The Official NASA App for Android
If you are a space buff, a future astronaut, or just love images from or about space, this is a must-have app. It's free, of course (not counting tax dollars that you may have already paid), and the app's main menu lists Missions, Images, Videos, Tweets, TV& Radio, News & Features, Centers, Featured, and Programs.
Most of those should be self-explanatory, but Centers takes you to a (Google) world map that well help you locate the NASA centers and also show your own current location. This can be handy if you are trying to visit one of the NASA Centers, for example.
Featured will take to to a list offering a curated view of articles pertaining to current missions. It would be easy to lose yourself for hours, admiring the graphics and reading the text here.
The Official NASA App is free.
Definitely a five-star experience.