The NASA website hosts a large number of images from the Soviet/Russian space agency, and other non-American space agencies. These are not necessarily in the public domain.
The SOHO (ESA & NASA) joint project implies that all materials created by its probe are copyrighted and require permission for commercial non-educational use. [2]
Uploaded a work by Kent Chojnacki, Manager, Systems Engineering & Integration (SE&I) Office (NASA employee) from https://ntrs.nasa.gov/api/citations/20220003725/downloads/22%203%207%20Kent%20IEEE%20paper.pdf with UploadWizard