The PhDs advertised in this call will be organized by the Louvain4Space. Louvain4Space is an exchange and promotion platform for the space projects at the UCLouvain. It was created in 2017 and actually has 83 members (https://uclouvain.be/en/research/louvain4space). Its goal is to share calls and best practices to respond to these calls, knowledge for synergetic research programs, network, etc. Pooling and sharing of information are crucial for UCLouvain's participation in space programs and related research.
The first project of Louvain4Space is the participation in a nanosat with University of Luxembourg. UCLouvain shall provide the antenna and process the data.
We are looking for two PhD students who will focus on the data calibration (validation with drones), pre-processing (on board and on land) and interpretation.
Figure 1: Geometry of the reflectometry using GNSS satellites (transmitter) and a nanosat (receiver)
Figure 2: L2UNA.
Goals of the PhDs
There are several methods of observing the earth including radar. Compared to observation in the optical domain, observation at radio frequencies (typically 10 MHz to 30 GHz) makes it possible to cross the clouds and obtain information of another type, such as that linked to the roughness of surfaces at centimeter scale. This information is essential for precision agriculture and climatology and the sustainable management of lands and seas.
Satellites with radar sensors can be very expensive and require very long development phases. The project presented here consists of exploiting the signals transmitted by GNSS satellites (such as GPS satellites) and reflected on the surface of the Earth (from the earth's crust or sea ice or from the sea, see Figure 1) and collecting them with one or several microsatellites, of the "cubesat" type (see Figure 2). This allows much more agility in the development of the sensors, a significant reduction in their cost (no transmitter) and the possibility of observing the same scenes from many different angles.
Global Navigation Satellite Systems (GNSS), originally designed for navigation, play an increasingly important role in remote-sensing applications. They are signals of opportunity for remote sensing. GNSS Reflectometry (GNSS-R) is recognized as an emerging technology for retrieving ocean wind speed, soil moisture, and altimetry applications.
This technology assumes that one can observe and track in particular the specular "point", where ground (or sea or ice) reflection occurs. When the signal generated by a GNSS satellite reaches a perfectly smooth surface, the reflection only takes place at a point called a specular point. If the surface has irregularities and roughness, the incident ray will be scattered in any direction upon contact with the surface. One talks about non-coherent diffuse reflection. This dispersion involves delays (code delays) and variations in frequency (Doppler shifts) for the received signal. The research takes the advantage of the L-band used by GNSS, which is less sensitive to atmospheric attenuation by atmospheric water vapor and precipitation than other higher frequency microwave sensors and is complementary to the classical ESA Sentinel Satellites using C-band.
The ultimate goals of the project are to develop new technologies around mechanics, electronics, telecommunications as well as remote sensing. For example, increased sensitivity to the "specular spot" can increase the signal-to-noise ratio and reduce interference with signals from other GNSS satellites. This involves building deployable antennas on board the microsatellite to focus energy on the specular spot. Besides the design of an antenna capable of providing these data, the ultimate goals are also to estimate the precision, to quantify the step forward that can be done, and develop an observation strategy in order to obtain the best information on land moisture, on ocean roughness and winds, and on ice sheet melt and icecaps evolutions. These objectives will help agriculture and climate research. All these themes can be the subjects of PHD theses of which the first year is founded thanks to the money from UCLouvain associated to Louvain4Space.
The ideal candidate has a MSc in Science or Engineering (students expecting to graduate this summer will also be considerate for the position) and combines many of the following characteristics:
- Knowledge in remote sensing (Radar, Reflectometry)
- Experience in data analysis
- Experience in GNSS
- Experience in radio link budget
- Experience in antenna design
- Working and writing proficiency in English.
Contract duration – Funding
The initial contract duration is one year (max two if necessary) and is directly financed by the Uclouvain. This period should allow the successful candidate to obtain a funding grant covering the remaining of his PhD project.
How to apply?