dissipates excessive heat from the cabin and from operating electronic equipment.

Thank goodness at least someone's interested in doing original research.

I was hoping SAMU would discover these on his own, but I guess you've already pointed him there and he just didn't want to go.

The equipment that needed cooling (basically most of it) is mounted on cold plates. Some of it is inside the cabin, some of it is in the bays outside the pressure hull in the lower rim of the command module. Cold plates are structures served by a coolant loop. This same coolant loop can cool the cabin atmosphere.

With the radiators being diametrically opposite, it is possible that one primary panel may face deep space while the other faces the sun, earth, or moon.

We still use the diametrically opposed radiator system today in systems with coolant loops. You pipe the heat from the sunny side to the shady side.

Futhermore, this last paragraph explicitly states that different points on the outside surface will be at different temperatures.

Aw, you gave away the answer to my first question.

Yes, temperature gradients do in fact exist in objects under solar radiation. Why SAMU continues to claim they don't is basically all the proof I need that SAMU doesn't really understand the thermal design of spacecraft.

Maybe when he discovers the definition of "form factor" he'll realize that just because a surface is visible to the sun doesn't mean it receives the full potential radiation from the sun.

Think about the worst case for solar radiation. That's when the tip of the CM is pointing directly at the sun, so that all the upper heat shield is constantly in the sun. But in the Apollo 13 configuration the CM would have been shaded by that gawdawful pig of an LM stuck to the nose. So the worst case can't have arisen for Apollo 13.

Best case, point the SPS at the sun, and the CM is is total darkness all the time.

Average (stationary) case, the sun is off to the side. Then only half the CM is visible to the sun, But since the aspect of the CM presented to the sun changes, the form factor changes. If you were to sample the skin temperature of the CM under this scenario, the hottest point would be the line from apex to base most directly aimed at the sun. The temperature would fall off as you measured around toward the dark side.

So the alleged 250 F temperature only applies to a foot-wide strip of metal most directly presented to the sun. The rest is cooler -- in many cases substantially cooler.

If the incident solar radiation is so great as you presume that it is the main heat load, then why do they need heaters in the cooling system?

In case their engine fails and strands them on the dark side of the moon. [img]/phpBB/images/smiles/icon_smile.gif[/img]

The ECS was both a heater and an air conditioner, cleverly using the same cabin radiator. As the air circulated, it passed over a radiator which could tap into the ECS coolant flow at different points. If the cabin is too cold, it taps into the coolant loop right after it picks up all the heat from the cold plates and before it goes to the SM radiators. This dumps some of the heat into the cabin air.

If the cabin is too warm, it taps into the coolant loop right after it comes back from the radiators so that some of the heat in the cabin air is pulled into the coolant before it goes to the cold plates. The resulting diminished capacity to cool the electronics is compensated by adjusting coolant flow.

Yes, it very clearly states that those radiators are exclusively for the electrical power system fuel cells, and do not control cooling for the rest of the electronics and electrical components within the Service Module or the Command Module.

SAMU is obviously confused by the nomenclature. The reference I gave provides a high-level description of the system layout in the CSM.