guilty), someone has to go and tell us when the first genuinely Earth-like planet will be discovered. Doing anything in early May 2011? Block out your diary.
Arbesman and Laughlin posted a few days back a rather provocative paper that includes the word 'Scientometric' in the title. [I had to look this up, since I first assumed this was lifted from an episode of the Simpsons. Apparently it's the science of measuring and analyzing science, well, there you are. Much is to do with the impact particular scientific works have on a field]. The paper, to be fair, employs some reasonable statistical methods to try to see what the trend line is for the rate of exoplanet discovery versus planetary properties. In this case the authors devise a metric for planetary habitability based - albeit in a fairly sophisticated way - on planet mass and distance from parent star, and then employ a favorite statistical trick called 'boot-strapping'. Bootstrapping is one of those methods that you resort to when you really have a limited idea of what it is that your sample is actually sampling - and when there is noisy data.
The results of their analysis suggest that early next year (the month of May) we might expect Doppler searches for exoplanets to turn up something in the Earth-mass range and in the liquid-water orbital zone around a star. Transit searches don't fare so well, with no convergence on a date, tough luck Kepler - although the reason is that there just aren't enough transiting planets yet discovered in the right orbital range to allow for a meaningful prediction. It's an admirably immodest prediction. They even refer to the so-called Hawthorne Effect - whereby their publicizing this result may in fact influence the race to achieve what they predict - although they suggest that astronomers will be too busy struggling with the challenges of the task to care much.
What I think is most interesting is not this result itself (if they're right they get to brag, if they're wrong no-one will really care), but that these - genuinely smart - guys went to the effort. That alone I think suggests that the scientific community is sensing convergence on the quarry. The caveat to all this is, at the risk of sounding pessimistic, that planets meeting this particular habitability metric could still be dry, barren, atmosphere-less rocks. Finding such worlds would indeed suggest that several boxes can be checked in the search for Earth-2, but it's not the end of the story.