Q&A with Keith Gendreau, principal investigator of the first X-ray space communications experiment (members only)

Russia’s next Progress cargo freighter rolled out to its launch pad in Kazakhstan on Tuesday in a final move before blasting off Thursday at the tip of a Soyuz rocket to resupply and refuel the International Space Station.

Ready for blastoff just after sunset Wednesday with a classified payload for the U.S. government’s spy satellite agency, a United Launch Alliance Atlas 5 rocket rolled out to its launch pad at Cape Canaveral late Tuesday afternoon after an unplanned trip back inside its integration building for repairs.

The two missions will be launched within roughly three weeks of one another from New Zealand. Liftoff of the Electron rocket with the PREFIRE-1 satellite occurred at 7:41 p.m. NZST (3:41 a.m. EDT, 0741 UTC) on Saturday.