X2 Vintage Low Palette Sci-fi Book Covers, Artists unknown, although they could be the same person as the drawing styles are close, I’m guessing these are from the 50′s or early 60′s. The lower image has a resemblance to the Imperial costumes from StarWars, most specifically a similarity with those worn by the gunner crews on the Death Star.
Images sourced via http://www.coverbrowser.com great resource, shame about the over eager Jpg compression !