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An example of a steel heat shield on a BMW E series engine Rigid heat shields have until recently commonly been made from solid steel, [5] but are now often made from aluminum. Some high-end rigid heat shields are made out of either aluminum, gold or composite, with most examples including a ceramic coating to provide a thermal barrier , which ...
The key to a reusable shield against this type of heating is very low-density material, similar to how a thermos bottle inhibits convective heat transfer. [citation needed] Some high-temperature metal alloys can withstand reentry heat; they simply get hot and re-radiate the absorbed heat.
MLI prevents both heat losses to the environment and excessive heating from the environment. Spacecraft components such as propellant tanks, propellant lines, batteries, and solid rocket motors are also covered in MLI blankets to maintain ideal operating temperature. MLI consist of an outer cover layer, interior layer, and an inner cover layer.
The slightly curved heat shield on the bottom consists of "21mm to 28mm thick ablator (glass-phenolic composite) which is held by brackets approximately 15mm from the 3.5mm thick aluminum AMg-6 substrate. VIM low-density silica fibrous insulation (8mm thick) is contained in the gap between the heat shield ablator and aluminum substrate." [9]
The heat shield absorbs some of this energy while much is also dissipated into the atmospheric gasses, mostly by radiation. During the latter stages of descent, a parachute is typically deployed and any heat shield is detached. Rockets may be located at the back shell to assist in control or to retropropulsively slow descent. Airbags may also ...
Atmospheric re-entry spacecraft use phenol formaldehyde resin as a key component in ablative heat shields (e.g. AVCOAT on the Apollo modules). As the heat shield skin temperature can reach 1000-2000 °C, the resin pyrolizes due to aerodynamic heating. This reaction absorbs significant thermal energy, insulating the deeper layers of the heat shield.
AVCOAT was used for the heat shield on NASA's Apollo command module. [4] In its final Apollo form, this material was called AVCOAT 5026–39. Although AVCOAT was not used for the Space Shuttle orbiters, NASA again used the material for its Orion spacecraft [5] first for the initial Orion test and then for a different type of heat shield for the later Orions.
The rounded shape (blunt body) of a capsule forms a shock wave that keeps most of the heat away from the heat shield, but a thermal protection system is still necessary. The space capsule must be strong enough to withstand reentry forces such as drag , and must reenter at a precise angle of attack to prevent a skip off the surface of the ...
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