Main Engine Cut Off

Falcon 9 Block 4

William Graham, for NASASpaceFlight:

Monday’s launch debuts a new revision to the Falcon 9, which is known unofficially as the Block 4. This upgrade increases the thrust provided by the rocket’s Merlin-1D engines and includes other upgrades ahead of a further revision, Block 5, which is expected to be introduced with Crew Dragon’s Demo-1 mission next year.