Live coverage: SpaceX supply ship returns to Earth

The Centaur upper stage launching the Cygnus space freighter Tuesday persevered through a velocity shortfall from the first stage of the Atlas 5 rocket, improvising with a longer firing to reach the correct orbit.

Elon Musk’s space transport company — chartered with a long-term goal of colonizing Mars — plans to send the first commercial mission to the red planet as soon as 2018, SpaceX announced Wednesday.

Now in the home stretch of a complex, multi-year upgrade, two space station astronauts floated outside the lab complex Thursday and pressed ahead with the third of four spacewalks the current crew is carrying out to complete the replacement of aging batteries in the station’s solar power system.