I can't verify what contract the employee signed with NASA. If they retain rights to use the work abroad (we don't know) they potentially could sue you. Again,

I can't verify what contract the employee signed with NASA. If they retain rights to use the work abroad (we don't know) they potentially could sue you. Again, the risk is minimal but it's present. I can't name you a specific case, only that if it ever gets to court a user of such an image in Germany never rightfully acquired a license and will therefore loose.