Spaceflight Simulator Wiki
This part or feature has been partially removed
This part or feature is still accessible in the game, but with some limitations.

The Radioisotope Thermoelectric Generator, abbreviated as RTG, is a part that is only found in blueprint editing by naming a part Placeholder RTG or in saved blueprints created before 1.5. It formerly generates 0.5 units of power and can be used to power up space probes and rovers.

Advantages and disadvantages

RTGs are better than other electric generators in rovers, because they're more compact (in 2×1 units that don't need to be extended to generate power) and durable if landed on, and can lower the rover's center of mass (making it more difficult to flip over).

In propelled spaceflight, solar panels are more efficient because of their higher power generation per tonne.

RTGs may be desirable in space stations, because of their compactness, but they're heavier per-watt, meaning more rocket journeys are necessary (carrying RTGs as payloads) for the same benefit as solar panels.


  • The RTG has the ionizing radiation hazard symbol on it. In 1.5, it is removed.
  • It is a grey block that occupies a perimeter of 2 units.
  • In real life, RTGs are used to power satellites and space probes, similarly to SFS.
  • Real RTGs use the decay of radioactive material such as 238Pu (plutonium-238) or any radioactive isotope to generate power. The output varies, depending on the isotope used, but slows down as less of the material remains, the intervals between halvings being called the half-life. However, RTGs in SFS have no half-life, and produce constant electricity.
  • The RTG can be formerly found in the Electric section in the building space. However, due to the electricity rework, it disappeared from the parts menu and only then and now accessed in blueprint edited rockets, and is now a gray block that has no function.

Basics ParachuteCapsuleHeat ShieldSeparatorFuel TanksHawk EngineValiant EngineKolibri EnginePeregrine EngineRCS ThrustersSide SeparatorSolid Rocket BoostersAerodynamic Nose ConeLanding Leg
6 Wide 6 Wide Aerodynamic Nose ConeFuel TanksSeparatorHeat ShieldEngine Base
8 Wide 8 Wide Aerodynamic Nose ConeFuel TanksSeparatorHeat ShieldEngine Base
10 Wide Fuel TanksSeparatorHeat ShieldEngine Base
12 Wide Fuel TanksSeparatorHeat ShieldEngine Base
Engines Titan EngineFrontier EngineHawk EnginePeregrine EngineValiant EngineKolibri EngineRCS ThrustersIon Engine
Aerodynamic Parts ParachuteSide ParachuteAerodynamic Nose ConeAerodynamic Fuselage
Fairings Fairing
Structural Structural Part
Other Docking PortLanding LegsIon EngineProbeRCS ThrustersWheelsSolar PanelFuel Pipe
Currently removed in Version 1.5
Removed in older versions
Probe (Large)Fairing AdapterAdapter