CSS Frontier

The CSS (colonial starship) Frontier is a starship that oversaw the exploration and colonization of the Yggdrasil System. It is primarily made up of two parallel counter-rotating cylinders, each 50 kilometers long and 12 kilometers in diameter. The Frontier departed from the Solar System in 2147 and arrived 120 years later, however, due to time dilation during its voyage, the passengers only experienced 116 years of travel.

Structure
The Frontier is a dual-cylinder colonial starship 50 kilometers long and 24 kilometers wide. Each cylinder has a tangential velocity of 210 m/s and makes a full rotation every 3 minutes. The inner surface area of each cylinder is 3,770 square kilometers and has a circumference of 37.7 km. To reduce strain on the structure, the apparent gravity is only half of one G and the air pressure is about half of Earth's air pressure at sea level. It is divided into four sections: Cylinder One, Cylinder Two, the transport bridge, and the engine complex.

Cylinder One
Cylinder One is the port cylinder, and looking forward from the aft of the ship, rotates clockwise. It is the "cold cylinder," having highs of 50* to 70* F from winter to summer respectively.

Cylinder Two
Cylinder Two is the starboard cylinder, and looking forward from the aft of the ship, rotates counter-clockwise. It is the "hot cylinder," having highs of 70* to 90* F from winter to summer respectively.

Transport Bridge
The transport bridge is located at the forward of the ship and connects both cylinders. Here, a microgravity transit vehicle allows passengers to travel from one cylinder to the other.

Engine Complex
The engine complex is located at the aft of the ship and is primarily the propulsion system. Thermal nuclear rocket engines accelerate the ship during maneuvers and are fueled by massive hydrogen tanks. While low thrust, they have a high specific impulse, and combined with the immense amount of fuel, the Frontier has an incredibly high delta-v, allowing the ship to carry out interstellar maneuvers. The nuclear reactors also power the electrical systems of the ship. The radiator wings are located here, which help cool the engines.

History
In 2103, asteroids were navigated into a high Earth orbit and mined for resources to begin construction of the Frontier, and the ship was completed in 2145. 100,000 applicants were selected to be the permanent population of the ship, and were brought to the ship through a series of space launches. It remained in orbit around Earth until 2147, when the ship began its departure out of the Solar System.

After the Frontier reached 25% of lightspeed, it began its coast through interstellar space. From the ship's relativistic perception of time, the arrival at the Yggdrasil System was made in 2263. The breaking maneuver was made by a combination of electric and magnetic sails that repulsed against the solar wind of the star, slowing down the ship without expending fuel.