After a moderate amount of exploring, you will come to a large, roundish, dead-end room with a large hexagon in the middle and a small hexagon to the left on a pedestal. Using the shield pulse (A button) on the small hexagon might open up one of the hidden areas surrounding the large hexagon. Apparently, the number of artifacts you have collected determines when the hidden areas will open. For this one, another source says 20 artifacts, but I only had 15 or 16 when it opened for me. Perhaps there has been a patch?
Inside each hidden area will be an upgrade for your character, and will unlock the respective achievement. This first one, the Mini Turbo, provides a random very short speed boost. Not very useful, but it might help in a few places.