There are several sources for media produced by governmental entities. Some of the content may be public domain and available for reuse. Always check the source for how to use and credit materials.
a long-term archive of digital data products returned from NASA's planetary missions, and from other kinds of flight and ground-based data acquisitions, including laboratory experiments.
"Search over 14.0 million records of museum objects, archives and library materials including more than 3.0 million online images, audio & videos and blog posts."