Fundamentals of Environment-Materials Interactions, Models and Design Approaches to Meet Emerging Space Needs

About the Atmospheric Reentry Physics GRC

The "Atmospheric Reentry Physics" conference will provide a single focal point to allow for the better integration and advancement of a multidisciplinary research community of scientists and engineers, representing government agencies, the private sector, and University systems across the world. The primary objectives of the conference are to foster improved communication across national and discipline boundaries, and to expose the atmospheric reentry community to new ideas and techniques from adjacent disciplines in the hopes of bringing new experimental techniques to bear on the problem as well as brainstorm about challenges faced by expanding the range of application of existing techniques.

The topic area encompasses the physics and chemistry relevant to a spacecraft entry into the Earth or a planetary atmosphere. At hypersonic speeds, strong shock waves form in front of the reentry spacecraft, and the boundary layer is typically highly turbulent, leading to complex compressible fluid dynamics. Such entries are further characterized by dissociation, ionization, and excitation of the gaseous species behind the hypersonic shock wave. At sufficiently high velocity, the hot atmospheric gas begins to radiate due to atomic and molecular excitation. This radiation can become strong enough that it is a significant source of heat transfer to the spacecraft. At the higher entry velocities, the heat generated at the vehicle surface is large enough that no material can withstand it without degrading. Therefore, a spacecraft design typically relies on ablating thermal protection materials, which are intended to pyrolize and char in response to the incident heat. These materials thus efficiently cool the spacecraft via energy absorption of the endothermic breakdown of the polymeric constituents, transpiration cooling as the pyrolysis gases percolate from the interior of the material toward the surface, and re-radiation from the hot char layer that forms on the surface. At the high altitude conditions typical of atmospheric entry, many or all of these processes can be in non-equilibrium, which greatly complicates the required physical models that must be employed in their simulation. Finally, all of these phenomena, including the fluid dynamics, molecular chemistry, radiation emission and transport, and ablative material response, can be coupled, requiring the development and validation of complex multi-physics models. Such models exist today at varying levels of fidelity and validation. A significant impediment to properly validating the models has been the inability to conduct truly flight-like experiments in ground-based laboratories. However, we believe that, under the auspices of the GRC, the current state of the art can be considerably advanced by bringing new ideas and methodologies to bear on the problem. The GRC series will focus on each of these elements (or the coupling between them) in turn, ensuring a dynamic, ever changing research discussion for many years to come.

Key Topics for the 2013 Conference Technical Program

"Fundamentals of Environment-Materials Interactions, Models and Design Approaches to Meet Emerging Space Needs"

• Random entries in the atmosphere: Leonids, Meteores and Meteorites
  What can we learn from the perspective of reentry technologies and models by observing and understanding these objects?
• Entry Technology Needs
  Are there unexplored options for reentry technologies that could fundamentally alter the way we design missions?
• Innovative Commercialization and Emerging Space Needs
  What reentry technologies, models and tools would make a difference in helping engineers working in the commercial sector?
• Surface reactions for hypersonic conditions
  What combination of modeling tools and experiments is optimal to capture the relevant physics (semi-empirical versus detailed surface kinetics)? What methods (i.e surface functionalization) are most suitable to control heating due to surface reactions (sublimation, oxidation, adsorption, desorption, recombination)?
• Thermal Decomposition and Transport Phenomena in Decomposing Ablators
  What combination of modeling tools and experiments is optimal to capture the relevant physics of the problem? What are the relevant pyrolysis gases and how do they interact with the material during their transport to the surface? Are the microstructural changes of the decomposing material important and how can they be modeled or measured experimentally?
• Physics Based Models for Uncertainty Quantification, Margins and Reliability
  What are the appropriate statstical methods? What does it take to connect design margins with quantified reliability? How does this best roll into a risk model for EDL? Is “test to failure” a better strategy for ground testing?
• Flight Validation, Instrumentation and Health Monitoring Systems
  What is the ultimate value of entry instrumentation? Can it be used for health system monitoring and reduce risks during entry?
• Computational Design and New Materials under Entry Conditions
  What does it take before computer models of material thermal and structural performance are predictive in nature? What nontraditional materials could potentially be used for heat management and protection (TPS)?
• Fundamental Development Needs to Support Entry Technologies
  What shall the top priorities be in terms of current fundamental developments? What should future Gordon Research Conferences on Atmospheric Reentry Physics target?

Participation

The structure of the technical program is designed to encourage three types of participation:

1. Technical experts, leaders and visionaries in the field who drive technological concepts for the 21st century space exploration, especially in the reentry technology area.
2. Scientist who have an idea and possess the knowledge, tool or technology (not necessarily specifically developed for Atmospheric Reentry) that could enable a future breakthrough
3. Engineers from commercial sector who are working in a very specific landscape (constrained environment) and on a schedule and do not have the resources and time to develop new technologies and tools. We are looking at them to share their expertise and wish list.

Goals

We strive to bring together an outstanding and diverse group of scientists and engineers at the forefront of Atmospheric Reentry from the academic, government and commercial sector. We strongly encourage younger scientists and students who feel they have something to say, to step forward and share their vision and thinking.

We think of this conference as a unique opportunity, an open minded environment where engineers at the forefront of Atmospheric Reentry come together with top scientists from critical research areas to discuss, prioritize and strategize in terms of advancements needed to enable development of modern, afordable reentry models and design tools as well as novel technologies to support Emerging Space and Exploration Needs. What should the community do and how to ensure that valuable ideas, fundamental discoveries and concepts and technological advancements are put to good use towards human exploration?