Comment on Open Source development at NASA

A comment on: http://open.nasa.gov/blog/2011/09/08/open-source-development-at-nasa/

I am all for OpenData and Open.NASA. But how does NASA being a government entity relate to how it “licenses” it’s data and software? What I mean is that, shouldn’t the things being “open sourced” be public domain, rather than licensed content? I agree that creating a license which is not widely recognized is not useful, that is the whole point behind Creative Commons. But are there cases where NASA is “over licensing” content that it shouldn’t because it is the content should be released into the public domain? Reference CC Salon in Jan 2011, Time segment 1:05:00 where Joi Ito talks about the issue. http://blip.tv/creative-commons/creative-commons-salon-mountain-view-what-does-it-mean-to-be-open-in-a-data-driven-world-4725230

What prevents, or what reasons are there for not putting NASA’s data and software, which it releases, in the public domain? Is that not more open?