On January 25, the U.S. Air Force (USAF) certified the latest version of the Space Exploration Technologies Corp. (SpaceX) Falcon 9 launch vehicle, known as Falcon 9 Upgrade, for use in National Security Space (NSS) missions. Falcon 9 Upgrade features increased thrust, an improved stage separation system and a stretched upper stage that can hold more propellant. The USAF certified the earlier version of the Falcon 9 in May 2015 after a nearly two-year process. The only other launch services provider certified for NSS missions is United Launch Alliance