SS-WA735c "Siphon"

Planetary Data
SS-WA735c, also known by the nickname Siphon, is a moderately sized gas giant located in the Goldilocks zone of its orange star primary. Its upper atmosphere is rich in water clouds and hydrogen –making the Siphon resemble a terrestrial's planet atmosphere from space–, but poor in oxygen and hydrocarbons. It is riddled with vast, planet sized storms, more virulent than its cold counterparts due to the proximity to its sun. It is thought that the planet was formed further than its current location, with the orbit decaying for millennia into its current position.

It possesses a relatively sparse moon system, with only a single major moon and a few metal-poor asteroids. Said satellite –named SS-WA735cb, or simply Pale due to its coloration– is large, being the size of a small planet and with an unusual rocky composition instead of typical frozen worlds; as well as containing a dense atmosphere. The planet is currently inhabitable, with a large quantity of CO2 suspended in the air and blanketing the surface under a scorching heat. From space

The planet and its moon house an extraterrestrial megastructure of unknown origin. A complicated array of artificial satellites orbit the planetary system, each equipped with a powerful magnet capable of creating truly astounding magnetic fields; with multiple automated factories scattered in perfect geosynchronous orbits that replenish lost satellites. Furthermore, the moon also contains structures equipped with larger magnetic fields and the infrastructure to support the corroding atmosphere. In addition, a planet-sized platform blanketed under a storm has been recently discovered levitating on the lower atmosphere of the gas giant.

Both the satellites and the platform work in tandem to syphon hydrogen gas off SS-WA735c to SS-WA735cb with incredible precision. The floating platform on Siphon ionizes the hydrogen gas of the atmosphere and launches it to space using a magnetic accelerator. Depending on the proximity, different satellites activate their magnetic fields and guide the hydrogen plume into Pale, where the receiving machines will force said material to react with the moon's poisonous atmosphere, creating elemental carbon and water with the side effects of creating storms within Pale. Said event usually shapes itself as a tail of glowing ionized gas emerging from the gas giant and landing on a dark splotch on the moon.

Inhabitants
Neither Siphon nor Pale posses any native life other than microorganisms suspended in Siphon's atmosphere, with neither celestial body show any signs of habitation beyond the megastructure. It is currently believed that the "siphoning" of hydrogen into Pale is a terraformation process to make the satellite a habitable world; as the removal of the CO2 in the atmosphere, as well as the addition of carbon and water, is slowly creating a more hospitable environment for carbon-based life to thrive in.

It is widely thought that this megastructure may have also been built in-situ. The lack of other natural satellites other than useless asteroids and Pale may point out to past extensive mining in order to set up the hydrogen delivery array. Additionally, multiple surveyor robots matching no known design but with similar regolith composition have been found on the remaining asteroids, shedding light to the possibility that a probe may have been sent from somewhere and built the whole array using local materials. However, the automatic machinery is far from finished terraforming the moon; indicating that whoever may have sent the original probe, it had been sent very long ago, and is still waiting for it to end its task of transforming a world.