In Returnal, you are restricted from some areas in the game unless you retrieve the Icarian Grapnel, the grappling hook of Returnal. You can once you get the tool, you will be able to access areas with an orange light or floating orbs.
Here's a guide on how to get the Grappling Hook in Returnal.
Returnal's Grappling Hook: How to Get the Grappling Hook
To get the grappling hook, you have to defeat the game's second boss, Ixion.
Ixion can be found in the second biome, the Crimson Wastes. When you defeat the first boss of the game, Phrike, you will earn the Crimson key which opens a portal door to the Crimson Gate, which takes you to the second biome.
Ixion is a tough challenge to defeat in the Crimson Wastes. It flies around the battle arena while shooting at you in the first phase of the battle. In the second and third phases, it uses area-filling attacks to hit you. When you've got Ixion weak enough in the final phase, it will only attack you with melee strikes. Be prepared to do a lot of dodging and evading in each phase to survive. Also keep an eye on his attack patterns, as they become predictable with each phase if you know what to look for.
Once you defeat Ixion, you will earn the Icarian Grapnel, which will operate as your grappling hook throughout the rest of the game.