A SpaceX Falcon 9 rocket, with the company’s Dragon spacecraft atop, stands in a vertical position at Launch Complex 39A at NASA’s Kennedy Space Center in Florida on Monday, April 21, in preparation for the 32nd commercial resupply services launch to the International Space Station. Dragon is delivering a variety of science experiments, including a demonstration of refined maneuvers for free-floating robots. Dragon also carries an enhanced air quality monitoring system that could protect crew members on exploration missions to the Moon and Mars, and two atomic clocks to examine fundamental physics concepts such as relativity and test worldwide synchronization of precision timepieces.