The “streets in space” are lined with garbage. Operational satellites that are vital to our everyday lives share their orbits with thousands of pieces of debris. An impact from such a debris object may destroy a satellite, or worse, threaten human spaceflight. At TU Delft, research is being conducted on exploiting the endless propulsion capabilities of solar sailing to clean up space. A spacecraft equipped with a solar sail rides on sunlight the way sailboats ride on the wind, making it a sustainable and cost-effective form of propulsion for a many-target active debris removal mission.

Though several solar-sail technology demonstration missions have successfully flown, and more are scheduled for the future, little is known about the effect of the harsh space environment on the optical and mechanical degradation and survivability of the sail material. Particularly for long duration missions, like a many-target active debris removal mission, degradation is expected to be significant and have an equally significant effect on the long-term performance of the sail.

Objective: the objective of this PhD project is to obtain realistic aging effects of solar-sail material through an extensive ground-based test campaign and to incorporate the derived effects into the orbital dynamics of a solar-sail active debris removal mission.

Background: Theoretical models for sail degradation exist and sail samples have flown as part of NASA's series of MISSE experiments towards the International Space Station with the aim of investigating sail degradation in the actual near-Earth space environment. However, theoretical models are very simplistic and conducting actual flight experiments whenever new advances in sail materials are being made is costly and time-consuming.

Methodology: To obtain the aging effects and assess the effect on the solar-sail orbital dynamics, this PhD project will take a hybrid approach of numerical modelling and experimental testing. The PhD candidate will run a test campaign at the Complex Irradiation Facility of the DLR Institute of Space Systems in Bremen, Germany. This unique facility has been developed to specifically investigate material surface changes, i.e., degradation, in space conditions. Different sail materials will be exposed to different types of radiation and examined using microscopic and spectroscopic methods. The resulting sail material aging data will then be transformed into a degradation model fit for purpose for orbital dynamics applications. The model will be validated against early- and late mission flight data of flown solar-sail missions like LightSail-2. Once validated, the model will be used to assess the effect of degradation on the orbital manoeuvring capabilities of a many-target solar-sail debris removal mission.

Research cooperation and supervision: This PhD project is jointly funded and supervised by the German Space Agency (DLR) and TU Delft. The PhD candidate will be employed and hosted by TU Delft in years 1 and 4 of the project and will be employed and hosted by DLR in Bremen, Germany, in years 2 and 3. Throughout the project, the supervisory team will consist of: Prof. Dr. Ir. Pieter Visser (TU Delft, promotor), Dr. Ir. Jeannette Heiligers (TU Delft, daily supervisor), and Dr. Patric Seefeldt (DLR, daily supervisor).

The expected starting date of the PhD project is March 2024 (though flexible if needed).

Applicants should have a university degree (MSc) in aerospace engineering, material science and engineering, mechanical engineering, or any other scientific or technical area relevant to the proposed research and have a strong background in numerical modelling and/or experimental testing.

Experience in astrodynamics, mission analysis and design is considered a plus, but more important are a strong motivation, demonstration of high-quality work, and being well-organised, precise, and creative.

Furthermore, the candidate should have excellent written and oral English communication skills.

Doing a PhD at TU Delft requires English proficiency at a certain level to ensure that the candidate is able to communicate and interact well, participate in English-taught Doctoral Education courses, and write scientific articles and a final thesis. For more details please check the Graduate Schools Admission Requirements.

Fixed-term contract: 4 years.

The PhD candidate will be employed and hosted by TU Delft in years 1 and 4 of the project at the predefined salary scale €2,770.00 - €3,539.00. In Years 2 and 3 of the project the PhD candidate will be employed and hosted by DLR in Bremen, Germany at a salary depending on qualification up to 50% paygrade according to German TVöD 13.

The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills.

The TU Delft offers a customisable compensation package, discounts on health insurance, and a monthly work costs contribution. Flexible work schedules can be arranged.

For international applicants, TU Delft has the Coming to Delft Service. This service provides information for new international employees to help you prepare the relocation and to settle in the Netherlands. The Coming to Delft Service offers a Dual Career Programme for partners and they organise events to expand your (social) network.

Delft University of Technology

Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context.

At TU Delft we embrace diversity as one of our core values and we actively engage to be a university where you feel at home and can flourish. We value different perspectives and qualities. We believe this makes our work more innovative, the TU Delft community more vibrant and the world more just. Together, we imagine, invent and create solutions using technology to have a positive impact on a global scale. That is why we invite you to apply. Your application will receive fair consideration.

Challenge. Change. Impact!

Faculty Aerospace Engineering

The Faculty of Aerospace Engineering at Delft University of Technology is one of the world’s most highly ranked (and most comprehensive) research, education and innovation communities devoted entirely to aerospace engineering. More than 200 science staff, around 270 PhD candidates and close to 3000 BSc and MSc students apply aerospace engineering disciplines to address the global societal challenges that threaten us today, climate change without doubt being the most important. Our focal subjects: sustainable aerospace, big data and artificial intelligence, bio-inspired engineering and smart instruments and systems. Working at the faculty means working together. With partners in other faculties, knowledge institutes, governments and industry, both aerospace and non-aerospace. Working in field labs and innovation hubs on our university campus and beyond. 

Click here to go to the website of the Faculty of Aerospace Engineering.