As you come around a curve there will be some covenant forces. Just blow them off the halo.
A turret and a ghost will attack outside the tunnel.
Keep following the path around to the right and back to the left.
Go back to the right around the rock. There will be a wraith blocking the path ahead.
At the end of the road will be some hornets.
Jump out of the scorpion and jump in one of the hornets. Sweet. What could go wrong now.
Oh that could do it. Two scarabs drop in to fight.
Fight the scarabs like you did in the tank. It will be easier to dodge their shots. Once they fall shoot the red glowing thing on their back to uncover the core.
Shoot the core and one less scarab to worry about.
Mop up any remaining covenant forces. Land near the ramp and jump out of the hornet.
Run up the ramp and the Oracle will extend the bridge. Run across the bridge to the Citadel.