Ecole Polytechnique Space Centre

The IonSat nanosatellite project aims at studying the life extension of very low orbit missions by using an electric thruster to maintain the altitude of a 6U cubesat (10 cm x 20 cm x 30 cm) in VLEO, at 300 km altitude.

As it approaches its final stages, this ambitious and exciting project requires motivated students ready to face the multidisciplinary difficulties of real space projects. In this context, we propose different PSC topics :

1. Finalization and production of the structure of IonSat. This topic implies the study of the response of the structure to both vibrations and temperature gradients.
2. Preparation of the tests required to validate the architecture and implementation of IonSat. This topic implies : Development of a flatsat model to test the compatibility of electronic systems, power consumption, batteries, and electrical interfaces. Identification/Creation of Electrical Ground Support Equipment to emulate the consumption of different components for the satellite.
3. Finalization and validation of the Datalink for IonSat. This topic implies : Adaptation of the radio transceiver to the IonSat system, definition of the packets of information to be exchanged with the ground, finalization of the RF parameters, and TC/TM messages simulation using the monitor control software for ground communication.
4. Implementation of the control algorithms used by the Attitude and Orbit Control System (AOCS). This implies the verification and validation of different mission plans, as well as the identification of orbit determination strategies.

IonSat is expected to be launched in 2025.

Subject.
CSEP proposes various Phase A studies for the preparation of its future nanosatellite projects.
This project aims to define a small satellite, the size of a CubeSat, to be used in support of the BepiColombo science mission. BepiColombo is an ESA-JAXA satellite launched in 2018 that will enter orbit with Mercury in December 2025.
BepiColombo will study, among other things, X-ray and UV emissions related to Mercury's exosphere.
With this PSC project, CSEP proposes to extend the scientific return of BepiColombo measurements with simultaneous synergic observations of Mercury made by a small student satellite orbiting the Earth.

Objectives.
The objective of this CSCP is to carry out a phase A study to define a nanosatellite which will carry out, in synergy with BepiColombo, UV / X-rays observation measurements of Mercury.

Subject.
This project, proposed by a future StartUp, aims to define a constellation of satellites with the objective of cataloguing small debris at altitudes above 550 km. Indeed, the large number of debris in orbit around the Earth represents a significant problem for satellites.
Every day, several collision alerts force satellites to perform emergency maneuvers. But small debris are only catalogued at low altitude because of the observation capabilities of ground stations.
In this context, a constellation in LEO could strongly improve the debris observation capabilities, which would allow a strong improvement of the alert system.

Objectives.
The objective of this CSP is to perform a Phase A study to define a constellation of satellites that will perform (optical) observation measurements of small debris at altitudes above 600 km.
This work involves studying the mission profile, defining the platform and its payload, and identifying COTS compatible with the mission specifications.

Subject.
Balloons are obviously one of the most suitable means to study atmospheric electricity: they allow to explore the altitude range site of most of the mechanisms at the origin of atmospheric electricity and the direct causes of many phenomena associated with it.
The objective of this PSC is to develop and fly under a balloon a light nacelle carrying an instrumentation allowing the measurement of the electric field, the conductivity of the atmosphere and the electromagnetic waves generated by the distant thunderstorms.
This project will thus serve as a test bench for new experimental techniques that could be proposed on stratospheric balloon flights within the framework of the STRATEOLE and STRATELEC programs under the aegis of CNES.

Objectives.
The objective of this PSC is to study the electromagnetic waves emitted in the atmosphere by thunderstorms. To do so, the students will have to (i) design, (ii) build and (iii) test a nacelle to measure the electromagnetic waves in situ. The nacelle will be launched during measurement campaigns, with small weather balloons.

Subject.
The X-Rocket project, from 2019, aims to launch and recover experimental rockets fully developed at CSEP as part of the CNES C'Space campaign.
Due to its complexity, this project allows students to test their abilities in a series of challenges, ranging from the aerodynamic design of the launcher, to the control electronics, to the manufacture of the rocket, to the mechanics of its recovery, to the launch of the rocket itself.
This PSC will provide students with a detailed and practical understanding of rocket operations and prepare them for a career in the aerospace field.

Objectives.
The objective of this PSC is to design, build, and recover the X-Rocket rocket. The challenge this year will be to successfully recover the rocket to a well-defined location.
To do this, students will need to (i) design the rocket, its components and recovery system, (ii) build it, (iii) launch it and (iv) recover it.

Subject.
The MiniX-Rocket project aims at the realization of a two-stage mini-rocket and its recovery during the launch.
To allow students to focus on the recovery method of the modules, the rocket will be built from the development kit provided by CNES.
This project will allow the students to confront the challenges related to the design of launchers from the point of view of aerodynamic stability and attitude control, as well as the difficulties of realizing the mechanisms related to the recovery systems.
MiniX-Rocket is a comprehensive project, which will allow students to design the launcher, manufacture it and finally test and validate it.
Thanks to its multi-physics profile, this project will significantly improve the students' knowledge and prepare them for a career in the aerospace field.

Objectives.
The objective of this PSC is to build and test a two-stage mini-rocket. This will require students to (i) design the rocket, its components and recovery systems, (ii) build it, and (iii) launch it to validate the concept.

Subject.
The Digital Twin project aims at the realization of a simulation tool that can support the CSEP launchers projects. Indeed, during the design of launchers, the possibility to simulate the rocket, to study and optimize its performances before its manufacture is essential for an efficient and low-cost production. This PSC project will allow students to study rockets in their entirety as well as the details of their aerodynamic properties, flight control algorithms, and state-of-the-art attitude control methods.
This comprehensive and detailed view will greatly enhance the students' knowledge and prepare them for a career in the aerospace field.

Objectives.
The goal of this PSC is to evolve the project to improve the fidelity of the model and its application spectrum. To do so, the students will focus on coupling the model with Ansys-type CFD simulation tools, and extending the model to autorotative mechanisms for rocket recovery.

Subject.
The Back On Earth project was initiated in 2019 with the goal of designing and testing a reusable space launch vehicle demonstrator powered by an electric motor.
One of the main interests of this project is to have students learn about the technological challenges of rocket stage recovery, a strong argument for current launch vehicles.
Previous PSCs have begun work on a first prototype demonstrator.
This prototype is controlled by a system of vanes governed by a control algorithm which allows to redirect the air flow at the exit of the engine (TVC system: Thrust Vectoring Control).

Objectives.
The objective of this PSC is to develop the project to reach the validation tests of the landing control system. To do this, the students will have to focus on (i) the structural optimization of the rocket, (ii) the development of the control algorithm through the realization of tests and (iii) the validation of the system with the first flights of the rocket.

The Exploration Company

We develop, produce and operate Nyx, a modular and reusable space orbital vehicle to be eventually refuelled in orbit, and which carries cargo – and potentially humans – in the longer run. To be able to dock to stations and carry out in-orbit refuelling, dedicated approach algorithms should be developed. Among others, we can list the following essential key technologies:

• Collaborative guidance
• Relative navigation
• Visual-based navigation

The objective of this project is to focus on preliminary visual-based navigation algorithms. We ambition to modify a quadcopter drone’s navigation algorithms and use its on-board camera to make it “touch” a target painted on a fixed object.

Subject.
Supported by the CSEP (Centre Spatial Etudiant du Polytechnique), the EVE project aims at the realization of a chemical engine with propellant combustion.
The main interest of the project is to allow CSEP students to acquire a detailed knowledge of the engines typically used for the propulsion of launchers.
The design of the engine and its feeder circuits, the realization of validation tests as well as the thrust optimization work will give the students a first-hand knowledge of the state of the art of rocket propulsion subsystems, thus preparing them for careers in the aerospace field.

Objectives.
The objective of this PSC is to advance the project to the first validation tests of the propulsion system and the verification of the engine thrust.
To do so, students will have to focus on (i) the definition and realization of an electronically controllable injection system, (ii) the manufacturing of the engine, (iii) the implementation of the engine validation tests and the verification of its thrust, and (iv) the thrust optimization.

Subject.
Recently, for numerous space missions, small satellites have been chosen over larger platforms. Although large platforms are capable of carrying different payloads simultaneously, small platforms such as nanosatellites are much less expensive.
They are therefore often chosen for validating subsystems and techniques, whereas large satellites are usually chosen for scientific missions carrying high TRL components.
The low cost of nanosatellites makes them compatible with the limited budgets of student space centers. This is the case for CSEP, which is currently focusing its efforts on IonSat and CROCUS, two nanosatellite missions.
However, nanosatellites have very strong constraints in terms of available mass and volume. As a result, deployable arms on nanosatellites are typically short and cannot deploy scientific instruments far from the platform.
But due to the proximity of the platform, the measurements of the scientific instruments are disturbed by the electromagnetic signals emitted at the satellite platform and, as a result, their signal-to-noise ratio is low.
The quality of these scientific measurements can be improved by mounting the sensors on long arms suitable for nanosatellite applications.  

Objectives.
The objective of this PSC is to begin the development of deployable booms that CSEP will use for nanosatellite applications.
Different types of deployable booms currently exist (e.g. STEM), but only a few companies are able to produce them in Europe.
Students will select the types of deployable booms to be developed, to ensure a deployable length of at least 1.5 m. They will create the specifications for the systems.
They will design the mechanism that meets the specifications. They will create prototypes and test them.

Subject.
Recently, for many space missions, small satellites have been chosen over larger platforms. Although large platforms are capable of carrying different payloads simultaneously, small platforms such as nanosatellites are much less expensive.
They are therefore often chosen to validate subsystems and techniques, whereas large satellites are generally chosen for scientific missions carrying high TRL components.
The low cost of nanosatellites makes them compatible with the limited budgets of student space centers. This is the case for CSEP, which is currently focusing its efforts on IonSat and CROCUS, two nanosatellite missions.
Nanosatellites will be the target of future CSEP space missions. In this context, to facilitate future missions, CSEP has the ambition to strengthen its heritage of high TRL components.
To this end, CSEP proposes to begin the development of attitude control subsystems to be used in future CSEP nanosatellite missions.  

Objectives.
The objective of this PSC is to begin the development of attitude control subsystems that CSEP will use for its future nanosatellite applications.
There are different types of attitude control subsystems (e.g. magnetorquers and reaction wheels). Students will select the types of subsystems to develop. They will create specifications for the subsystems. They will design a subsystem that meets the specifications. They will create prototypes and test them.

Long-duration crewed space missions require bioregenerative life support solutions to improve mission sustainability and resiliency in the harsh environment of space. Understanding the impact of the space environment on Earth ecosystems is a critical next step in developing such solutions. This manuscript presents the experimental design of the SCAMPI Project (Saltwater Crustacean, Algae, and Microbe Population Investigation), a student mission to investigate the effect of microgravity and increased radiation on a multitrophic aquatic closed ecological system.
The team is developing a custom payload, consisting of a sealed aquarium and instrumentation suite, to be integrated into the ICE Cubes facility onboard the International Space Station. Remote monitoring will collect data and imagery on the biotic and abiotic factors within the closed environment, informing a digital twin simulation that is being developed concurrently. This experiment will be the latest in a short list of ecosystem-scale experiments to fly in space, and address fundamental knowledge gaps, including microbial community dynamics in microgravity. Ultimately, SCAMPI will provide data to inform the design of future closed ecological life support technologies by validating the hypothesis that Earth's ecosystems can function nominally in the space environment. The experiment is currently being built as a part of ESA’s PETRI program and anticipates launching in early 2025.

The project is currently under review from ESA safety panels and we would like to include the team from polytechnique in the development of the hardware needed for the scientific payload through the PSC "SCAMPI : Investigation of an aquatic system in microgravity". This includes and is not limited to the following goals:

• Develop a leak-free mechanical structure to host 0.7L aquarium
• Design an instrumentation suite to monitor the health of the aquarium

 
The second project "SCAMPI : Modeling of an aquatic system in microgravity" aims at developing from scratch an ecological model that accounts for the dynamics of the aquatic ecosystem. This refers, but is not limited, to :

• Matter cycle exchanges
• The evolution of the population
• Comparison between the behavior in microgravity and the behavior on Earth

A third, more fundamental project looks at bubble formation in microgravity. Indeed, in space, due to vibration or sloshing in a tank partially field by liquid and air, instabilities and fragmentation at the phase interface can lead to formation of small liquid or air bubbles creating a complex bi-phase system. In a microgravity environment, that is with negligible buoyancy force, this situation can be particularly problematic. Therefore, finding a way to aggregate these bubbles is of great interest.

Let’s consider a volume V delimited by a solid not-deformable surface S filled with a Newtonian fluid in a microgravity field. We assume initially that the volume contains n bubbles of air, taking a spherical shape of radius rb to minimize the Helmholtz free energy at equilibrium. Each bubble i has an initial position Mi(t0) and momentum pi.

The solid volume has certain coordinates relative to a frame attached to the volume, that is translating and rotating relative to an inertial system. We neglect the deformation of the bubble at first approximation.

The problem is to find the trajectory of the particles in the moving volume and to study the coalescence of the bubbles within the volume. An application is to find a particular movement of the tank that lead to a total coalescence of the bubbles into one final bubble which might offer a novel method to optimize satellite maneuvers through minimizing bubble formation in tanks and in general fluid management systems.
1.1 General equations
The first problem is to find the trajectory of governing equation of a bubble and fluid movement in a large volume of water moving relative to an inertial frame of reference.
1.2 Finite rotating tank problem
The second problem is to apply the equations to a finite cylinder of radius r0 and length l0 rotating relative to an inertial reference
frame. We aim to find the time for the bubble to reach a stationary position and particularly to study the conditions for coalescence of several bubbles. If the Weber number is larger than a certain value that remains to be found, then the approximation of not-deformable shape can no longer be valid. After studying the rotation of the cylinder, several other movements can be explored, especially oscillatory movements.

The project will be co-tutored by Olivier Marchand : olivier.marchand(at)ladhyx.polytechnique.fr and Tarek Ben Slimane : tarek.ben-slimane(at)polytechnique.edu

Carried out in collaboration with ONERA and the Ecole Polytechnique Space Center (CSEP), this project aims to prepare the scientific exploitation of the ChaRging On CUbeSat (CROCUS) mission. Since 2017, this mission aims to better understand the phenomena of Electrostatic Discharge (ESD) observed at the satellites' surfaces. This will help to validate techniques to regulate the value of spacecraft potential and, as a consequence, better protect the satellite from discharges. To do this, we use the SPIS software, the reference software for the study of interactions between plasma and satellites.

Objective: evolution of numerical analyses in support of the finalization of the CROCUS satellite and in support of the practical tests carried out at ONERA. This work includes the fine modeling of the plasma-CROCUS interaction through high definition SPIS simulations, the study of the deorbiting of the satellite, the modeling of the spacecraft potential regulator system.

CROCUS is expected to be launched in 2024-2025.