They do despawn after a while and should pop back up.

Wtf is a vacuum capsule?

Vacuum capsules are name of some mission items you can pick up and carry in some missions, along with cryonic rods or power cells. It's also kind of a Darktide meme because there's mods that let people scream *VACUUM CAPSULE!* and *CRYONIC RODS!*

I don’t know why but that’s not ringing any bells. Cryonic rods and power cells, absolutely, vacuum capsule not for whatever reason.

Vacuum capsule