Ordered the Prawn

The quickest Prawn Suit blueprint is inside the Aurora: the ship's vehicle bay holds two intact suits, and scanning both completes the blueprint between them (wreck fragments elsewhere also count if you'd rather not go in). You'll need the post-repair Aurora trip anyway (Extinction Event Avoided), so do both in one expedition.

Build it at the Mobile Vehicle Bay - the mech is your deep-biome workhorse, and with the depth modules it's how you'll walk the lava zones for Thermal Activity and Fourteen Thousand Leagues Under the Sea.