Ina Structure (IMAGE) Brown University Caption Apollo images of D-shaped Ina structure, where gas releases may have exposed fresh surfaces. Main image shows very few craters within the depression. Low-angle illumination (inset) reveals sharp features with little weathering. Credit NASA Usage Restrictions NASA still images, audio files and video generally are not copyrighted. You may use NASA imagery, video and audio material for educational or informational purposes, including photo collections, textbooks, public exhibits and Internet Web pages. This general permission extends to personal Web pages. This general permission does not extend to use of the NASA insignia logo (the blue License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.