Photos: Atlas 5 rocket aims for International Space Station

The sixth and final satellite in the U.S. military’s network of ultra-secure, nuclear-hardened AEHF communications relay stations has arrived in Florida for final preparations for liftoff in March on a United Launch Alliance Atlas 5 rocket, the first of nearly 20 U.S. Space Force missions planned for launch in the first year of operations for the new military service.

A hundred days after the last U.S. commercial resupply of the International Space Station by a Cygnus cargo ship launched atop an Atlas 5 rocket, the booster and freighter duo will do it again Tuesday.

Eight miniature weather observatories, each the size of a piece of carry-on luggage, were installed on a specially-designed deployer module and mounted on the front end of an air-launched Pegasus XL rocket to prepare for Monday’s flight into orbit.