"USGS-authored or produced data and information are considered to be in the U.S. public domain." The satellite imagery is fair game guys the images on the site arnt but the satellites are. We just need to credit them
"When using information from USGS information products, publications, or Web sites, we ask that proper credit be given. Credit can be provided by including a citation such as the following:
Credit: U.S. Geological Survey
Department of the Interior/USGS
U.S. Geological Survey/photo by Jane Doe (if the photographer/artist is known)"
heres the link https://www2.usgs.gov/laws/info_policies.html