Heats generated during atmospheric entry

[Loren Booda]

Consider a hypothetical planet of given radius and mass. What atmospheric density would generate the most frictional heating on a standard sphere falling from infinity to the planet surface?

 

[Danger]

Neutronium, although I don't think that most people would categorize it as an 'atmosphere'.

 

[Loren Booda]

Wouldn't neutronium, not being a fluid, inhibit the sphere from falling to the planet? I was thinking more of a gaseous atmosphere, whose density at anyone altitude (for the hypothetical planet mentioned) happens to be dependent on its depth, or total mass

 

[russ_watters]

At high energy, everything is a fluid. The question doesn't have an answer other than higher density = more friction.

 

[Loren Booda]

How about higher density --> 1. more buoyancy; 2. slower entry (due to friction overall); 3. greater heat conduction

 

[russ_watters]

If you're dropping the object from infinity, the entry speed is determined by gravity. A thicker atmosphere doesn't change that, it just slows the object down faster once it gets there (generating more heat).

Buoyancy is not ever a factor.

Conduction and convection are not factors.