User:Rush1970/Heat shield

Article Draft

Spacecraft[edit]

Main articles: Atmospheric entry § Thermal protection systems, and Aeroshell

See also: Atmospheric entry and Reusable launch system

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Spacecraft that land on a planet with an atmosphere, such as Earth, Mars, and Venus, currently do so by entering the atmosphere at high speeds, depending on air resistance rather than rocket power to slow them down. A side effect of this method of atmospheric re-entry is aerodynamic heating, which can be highly destructive to the structure of an unprotected or faulty spacecraft. An aerodynamic heat shield consists of a protective layer of special materials to dissipate the heat. Two basic types of aerodynamic heat shield have been used:

• An ablative heat shield consists of a layer of plastic resin, the outer surface of which is heated to a gas, which then carries the heat away by convection. Such shields were used on the Mercury, Gemini, and Apollo spacecraft, and are currently used by the SpaceX Dragon 2 spacecraft and the Orion spacecraft.
• Possible Additions:
  • Design Process leading to use of shielding
  • Further uses of heat shields in space related craft
    • Ablative shielding used for external tanks of the space shuttle
    • Ablative Shielding used for Mars Rover
    • Used in designing SpaceX craft
  • Important developments in the ablative heat shield technology
    • SLA Ablator
    • PICA Ablator
• A thermal soak heat shield uses an insulating material to absorb and radiate the heat away from the spacecraft structure. This type was used on the Space Shuttle, consisting of ceramic or composite tiles over most of the vehicle surface, with reinforced carbon-carbon material on the highest heat load points (the nose and wing leading edges). Damage to this material on the left wing caused the 2003 Space Shuttle Columbia disaster.

With possible inflatable heat shields, as developed by the US (Low Earth Orbit Flight Test Inflatable Decelerator - LOFTID) and China, single-use rockets like the Space Launch System are considered to be retrofitted with such heat shields to salvage the expensive engines, possibly reducing the costs of launches significantly.

The Russian Vostok 1, the first manned spacecraft, used ablative heat shielding made from asbestos fabric in resin. The succeeding Mercury and Gemini missions both used fiber glass in the resin, while the Apollo spacecraft using a quartz fiber reinforced resin. The first use of a super-light ablator(SLA) spacecraft purposes was for the Viking Landers in 1976. This material would also be utilized for the Pathfinder mission. Phenolic impregnated carbon ablators(PICA) was used for the Stardust mission launched in 1999.

Response to Peer Review:

• Add information about the make of the Mercury and Gemini ablators.
  • Comment: "Also in that paragraph, the Mercury, Gemini, and Apollo spacecrafts are mentioned but they were also mentioned as using ablative heat shields in a previous paragraph. I don't think that they need to be mentioned twice except for the Apollo spacecraft since good detail was provided about the make of the shield that wasn't provided earlier in the article. If you're able to find information about the make of the shields in the Mercury and Gemini spacecrafts, that could be a good addition as well."
    • If information is not available, may need to focus on Apollo only.
    • Could possibly remove "Such shields were used on the Mercury, Gemini, and Apollo spacecraft, and are currently used by the SpaceX Dragon 2 spacecraft and the Orion spacecraft." in existing section in favor of more detailed examination.
• Find more historical context for the thermal soak type of heat shield.
  • Comment: "I think the paragraph I mentioned could be moved up to the ablative heat shield section since each of the mentioned spacecrafts in your paragraph utilized that style of heat shield. However, if you plan to add examples of the thermal soak heat shield to that paragraph later on I think it's fine where it is."
• Add information about the future technologies/applications
  • Comment: "adding what new technologies are being developed now and what could be done with them in the future would be a good addition to this section"
    • Likely, most reliable sources will be from NASA and other space agencies
    • Most of future technologies will likely involve ablative shielding rather than thermal soak shield.
• General:
  • Add more hyperlinks
  • Make sure tone fits Wikipedia standards
  • Find citations for overall article and for the section
    • Comment: " I think getting some more sources would help you make additions. Lastly, looking at the Wikipedia page for the article I see some stuff that doesn't have a citation."
      • Need to find more diverse sources rather than being reliant on one source

With possible inflatable heat shields, as developed by the US (Low Earth Orbit Flight Test Inflatable Decelerator - LOFTID) and China, single-use rockets like the Space Launch System are considered to be retrofitted with such heat shields to salvage the expensive engines, possibly reducing the costs of launches significantly. On November 10, 2022, LOFTID was launched using an Atlas V rocket and, then, detached in order to reenter the atmosphere. The outer layer of the heat shield consisted of a silicon carbide ceramic. The recovered LOFTID has minimal damage.

In modern vehicles, passive cooling can be found as reinforced carbon–carbon material instead of metal. This material constitutes the thermal protection system of the nose and the front edges of the Space Shuttle and was proposed for the vehicle X-33. Carbon is the most refractory material known with a sublimation temperature (for graphite) of 3825 °C. These characteristics make it a material particularly suitable for passive cooling, but with the disadvantage of being very expensive and fragile. Some spacecraft also use a heat shield (in the conventional automotive sense) to protect fuel tanks and equipment from the heat produced by a large rocket engine. Such shields were used on the Apollo Service Module and Lunar Module descent stage. The Parker Solar Probe , designed to enter the corona of the Sun, experiences a surface temperature of 2,500 °F. To withstand this temperature without damage to its body or instruments, the spacecraft uses a carbon-carbon ceramic with a layer of carbon foam in between as a heat shield. The probe was launched into space on August 18, 2018.

Example of Ablative Heat Shield used for Gemini Missions