Neat, but why does Nasa have, or need a Tumblr? Why do I have to go there, when I'm already going to nasa.gov?
Tumblr seems less frictionless.
I understand why they use YouTube for video hosting (video hosting is difficult and expensive) and have a prescence on social media (to reach a wider audience), but yeah, Tumblr is a bit strange.
NASA's online prescence is a bit fragmented in the first place, their different facilities have their own websites, social media accounts, etc.