PhD Position (M/F): Spaceborne Doppler Wind Lidar Design

Job Description

Thesis Subject

Development of an Optical Test Bench Representative of the MADWIL Doppler Wind Lidar for the Study of Martian Winds

The Martian atmosphere is one of the most Earth-like climate systems in the Solar System. Despite decades of orbital and in situ observations, Martian winds have only been measured sporadically and at very limited locations. Yet, they play a central role in nearly all the processes shaping the planet's climate and surface. The near absence of direct wind measurements makes Martian winds the “missing piece” of the climate puzzle. This major observational gap currently limits the improvement of Martian Global Climate Models and our ability to reconstruct the planet's past climate evolution.

To address this challenge, the European Space Agency (ESA) is preparing a Mars mission whose payload will include a Doppler wind lidar called MADWIL (Mars Atmospheric Doppler Wind Interferometer Lidar). This pioneering instrument will be capable of measuring horizontal winds throughout the atmospheric column with a vertical resolution of approximately 1 km on a global scale, representing a breakthrough comparable to that achieved for Earth by the ADM-Aeolus wind lidar mission. Wind measurements rely on the backscattering of Martian dust, which is ubiquitous throughout the Martian atmosphere all year round, enabling wind retrievals across the entire troposphere.

The Doppler measurement concept is based on a Quad Mach–Zehnder (QMZ) interferometric technology. This technique has been under development at LATMOS for several decades and is regarded as one of the most promising approaches for orbital wind measurements. The objective of this PhD project is to develop a complete optical test bench representative of the MADWIL lidar, enabling laboratory validation of its expected performance and verification of its optical architecture.

Your Work Environment

The LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales) is a joint research unit (UMR 8190) under the supervision of CNRS, Sorbonne Université, and UVSQ (Université Versailles-Saint-Quentin). Based primarily in Guyancourt (Yvelines) and Paris (Jussieu), the laboratory has a team of approximately 230 members, including researchers and faculty, engineers and technicians (IT staff), and around 30 PhD students and postdocs. The PhD student will be supervised by Dr. Franck Montmessin, chief of the Solar system department.

The PhD work will be structured around the following tasks:

1. Optical Test Bench Design (Modeling and Martian Requirements)

* Analysis of the scientific requirements for Martian wind measurements, including measurement range, altitude coverage, aerosol properties, and spectral contrast.
* Translation of these scientific requirements into representative optical specifications.
* Design of a complete optical test bench incorporating a 532 nm laser source, transmitter optics, a Martian backscatter simulator, optical fiber coupling, a Quad Mach–Zehnder (QMZ) interferometer, and detection electronics.

2. Experimental Implementation

* Assembly and precise alignment of the complete optical chain.
* Development and implementation of a Martian backscatter simulator.
* Integration of the QMZ interferometer and assessment of its thermal and mechanical stability.

3. Advanced Characterization

* Measurement of interference fringe contrast, Doppler sensitivity, and phase stability.
* Performance characterization under conditions representative of the Martian environment, with particular emphasis on low photon flux and photon noise-limited operation.
* Evaluation of the system's sensitivity to optical misalignments.

4. Dissemination and Scientific Outreach

* Presentation of results to CNES, ESA, and industrial partners involved in the MADWIL consortium.
* Participation in conferences dedicated to planetary science and optical instrumentation.
* Preparation of at least one peer-reviewed scientific publication reporting the laboratory validation of the MADWIL measurement concept.

Constraints and risks

Risks

* Operation and handling of laser systems.

Desired Skills and Qualifications

* Academic background in optics, photonics, instrumentation, or physics.
* Strong interest in planetary exploration and Martian science.
* Experience with laser systems, fiber optics, and low-light-level (photon-limited) detection techniques.
* Excellent experimental skills, with a rigorous approach to laboratory work and a strong interest in space instrumentation.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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