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]
from http://interstellarexplorer.jhuapl.edu/mission/previous_approaches.html
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Captions
A NASA/JPL illustration of the TAU spacecraft using nuclear electric propulsion from a fission reactor and 40,000 kg of xenon for propellant to reach 1000 AU in 50 years.