First off, such a small mistake that I don't think most people mind, so no point in making a comment about it.
Secondly, HN automatically does that with titles. If you put NASA when you submit, HN will correct it to Nasa. Then you can change it back to NASA if you edit the title.
Thirdly, The Oxford Dictionary of Abbreviations lists NASA as "NASA (or Nasa)" so seems correct at least somewhere in the world, but probably not in the US.
