From Halopedia, the Halo wiki
Halo: Original Soundtrack
Martin O'Donnell and Michael Salvatori
Rock Anthem for Saving the World
The Maw is the seventeenth piece included in the Halo: Original Soundtrack. It is also used as the beginning of Dust and Echoes.
It starts playing at the opening cutscene of the level The Maw, the namesake for the piece, when the Master Chief and Cortana, riding in a Banshee head back to the Pillar of Autumn.
The track was rearranged into the following: