A pair of cosmonauts suited up for a dry run of Wednesday's spacewalk while Dragon will hang on to the International Space Station for a few more days.

Commander Max Suraev and Flight Engineer Alexander Samokutyaev spent Monday readying the Russian Orlan spacesuits they will wear when they exit the Pirs docking compartment Wednesday for a six-hour spacewalk. The duo donned their spacesuits for a spacewalk dry run. They checked suit controls and communications gear and conducted preliminary leak checks.

They are scheduled to open the Pirs docking compartment hatch to the vacuum of space at 9:24 a.m. EDT to begin the third spacewalk for Expedition 41.

The spacewalkers will be outside the station's Russian segment to jettison science and communications gear no longer being used. They will also remove a protective cover from a biological exposure experiment, collect samples of particulate matter on the Pirs docking compartment and photograph the station's Russian exterior.

The departure of SpaceX CRS-4 has been delayed until Saturday. Dragon's release for a Pacific Ocean splashdown had been scheduled for Tuesday. However, mission officials determined high sea states caused by storms in the splashdown zone exceeded recovery rules.

The crew spent part of the weekend loading non-critical items into Dragon which is berthed to the Earth-facing port of the Harmony node. With Dragon hatch closure now set for the end of the week, NASA astronauts Reid Wiseman and Barry Wilmore along with European Space Agency astronaut Alexander Gerst took Monday off.

The first female cosmonaut to live and work aboard the station, Elena Serova, spent Monday on a variety of science and maintenance tasks. She activated gear for the Cascade biological experiment which investigates cell cultivation. Serova also cleaned fan grilles, changed dust filters and updated the inventory management system.

Meanwhile, another commercial space freighter is waiting to take the place of SpaceX CRS-4 at the Harmony node. Orbital Sciences is preparing its Antares rocket at Wallops Flight Facility in Virginia for the Cygnus cargo vehicle's third resupply flight. It is currently targeted for launch no earlier than Oct. 27.