Snapshots from Atlas 5 launch

After a year-long delay to troubleshoot recurring erroneous data signatures from the rudder of Northrop Grumman’s air-launched Pegasus XL rocket, NASA is eager to send a $252 million research satellite into orbit as soon as Thursday night off Florida’s east coast on a mission to probe the ionosphere, a region near the boundary between Earth’s atmosphere and space.

Track the progress of the Soyuz TMA-19M spacecraft and its three-man crew through Tuesday’s countdown, launch and docking with the International Space Station.

A United Launch Alliance Delta 2 rocket fired away from a California military base and disappeared into an overcast cloud deck Saturday on its final flight, carrying a NASA research satellite into orbit and closing the book on a nearly 30-year legacy of launches.