Story-related and cannot be missed. Just travel to Noveria and follow the quest objectives.
*** Spoiler - click to reveal ***The only hint you need for Noveria is to keep 100x Omni-gel if you want to boost the repairs on the station. Good luck!
If you need more detailed walkthrough, here it is, step by step. Please note, it's the quickest route, not necessarily the most "Paragon-ish":
- Deal with the situation in the hangar and talk to Gianna Parasini
- Talk with hanar merchant Opold and accept his smuggling side-quest
- Instead of finishing it, after you get the package, talk to Administrator Anoleis and tell him about the case
- You will be given the Garage Pass you need, go there and eliminate the enemies
- You are free to ride the Mako and the route is linear, you will be stopped by some Geth enemies and turrets
- Kill all the enemies at Peak 15's garage and get to the core
- Here's where the 100x Omni-gel comes handy - one less repair
- Have the landlines and the reactor repaired - as you can guess, it's a bit of fighting and a simple repair pop-up
- Head down the tunnel toward the tram. If your Electronics skill is high enough, you will be able to burn rachni, otherwise you'll have to shoot them
- At the Rift Station, go to the Med Bay and talk to Dr. Zev Cohen - he will give you a sub-quest, after which you'll have a solution how to progress further
- The rest of the mission is more or less linear and I don't want to spoil the fun - good luck!