NASA images which appear on the internet are mostly not copyrighted, which means that you can usually use them for non-commercial purposes without permission. You can link NASA material to your own website, use it for educational purposes etc, and this includes text, audio, visual material etc.
If you use the material for commercial purposes you must not suggest in any way that your product etc has the endorsement of NASA or that they are in any way behind your advertising campaign. Using any image that shows an actual person without permission could also be illegal, as it could be against that person's right to privacy.
You may not the NASA logo or other official symbols under any circumstances unless you have specific permission to do so from NASA.
If you have any doubts about what you can use, you should contact NASA directly or read their official guidelines, given here.