ablation
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Ablation of Mercury capsule model.
Credit: NASA
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Removal of the surface layers of a meteorite
during its passage through the atmosphere.
• METEORS
AND METEORITES
- Removal of surface material such as occurs in a combustion
chamber, or the controlled degradation of the leading surfaces of
a spacecraft during atmospheric reentry
or passage through a dusty medium in space, such as the tail of a comet.
An expendable surface made of ablative material may be used as a coating
in a combustion chamber, or on the heat shield of a reentry vehicle.
As the ablative material absorbs heat it changes chemical or physical
state and sheds mass, thereby carrying the heat away from the rest of
the structure.
See also reentry thermal
protection.
• REENTRY
PHYSICS AND TERMINOLOGY
- In glaciology, the loss of snow and ice from the surface of a glacier
by melting, evaporation, or sublimation;
also, the quantity so lost.
• GEOLOGY
AND PLANETARY SCIENCE
- The removal of dead or diseased tissue by excision (cuttig away with
a sharp instrument), cryosurgery (freezing), radiotherapy, diathermy
(burning), or laser treatment. Ablation of the thyroid
gland is achieved with radioactive iodine
isotopes.
• HEALTH
AND DISEASE
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