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The radiators are special devices that can cool other parts of a craft, consuming a small amount of electric charge when operating.

They dissipate heat into space (radiative) and atmosphere (convective). To do this efficiently, they make themselves hotter by transferring heat in, but they self-limit to avoid overheating to destruction. Their efficiency can be limited by ambient conditions, but for many uses it is constrained more by arbitrary functional caps. They are essential for maintaining resource harvester and converter cores at their optimal thermal efficiencies.


  • Rigid, fixed Panels, only cool the part they are directly attached to, and parts directly connected to that part.
  • Deployable Thermal Control Systems (TCS), take heat from every part of the vessel (as if plumbed in with a cooling fluid loop). Like the deployable Solar Panels, these automatically rotate depending on the relative direction of Kerbol, but turn edge-on to minimise their exposure to the sun's radiation. They all have "Tracking Speed: 0.1". While deployed, they will break off under 2.5kPa of dynamic pressure - moving too fast through a fairly thick atmosphere (e.g. ~67m/s at sea level on Kerbin, edge toward motion). Unlike the fixed panels, no other parts can be attached to these.
Image Part Radial size Cost
Max. Temp.
Deployable Electricity
Radiator Panel (edge) Radial mounted 450 0.03 2 500 12 50 No 0.025
(1.5 ⚡/min)
Radiator Panel (small).png
Radiator Panel (small) Radial mounted 150 0.01 2 500 12 50 No 0.025
(1.5 ⚡/min)
Radiator Panel (large).png
Radiator Panel (large) Radial mounted 450 0.05 2 500 12 50 No 0.025
(1.5 ⚡/min)
Thermal Control System (small).png
Thermal Control System (small) Radial mounted 450 0.05 2 500 12 50 Yes 0.025
(1.5 ⚡/min)
Thermal Control System (medium).png
Thermal Control System (medium) Radial mounted 2 250 0.25 2 500 12 50 Yes 0.125
(0.1 ⚡/sec)
Thermal Control System (large).png
Thermal Control System (large) Radial mounted 9 000 1.0 2 500 12 50 Yes 0.5
(0.5 ⚡/sec)


To begin functioning, "Activate Radiator" must be selected from a panel's right click interface, or "Extend/Retract Radiator" for the thermal control systems, which also deploys them. Alternatively these functions can be bound to action groups, with the "Toggle Panels" option allowing a single action group to start and stop many radiators simultaneously.


Radiators only remove heat from the inside of parts (which constitute the vast majority of their thermal capacity), not their skin, which may be at a very different temperature. Heat may be accumulated from external sources (e.g. re-entry or sunlight from Kerbol) or be generated by reaction engines or the cores of resource harvester drills or converters, while they are active.

Cooling Specifications

All radiators:

  • "Transfer Rate: 10%".
  • "Cools up to 4x part temp".
Image Part Core Heat xFer (kW) Max Cooling (kW)
Radiator Panel (edge) 150 2 234
Radiator Panel (small).png
Radiator Panel (small) 50 1 048
Radiator Panel (large).png
Radiator Panel (large) 200 3 644
Thermal Control System (small).png
Thermal Control System (small) 50 3 139
Thermal Control System (medium).png
Thermal Control System (medium) 250 19 494
Thermal Control System (large).png
Thermal Control System (large) 1 000 85 077

Core cooling (of drills and converters) is primarily limited by a radiator's "Core Heat xFer" (transfer) stat. This is always a small fraction of what a radiator can actually dissipate, under most circumstances, indicated by the "Max Cooling" figure.

Core Cooling

To maintain an active drill or converter core at optimal thermal efficiency, radiators must provide enough unused Core Heat Transfer capacity to fulfil the "Required Cooling" stat, shown below:

Image Part Required Cooling (kW) Max Cooling(kW)
'Drill-O-Matic Junior' Mining Excavator.png
'Drill-O-Matic Junior' Mining Excavator 50 50
'Drill-O-Matic' Mining Excavator 100 100
Convert-O-Tron 125.png
Convert-O-Tron 125 100 75*
ISRU Converter.png
Convert-O-Tron 250 200 200

(*) The Convert-O-Tron 125 is a special case - it can not be maintained at optimal thermal efficiency because its "Max cooling" cap of 50kW is below it's required cooling (100kW). With the help of radiators, it will still reach equilibrium, albeit a little hotter than the optimal 1000K. This is possible because core heat production scales down at higher core temperatures, as the thermal efficiency drops off.

Also note, for both Converters, that the required cooling figure is per active conversion mode, with each unit able to have any, or all, of their four ore conversion modes active at the same time. Hence the Convert-O-Tron 250's required cooling can also exceed its maximum permitted (e.g. 3 modes will produce 600kW of core heating).


  • "Fixed" radiators now also need to be activated before they start working.