Video: Russian cargo ship spinning

After four years of brainstorming, custom tool development and training, two astronauts plan to venture outside the International Space Station Friday for the first of four spacewalks to repair a $2 billion cosmic ray detector. The excursions are considered the most challenging since work to service the Hubble Space Telescope.

A Russian cosmonaut, a NASA astronaut and an Italian wrapping up her first space flight boarded a Russian Soyuz ferry craft early Thursday, undocked from the International Space Station and plunged back to Earth, landing safely on the steppe of Kazakhstan to close out an extended 200-day mission.

Astronaut Shane Kimbrough and his two Russian crewmates — Soyuz MS-02 commander Sergey Ryzhikov and flight engineer Andrey Borisenko — undocked from the International Space Station and plunged back to Earth Monday, landing on the steppe of Kazakhstan to close out an extended 173-day mission.