ESA Graduate Trainee in Spacecraft Heat Shield Development and Modelling

Our team and mission

This ESA Graduate Traineeship will be with the Low-Earth-Orbit Cargo Return Service (LCRS) Project Team, based at the European Astronaut Centre (EAC) in Cologne, Germany. The EGT will be fully integrated into the team, working in close collaboration and maintaining daily interaction with its members.

The LCRS project focuses on developing cargo transportation services for human outposts in Low-Earth Orbit, with two companies under contract to each perform a demonstration mission to the International Space Station (ISS). In the future, the LCRS vehicle may be further developed into a crew transportation vehicle and adapted for cislunar missions.
 

You are encouraged to visit the ESA website: http://www.esa.int

Field(s) of activity/research for the traineeship

A spacecraft entering the atmosphere of Earth or another planet must withstand severe heat loads, which depend on factors such as entry speed, entry angle, vehicle geometry, vehicle mass, and the type of atmosphere. A heat shield is used to protect spacecraft from these intense thermal loads, ensuring the thermo-structural integrity of the vehicle throughout its mission.

There are two primary types of heat shields: reusable systems, typically made from ceramic matrix composite materials, and expendable systems, generally based on ablative materials.

• Ceramic matrix composites withstand heat loads without losing mass or changing shape. However, they are costly to manufacture and maintain, and they are vulnerable to oxidative environments during re-entry and high mechanical loads.
• Ablative materials are lightweight, carbon-based composites with organic resin binders. They are the thermal protection systems of choice for missions involving extremely high heat loads, particularly when cost and mass are critical constraints.

The proposed activity focuses on the characterisation, understanding, modeling, and prediction of the behavior of a new class of low-density ablative materials designed for high-enthalpy re-entry missions. These materials are identified as especially suitable for the LCRS demonstration mission.

When ablative materials are subjected to high temperatures during re-entry, complex processes occur:

• Part of the incoming heat is rejected through surface radiation due to the high surface temperature.
• Additional heat is consumed by material phase changes, such as sublimation, and chemical processes like pyrolysis.
• Phenomena such as film cooling, caused by outgassing, and radiation blocking by particles in the boundary layer also play significant roles.

As a result, ablative materials undergo both chemical and physical changes, losing a substantial portion of their original thickness in a process known as recession. This material loss is a critical consideration in the design of an ablative heat shield, as the remaining thickness must be sufficient to maintain functionality until the mission concludes. Recession behavior is typically investigated in arc jet facilities.
Equally important is the characterisation of mechanical properties, especially for heat shields experiencing significant recession. The ablative heat shield must endure aerodynamic loads and transfer those loads to the spacecraft’s underlying structure. Therefore, precise knowledge of both thermo-ablative and mechanical properties is essential for effective heat shield design.

As an ESA Graduate Trainee, your activity will be composed by the following main tasks:

1)    Bibliographic survey. 
General learning on main thermal protection systems (TPS) and heatshields applied in space missions. Learning on most common TPS ablative materials, key properties, testing characterisation techniques, thermo-ablative and mechanical modelling, available thermo-ablative analysis and mechanical analysis tools, recession prediction, selection criteria, mission design methodologies.

2)    LCRS ablative heatshield modelling. 
Collection of the LCRS ablative heatshield material characterisation data. Assessment of the properties. Thermo-ablative modelling of the specific ablator selected for application as LCRS heatshield. Learning objective is the understanding of how simulation tools can be generated and used for the design of space vehicles heatshield.
(Note: For the thermo-ablative analysis ESA engineers currently apply the simulation software module called ABLAT, embedded in the standard thermal analysis software ESATAN)

3)    LCRS ablative heatshield design assessment.
The sizing of the LCRS heatshield in terms of total thickness and recession thickness, structural properties, thermal properties will be verified and assessed. Learning objective is the understanding of design methodologies applied to the heatshield of a spacecraft.

Technical competencies

Behavioural competencies

Result Orientation

Operational Efficiency

Fostering Cooperation

Relationship Management

Continuous Improvement

Forward Thinking

For more information, please refer to ESA Core Behavioural Competencies guidebook

Education

You should have just completed, or be in the final year of your master’ s degree in Aerospace Engineering, or Mechanical Engineering, or Materials Engineering, or any engineering discipline relevant to thermal and mechanical analysis of thermal protection systems.

Additional requirements

You should have good interpersonal and communication skills and should be able to work in a multicultural environment, both independently and as part of a team. Previous experience of working in international teams can be considered an asset. Your motivation, overall professional perspective and career goals will also be explored during the later stages of the selection process.