The Kepler Mission was designed to take a census of Earth-like planets in the galaxy. No such planet is known yet, but if it was discovered, it would be an excellent candidate in the search for life (as we know it). The confirmation of one will undoubtedly come with much excitement.
Kepler focuses on one region of sky, viewing fields again and again, looking for subtle changes in the light output of stars. Stars may vary in brightness intrinsically, or may have companion stars. "Starspots," like sunspots on other stars, may vary the light just a bit as well. So, not every candidate will be a planet.
Although the goal of Kepler is to find Earth-like planets, many other types of worlds will be found along the way. Follow-up work for all of these candidates will involved many hours of ground-based telescope work and plenty of human power to sort through the data.
The controversy comes with how the data are being released to the astronomical community, as reported on in the New York Times today. The 43-day data set contains 750 planet candidates, 350 if which will be released to the astronomical community. This is necessary to deal with the sheer number of discoveries. This is a good thing for astronomers everywhere, right?
The 400 candidates are being withheld by the Kepler team so that they can do follow-up work and publish their results. This is generally considered a fair system where the principal investigators have the data for a set amount of time before having to make it public.
In the "publish or perish" environment of academia, it is necessary to ensure that you have the publications to back up your work. And when you work on designing, building, and prepping for a space mission, well, you may not be publishing as much. This is why NASA missions often hold the data secret for a year. The ground-based National Radio Astronomy Observatory holds data proprietary for a year as well, and the National Optical Astronomy Observatory for 18 months.
Proprietary periods are nothing new, and provide a balance that helps observers out while preserving the openness of science in the long run. The complaints from the community stem from an extension of the proprietary period for the Kepler team that was granted in April. All of the data were set to be released this month, but the extension is until February 2011.
Today's partial release has re-ignited the debate. Some critics claim that the Kepler team is being too conservative.
To be fair, however, with all the data rolling in, is it not best to be conservative and limit the number of "false positives" that creep out? Also, in announcing the presence of an Earth-like planet to much fanfare, you probably want to be darn sure of what the data sets are telling you.
More eyes on the data could be a good thing for the search as a whole, but I think that NASA still has to be concerned for the careers of the scientists, and presumably students, working with these proprietary data.
Knowing a little bit myself of what it is like to work with a budding instrument from scratch, it would be disheartening to not have enough time to publish results before someone else got to work with the data. So, maybe that's why I have sympathy for the Kepler team.
Science is an open process and requires a vibrant community. For that, I am glad that the extension to 2013 that was originally requested was not granted. But, given the sheer number of candidates that Kepler has racked up in just 43 days, I can't blame the mission scientists for wanting, and getting, a little bit more time to get their science right.
And, hopefully, when that exo-Earth is discovered, we'll remember that the search and discovery was a large community effort, no matter who gets the first-author spot.