LI-900 silica tile (shuttle HRSI) LI-900
Silica (SiO2) glass fibre tile: 100% SiO2 per TPSX
Also known as LI-900
LI-900 is a rigid tile of silica glass fibre that was the black high-temperature reusable surface insulation (HRSI) on Space Shuttle orbiters.
Evidence level
5 of 5
Flown or field-proven
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Insulation
0.0476 W/m-K
Temperature
1260 °C
Reuse
To 1648K (2500F)
Recipe, share of the weight
- SiO2 not statedSilica glass fibre
- not statedAir in the pores
Best for
Reusable insulation on the hot underside of a re-entering vehicle, where very low density and low thermal conductivity matter more than strength (Wikipedia states the design aim as minimising thermal conductivity while giving maximum thermal shock resistance)
Weakest at
Strength. TPSX gives a tensile strength of 1.65e+05 Pa through the thickness at room temperature, and Wikipedia says the tile is unsuitable for high-stress areas such as around the landing gear doors and windows
Risk at a glance
- People None found. Silica substance only, no tile SDS
- If it fails High. Low strength in high-stress areas
- Corrosion Low. The 1972 NASA program reports that LI-900 with its coating can be reused to 1648K (2500F) without significant loss of mechanical or thermal performance.
Quick facts: LI-900
| Property | Value | Basis |
|---|---|---|
| Density | 0.14 g/cm³ | 2 sourced values across conditions |
| Thermal conductivity | 0.048 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | 0.4 ppm/K | 1 sourced value |
| Melting point | 1,705 °C | 1 sourced value |
| Maximum service temperature | 1,260 to 1,375 °C | 2 sourced values across conditions |
What is the density of LI-900 silica tile (shuttle HRSI)?
LI-900 silica tile (shuttle HRSI) has a density of 0.14 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of LI-900 silica tile (shuttle HRSI)?
LI-900 silica tile (shuttle HRSI) has a thermal conductivity of 0.048 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of LI-900 silica tile (shuttle HRSI)?
LI-900 silica tile (shuttle HRSI) has a coefficient of thermal expansion of 0.4 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of LI-900 silica tile (shuttle HRSI)?
LI-900 silica tile (shuttle HRSI) has a melting point of 1,705 °C. The source and test conditions are listed in the properties table on this page.
What is the maximum service temperature of LI-900 silica tile (shuttle HRSI)?
LI-900 silica tile (shuttle HRSI) has a maximum service temperature of 1,260 to 1,375 °C. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is LI-900 silica tile (shuttle HRSI) used for?
Uses recorded in the sources include Black high-temperature reusable surface insulation (HRSI) tiles on the Space Shuttle orbiter underside; White low-temperature reusable surface insulation (LRSI) tiles on the upper surface; All-silica rigidized surface insulation (RSI) thermal protection system concept for the Space Shuttle.
Why it exists
LI-900 was developed as a lightweight, all-silica reusable insulation for the Space Shuttle. Lockheed's earlier all-silica material of the same family was tested extensively before LI-900 (1972 NASA report). The program reduced the density to 144 kg/m^3 (9 lb/cu ft) to create LI-900 (NTRS 19740020226). The design trades strength for insulation: TPSX gives a low thermal conductivity, and Wikipedia says optimising the thermal properties reduced the overall strength. NASA Technical Paper 3276 gives a method for predicting the thermal conductivity of this class of silica insulation, and extends it to the upper temperature limits (NTRS 19930008736, abstract).
Where it's used
Underside of the Space Shuttle (black HRSI tiles)
A typical Shuttle carried about 20,000 HRSI LI-900 tiles, according to Wikipedia. Black tiles have higher emissivity, so they shed heat faster during re-entry.
Upper surface of the Space Shuttle (white LRSI tiles)
The white LI-900 tiles have higher thermal reflectivity and face the sun to reduce solar gain. A typical Shuttle carried about 725 LRSI LI-900 tiles, according to Wikipedia.
1972 NASA all-silica TPS concept
The 1972 report presents the materials and design technology for the all-silica LI-900 RSI TPS concept and states that the tile demonstrated that it meets Space Shuttle mission and life requirements.
Recipe
Silica (SiO2) glass fibre tile: 100% SiO2 per TPSX; 99.9% pure silica glass fibres per Wikipedia
LI-900 is a tile of silica glass fibre with most of its volume taken up by air. Wikipedia says the tile is made from very pure quartz sand, but the sources fetched do not describe how the tiles were made.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Silica glass fibre SiO2 | not stated | The solid framework of the tile. Wikipedia says the design aim was to minimise thermal conductivity while giving maximum thermal shock resistance. |
| Air in the pores | not stated | Most of the tile volume. Together with the fibre it sets the bulk density of 144 kg/m^3 (9 lb/ft^3). |
Weight shares are as printed in the sources.
What it can do
Insulation
0.0476 W/m-K
measured
Through the thickness the tile has a thermal conductivity of 4.76e-02 W/m-K, as printed by TPSX. TPSX marks this as a dynamic value for transient environments.
Temperature
1260 °C
measured
TPSX predicts a multiple-use temperature limit of 1.59e+03 K. Wikipedia says the tile can be heated to 1,204°C and then plunged into cold water without damage.
Reuse
To 1648K (2500F)
The 1972 NASA program found that the LI-900 material and coating system can be reused to 1648K (2500F) with no significant degradation of its mechanical and thermal performance (NTRS 19740020226, conclusions).
Strength
At room temperature the tensile strength is 1.65e+05 Pa through the thickness (TPSX). Wikipedia says the tile is unsuitable for high-stress areas.
How it compares
Within the NASA and Wikipedia sources, LI-900 trades strength for insulation. Wikipedia says a stronger version of the tile exists, which gives more strength and insulation but carries a considerable weight penalty. Its figures are not included here because they are for a different grade. The table below sets LI-900's density, thermal conductivity and tensile strength side by side.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | LI-900 |
|---|---|
| Thermal behavior and safety | |
| Thermal conductivity, through the thickness | 0.0476 W/m-K3 |
| Melting point, as stated in the TPSX notes | 1978 K8 |
| Physical and electrical | |
| Bulk density, uncoated tile | 144 kg/m^31 |
| Bulk density, stated in article | 144.2 kg/m^32 |
| Temperature behavior | |
| Softening onset, as stated in the TPSX notes | 1644 K9 |
| Other measurements | |
| Emissivity, uncoated tile | 0.88 -4 |
| Thermal expansion (CTE) | 4.05×10^-7 1/K5 |
| dielectric constant | 1.13 -6 |
| Loss tangent | 4×10^-4 -7 |
| Reuse temperature, 1972 NASA program | 1648 K10 |
| Black HRSI tile protection limit | 1260 °C11 |
| Air volume fraction, as stated in the Wikipedia article | 94 %12 |
Why choose it, and why not
Good for
- Low thermal conductivity: 4.76e-02 W/m-K through the thickness (TPSX), the property the tile was designed for.
- Reuse at high temperature: the 1972 NASA program reports reuse to 1648K (2500F) without significant degradation.
- Thermal shock: the tile can be heated to 1,204°C and plunged into cold water without damage (Wikipedia).
Watch out for
- Low strength: the tensile strength is 1.65e+05 Pa through the thickness (TPSX), and Wikipedia says the tile is unsuitable for high-stress areas.
- Coated and uncoated numbers differ in scope. TPSX gives the density and emissivity for the uncoated tile, while the black flight tile is coated.
- The sources disagree on tile counts, air fraction and manufacturer. Each value is stated with its source (see gaps).
LI-900 suits reusable insulation where low density and low thermal conductivity matter more than strength. The NASA data support reuse to 1648K (2500F). The emissivity of the coated tile is not in the sources we hold. PubChem classifies the silica substance, but we hold no classification for the LI-900 tile itself.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | LI-900 (Rigid tile) |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Bulk density, uncoated tile | Measured value on the TPSX property table (source column: measured; interpolated(T) flag as printed) | state uncoated tilestandard conditions TPSX STP flag TRUE for the density rowuncertainty 2.11e+00 kg/m^3 as printed | — |
| 2 | Bulk density, stated in article | Stated value in the Stated properties list of the Wikipedia LI-900 article | basis stated as 9 lb/ft3 in the same sentence | The Wikipedia Space Shuttle TPS article gives 140 kg/m3 in its text and 144 kg/m3 in its density table, so the sources differ by a rounding step. |
| 3 | Thermal conductivity, through the thickness | Measured value on the TPSX property table (source column: measured; STP flag TRUE) | direction through the thicknessregime dynamic values for transient environments (as the TPSX row notes)uncertainty 8.57e-03 W/m-K as printed | — |
| 4 | Emissivity, uncoated tile | Measured at room temperature on the TPSX property table, ref 3 | state uncoated tiletemperature room temperature measured; higher temperatures extrapolated (TPSX note)uncertainty 4.40e-02 as printed | The value is for the uncoated tile. The black flight tile carries a coating, and no emissivity for the coated tile was found in our sources. |
| 5 | Thermal expansion (CTE) | Measured value on the TPSX property table (source column: measured; STP flag TRUE) | basis isotropic, assumed by TPSXuncertainty 4.86e-08 1/K as printed | — |
| 6 | dielectric constant | Measured value on the TPSX property table (source column: measured; flag nonstp as printed) | frequency 10 GHztemperature room temperatureuncertainty 5.65e-03 as printed | — |
| 7 | Loss tangent | Measured value on the TPSX property table (source column: measured; flag nonstp as printed) | frequency 10 GHztemperature room temperatureuncertainty 2.00e-05 as printed | — |
| 8 | Melting point, as stated in the TPSX notes | Stated in the TPSX notes on the temperature limit rows, not a separate measured row | basis approximate; printed as 'melts at about 1978K (3100F)' | — |
| 9 | Softening onset, as stated in the TPSX notes | Stated in the TPSX notes on the temperature limit rows, not a separate measured row | basis the material softens above this temperature; printed as '1644K (2500F)' | — |
| 10 | Reuse temperature, 1972 NASA program | Stated in the report conclusions as a summary of program tests, not a separate table row | material LI-900 with its coatingbasis program test results as summarised in the report conclusions; printed as '1648°K (2500°F)'text source OCR text layer of the NTRS PDF | — |
| 11 | Black HRSI tile protection limit | Stated in the Wikipedia TPS article as a design statement, not a test row | tile black HRSI tile on the Space Shuttle orbiter undersidebasis printed as '1,260 °C (2,300 °F)' in the Wikipedia TPS article | — |
| 12 | Air volume fraction, as stated in the Wikipedia article | Stated in the Wikipedia LI-900 article text, not a measured row | basis by volume; printed as '94% air by volume' in the composition sentence | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Repeated re-entry heating and reuse | low | The 1972 NASA program reports that LI-900 with its coating can be reused to 1648K (2500F) without significant loss of mechanical or thermal performance.1 |
| Water in tiles that are not waterproofed, during ascent and re-entry | low | High water content in non-waterproofed tiles can cause a slight loss of coating during ascent and re-entry.2 |
| Cold soak followed by a re-entry heat pulse | low | A cold soak at 116K (-250F) followed by a re-entry heat pulse had no effect on the LI-900 material, according to the 1972 report.3 |
| Quench from high temperature into cold water | low | Wikipedia says the tile can be heated to 1,204°C and plunged into cold water without damage.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Repeated re-entry heating and reuse | The report's conclusions say the LI-900 material and coating system has reuse capability to 1648K (2500F), and that its mechanical and thermal performances do not significantly degrade with use. It adds that the strength properties are not appreciably affected by high-temperature reuse. | basis program test results as summarised in the report conclusionsmaterial LI-900 with its coatingtext source OCR text layer of the NTRS PDF; the scan was not checked visually |
| 2 | Water in tiles that are not waterproofed, during ascent and re-entry | The report says the slight coating loss had no effect on heat-shielding capability. | tile non-waterproofed, high water contentenvironment ascent and re-entry thermal and pressure environmenttext source OCR text layer of the NTRS PDF |
| 3 | Cold soak followed by a re-entry heat pulse | The report says LI-900 and its coating are compatible and, because of their low thermal expansion, the materials are thermally shock-resistant. | cold soak 116K (-250F) as printedtext source OCR text layer of the NTRS PDF; the OCR reads the cold-soak temperature with some error |
| 4 | Quench from high temperature into cold water | The article gives this as a stated property. It is a single statement about thermal shock; the article gives no cycle count or test series. | temperature 1,204°C (1,477K; 2,199F) as printedmedium cold water |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
PubChem's ECHA entries cover the silica substance, not the tile. Vitreous silica is reported as not meeting GHS criteria, and amorphous silica is an irritant (H315, H319, H335). We found no safety data sheet for LI-900 itself.
- The tile
- The TPSX record and the Wikipedia articles describe composition, density and temperature limits, but they say nothing about hazards to people.
On the vehicle
These are design limits and test results for the tile on the orbiter, not incident reports.
- Re-entry heat
- The black HRSI tiles were used where the re-entry temperature was below 1,260°C, according to the Wikipedia Space Shuttle TPS article.
- Softening
- TPSX says the tile softens above 1644K (2500F) and melts at about 1978K (3100F).
- Strength
- Wikipedia says the tile is unsuitable for high-stress areas such as around the landing gear doors and windows.
Handling and storage
- Storage
- The sources fetched in this run give no storage rule for LI-900 (see gaps).
- Water
- The 1972 report says high water content in tiles that are not waterproofed can cause a slight coating loss during ascent and re-entry.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Low strength in high-stress areashigh severity | Use in high-stress areas such as around the landing gear doors and windowsWikipedia says optimising the tile's thermal properties reduced its overall strength, so the tile was unsuitable for those areas. |
| Softening at high temperaturehigh severity | Exposure above the multiple-use temperature limitTPSX says the tile softens above 1644K (2500F) and melts at about 1978K (3100F). Its predicted multiple-use limit is 1.59e+03 K. |
| Coating loss from water in the tilelow severity | High water content in a tile that is not waterproofed, during ascent or re-entryA slight loss of coating. The report says there was no effect on heat-shielding capability. |
| Tension failure at the strain isolation pad of the HRSI systemmoderate severity | Stepped tension loading of an HRSI specimen, examined by microscope at each load stepA local failure occurred that the authors associate with load transfer through transverse fibres in the strain isolation pad (SIP), the tension failure mode of SIP behaviour. |
Handling and storage
- Each tile is fitted individually. The Wikipedia Space Shuttle TPS article says about 24,300 unique tiles were individually fitted on the vehicle.
- Keep water out of tiles that are not waterproofed. The 1972 report links high water content to a slight coating loss during ascent and re-entry.
Mitigations
- The strain arrestor plate reduces tile and coating stresses under all load and temperature conditions, according to the 1972 report.
Supply and geography
How common the raw materials are and where they come from.
Industrial silica sand (quartz sand, the feedstock for silica glass)
USGS: quartz-rich sand and sandstone, the main sources of industrial silica sand, occur throughout the world. The US reserve is rated Large.
- Top producers (2025)
- United States 27.9%, China 21.4%, Netherlands 15.8%
- Recycling
- USGS: about 33% of glass containers are recycled, and recycled cullet is a significant proportion of reused silica.
- Substitutes
- USGS: alternatives for glassmaking, foundry and molding sands are chromite, olivine, staurolite and zircon sands.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: li-900-tile
spore_version: 0.2
family: silica
name: LI-900 silica tile (shuttle HRSI)
abbreviation: LI-900
role: Reusable surface insulation tile (black HRSI on the Space Shuttle orbiter)
category: thermal-protection
type: reusable-tiles
summary: |
LI-900 is a rigid tile of silica glass fibre that was the black high-temperature reusable surface insulation (HRSI) on Space Shuttle orbiters. NASA's TPSX database gives a density of 1.44e+02 kg/m^3 for the uncoated tile and a through-thickness thermal conductivity of 4.76e-02 W/m-K, both marked as measured. TPSX also gives a predicted multiple-use temperature limit of 1.59e+03 K. Wikipedia says a typical Shuttle carried about 20,000 HRSI LI-900 tiles, and that optimising the tile's thermal properties reduced its overall strength.
best_for: Reusable insulation on the hot underside of a re-entering vehicle, where very low density and low thermal conductivity matter more than strength (Wikipedia states the design aim as minimising thermal conductivity while giving maximum thermal shock resistance)
weakest_at: Strength. TPSX gives a tensile strength of 1.65e+05 Pa through the thickness at room temperature, and Wikipedia says the tile is unsuitable for high-stress areas such as around the landing gear doors and windows
identity:
formula: 'Silica (SiO2) glass fibre tile: 100% SiO2 per TPSX; 99.9% pure silica glass fibres per Wikipedia'
designations:
- system: Trade name
code: LI-900
note: Rigid tile
source: tpsx-li900
where: Material name field, 'LI-900 Rigid Tile'
source: tpsx-li900
where: Material name and Composition fields (TPSX Material id 1); the composition is also stated in the Wikipedia LI-900 article
tags:
environments:
- re-entry
applications:
- heat-shields
- thermal-control
properties:
- benchmark: density
label: Bulk density, uncoated tile
value: 144
unit: kg/m^3
scope: material
conditions:
state: uncoated tile
standard_conditions: TPSX STP flag TRUE for the density row
uncertainty: 2.11e+00 kg/m^3 as printed
method: 'Measured value on the TPSX property table (source column: measured; interpolated(T) flag as printed)'
status: ground
source: tpsx-li900
where: Properties at Standard Conditions (SI units) table, row Density, ref 1
- benchmark: density
label: Bulk density, stated in article
value: 144.2
unit: kg/m^3
scope: material
conditions:
basis: stated as 9 lb/ft3 in the same sentence
method: Stated value in the Stated properties list of the Wikipedia LI-900 article
status: ground
note: The Wikipedia Space Shuttle TPS article gives 140 kg/m3 in its text and 144 kg/m3 in its density table, so the sources differ by a rounding step.
source: wiki-li900
where: Stated properties, Bulk density
- benchmark: thermal_conductivity
label: Thermal conductivity, through the thickness
value: 0.0476
unit: W/m-K
scope: material
conditions:
direction: through the thickness
regime: dynamic values for transient environments (as the TPSX row notes)
uncertainty: 8.57e-03 W/m-K as printed
method: 'Measured value on the TPSX property table (source column: measured; STP flag TRUE)'
status: ground
source: tpsx-li900
where: Properties at Standard Conditions table, row Thermal Conductivity (Thru-the-Thickness), ref 4
- benchmark: emissivity
label: Emissivity, uncoated tile
value: 0.88
unit: '-'
scope: material
conditions:
state: uncoated tile
temperature: room temperature measured; higher temperatures extrapolated (TPSX note)
uncertainty: 4.40e-02 as printed
method: Measured at room temperature on the TPSX property table, ref 3
status: ground
note: The value is for the uncoated tile. The black flight tile carries a coating, and no emissivity for the coated tile was found in our sources.
source: tpsx-li900
where: Properties at Standard Conditions table, row Emissivity, ref 3
- benchmark: cte
value: 4.05e-7
unit: 1/K
scope: material
conditions:
basis: isotropic, assumed by TPSX
uncertainty: 4.86e-08 1/K as printed
method: 'Measured value on the TPSX property table (source column: measured; STP flag TRUE)'
status: ground
source: tpsx-li900
where: Properties at Standard Conditions table, row Coefficient of Thermal Expansion (Isotropic), ref 6
- benchmark: dielectric_constant
value: 1.13
unit: '-'
scope: material
conditions:
frequency: 10 GHz
temperature: room temperature
uncertainty: 5.65e-03 as printed
method: 'Measured value on the TPSX property table (source column: measured; flag nonstp as printed)'
status: ground
source: tpsx-li900
where: Properties at Standard Conditions table, row Dielectric Constant, ref 6
- benchmark: dissipation_factor
label: Loss tangent
value: 0.0004
unit: '-'
scope: material
conditions:
frequency: 10 GHz
temperature: room temperature
uncertainty: 2.00e-05 as printed
method: 'Measured value on the TPSX property table (source column: measured; flag nonstp as printed)'
status: ground
source: tpsx-li900
where: Properties at Standard Conditions table, row Loss Tangent, ref 6
- benchmark: melting_point
label: Melting point, as stated in the TPSX notes
value: 1978
unit: K
scope: material
conditions:
basis: approximate; printed as 'melts at about 1978K (3100F)'
method: Stated in the TPSX notes on the temperature limit rows, not a separate measured row
status: ground
source: tpsx-li900
where: Properties at Standard Conditions table, notes on rows Multiple Use and Single Use Temperature Limit
- benchmark: softening_temperature
label: Softening onset, as stated in the TPSX notes
value: 1644
unit: K
scope: material
conditions:
basis: the material softens above this temperature; printed as '1644K (2500F)'
method: Stated in the TPSX notes on the temperature limit rows, not a separate measured row
status: ground
source: tpsx-li900
where: Properties at Standard Conditions table, notes on rows Multiple Use and Single Use Temperature Limit
- benchmark: max_service_temp
label: Reuse temperature, 1972 NASA program
value: 1648
unit: K
scope: material
conditions:
material: LI-900 with its coating
basis: program test results as summarised in the report conclusions; printed as '1648°K (2500°F)'
text_source: OCR text layer of the NTRS PDF
method: Stated in the report conclusions as a summary of program tests, not a separate table row
status: ground
source: ntrs-19740020226
where: Conclusions, Volume 1 (OCR text layer)
- benchmark: max_service_temp
label: Black HRSI tile protection limit
value: 1260
unit: °C
scope: material
conditions:
tile: black HRSI tile on the Space Shuttle orbiter underside
basis: printed as '1,260 °C (2,300 °F)' in the Wikipedia TPS article
method: Stated in the Wikipedia TPS article as a design statement, not a test row
status: flight
source: wiki-tps
where: Black HRSI tile statement, Space Shuttle thermal protection system article
- benchmark: porosity
label: Air volume fraction, as stated in the Wikipedia article
value: 94
unit: '%'
scope: material
conditions:
basis: by volume; printed as '94% air by volume' in the composition sentence
method: Stated in the Wikipedia LI-900 article text, not a measured row
status: ground
source: wiki-li900
where: Article text, composition sentence
corrosion:
- environment: Repeated re-entry heating and reuse
headline: The 1972 NASA program reports that LI-900 with its coating can be reused to 1648K (2500F) without significant loss of mechanical or thermal performance.
effect: The report's conclusions say the LI-900 material and coating system has reuse capability to 1648K (2500F), and that its mechanical and thermal performances do not significantly degrade with use. It adds that the strength properties are not appreciably affected by high-temperature reuse.
rating: low
conditions:
basis: program test results as summarised in the report conclusions
material: LI-900 with its coating
text_source: OCR text layer of the NTRS PDF; the scan was not checked visually
source: ntrs-19740020226
where: Conclusions, Volume 1 (OCR text layer)
- environment: Water in tiles that are not waterproofed, during ascent and re-entry
headline: High water content in non-waterproofed tiles can cause a slight loss of coating during ascent and re-entry.
effect: The report says the slight coating loss had no effect on heat-shielding capability.
rating: low
conditions:
tile: non-waterproofed, high water content
environment: ascent and re-entry thermal and pressure environment
text_source: OCR text layer of the NTRS PDF
source: ntrs-19740020226
where: Summary, coating compatibility paragraph (OCR text layer)
- environment: Cold soak followed by a re-entry heat pulse
headline: A cold soak at 116K (-250F) followed by a re-entry heat pulse had no effect on the LI-900 material, according to the 1972 report.
effect: The report says LI-900 and its coating are compatible and, because of their low thermal expansion, the materials are thermally shock-resistant.
rating: low
conditions:
cold_soak: 116K (-250F) as printed
text_source: OCR text layer of the NTRS PDF; the OCR reads the cold-soak temperature with some error
source: ntrs-19740020226
where: Summary, coating compatibility paragraph (OCR text layer)
- environment: Quench from high temperature into cold water
headline: Wikipedia says the tile can be heated to 1,204°C and plunged into cold water without damage.
effect: The article gives this as a stated property. It is a single statement about thermal shock; the article gives no cycle count or test series.
rating: low
conditions:
temperature: 1,204°C (1,477K; 2,199F) as printed
medium: cold water
source: wiki-li900
where: Stated properties list
risks:
hazards:
- text: PubChem reports that vitreous silica (EC 262-373-8) does not meet GHS hazard criteria, as 1614 of 1682 company reports say. This describes the silica substance, not the LI-900 tile, for which we found no safety data sheet.
ghs: []
source: pubchem-sio2
where: Safety and Hazards, GHS Classification, ECHA entry 'Silica, vitreous' (ref. 102)
- text: PubChem lists amorphous silica (EC 601-216-3) as an irritant with pictogram GHS07 and signal word Warning. Its hazard statements are H315 (causes skin irritation), H319 (causes serious eye irritation) and H335 (may cause respiratory irritation), aggregated from 2540 company reports.
ghs:
- H315
- H319
- H335
source: pubchem-sio2
where: Safety and Hazards, GHS Classification, ECHA entry 'AMORPHOUS SILICA' (ref. 100)
- text: PubChem lists cristobalite, a crystalline form of silica (EC 238-455-4), as Danger with pictogram GHS08. Its hazard statements are H350 (may cause cancer) and H372 (causes damage to organs through prolonged or repeated exposure). Wikipedia describes LI-900 as silica glass fibres, so this crystalline-form entry is not applied to the tile.
ghs:
- H350
- H372
source: pubchem-sio2
where: Safety and Hazards, GHS Classification, ECHA entry 'Cristobalite' (ref. 98)
failure_risks:
- mode: Low strength in high-stress areas
trigger: Use in high-stress areas such as around the landing gear doors and windows
consequence: Wikipedia says optimising the tile's thermal properties reduced its overall strength, so the tile was unsuitable for those areas.
severity: high
source: wiki-li900
where: Problems section
- mode: Softening at high temperature
trigger: Exposure above the multiple-use temperature limit
consequence: TPSX says the tile softens above 1644K (2500F) and melts at about 1978K (3100F). Its predicted multiple-use limit is 1.59e+03 K.
severity: high
source: tpsx-li900
where: Properties at Standard Conditions table, notes on rows Multiple Use and Single Use Temperature Limit
- mode: Coating loss from water in the tile
trigger: High water content in a tile that is not waterproofed, during ascent or re-entry
consequence: A slight loss of coating. The report says there was no effect on heat-shielding capability.
severity: low
source: ntrs-19740020226
where: Summary, coating compatibility paragraph (OCR text layer)
- mode: Tension failure at the strain isolation pad of the HRSI system
trigger: Stepped tension loading of an HRSI specimen, examined by microscope at each load step
consequence: A local failure occurred that the authors associate with load transfer through transverse fibres in the strain isolation pad (SIP), the tension failure mode of SIP behaviour.
severity: moderate
source: ntrs-tm81821
where: Abstract (NTRS TM-81821)
handling:
- text: Each tile is fitted individually. The Wikipedia Space Shuttle TPS article says about 24,300 unique tiles were individually fitted on the vehicle.
source: wiki-tps
where: Detailed description
- text: Keep water out of tiles that are not waterproofed. The 1972 report links high water content to a slight coating loss during ascent and re-entry.
source: ntrs-19740020226
where: Summary (OCR text layer)
mitigations:
- text: The strain arrestor plate reduces tile and coating stresses under all load and temperature conditions, according to the 1972 report.
source: ntrs-19740020226
where: Summary, strain arrestor plate paragraph (OCR text layer)
uses:
- application: heat-shields
device: Black high-temperature reusable surface insulation (HRSI) tiles on the Space Shuttle orbiter underside
example: A typical Shuttle carried about 20,000 HRSI LI-900 tiles. Black tiles have higher emissivity, so they shed heat faster, which helps maximise heat rejection during re-entry.
source: wiki-li900
where: Black and white tiles section
- application: thermal-control
device: White low-temperature reusable surface insulation (LRSI) tiles on the upper surface
example: The white LI-900 tiles have higher thermal reflectivity and face the sun to reduce solar gain. A typical Shuttle carried about 725 LRSI LI-900 tiles.
source: wiki-li900
where: Black and white tiles section; use on the Space Shuttle orbiter
- application: heat-shields
device: All-silica rigidized surface insulation (RSI) thermal protection system concept for the Space Shuttle
example: The 1972 NASA report presents the materials and design technology for the all-silica LI-900 RSI TPS concept and says the tile demonstrated that it meets Space Shuttle mission and life requirements.
source: ntrs-19740020226
where: Abstract and conclusions (OCR text layer)
documents:
- title: 'NASA Ames TPSX record: LI-900 Rigid Tile (Material id 1)'
type: database
url: https://tpsx.arc.nasa.gov/Material?id=1
year: 2006
- title: Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1 (NTRS 19740020226, PDF)
type: report
url: https://ntrs.nasa.gov/api/citations/19740020226/downloads/19740020226.pdf
year: 1972
- title: Silicon dioxide, PubChem CID 24261 (Safety and Hazards, GHS Classification)
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/Silicon-dioxide
year: 2026
- title: Mineral Commodity Summaries 2026, Sand and Gravel (Industrial), USGS
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-sand-industrial.pdf
year: 2026
- title: NASA TP-3276, Prediction of Rigid Silica Based Insulation Conductivity (NTRS 19930008736, PDF)
type: report
url: https://ntrs.nasa.gov/api/citations/19930008736/downloads/19930008736.pdf
year: 1993
- title: NASA TM-81821, Microstructural characterization of the HRSI thermal protection system (NTRS 19800015948, PDF)
type: report
url: https://ntrs.nasa.gov/api/citations/19800015948/downloads/19800015948.pdf
year: 1980
gaps:
- 'Supply: no producer, capacity or critical-mineral listing for the LI-900 tile maker was found. The supply section gives USGS world industrial sand figures as feedstock context, not LI-900 production. No critical-mineral list entry for silica was read in this run.'
- 'Hazards: no safety data sheet exists in our sources for LI-900 itself. The hazard entries use PubChem ECHA records for vitreous and amorphous silica, which describe the substance, not the tile. The crystalline (cristobalite) entry is listed for completeness and is not applied to the tile.'
- 'Emissivity of the coated black flight tile: TPSX gives 8.80e-01 for the uncoated tile only, and no value for the coated tile was found.'
- 'Coating: the composition of the reaction-cured glass (RCG) coating rests on one Wikipedia sentence (tetraboron silicide and borosilicate glass listed). The Wikipedia RCG article returned HTTP 404, and no second source was reached.'
- 'Manufacturer: TPSX names United Space Alliance; Wikipedia names Lockheed Missiles and Space Company, and the 1972 report is a Lockheed (LMSC) report. Both are stated side by side; the conflict is not resolved.'
- 'Tile counts: Wikipedia LI-900 gives about 20,000 HRSI tiles per typical Shuttle. The Wikipedia Space Shuttle TPS article gives 20,548 HRSI tiles, about 24,300 unique tiles, and 31,000 tiles on Columbia in 1979. These are not reconciled.'
- 'Air fraction: 94% by volume (Wikipedia LI-900) against ninety percent empty space (Wikipedia Space Shuttle TPS).'
- 'Temperature limits come from different tests and are not converted into one number: 1,260°C for black HRSI tiles (Wikipedia TPS), 1,204°C heat-and-quench (Wikipedia LI-900), 1644K softening (TPSX) and 1648K reuse (1972 report).'
- 'Report date: the NTRS record prints 30 December 1972 for ID 19740020226 (NASA-CR-134326, LMSC-D282673-VOL-1, contract NAS9-12856). The ID prefix suggests 1974, so the record date is used.'
- The 1972 report was read from its OCR text layer. The reuse (1648K), cold-soak (116K) and water statements were not checked against the scanned pages.
- Atomic weights for the recipe parts were not printed by any source fetched in this run, so they are left out.
- 'Not found: moisture absorption, a quantified thermal-shock or cycle-life result for LI-900, mechanical data for the coated tile, and flight failure history.'
- 'Left out: the TPSX reuse flight limit (100 flights, predicted) and the purchase cost (predicted, per m^2), because cost is not a material property and the flight limit is only predicted.'
- 'Media: no image files were fetched, so the media section is left out.'
- 'Sources: 8 sources are cited. NASA TP-3276 is cited for its stated method only; no value was taken from it, because its conductivity figures were not readable in this run.'
- 'Scientific notation: the new rows leave out TPSX values printed in e-notation (specific heat, in-plane thermal conductivity, emissivity, tensile and compressive strengths, moduli, predicted temperature limits, cost). The existing rows are unchanged.'
- 'Property names: softening_temperature and porosity are not in spores/property-canon.yaml, so they use short snake_case names.'
supply:
- subject: Industrial silica sand (quartz sand, the feedstock for silica glass)
abundance: 'USGS: quartz-rich sand and sandstone, the main sources of industrial silica sand, occur throughout the world. The US reserve is rated Large.'
producers:
- country: United States
share_percent: 27.9
year: 2025
- country: China
share_percent: 21.4
year: 2025
- country: Netherlands
share_percent: 15.8
year: 2025
recycling: 'USGS: about 33% of glass containers are recycled, and recycled cullet is a significant proportion of reused silica.'
substitutes:
- 'USGS: alternatives for glassmaking, foundry and molding sands are chromite, olivine, staurolite and zircon sands.'
source: usgs-mcs2026-sand
where: 'World Mine Production and Reserves table, 2025 column in thousand metric tons (world total printed as 430,000, rounded). Shares calculated by Space Mushroom: 120,000, 92,000 and 68,000 divided by 430,000. Recycling and Substitutes sections. USGS also gives Canada as 84% of US imports, 2021 to 2024.'
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 12
unreachable: 1
caveats: 3
note: Read by an AI assistant on 2026-11-01 from the TPSX record, Wikipedia pages and the NTRS report text. The Wikipedia RCG page returned 404; the NTRS text came from an OCR layer.
story:
recipe:
line: LI-900 is a tile of silica glass fibre with most of its volume taken up by air. Wikipedia says the tile is made from very pure quartz sand, but the sources fetched do not describe how the tiles were made.
parts:
- name: Silica glass fibre
symbol: SiO2
share: 100% SiO2 (TPSX composition); 99.9% pure silica glass fibres (Wikipedia LI-900)
role: The solid framework of the tile. Wikipedia says the design aim was to minimise thermal conductivity while giving maximum thermal shock resistance.
- name: Air in the pores
share: 94% by volume (Wikipedia LI-900); ninety percent of the volume empty (Wikipedia Space Shuttle TPS)
role: Most of the tile volume. Together with the fibre it sets the bulk density of 144 kg/m^3 (9 lb/ft^3).
risk_groups:
- title: For people
level: 0
verdict: Silica substance only, no tile SDS
lead: PubChem's ECHA entries cover the silica substance, not the tile. Vitreous silica is reported as not meeting GHS criteria, and amorphous silica is an irritant (H315, H319, H335). We found no safety data sheet for LI-900 itself.
points:
- label: The tile
line: The TPSX record and the Wikipedia articles describe composition, density and temperature limits, but they say nothing about hazards to people.
- title: On the vehicle
lead: These are design limits and test results for the tile on the orbiter, not incident reports.
points:
- label: Re-entry heat
line: The black HRSI tiles were used where the re-entry temperature was below 1,260°C, according to the Wikipedia Space Shuttle TPS article.
- label: Softening
line: TPSX says the tile softens above 1644K (2500F) and melts at about 1978K (3100F).
- label: Strength
line: Wikipedia says the tile is unsuitable for high-stress areas such as around the landing gear doors and windows.
- title: Handling and storage
points:
- label: Storage
line: The sources fetched in this run give no storage rule for LI-900 (see gaps).
- label: Water
line: The 1972 report says high water content in tiles that are not waterproofed can cause a slight coating loss during ascent and re-entry.
why: 'LI-900 was developed as a lightweight, all-silica reusable insulation for the Space Shuttle. Lockheed''s earlier all-silica material of the same family was tested extensively before LI-900 (1972 NASA report). The program reduced the density to 144 kg/m^3 (9 lb/cu ft) to create LI-900 (NTRS 19740020226). The design trades strength for insulation: TPSX gives a low thermal conductivity, and Wikipedia says optimising the thermal properties reduced the overall strength. NASA Technical Paper 3276 gives a method for predicting the thermal conductivity of this class of silica insulation, and extends it to the upper temperature limits (NTRS 19930008736, abstract).'
uses:
- where: Underside of the Space Shuttle (black HRSI tiles)
line: A typical Shuttle carried about 20,000 HRSI LI-900 tiles, according to Wikipedia. Black tiles have higher emissivity, so they shed heat faster during re-entry.
- where: Upper surface of the Space Shuttle (white LRSI tiles)
line: The white LI-900 tiles have higher thermal reflectivity and face the sun to reduce solar gain. A typical Shuttle carried about 725 LRSI LI-900 tiles, according to Wikipedia.
- where: 1972 NASA all-silica TPS concept
line: The 1972 report presents the materials and design technology for the all-silica LI-900 RSI TPS concept and states that the tile demonstrated that it meets Space Shuttle mission and life requirements.
can_do:
- label: Insulation
benchmark: thermal_conductivity
line: Through the thickness the tile has a thermal conductivity of 4.76e-02 W/m-K, as printed by TPSX. TPSX marks this as a dynamic value for transient environments.
- label: Temperature
benchmark: max_service_temp
line: TPSX predicts a multiple-use temperature limit of 1.59e+03 K. Wikipedia says the tile can be heated to 1,204°C and then plunged into cold water without damage.
- label: Reuse
value: To 1648K (2500F)
line: The 1972 NASA program found that the LI-900 material and coating system can be reused to 1648K (2500F) with no significant degradation of its mechanical and thermal performance (NTRS 19740020226, conclusions).
- label: Strength
benchmark: ultimate_tensile_strength
line: At room temperature the tensile strength is 1.65e+05 Pa through the thickness (TPSX). Wikipedia says the tile is unsuitable for high-stress areas.
compare: Within the NASA and Wikipedia sources, LI-900 trades strength for insulation. Wikipedia says a stronger version of the tile exists, which gives more strength and insulation but carries a considerable weight penalty. Its figures are not included here because they are for a different grade. The table below sets LI-900's density, thermal conductivity and tensile strength side by side.
compare_rows:
- label: Bulk density
benchmark: density
- label: Thermal conductivity, through the thickness
benchmark: thermal_conductivity
- label: Tensile strength, through the thickness
benchmark: ultimate_tensile_strength
handling:
- Each tile is fitted individually. The Wikipedia Space Shuttle TPS article says about 24,300 unique tiles were fitted on the vehicle.
- Keep water out of tiles that are not waterproofed. The 1972 report links high water content to a slight coating loss during ascent and re-entry.
- Keep high loads away from the tile's high-stress areas. Wikipedia says the tile is unsuitable for the areas around the landing gear doors and windows.
- Use a strain arrestor plate between the tile and its bond where the design allows. The 1972 report says it reduces tile and coating stresses under all load and temperature conditions.
good_for:
- 'Low thermal conductivity: 4.76e-02 W/m-K through the thickness (TPSX), the property the tile was designed for.'
- 'Reuse at high temperature: the 1972 NASA program reports reuse to 1648K (2500F) without significant degradation.'
- 'Thermal shock: the tile can be heated to 1,204°C and plunged into cold water without damage (Wikipedia).'
watch_out:
- 'Low strength: the tensile strength is 1.65e+05 Pa through the thickness (TPSX), and Wikipedia says the tile is unsuitable for high-stress areas.'
- Coated and uncoated numbers differ in scope. TPSX gives the density and emissivity for the uncoated tile, while the black flight tile is coated.
- The sources disagree on tile counts, air fraction and manufacturer. Each value is stated with its source (see gaps).
verdict: LI-900 suits reusable insulation where low density and low thermal conductivity matter more than strength. The NASA data support reuse to 1648K (2500F). The emissivity of the coated tile is not in the sources we hold. PubChem classifies the silica substance, but we hold no classification for the LI-900 tile itself.
sources:
tpsx-li900:
title: LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)
id: TPSX Material id=1; property rows dated 2006-01-05 on the page
url: https://tpsx.arc.nasa.gov/Material?id=1
year: 2006
kind: database
license: public domain (NASA)
wiki-li900:
title: LI-900 (Wikipedia article)
id: Wikipedia article, accessed 2026-11-01
url: https://en.wikipedia.org/wiki/LI-900
year: 2026
kind: web
license: CC BY-SA 4.0 (Wikipedia text, cited not reproduced)
wiki-tps:
title: Space Shuttle thermal protection system (Wikipedia article)
id: Wikipedia article, accessed 2026-11-01
url: https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system
year: 2026
kind: web
license: CC BY-SA 4.0 (Wikipedia text, cited not reproduced)
ntrs-19740020226:
title: Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1
id: NTRS 19740020226; NASA-CR-134326; LMSC-D282673-VOL-1; contract NAS9-12856; published 30 December 1972 per NTRS record
url: https://ntrs.nasa.gov/citations/19740020226
year: 1972
kind: report
license: public domain (NASA)
pubchem-sio2:
title: Silicon dioxide, PubChem CID 24261 (Safety and Hazards, GHS Classification)
id: CID 24261; GHS data from ECHA C&L Inventory and NITE-CMC as shown on the page, read 2026-11-01
url: https://pubchem.ncbi.nlm.nih.gov/compound/Silicon-dioxide
year: 2026
kind: database
license: public domain (NCBI)
usgs-mcs2026-sand:
title: Mineral Commodity Summaries 2026, Sand and Gravel (Industrial), USGS
id: USGS MCS 2026, industrial sand and gravel chapter, 2025 estimates; version read 2026-11-01
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-sand-industrial.pdf
year: 2026
kind: report
license: public domain (USGS)
ntrs-tp3276:
title: Prediction of Rigid Silica Based Insulation Conductivity (NASA Technical Paper 3276)
id: NASA TP-3276, January 1993; NTRS 19930008736; Williams and Curry
url: https://ntrs.nasa.gov/citations/19930008736
year: 1993
kind: report
license: public domain (NASA)
ntrs-tm81821:
title: Microstructural characterization of the HRSI thermal protection system for space shuttle (NASA Technical Memorandum 81821)
id: NASA TM-81821; NTRS 19800015948; Ransone and Rummler; year taken from the NTRS ID prefix
url: https://ntrs.nasa.gov/citations/19800015948
year: 1980
kind: report
license: public domain (NASA)
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1) | database | 2006 | 10 values | |
| LI-900 (Wikipedia article) | web | 2026 | 6 values | |
| Space Shuttle thermal protection system (Wikipedia article) | web | 2026 | 2 values | |
| Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1 | report | 1972 | 8 values | |
| Silicon dioxide, PubChem CID 24261 (Safety and Hazards, GHS Classification) | database | 2026 | 3 values | |
| Mineral Commodity Summaries 2026, Sand and Gravel (Industrial), USGS | report | 2026 | 1 value | |
| Prediction of Rigid Silica Based Insulation Conductivity (NASA Technical Paper 3276) | report | 1993 | 0 values | |
| Microstructural characterization of the HRSI thermal protection system for space shuttle (NASA Technical Memorandum 81821) | report | 1980 | 1 value |
Updated