Grains and Craters (IMAGE) American Physical Society Caption Low-packed projectiles produce simple shallow craters with a thin layer of the projectile material covering it. High packed ones produce deeper craters and central peaks surrounded by the sprayed material. Credit F. Pacheco-Vazquez and J.C. Ruiz-Suarez Usage Restrictions None 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.