Two Expedition 36 astronauts will venture outside the International Space Station Tuesday (July 9) on the first of two spacewalks this month to prepare the orbiting complex for a new Russian module and perform additional installations on the station's backbone.
Flight Engineers Chris Cassidy of NASA and Luca Parmitano of the European Space Agency are slated to begin the 6.5-hour spacewalk from the Quest airlock at 7:10 a.m. CDT (1210 GMT).
After the spacewalkers exit the hatch, Cassidy will move to the top of the Z1 truss to remove and replace a Space-to-Ground Transmitter Receiver Controller. This unit, one of two that allows for independent strings of Ku-band communication for video and data, failed last year.
In parallel to this, Parmitano will head out to the Express Logistics Carrier-2 (ELC-2) on the starboard truss and retrieve two experiments that were part of Materials International Space Station Experiment-8, or MISSE-8.
The Optical Reflector Materials Experiment III (ORMatE-III) and the Payload Experiment Container, which assessed the impacts of the space environment on materials and processor elements, are slated to return to Earth aboard the SpaceX-3 commercial cargo craft later this year.
While he's out on the on the starboard truss, Parmitano will also photograph the Alpha Magnetic Spectrometer-02 (AMS-02) to provide the research team a visual assessment of the condition of this state-of-the-art particle physics detector.
The two spacewalkers will team back up to remove two Radiator Grapple Bars (RGBs) and install one on the port side truss and the other on the starboard side so they will be more strategically located.
The RGBs, which are intended to aid in the removal and replacement of failed thermal radiators, were delivered to the station aboard SpaceX-2. While riding at the end of the station's Canadarm2 robotic arm under the control of flight engineer Karen Nyberg, Parmitano will transport the RGBs to the worksites where Cassidy will bolt them down.
As Parmitano rides the arm back from the starboard side to port, he will use this opportunity to remove a failed camera assembly. The Mobile Base Camera Light Pan-Tilt Assembly, which failed back in May 2012 just before the arrival of the Japanese H-II Transfer Vehicle, was one of the prime viewing systems for monitoring visiting vehicles.
Mission managers plan to bring the assembly back to Earth for refurbishment and return it to the station later as a valid spare.
While Parmitano removes the camera assembly, Cassidy will route power cables to support the addition of the new Russian Multipurpose Laboratory Module (MLM) scheduled to arrive at the station later this year. Cassidy will route cables from the Unity node to the interface between the Pressurized Mating Adapter-1 and the Zarya module. The station cosmonauts will complete that set up during a future spacewalk.
The new module, known as Nauka, will serve as a research facility, docking port and airlock for future Russian spacewalks and will replace the Pirs docking compartment.
With those tasks complete and the RGBs installed, Cassidy will begin the installation of two Z1 truss Y-bypass jumpers to provide power redundancy and stability for critical station components. The bypass jumper installation will be completed during the July 16 spacewalk.
In conjunction with some cable reconfigurations completed earlier this year inside Unity, the two Y-bypass jumpers will allow the station team to quickly regain critical loads in the event of a loss of one of the external power modules without the need to commit to a spacewalk.
The two spacewalkers will round out their excursion installing a multi-layer insulation cover to protect the docking interface of Pressurized Mating Adapter-2 mounted to the Harmony module.
Cassidy, who is designated EV1 for the spacewalk, will wear a U.S. extravehicular mobility suit bearing red stripes. This spacewalk will be the fifth of Cassidy's career.
Parmitano, designated EV2, will wear a spacesuit with no stripes and will be making the first spacewalk of his career. He will become the first Italian astronaut to walk in space.
Astronaut Shane Kimbrough at the Mission Control Center in Houston will provide ground support for the spacewalkers.