Carbon Dioxide Engine

The Carbon Dioxide Engine is a rocket engine that uses Carbon Dioxide as fuel and is available as the simplest propulsion option for early space travel. It is intended for short-range missions and basic orbital work, making it a practical choice for reaching nearby destinations before more advanced engines become available. Rockets using this engine can send Duplicants into space and recover rare resources, but the engine’s limited performance makes it best suited to modest trips rather than long expeditions.

Its main advantage is ease of fueling. After landing, it is possible to collect Carbon Dioxide produced by the colony and pipe it back into the engine, and a Gas Filter may be useful to keep unwanted gases out of the supply. This makes turnarounds simple, especially when the rocket is stationed near a base that produces plenty of Carbon Dioxide. A Canister Drainer and a few pipe segments can also be used after landing to refill the engine efficiently, which is especially convenient for shuttle-style operations.

The Carbon Dioxide Engine has several strict limitations. It cannot use additional fuel tanks, so the engine module itself determines the total fuel storage and therefore the rocket’s range. This gives the rocket a maximum range of 6 tiles. The engine also supports only a maximum rocket height of 10 tiles, which makes cargo-heavy or highly expanded designs impractical. Unlike other engines, it does not generate electricity.

When launching or landing, a rocket with a Carbon Dioxide Engine produces a Carbon Dioxide exhaust cloud at about 200°C, regardless of the temperature of the fuel stored inside the engine. If this exhaust does not dissipate into open space, it will scald Duplicants nearby, although it is still far less dangerous than the exhaust produced by stronger engines. Careful pad placement and clear venting space help avoid unnecessary accidents during takeoff and landing.

The engine also has a useful quirk: supplying non-Carbon Dioxide gases does not cause the engine to take damage from wrong-element input, and the incorrect gas is released into the environment regardless of surrounding pressure. This behavior can be used to build a high-pressure gas reservoir if desired.

Because of its range and height limits, the Carbon Dioxide Engine is most useful for orbital research and for travel between the starting planetoid and a nearby neighbor. It is a straightforward, low-complexity engine for colonies that need a small but reliable step into spaceflight before moving on to more capable rockets.