Material Systems Directorate Material Support Date Mini Secure Digital most significant digit Microgravity Science Division Microsoft System Diagnostics Maintenance Support Device Management Systems Division Materials Sciences Division MARS Supplemental Data Mass Selective Detector MASUDA Matrix Spike Duplication mean square displacement minimum safe distance Ministry of Social Development Mission Support Directorate Macromolecular Structure Database Manual Simulations Division Marble spleen disease marginal support date Marine Safety Detachment Mass Storage Device Master of Science in Dentistry Master Scuba Diver Master Slave Determination Materials Science Division Mean Solar Distance Medium Speed Data membrane-spanning domain