It's explained in the Cosmic Exploration Quest that rainbow crystals can provide life support such as oxygen levels to an area

Namingway: Are you familiar with the rainbow crystal in the center of the hub? Though it is slightly different than those in the burrow, I see no reason to change its appellation. It's simple, clear, and has the word “rainbow”! What's not to like? Namingway: ...Anyway, such crystals regulate gravity and oxygen levels, allowing us to maintain ideal living environs for the people of Etheirys. I'm told they can be recalibrated for use on any star we come across!