(SPOILERS) in my opinion, you should first finish everything in the lost river. Go down and hatch the eggs/ cure the virus and that will definitely require the depth modules. Once you get out of there, turn off the QEP, and blast off. Oh, and remember to bring back lots of ion cubes, nickel, and kyanite from the LR and ALZ. Good luck!

In case you need the Neptune blueprint, you'll need to make a trip to the Aurora. Remember to bring a propulsion cannon, a few medkits, some batteries, a flashlight, a scanner, and some fire extinguishers. Go in from the gap in the front and I'll leave the rest to you.