There shall be no infringement of Copyright for:

1. Publication, Distribution, Communication, and/or Reproduction of State emblems and national anthem in accordance with their original nature;
2. Any Publication, Distribution, Communication, and/or Reproduction executed by or on behalf of the government, unless stated to be protected by laws and regulations, a statement to such Works, or when Publication, Distribution, Communication, and/or Reproduction to such Works are made;
...
5. Reproduction, Publication, and/or Distribution of Portraits of the President, Vice President, former Presidents, former Vice Presidents, National Heroes, heads of State institutions, heads of ministries/nonministerial government agencies, and/or the heads of regions by taking into account the dignity and appropriateness in accordance with the provisions of laws and regulations.

• Use of NASA logos, insignia and emblems is restricted per U.S. law 14 CFR 1221.
• 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.
• Materials based on Hubble Space Telescope data may be copyrighted if they are not explicitly produced by the STScI.[1] See also {{PD-Hubble}} and {{Cc-Hubble}}.
• 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]
• Images featured on the Astronomy Picture of the Day (APOD) web site may be copyrighted. [3]
• The National Space Science Data Center (NSSDC) site has been known to host copyrighted content. Its photo gallery FAQ states that all of the images in the photo gallery are in the public domain "Unless otherwise noted."