Northrop Grumman’s NG-21 Cygnus resupply spacecraft is set to launch atop a SpaceX Falcon 9 rocket from Florida. Aboard will be several thousand kilograms of cargo bound for the International Space Station’s Expedition 71 crew.

Cygnus spacecraft have historically launched atop Antares rockets, the first stage of which is manufactured in Ukraine. Because of Russia’s unprovoked war in that country, Northrop Grumman is no longer able to procure this hardware.

Northrop Grumman is working with U.S.-based Firefly Aerospace to design and build a new first stage to form the Antares 330 rocket. However, its isn’t expected to be available until at least mid-2025.

Until then, Northrop Grumman has contracted SpaceX to launch at least three Cygnus spacecraft until Antares 330 is available.

A similar situation occurred between 2014 and 2017 when an Atlas V rocket was utilized for several missions following the Oct. 28, 2014, failure of an Antares rocket.