Image Credit: NASA;
This work is in the public domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the US Code.
Generally speaking, works created by U.S. Government employees are not eligible for copyright protection in the United States. See Circular 1 "COPYRIGHT BASICS" from the U.S. Copyright Office.
NASA still images, audio files and video generally are not copyrighted. You may use NASA imagery, video and audio material for educational or informational purposes, including photo collections, textbooks, public exhibits and Internet Web pages. This general permission extends to personal Web pages.
If the NASA material is to be used for commercial purposes, especially including advertisements, it must not explicitly or implicitly convey NASA's endorsement of commercial goods or services. If a NASA image includes an identifiable person, using the image for commercial purposes may infringe that person's right of privacy or publicity..