Doisac

Doisac is the homeworld of the Jiralhanae. The planet is classified as a "super-Earth", notably boasting a surface gravity of 2.1G. The planet blurs the line of habitability for most species of the Milky Way, combining extreme surface conditions with

History
Doisac is thought to be a relatively young planet, forming as little as 3.1 billion years ago. As such, the planet is highly active, with plate tectonics and regular volcanism still ongoing. Life is thought to have formed on the planet within the last 500 million years, raising many questions as to how life was able to evolve so quickly on such a young planet. However, the hostility of Doisac's environment ensures that archaeological and geological evidence is near-impossible to ascertain; many proponents of the Out-of-place biota theorem suggest that Doisac may have been subject to tampering by advanced alien civilisations - though evidence of such activites has yet to acquire any real evidence. Due to the young age of Doisac and life as a whole on the planet, Doisac is not believed to have undergone many mass extinctions, possibly making the life currently existing on the planet to be some of the first to arise on it.

The Jiralhanae species are thought to originate around 250,000 years ago, quickly coming to spread across Doisac's main supercontinent. A period of particularly intense global cooling around 175,000 years ago is thought to have dried the seas significantly, opening up many land bridges to the various archipelago islands around Doisac and allowing the Jiralhanae to spread to remote islands, before a period of global warming thawed the polar ice caps and cut off the island chains. This period of cooling and warming is thought to have been caused by the eruption of the Jerion supervolcano located on Doisac's northern hemisphere.

Doisac was later one of many worlds indexed by the Forerunners, and chosen for reseeeding following the firing of the Halo Array around 100,000 years ago. Some archaeological evidence suggests the Jiralhanae had, by this time, advanced to a level of civilisation and technology roughly equivalent with Earth's classical era - though this is uncertain. Following the Jiralhanae's reseeding, they proceeded to repopulate the various islands across Doisac to establish a global civilisation. Industrialisation soon followed and by the 10th century CE, the Jiralhanae residing on the Mbreultu supercontinent had discovered steam power. The following centuries saw an explosion of Jiralhanae technology and population across Doisac as new transportation and agricultural technologies allowed the Jiral to populate the planet like never-before seen. This explosion of population and lack of resources soon led to the First Immolation, a worldwide nuclear holocaust which is estimated to have killed between 7-8 billion Jiralhanae. The global wildfires ignited by the war lasted for decades and destroyed almost all life on the surface, leading to a long period of recovery.

Over the following millennium of Jiralhanae expansion across nearby space, several conflicts had Doisac see a few near-misses with asteroid impacts (one natural and several artificially-induced) and a brush with renewed nuclear tensions. By the 2480s, Doisac saw itself the target of a brutal and short conquest by the Covenant empire, following various frontier wars between the Jiralhanae clans and the Covenant's frontier worlds. Covenant warships arrived over Doisac, in 2490, and began a short campaign of orbital bombardment to subdue the planet's polities - predominantly the Co-Dominium of Doisac - into submission. The Co-Dominium soon bent the knee, bringing Doisac into the territories of the Covenant. To ensure the Jiralhanae's compliance, the Covenant established the Station of Sundered Fortune in orbit to act as an official observation post and gateway to Doisac for emissaries and diplomats to meet with Co-Dominium representatives. The station was additionally fitted with a large energy projector for potential glassing against unruly cities. As the Jiralhanae were integrated into Covenant proper, the need to hold a gun to the planet was lessened, and eventually the station's weapons were repurposed for the interests of orbital defense.

During the Human-Covenant War, the valiant service of the Jiralhanae in the campaign against humanity saw a new proclomation given by the Prophet of Truth; in celebration of the Jiralhanae achievements, Covenant engineers were to be deployed to Doisac to begin the lengthy process of re-terraforming the planet back to a habitable state - and even altering the planet's biosphere to be more friendly to life. This deal was made with Tartarus as part of a long series of reforms planned by the Prophet culminating in the Great Schism.

As news of the Schism's outbreak and the fall of High Charity reached Doisac, the planet fell to infighting almost immediately.

Topography
As a super-Earth, Doisac is characterised by its relatively low land area when compared to most garden worlds. Doisac boasts 85% surface coverage as ocean, leaving a total combined land area roughly the size of Africa for the Jiralhanae to live on. This land is spread across the Mbreultu supercontinent and thousands of small islands, including one particular archipelago in the Roghan sea. The planet has a fairly flat and even surface, owing to the intense gravity not allowing for large land formations. As such, Doisac's largest mountains are comparable to the highlands of Earth or Reach.

Mbreultu is mostly comprised of flat plains, grasslands, desert and some jungle broken up by the low-lying Djorian Spine - a series of large hills running north-to-south along the supercontinent and forming a natural divide on the otherwise relatively flat terrain. Four major river networks further break up the territory, with the water erosion accelerated by the gravity to form vast canyons and river valleys.

The Roghan sea lies to the east of Mbrueltu, between the supercontinent and a large archipelago of over a thousand islands. The oceans of Doisac are fairly shallow, with the seabed exhibiting similar flatness to the land. As such, periods of intense sea level reduction are capable of drying certain particularly elevated parts of the sea bed and exposing them to air, creating vast dry salt flats across which land journeys can be attempted. This mechanism allowed primitive Jiralhanae to spread across the sea to the various islands of the archipelago, eventually forming a seafaring culture that would eventually spread to the islands of the northern and southern poles.

As a young planet, Doisac is appropriately extremely tectonically active. As such, much of the planet is covered in volcanoes and gaseous vents - some of these volcanoes form the tallest mountains on the planet, with the pressure of the forces below counteracting the gravitic pull of Doisac. These structures can be found on both land and underwater, and are responsible for providing a near-continuous blanket cover of ash and smoke to Doisac's sky - resulting in near-permanently overcast weather. This layer of smog also serves as an effective blanket for trapping heat and greenhouse gases, allowing Doisac to sustain a large variety of life despite the relative lack of sunlight it recieves compared to other worlds.

Most of Doisac's land lies within the equatorial tropical band - itself extended several degrees both north and south when compared to Earth. As a result, most Doisacian life is adapted predominantly for warmer temperatures. The increased temperature also means that Doisac has little in the way of polar ice caps. Cycles of global warming and cooling do exist on Doisac as on Earth, with the planet's oceans drying considerably to form ice caps in the ice ages. As of the 26th century, Doisac has been recovering from an artificially-induced ice age, and has very little ice to speak of.

Due to the rapid industrialisation of the Jiralhanae followed by the First Immolation and the subsequent lack of dedicated cleanup efforts, Doisac is still coated in radioactive particulate alongside the remains of the potent chemical and biological weapons and industrial waste once deployed centuries ago. This makes traversing Doisac ever-the-more dangerous, as some cities still retain a shroud of poison gas and other toxins, a relic of the Jiralhanae's by-gone industrial era. Cities litter Doisac's surface in a variety of forms. Due to the naturally-occurring seasonal wildfires that ravaged Mbreultu regularly, combined with frequent earthquakes, Jiralhanae engineers in the Age of Legends prioritised survivability and practicality in their architecture over art and aesthetics. The planet's gravity ensures that most structures are squat, with liberal use of pyramoidal forms and supporting columns. As such, many ancient Jiralhanae cities survive into the modern day, despite centuries of neglect and abuse. Some have been reclaimed by the modern inhabitants of Doisac, though many still remain abandoned due to the aforementioned presence of contaminants and radiation.

Atmosphere
The atmospheric pressure of Doisac is similarly high, owing to its gravity. However, this atmosphere is a thin one, with the gravity of Doisac hugging the atmosphere tightly to its surface. As a result, the atmosphere does not extend far off Doisac's surface, and pressure drops extremly quickly at the already-modest altitudes of Doisac's highlands. The higher altitudes experience high wind speeds compared to the relative stillness of the lower altitudes, allowing for particulate in the atmosphere to be quickly disseminated across the planet.

Wildfires and Burns
The presence of fairly dry inland terrain, high oxygen content in the air and ever-present volcanism ensure that Doisac is embroiled in near-constant "Burns"; wildfires ignited through natural processes that are capable of ravaging large swaths of land. These regular wildfires are responsible for replenishing Doisac's soils with new supplies of minerals, allowing new generations of plants to grow. The burns are a regular occurrence, prompting many of the early Jiral tribes to become nomadic in nature, to avoid their settlements being destroyed in the fires. These tribes soon learned to harness the power of mules and chariots, eventually learning to construct entire buildings on wheels, pulled along by domesticated megafauna.

The wildfires of Doisac also prompted the Jiralhanae to begin constructing with more hardy materials such as stone and metal, with Jiralhanae civilisation stabilising between the city-states of the hills, rivers and coasts and the nomadic tribes of the plains.