MSc thesis: GRACE Follow-On data analysis

MSc thesis

Job Code:

Job Offer from February 09, 2021

GRACE Follow-On (Gravity Recovery and Climate Experiment) is a joint DLR/NASA space mission, comprising of two identical spacecraft in almost identical low Earth orbits. By precisely tracking the inter-spacecraft distance variations, it is possible to deduce Earth’s underlying gravity potential. Besides the static part of this gravity potential, it is also possible to compare monthly “snapshots” of the gravity field and use these to keep track of many features of the hydrological cycle, for example ground-water storage, ice-cap mass loss and the global sea-level. In addition to the microwave-ranging instrument, which has already been used for the original GRACE mission (2002-2017), GRACE-FO uses a novel Laser Ranging Interferometer (LRI) for the ranging measurements.

In the past years, the AEI has lead to the development of the LRI architecture and supported testing of the hardware. Since the launch and commissioning of the spacecraft in May 2018, the GRACE-FO group at AEI continuously monitors the telemetry and analyzes the data quality to learn about the instrument’s behavior in space and possible aging processes.

Here we offer a master thesis project in one of the following two topics:

A) Deriving and Validating Pre-Fit Residuals

We are interested to learn about the instrument’s data quality at the pre-fit level, which means after subtracting known gravitational and non-gravitational effects causing inter-satellite motion from the measured ranging data. The modeled motion can be derived from various force models, usually in combination with numerical orbit integration. This will help to determine the instrument noise sources. In order to compute the forces acting on the orbiters, we use a collection of in-house developed Matlab routines - called the gravity field recovery (GFR) toolbox.

This project focuses on validating and improving the GFR toolbox and its algorithms. The student will learn about

  • state-of-the-art force models for spacecraft in a low-Earth orbit, i.e. third body forces, atmospheric drag, static and dynamic Earth gravity field.
  • programming in a collaborative environment using git and gitlab
  • numerical methods and data analysis techniques

Once the code of the GFR toolbox is validated, we might use it for precise orbit determination and gravity field recovery.

B) Characterization of features in LRI ranging data:

It is known that LRI range measurements contain effects from satellite rotations (tilt-to-length coupling) and from linear accelerations caused by the attitude control system i.e. cold-gas thrusters. Both effects falsify the range measured of the LRI and thus need to be modeled and subtracted eventually.

This project focuses on analysis of the raw instrument data to improve the data quality and the understanding of the instrument. The student will learn about

  • In-depth insight into the LRI data streams, which include not only ranging data but also thermal and electronic aspects alongside various other metrics
  • Supporting a space satellite mission
  • Programming in a collaborative environment using git and gitlab
  • numerical methods and data analysis techniques

The tools for both projects are mainly written in Matlab programming language. A theory background in physics and/or geodesy, as well as experience in programming (Matlab or Python) is preferred for this project.

Please contact: Malte Misfeldt ()

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