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LI-900 is a type of reusable surface insulation tile developed and manufactured by
NASA facts on the Orbiter Thermal Protection System
Space Shuttle program Thermal protection Lockheed Corporation
Lockheed Missiles and Space Company
Lockheed Missiles and Space Company (LMSC) was a unit of the Lockheed Corporation "Missiles, Space, and Electronics Systems Group." LMSC was started by Willis Hawkins who served as its president. After Lockheed merged with Martin-Marietta the ...
in Sunnyvale, California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. It was designed for use on the Space Shuttle orbiter
The Space Shuttle orbiter is the spaceplane component of the Space Shuttle, a partially reusable orbital spacecraft system that was part of the discontinued Space Shuttle program. Operated from 1977 to 2011 by NASA, the U.S. space agency, thi ...
as part of its thermal protection system
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the entr ...
to minimize thermal conductivity
The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...
while providing maximum thermal shock
Thermal shock is a type of rapidly transient mechanical load.
By definition, it is a mechanical load caused by a rapid change of temperature of a certain point.
It can be also extended to the case of a thermal gradient, which makes different pa ...
resistance.
Statistics
LI-900 has a bulk density of 144.2 kg/m3 (9 lb/ft3). It was for this reason that it was called the LI-900. It is made from 99.9% pure silica glass fibres, and is 94% air by volume. An LI-900 tile can be heated to and then immediately plunged into cold water and suffer no damage. Black and white tiles were used on the Space Shuttle to control the temperature of the vehicle while in orbit. * White tiles (known as LRSI) were used mainly on the upper surface and have higher thermal reflectivity. These are therefore pointed towards the sun in order to minimize solar gain. * Black tiles (known as HRSI) are optimized for maximum emissivity, which means they lose heat faster than white tiles. This property is required in order to maximise heat rejection during re-entry. There are typically 20,000 HRSI LI-900 tiles on a Space Shuttle, and 725 LRSI LI-900 tiles.Problems
Strength
As a result of optimizing its thermal properties, overall strength was reduced. The tile was therefore not suitable to be used in high-stress areas such as around the landing gear doors and windows. To solve this, a higher strength version of the LI-900 material was produced, with a bulk density of 352.4 kg/m3 (22 lb/ft3), which was called the LI-2200. This tile provided the strength and insulating properties, but with a considerable weight penalty.See also
*Space Shuttle thermal protection system
The Space Shuttle thermal protection system (TPS) is the barrier that protected the Space Shuttle Orbiter during the searing heat of atmospheric reentry. A secondary goal was to protect from the heat and cold of space while in orbit.
Material ...
* Atmospheric reentry
References
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NASA facts on the Orbiter Thermal Protection System
Space Shuttle program Thermal protection Lockheed Corporation