Astronauts Reid Wiseman of NASA and Alexander Gerst of the European Space Agency will work outside the International Space Station for about 6-1/2 hours Tuesday. The spacewalkers will relocate a failed pump module and install gear that provides back up power to external robotics equipment.

The duo reviewed their timeline and prepared the Quest airlock where they will stage the spacewalk scheduled for 8:10 a.m. EDT. They also checked out their SAFER (Simplified Aid for EVA Rescue) jetpacks that would allow a spacewalker to propel back to the station in the unlikely event of a separation from the vehicle.

Flight Engineer Barry Wilmore of NASA assisted Wiseman and Gerst during the afternoon and trained for his role as the robotic arm operator. He will be the spacewalk coordinator and operate the Canadarm2 in support of maneuvering Gerst during the course of the spacewalk.

Wilmore will join Wiseman for an Oct. 15 spacewalk. Gerst will switch roles and be the coordinator and robotic arm operator. The spacewalkers will replace a failed voltage regulator and move external camera equipment.

Meanwhile, medical work, science and maintenance are always ongoing aboard the orbital laboratory as it operates 24 hours a day, seven days a week.

Gerst started his day in the Japanese Kibo laboratory checking the water quality in the Aquatic Habitat that is currently housing Zebrafish.

They are part of an experiment that observes muscle atrophy in microgravity and why it occurs. Results from the study could lead to new treatments for weakened muscles and countermeasures to maintain astronaut health during long duration space missions.

Gerst and Wiseman then partnered up for standard health checks before a spacewalk. The duo checked each other's ears, blood pressure and temperature. Wilmore processed blood, urine and saliva samples then stored them in a science freezer during the morning.

The station's newest cosmonauts, Alexander Samokutyaev and Elena Serova, each had an hour for an orientation session. The pair familiarized themselves with various station systems and operations including safety procedures.

At the beginning of the day, Samokutyaev joined Commander Max Suraev for a review of an upcoming Russian spacewalk. They will exit the Pirs docking compartment Oct. 22 to jettison obsolete hardware and photograph the exterior of the station's Russian segment.

During the afternoon, Samokutyaev and Suraev were inside the Zarya cargo module installing overlay sheets on interior panels. The commander wrapped up his workday updating the inventory management system and stowing items for disposal inside the ISS Progress 56 resupply vehicle.

Serova worked on science throughout her work day. She first mixed samples in a bioreactor for the Cascade cell cultivation experiment. Next she downloaded dosimeter readings then prepared the dosimeters for Tuesday's spacewalk.

Finally, she charged batteries, mounted hardware and conducted observations for the Relaxation experiment. That study observes chemical reactions due to jet exhaust and body reentries in the Earth's upper atmosphere.