Heat Shields - Things Kerbal Space Program Doesn't Teach
Why Space Exploration Stack Exchange recommends it
Space Stack Exchange answerers link it when explaining why re-entry heating happens and how heat shields deal with it.
Recommended by 3 people across 3 different months, 2019 to 2021.
What it is
Scott Manley explains the aerothermodynamics of atmospheric re-entry and how spacecraft heat shields work, covering how kinetic energy becomes heat and the engineering used to protect hardware. It is a roughly 18-minute explainer that goes beyond what Kerbal Space Program shows players.
What people said
Recommends Jarred Allen · 2019-01 · Space Exploration Stack Exchange · on “What's the minimium velocity for re-entry flames to start?”
Spacecraft usually do not burn on re-entry, in the usual sense of burning. Burning implies a combustion reaction, which does not happen on a spacecraft designed for it, and even spacecraft not designed for it usually won't burn, because they're not made of flammable materials; they just break apart under the thermal and physical stresses. However, upon re-entry from orbit, there is a lot of re-entry heating. This is caused by adiabatic compression [LINK] , a process in which air heats up as it is compressed. The air heats up a lot from this compression, which is what causes the bright glow of re-entry. This will happen in the vicinity of any object which is traveling at hypersonic speed [LIN
Recommends Schwern · 2019-02 · Space Exploration Stack Exchange · on “Cheapest rocket to go to space?”
They say space is hard [LINK] . If you simply plop a big tube full of fuel and oxidizer on top of a surplus engine and light it, you will not go to space today [LINK] . To get a feel of the smallest shoestring you can have and still get to space, look at Rocket Lab [LINK] in New Zealand. They've spent the last 10 years or so developing the ability to reliably go to space. Their Electron rocket [LINK] is one of the smallest orbital rockets ever designed. It can send about 150 kg into orbit for the low, low price of $6 million. At \$40,000/kg that's quite expensive; SpaceX can lift much more at prices below \$10,000/kg. What Electron offers is fast turn around time, a unique launch location (N
Recommends Wesley Adams · 2021-04 · Space Exploration Stack Exchange · on “Would it be possible to avoid the heat-from-friction problem when re-entering the atmosphere by performing (vertical) "U-turns"?”
What you're suggesting is an aerodynamic reentry, where aerodynamic surfaces are used to slow the rate of descent into the lower atmosphere. In the real world, heat shields are often shaped in such a way as to generate lift. But wings are almost never used. That's because it's very hard to make an aero-spacecraft that's able to maintain level flight at hyper sonic velocities. It's a common misconception that friction is the primary source of heat on reentry. In actuality, the vehicle creates a zone of extremely compressed air ahead of itself. This increase in pressure super heats the atmosphere. The problem with efficient (level-flight capable) aerodynamics at near-orbital velocities is that