Notable AVCOAT Installations
editAVCOAT for Orion Crew Module
editThe Orion Crew Module was first designed by NASA’s Constellation Program (Cancelled), but later adapted the Space Launch System (SLS) to replace the Space Shuttle Program. This spacecraft was planned to take astronauts to the International Space Station in 2015 and to the moon in 2020.
In the past, honeycomb like paste-like fiberglass material is gunned into each cells individually. On the other hand, the Orion heat shield is bonded onto the base of the heat shield.
To protect the Crew Module during Earth re-entry, the dish shaped AVCOAT heat shield ablator system was selected. NASA announced that this module will encounter temperature as high as 5,000 degrees Fahrenheit[1]. Licensed by Textron[2] ,
AVCOAT material is produced New Orleans’s Michoud Assembly Facility by Lockheed Martin. This heat shield will be installed at the base of the crew module to provide a controlled erosion moving heat away from the crew module into the atmosphere. This process of erosion is called “ablation” - where materials are removed by vaporization or erosion by continuous contact with the supersonic velocity of gas flow and high temperature; thus the construction of honeycomb structure was made.
John Kowal, Orion’s thermal protections systems manager at Johnson Space Center, discussed the biggest challenge with AVCOAT has been reviving the technology for manufacturing with similar performance as demonstrated in the Apollo Missions.[3]
The EFT-1 mission is expected to allow two orbits of Earth providing the opportunity for Orion’s systems to be tested. This duration is expected to be four hours with the splash down in the ocean.[4]
AVCOAT for Apollo Missions
editAVCOAT was first used on the parts of the Apollo spacecraft orbiter and as a unit attached to the crew module in the past. It is a honeycomb structure. According to NASA, this is made of silica fibers with an epoxy novalic resin filled in a fiberglass-phenolic manufactured directly onto the heat shield.[5]
According to NASA’s Apollo Flight Test Analysis, AVCOAT 5026-39/HC-G material was tested on the nose cap of a peacemaker vehicle.[6] The temperature and ablation measurements were made at four locations on the nose cap. The report noted that the wear of the shield is due to the aerodynamic shear and heating rate. The report also noted that scientists believed that the ablation was done in a controlled manner.
After the Apollo missions, the production was then put in place for the purpose of studying.
AVCOAT Heat Shield Research and Installation for Orion Crew Module
editThe AVCOAT material heat shield we through several testing before the choosing and the installation. According to the Investigating the Thermochemical Response of Avcoat TPS from First Principles for Comparison with EFT-1 Data, things being tested on the heat-shield include: model gas transport, heat transfer, and TPS material regression.[7]
Orion’s 16.5 feet AVCOAT Heat Shield was secured onto the Orion Crew Module using 68 bolts by Technicians at NASA’s Kennedy Space Center (KSC) in Florida. This heat-shield is covered in titanium truss and a composite substitute with an addition skin made of carbon fiber layers. Orion’s heat-shield was designed and manufactured by Lockheed Martin. According to Space Daily, the heat shield is like pieces of a honeycomb puzzle that all must fit together perfectly and that the bolt fittings must be lined up. [8]
After the heat-shield's installation, access to components of the crew module became difficult or no longer accessible.
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- ^ Clem, Kylie; Clem, Rachel (April 7, 2009). "NASA Selects Material for Orion Spacecraft Heat Shield". NASA News Release. NASA. Retrieved 2 April 2019.
- ^ Herridge, Linda. "Heat shield install brings Orion spacecraft closer to space". SpaceDaily. KSC News. Retrieved 2 April 2019.
- ^ Prucey, Rachel; Clem, Kylie. "NASA Selects Material for Orion Spacecraft Heat Shield". NASA News Releases. NASA. Retrieved 3 April 2019.
- ^ Kramer, Miriam. "NASA's 1st Orion Spaceship Gets World's Largest Heat Shield (Photos)". Space.com. Retrieved 3 April 2019.
- ^ Prucey, Rachel; Clem, Kylie. "NASA Selects Material for Orion Spacecraft Heat Shield". NASA News. NASA. Retrieved 3 April 2019.
- ^ Graves, Randolph A.; Witte, William G. (August, 1968). "Flight-Test Analysis of Apollo Heat-shield Material Using the Peacemaker Vehicle System" (PDF). NASA Scientific and Technical Information (STI) Program. D (4137): 11. Retrieved 3 April 2019.
{{cite journal}}: Check date values in:|date=(help); More than one of|pages=and|page=specified (help) - ^ Levin, Deborah. "Investigating the Thermochemical Response of Avcoat TPS from First Principles for Comparison with EFT-1 Data". NASA News. University of Illinois, Urbana-Champaign. Retrieved 3 April 2019.
- ^ Herridge, Linda. "Heat shield install brings Orion spacecraft closer to space". SpaceDaily. KSC News. Retrieved 2 April 2019.