U.S. spacewalk 94 was slated to have NASA astronauts Mike Fincke and Zena Cardman perform a variety of operations around the orbiting outpost during the roughly 6.5-hour-long event. A new date for the spacewalk hasn’t been announced.

Physicists are gearing up to send a re-engineered science instrument originally designed for lofty balloon flights high in Earth’s atmosphere to the International Space Station next week to broaden their knowledge of cosmic rays, subatomic particles traveling on intergalactic routes that could hold the key to unlocking mysteries about supernovas, black holes, pulsars and dark matter.

While a SpaceX Dragon cargo ship closed in on the International Space Station early Sunday, a Russian Soyuz spacecraft blasted off from frigid Kazakhstan, boosting a fresh three-man crew into orbit for a two-day flight to the lab complex.