Before destroying the Silos in Ransom Keep, you can explore the area to get some collectibles. Collectibles like Spartan Cores can help you upgrade your Suit abilities. There are a total of 5 Collectibles in Ransom Keep and this guide will show you how you can get all of them.
You can find the Spartan Core at the southwest part of the Ransom Keep. From the road, go up to climb up to the left part of the buildings and you will see a stack of supplies. The spartan core is next to some crates.
Banished Audio Logs
From the Spartan Core Location, go across the bridge and turn left, you will see the Audio Log next to some tanks.
The second Banished Audio Log is in the middle of the Ransom Keep. Go inside the building to your left and you will find the Audio Log leaning on the wall next to some boxes.
UNSC Audio Log
In the same area where you found the second Banished Audio Log, head towards the mountain to the north and climb up using your Grapple. The first Audio Log is on top of a crate next to some wood.
From the last location, jump down the mountain and head towards the glowing red entrance in the middle. Keep following the path until you reach the end of the road. You will find the last collectible on the ground.