Fuel
The Last Caretaker Sabatier Reactor: What Goes In, What Comes Out and Why It Stops
Short answer: The Sabatier Reactor makes the Exodus rocket’s methane and oxygen. Unlock it at skill tier 16, then feed it fresh water (never salt water), electricity and CO2 from a petrol generator; methane and oxygen come out of their own outlets together, and with no CO2 it makes oxygen only. When it stops, the usual cause is a full oxygen tank: leave one of its four oxygen outlets unplugged so the spare oxygen escapes.
Game version: Early Access, Update 6 (October 19, 2026); parts and skill tier from the Update 6 game data, fixes checked in Steam threads from November 2025 to July 2026
Sabatier Reactor Setup, Step by Step
- Unlock it. Skill tier 16, together with the Methane Tank and the Oxygen Tank, then make the ten parts listed below.
- Place it at Exodus Station. Close to the rocket, so the gas does not have to travel. Exodus Station on the map
- Bring fresh water. Water pump, then a Water Purifier, then a water tank, then the reactor. Salt water will not do. pump and purifier setup
- Add CO2 and power. Build a Large Electric Generator beside it, run petrol in, Gas Cable from its CO2 port to the reactor, and its power into the reactor along with your batteries. where CO2 comes from
- Hose the outlets. Methane outlet to a Methane Tank, one oxygen outlet to an Oxygen Tank. Leave the other three oxygen outlets empty.
- Switch it on. Methane and oxygen come out together. If it stops, go through the fixes below.
What the Sabatier Reactor Does
What does the Sabatier Reactor do?
It makes the gases for the Exodus rocket. Feed it fresh water, electricity and CO2, and methane and oxygen come out of their own outlets at the same time. With no CO2 coming in, it makes oxygen only.
A broken Sabatier Reactor stands at Exodus Station, with an Oxygen Tank and a Methane Tank beside it.
See also: oil, methane and every other fuel
How much methane and oxygen does the rocket need?
A full launch of the Exodus rocket takes 3,000 L of methane, 12,000 L of oxygen and 60 kWh of electricity.
See also: rocket fuel
Unlock, Parts and Power
When do you unlock the Sabatier Reactor?
Skill tier 16, for 4 skill points. The Methane Tank and the Oxygen Tank unlock at the same tier, so take all three together.
See also: the skill tree
What parts does the Sabatier Reactor need?
4 Storage Cylinders, 8 Connector Ports, 8 Alloy Frames, 4 Cooling Radiators, 2 Filtering Systems, 1 Logic Chip, 3 Nano Mesh, 1 Power Core, 1 Isotope Stabilizer and 1 Storage Matrix.
See also: the parts in the item database
How much power and water does it use?
About 60 kW while it runs, whether or not it is making methane, so back it with batteries and a steady supply rather than a few solar panels.
Flat out it takes 5,000 L of fresh water and up to 72,000 L of CO2 an hour, and puts out up to 72,000 L of oxygen and as much methane.
See also: power grid calculator
How to Hook It Up
What water does the Sabatier Reactor need?
Fresh water only. Pump sea water through a Water Purifier (skill tier 7) and hose the fresh water into the reactor; with salt water in the line it makes no methane.
Put a water tank between the purifier and the reactor, so a short dip in the supply does not stop it. Some players add a CO2 tank between the generator and the reactor for the same reason.
See also: pump and purifier setup
Where does its CO2 come from?
A Large Electric Generator (skill tier 15) burning petrol right beside the reactor. It gives off about 60,000 L of CO2 an hour from the port on its top: run a Gas Cable from there to the reactor. Its electricity can feed the reactor as well.
The boat’s diesel engine gives off CO2 too, but far less. The reactor still draws its full power while it waits for gas, so a boat-fed reactor drains batteries for little methane.
See also: all about CO2
Where do the methane and oxygen go?
It has one methane outlet and four oxygen outlets. One hose on any oxygen outlet carries all the oxygen, and an outlet with nothing plugged in lets its gas out into the air.
Run Gas Cable from the methane outlet to a Methane Tank, or to Methane Barrels (500 L each, skill tier 18), and from one oxygen outlet to an Oxygen Tank.
Where should you build it?
At Exodus Station, close to the rocket, so the methane and oxygen do not have to travel. A reactor on the boat works, but then you have to get the gas to the rocket.
See also: Exodus Station on the map
Sabatier Reactor Not Working
Why did my Sabatier Reactor stop?
Almost always a full oxygen tank. With every oxygen outlet hosed to a tank, the reactor stops as soon as that tank is full, and oxygen fills up long before the methane does. Unplug one of the four oxygen outlets: the spare oxygen then escapes and the methane keeps coming.
Why does it make oxygen but no methane?
No CO2 is reaching it. Check that the generator or engine is running and that its Gas Cable ends in the reactor’s CO2 inlet. Salt water stops the methane too, so make sure the water comes from a purifier.
Why does the generator stop when its CO2 line reaches the reactor?
The reactor is not taking the gas, so the CO2 has nowhere to go. It is short of water or power, or one of its output tanks is full. Fix that and the generator starts again.
See also: CO2 and the generator
Everything is connected and it still will not run. What now?
Check that the power cable is still plugged in (it is easy to forget after unplugging it to build tanks nearby) and that the batteries feeding the reactor are not empty.
Then check the hoses. Each pipe segment shows an arrow for the flow, and one pointing the wrong way blocks it. Hoses also come loose: unplug every line and reconnect them one at a time, or save and reload.
See also: other known problems
