Skipping Grapple Swing
It is possible to cross the gap without Grapple Swing with a Spring Space Jump and abusing terminal fall. This spawns Samus on the upper ledge on the other side. Conveniently, the Missile can also be grabbed at this point, without the need to activate the Bryyo Map.
From G.F.S. Theseus
By performing a Slope Jump and touching the Grapple Point, terminal fall can be abused. This spawns Samus on the upper ledge. From here, jump across the gap to Gateway. The Missile can also be grabbed at this point as mentioned above.