Apollo Command Module, Conceptually Depicted (image) American Institute of Physics Share Print E-Mail Caption As spacecraft, like the Apollo Command Module depicted in this artist's concept, enter the atmosphere, a plasma sheath engulfs them that can cut off communication signals with the ground. Credit NASA Usage Restrictions This image may be used only with appropriate credit. Share Print E-Mail 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.