Russia’s Proton rocket took off on its first launch of the year Sunday with a commercial satellite to expand Inmarsat’s next-generation mobile communications network. Liftoff occurred at 1231 GMT (7:31 a.m. EST), and it took more than 15 hours to place the Inmarsat spacecraft in the correct orbit.

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.

The first official launch weather outlook issued Tuesday by U.S. Air Force meteorologists predicts an 80 percent chance of favorable conditions for the predawn liftoff Saturday of SpaceX’s Crew Dragon spacecraft on a test flight to the International Space Station.