The flight is dubbed the NROL-37 mission, the purpose of which remains classified since it "supports national security." Despite the intense level of secrecy, NROL-37 does have one very cryptic mission patch associated with it. According to the NRO, the patch "depicts a knight, a symbol of courage with a chivalrous code of conduct representing bravery, training, and service to others. The knight stands in front of the U.S. flag in a defensive posture as to protect at all cost." The eagle on the knight’s chest is supposed to represent freedom, according to the NRO, while the sword is "a message of tenacious, fierce focus with the claws representing extreme reach with global coverage."
Another clue about NROL-37 is the Delta IV rocket it’s launching on. This is the heavy version of the rocket, which is the largest vehicle that ULA makes. The Delta IV Heavy consists of one main rocket core with two additional boosters attached to either side, which makes for an impressive sight during takeoff. Altogether, those boosters create a whole lot of thrust capable of getting upwards of 30,000 pounds into geosynchronous transfer orbit — a very elliptical orbit located high above Earth’s surface. The satellite needed for the NROL-37 mission is likely pretty hefty and will travel to a very high orbit if it needs the heavy version of the Delta IV to carry it into space.
The Delta IV Heavy may be ULA’s largest vehicle, but it also doesn’t fly too often. The last time the vehicle flew was in 2014, when it lofted an uncrewed test version of NASA’s Orion crew capsule into space. Since the Delta IV Heavy’s first flight in 2004, this version of the rocket has only flown eight times, and most of those