In Destiny 2, you get to utilize a new ability called Matterspark that lets you go through tight spaces for a limited time. This ability can be further upgraded to Matterspark IV, which offers an increased time to remain as a Matterspark. To attain this upgrade, you will require 4 Strangelet Capsules. While two are tied to quests, there are 2 more to find and they are not clearly marked on the map. This guide will explain how to upgrade to Matterspark IV in Destiny 2.
Secret Strangelet Capsule Locations Destiny 2
There are 2 secret Strangelet Capsules to find that will help you unlock Matterspark IV. Before you can get into it, you need to be at Fabled World Tier, which unlocks after you complete the entire campaign in normal or legendary difficulty or reach 150 Power. Then, head over to the Altar of Relativity and pick up the Explore Kepler quest. The two secret Strangelet Capsules are located at Outer Steppes and Exile’s Accord, and we will detail the location below.
Outer Steppes Secret Strangelet Capsule Location

Teleport to The Stacks in Outer Steppes. Upon reaching the location, jump down to find a Relocator beside a Brig. Use the Relocator at the portal beyond the partially closed door on the bridge above. Hop back down and step onto the portal to be transported inside. On the left side of the entrance is a hole on the floor, drop down and use the Matterspark ability to go through the tunnels.

Interact with the console at the end of the tunnel, then head back to the room. Plant a raid flag nearby, then activate the signal beacon. Unlock the door on the right side of the entrance and defeat the enemies that spawn here. Once done, the shield around the Strangelet Capsule will be unlocked, which can be picked up now and added to your collection.
Exile’s Accord Secret Strangelet Capsule Location

Teleport to the Curtilage Divide and head to the right from the spawn point. Keep heading right till you find a generator and a tunnel beside it. Enter Matterspark mode and go through the tunnel till you reach the area where you need to solve the Curtilage Divide puzzle. After that, head left once you reach the second area where the Transient mission can be picked up.

Instead of entering the room where the mission starts, head further left while you are on top of the floating platform. You will spot a second Relocator to pick up. Next, make your way to the central structure where the shielded Strangelet Capsule is and head over to the opposite side. There is a charge matter realignment right across, on the upper platforms.
Collecting the Second Secret Strangelet Capsule

Make your way over there and interact with it, then use your charged up power on the metal plates above. Once they turn into platforms, make your way further up and use the Relocator at the portal beyond the laser guarded door. Use the portal beside you to get inside, then activate the System Purge.
Head back to the central structure and place a raid flag. Jump down below to find another Purge system to activate. This will spawn the boss, and alongside the fight, you also need to locate and diffuse two mines around the area. Keep fighting the boss and diffusing the mines till the boss is dead, which will unlock your second Strangelet Capsule for the taking.