Artist's concept of possible exploration of the surface of Mars (2005) chromolithograph art by NASA. Original public domain… https://www.rawpixel.com/image/11551191/image-background-face-personFree Image from public domain licenseArtist's concept of possible exploration of the surface of Mars (2005) chromolithograph art by NASA. Original public domain… https://www.rawpixel.com/image/11493516/image-background-face-personFree Image from public domain licenseRussian Search and Rescue helicopter that was grounded by low visibility at the Arkalyk Airport in Kazakhstan. Original from… https://www.rawpixel.com/image/418587/military-helicopterFree Image from public domain licenseRussian Search and Rescue helicopter that was grounded by low visibility at the Arkalyk Airport in Kazakhstan. Original from… https://www.rawpixel.com/image/418584/free-photo-image-rotor-engine-helicopter-pilot-nasaFree Image from public domain licenseA wounded U.S. Marine is carried across the small flight deck of the hospital ship USS Repose (AH-16) after being… https://www.rawpixel.com/image/9654923/photo-image-face-person-medicineFree Image from public domain licenseCasualties are received by helicopter on board the Navy hospital ship USS Repose (AH-16) minutes away from a Vietnam combat… https://www.rawpixel.com/image/9654925/image-face-person-medicineFree Image from public domain licenseMartin, South Dakota. The largest town within fifty-mile radius. Sourced from the Library of Congress. https://www.rawpixel.com/image/12283083/photo-image-cloud-person-skyFree Image from public domain license[Untitled photo, possibly related to: Aerial tramway leaving from mine in distance to the mill. Because of the… https://www.rawpixel.com/image/12149109/image-plant-art-skyFree Image from public domain license