming events caused by transiting planets. Given the small size of many planets and their likely orbits, such events will be rare (don’t miss the 2012 transit of Venus---this won’t happen again until 2117), but if all stars have Earth-like planets, Kepler should detect about 500 of them.

One thing I’ve noticed is that most people seem to want there to be other Earths out there. For example, from the March 2 NYT article on the Kepler mission:

When a reporter departed from journalistic objectivity to venture a hope that other Earths are out there, Dr. Fanson happily joined in. “I hope the answer is yes,” he said. “I hope the universe is teeming with planets like Earth.”

It’s exciting to think about other Earths. But is it rational to hope they exist? To be truly Earth-like and potentially habitable they would need to have oxygen-rich atmospheres, which implies that they already have life. The record of what happens when isolated biospheres come into contact with each other is not a happy one for at least one of the two life systems. But the public and many scientists seem to yearn to find life on other planets, and are disappointed when experiments fail to detect it, as in the classic Onion headline “Mean Scientists Dash Hope of Life On Mars.”