# Tag Info

25

Reaction control system jet interactions with a vehicle's aerodynamic flowfield can be counterintuitive. Here's a capsule simulation results graphic showing similar spreading effects below the jet as well as laterally (from the first link below). This paper states in reference to Apollo: Interference heating in the case of the yaw and roll jets covered ...

9

Ammonia is used because it has excellent heat transfer properties (as you mention) and a low freezing point. Because of its toxicity, the ISS has internal coolant loops which use water as a heat transfer fluid. Only the heat exchangers where the two systems interface allow for the possibility of ammonia leaks into the cabin. After detailed engineering ...

5

New Horizon's Integrated Electronics Modules are not pressurized. The spacecraft's thermal control system works by managing radiant and conductive heat transfer, not by convection. The approach taken by New Horizons is to retain heat like a thermos bottle – New Horizons is already in the vacuum of space where no conductive and convective heat will be lost ...

5

Unfortunately telemetry readings aren't shown on ISSLive.com (Tristan has actually pointed out to me there is no telemetry, which to me is a surprise, but there you go). See this analysis for the ISS. It is an analysis rather than a measurement and was performed in 1997 and so take it with a pinch of salt. Headline is -100 degF (-73°C) in eclipse to +150 ...

4

You asked for corrections, and indeed I see three immediately. They involve: a material's emissivity; its specific heat; and the concept of back radiation. The full-up expression of the Stefan-Boltzmann law for calculating radiated power is P = A${\epsilon}{\sigma}T^4$, where P is the radiated power, A is the effective radiating area, and $\epsilon$ is the ...

3

I find it useful to start with the basics: steady state. In real practical systems, there's all sorts of transients and dynamics to deal with, but the fundamentals can be understood in the steady state case. At the absolute basics of this, you have $S=I-O$. Storage rate is the difference between the input rate and the output rate. This is a very general ...

3

As you used the ISS as an example, one may look up what kind of pump power is required for all of that: https://www.nasa.gov/pdf/473486main_iss_atcs_overview.pdf 2x PFCS ("Pump Flow Control Subassemblies"), each at 275W. What costs energy in a cooling system is moving fluid around. In the case of the ISS, it's around 7.5tons per hour. (But if you ...

2

I think one thing to consider here is that the ISS's solar panels are not fixed and rotating with the station, they have their own rotating action (see ) so they always face the sun. The idea to have solar panels always blocking the sun from hitting the habitat (and probably more importantly the propellant tanks which likely ...

1

This is a partial answer hoping to address some points in the question that may help the OP to formulate it better. I understand heat is a scalar, and power is a vector. Heat is measured in joules and power is measured in joules/second (the watt). This is close, but power doesn't have to be a vector by itself; a 100 W light bulb (remember those) doesn't ...

1

How much aerodynamic heating is left in the atmosphere, vs how much is retained/reabsorbed tl;dr: By necessity nearly all of it must be left in the atmosphere or radiated into space or towards Earth, and only a tiny bit could be absorbed. Using $E = 1/2 m v^2$ and an initial velocity of 7800 m/s, we see that each kilogram of a reentering body starts with ...

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