The PlayStation 3 and Vita versions of this mission are related to a trophy named "Gate Crasher Masher", completing this mission will reward you with a bronze trophy.
In this mission you have to both defend the front gate as well as destroy 13 Marauder catapults. You can actually choose which of the buggies to use for this mission, with most commonly the Sand Shark or Dune Hopper being available. If you have also defeated the "Chase down metal head beasts" mission you can also use the Gila Stomper. The first two have the advantage of speed, while the Gila Stomper has much better armor as well as having an accurate auto-targeting turret which makes hunting down any enemies very easy. The Sand Shark just fires straight ahead but you can control where it fires. Lastly the Dune Hopper lacks the range and the armor of the other two, but it's grenades are very powerful and have decent explosion damage as well.
The main targets here are the catapults and the burning marauder buggies that attempt to crash into the gate. Both of these are marked by a large red and a large orange blip respectively on the mini-map, with the small red ones reserved for the normal enemy buggies. Don't concentrate on these but do use their dropped turbo boosts when you can.
As long as you destroy the two main targets as soon as they appear you will successfully fend of the Marauders. Once you defeat the last of the Marauders, the game will automatically transition into Take out Marauder stronghold with no choice of doing any other mission until completed.