Videos: Replays from successful Atlas 5 launch of TDRS-M

A refrigerator-sized satellite soared into orbit aboard an air-launched Northrop Grumman Pegasus XL rocket Thursday night over the Atlantic Ocean, finally setting off on a $252 million mission to probe the dynamic boundary region where space and Earth’s atmosphere meet.

The fourth and last spacecraft in BlackSky’s initial flock of commercial Earth-imaging microsatellites successfully launched Monday aboard a Rocket Lab Electron rocket with three other payloads, setting the stage for the final assembly and launch of at least 20 more BlackSky orbiting surveillance platforms starting later this year.

Russian commander Sergey Prokopyev, German flight engineer Alexander Gerst, and NASA astronaut Serena Auñón-Chancellor closed out a nearly 197-day space mission with a landing in Kazakhstan aboard their Soyuz MS-09 crew carry ship at 0502 GMT (12:02 a.m. EST) Thursday. The Soyuz crew undocked from the International Space Station at 0140 GMT (8:40 p.m. EST Wednesday) to begin their return to Earth.