USGS.gov's Landsat 9: Payloads stacked atop Atlas V for launch includes the following:
A fourth and final burn by the Centaur's RL10C-1 cryogenic main engine executes a deorbit maneuver nearly three hours after liftoff to dispose of the stage in a safe manner that does not contribute to space debris or cause an uncontrolled re-entry.
To date, Atlas V missions have required no more than three Centaur burns. The stage has the capacity to do more, and the flight design of the Landsat 9 and EFS mission takes advantage of that capability.
Question: Just how much of a spaceflight first will the fourth 2nd stage burn of the Landsat 9 launch be? First time it was required for this 2nd stage? First time even tried in orbit? First time for any 2nd stage in LEO? First time for any 2nd stage engine ever?