PhD Position Relative Acceleration Modelling for the GRACE and GRACE-FO Satellite Missions

The GRACE and GRACE-FO satellite missions measure how Earth’s gravity field changes over time, which gives invaluable data on how fast the ice sheets melt, how much ocean mass changes contribute to sea level rise, and many other geophysical processes. Both GRACE and GRACE-FO missions experienced challenges concerning the accelerometers. While the GRACE satellites were designed for a lifetime of 4 years, they were successfully operated for an astonishing 15 years. Near the end of the mission, degrading battery power prevented the accelerometer on the second GRACE satellite from being powered. In the case of the GRACE-FO mission, an anomaly occurred a few weeks after launch, after which the accelerometer on the second GRACE-FO satellite performed worse than expected. In both cases, the emergency solution is to transform the data from the well-performing accelerometer on the first satellite to represent the forces acting on the second satellite, a process called transplanting the accelerometer data. This transplantation requires accurate aerodynamic forces and radiation pressure modelling, an expertise typically not needed for gravity field research. Therefore, it is unsurprising that NASA’s current implementation of the accelerometer data transplant has room for improvement.

This PhD project aims to take the accuracy of the accelerometer transplant data to the next level and thereby make a crucial contribution to the GRACE and GRACE-FO missions. You will achieve this goal by developing a new procedure based on state-of-the-art aerodynamic and radiation pressure models originally created for atmospheric research. These models are based on a photorealistic satellite representation, ray-tracing algorithms, and a detailed description of the satellite surface properties. We plan to publish the procedure as open-source software. You will demonstrate the superior accuracy of the transplant using data periods when the accelerometers were operating well on both satellites. Further, you will assess the impact of the enhanced accelerometer transplant data on the gravity field models, for which we have established a cooperation with NASA’s Jet Propulsion Laboratory and the Center for Space Research of the University of Texas at Austin, US, two of the three main processing centres of GRACE and GRACE-FO data.

You will be working in a team of PhD candidates, researchers, and professors, with extensive experience in satellite missions, precise orbit determination, and atmospheric and gravity field research. The research team is part of the Astrodynamics and Space Missions section of the Faculty of Aerospace Engineering at the Delft University of Technology. Dr. Christian Siemes will be your supervisor and point of contact, provide guidance, and support you on your PhD journey. You will be enrolled in Delft University of Technology’s Graduate School, which will help you develop discipline-related, research, and transferable skills.

We are looking for a talented PhD candidate with the following profile:

• Master’s degree in a relevant field, e.g. aerospace engineering.
• Affinity with analysing data from satellite missions.
• Good programming skills.
• Critical thinking.
• Ability to work independently.

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 .

Doctoral candidates will be offered a 4-year period of employment in principle, but in the form of 2 employment contracts. An initial 1,5 year contract with an official go/no go progress assessment within 15 months. Followed by an additional contract for the remaining 2,5 years assuming everything goes well and performance requirements are met.

Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities, increasing from € 2770 per month in the first year to € 3539 in the fourth year. As a PhD candidate you will be enrolled in the TU Delft Graduate School. 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 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!

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.

Are you interested in this vacancy? Please apply no later than 10 March 2024 via the application button and upload your:

• Motivation letter
• CV
• Contact information of one reference (name and e-mail address)

Please note:

• The short-listed candidates will be interviewed online.
• You can apply online. We will not process applications sent by email and/or post.
• Please do not contact us for unsolicited services.

For more information about this vacancy, please contact Christian Siemes ([email protected] ).

A pre-employment screening can be part of the selection procedure.