| Customer: ESA/ESTEC (2003 – 2006) | |
 | Smart TPS can be defined as systems able to "feel" an applied thermo-mechanical environment and to change their basic properties to "react or adapt" to the environment. More than 30 concepts have been identified, around 5 concepts have been assessed in more detail, and 1 concept has been breadboarded and tested. This was an adaptive paint which protects the cold structure in case of failure of the hot ceramic cover shingles of a space re-entry vehicle. |
The Thermal Protection System (TPS) is an essential subsystem of each space vehicle or component that must be operated in a high temperature environment. Examples are re-entry vehicles and rocket engines. Generally the TPS is a combination of special materials (e.g. ceramics, high temperature metals or polymers) whose thermal and mechanical properties allow working safely in extreme environments. Thermal Protection Systems for re-entry vehicles are rather consolidated systems. Also in Europe many technologies are at a very mature level and some are already flight qualified. However, TPS systems still contribute significantly to the mass and complexity of the whole vehicle.
For re-usable vehicles maintenance of current TPS systems is extremely extensive and contributes considerably to the high turn-around cost. For these reasons development of TPS systems should be continued taking into account new developments in the field of advanced materials and technologies and, in particular, the application of Smart TPS concepts. It is believed that Smart TPS can be beneficial in terms of mass and complexity when compared to conventional TPS. In addition, Smart TPS might reduce the need of inspection and repair during refurbishment.
Smart TPS can be defined as systems able to "feel" an applied thermo-mechanical environment and to change their basic properties to "react or adapt" to the environment. As soon as the harsh environment conditions cease the smart TPS would be able to come back to their original status.
The concepts listed in the following have been considered as possible candidates.
- Variable Curvature Systems: Systems made up of materials that, under thermal load, are able to change curvature so to reduce the incoming heat fluxes (possibly applicable to leading edges, noses, etc.). This effect may be used onboard of reusable launchers so to have a sharp leading edge during the ascent phase and atmospheric flight and a blunt leading edge during entry.
- Variable Emissivity Coatings: Coatings based on materials that undergo reversible phase changes after a certain temperature threshold and increase the surface thermo-optical properties in order to reject larger amounts of heat.
- Self-Healing Materials: Ceramic materials with self-healing properties, able to fill automatically micro-cracks generated by the thermo-mechanical environment. Use of such concepts would improve the reusability for several flights.
- Concepts based on emerging materials, e.g. nano-materials.
But also many other ideas like heat pipes have been generated and studied. The activity has reviewed the availability of advanced materials and technologies and to define potential Smart concepts making use of such materials and technologies for the application in Thermal Protection Systems of expandable or reusable re-entry vehicles.
A very valuable contribution was elaborated by HPS's subcontractor, the University of Rome "La Sapienza", Prof. Gaudenzi.
Publications:
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Statement of Work:
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