For more information about the system this planet is in, see Primus System
Rhea is the fourth planet in its system, and is close enough to Primus that the two are considered sister planets.
Rhea's surface is nearly 45% land, with the rest taken up by oceans. Its oceans are composed of water, however various metals are dissolved in so as to support the lifeforms of Primus, causing them to appear red, rather than the typical blue.
Of the thirteen planets in the Primus System, only Rhea was a suitable candidate for terraforming activity. Due to their inexperience with large-scale bioengineering of this nature at the time, the terraforming of Rhea took place over several millennia to minimize errors and allow for long-term analysis of data. The planet's atmosphere was first thickened over the course of several hundred years to regulate its temperature and composition, while machinery was built up at key locations to prepare for the next step. The sub-surface ice was chemically and physically melted into water, creating oceans so that microscopic lifeforms could be introduced. Plant life was added in several stages, followed by animal life, completing the process.
Its proximity to Primus allowed for nigh-instantaneous communication between the two worlds, taking only minutes each way, opposed to planets in other systems which required years between contact, and even the invention of FTL only brought that delay down to hours or days. The years of information from Rhea's terraforming served as the basis for various environmental modeling programs developed by the Norb, which was one of the final stages of development they required before expanding to other solar systems. The research done on this planet also laid out the groundwork for adapting the Norb to Boron and Carbon based organisms in the future.