ablation

ablation

1. Medicine the surgical removal of an organ, structure, or part

2. Astronautics the melting or wearing away of an expendable part, such as the heat shield of a space re-entry vehicle on passing through the earth's atmosphere

3. Geology the wearing away of a rock or glacier

ablation

(ab-lay -shŏn) The loss of material from the surface of a moving body as a result of vaporization, friction, etc. For example, atmospheric atoms and molecules erode the surface of a meteoroid and damage the protective heat shield of a returning space shuttle.

Ablation

 

in glaciology, the wasting of the mass of a glacier or snow cover as a result of thawing, evaporation, or mechanical removal—for example, wind ablation or the falling of icebergs. It is caused chiefly by climatic factors.

Three types of ablation are distinguished according to place of appearance: subglacial (or bottom), internal, and surface. The internal heat of the earth, springs (particularly warm ones) surfacing in the glacier bed, and heat caused by the friction of the glacier in its bed are some of the causes of subglacial ablation. Internal ablation is caused by friction between the glacier components and by the circulation of water and air. The glacier surface receives warmth predominantly from solar radiation and from the air. The thermal balance of the glacier surface is the basis of all surface ablation processes. The term “ablation” is sometimes used as well as a synonym for “surface washoff.”

ablation

[ə′blā·shən]

(aerospace engineering)

The intentional removal of material from a nose cone or spacecraft during high-speed movement through a planetary atmosphere to provide thermal protection to the underlying structure.

(geology)

The wearing away of rocks, as by erosion or weathering.

(hydrology)

The reduction in volume of a glacier due to melting and evaporation.

(medicine)

The removal of tissue or a part of the body by surgery, such as by excision or amputation.