Disaster on Mars, Part II — Heat

Designing for not Freezing (or Cooking) to Death

The next problem I want to tackle in disaster terms for a Martian habitat is the problem of heat. In this scenario, active cooling and heating are out of commission, possibly because of a total or partial loss of power. For our design, we want to maximize the time that astronauts have to restore thermal regulation to the habitat.

Getting a Grip on Thermal Transfer

The quickest way to wrap our heads around the problem of heat, whether it's too much or too little, is by looking at Newton’s Law of Cooling:

Qv = A * k * dT

In this formula, A is surface area in square meters, dT is the temperature gradient between an object and its surroundings, and k is a coefficient that reflects the thermal transmittance of the medium, the medium being the atmosphere on the surface of Mars — this is referred to as the u-value. The average temperature of the surface of Mars is -63 Celsius, and we want to warm it up to somewhere around 22 degree Celsius (about 72 degrees Fahrenheit), for a total of 85 degrees.

It’s not difficult to plug in numbers for a habitat size, and end up with the total heat transfer involved, but we can skip ahead in our thinking and focus on that u-value — the degree to which heat is…