The ARIEL Instrument Control Unit design for the M4 Mission Selection Review of the ESA's Cosmic Vision Program

The Atmospheric Remote-sensing Infrared Exoplanet Large-survey mission (ARIEL) is one of the three present candidates for the ESA M4 (the fourth medium mission) launch opportunity. The proposed Payload will perform a large unbiased spectroscopic survey from space concerning the nature of exoplanets atmospheres and their interiors to determine the key factors affecting the formation and evolution of planetary systems. ARIEL will observe a large number (>500) of warm and hot transiting gas giants, Neptunes and super-Earths around a wide range of host star types, targeting planets hotter than 600 K to take advantage of their well-mixed atmospheres. It will exploit primary and secondary transits spectroscopy in the 1.2-8 um spectral range and broad-band photometry in the optical and Near IR (NIR). The main instrument of the ARIEL Payload is the IR Spectrometer (AIRS) providing low-resolution spectroscopy in two IR channels: Channel 0 (CH0) for the 1.95-3.90 um band and Channel 1 (CH1) for the 3.90-7.80 um range. It is located at the intermediate focal plane of the telescope and common optical system and it hosts two IR sensors and two cold front-end electronics (CFEE) for detectors readout, a well defined process calibrated for the selected target brightness and driven by the Payload's Instrument Control Unit (ICU).Comment: Experimental Astronomy, Special Issue on ARIEL, (2017

STR: a student developed star tracker for the ESA-LED ESMO moon mission

In the frame of their engineering degree, ISAE’s students are developing a Star Tracker, with the aim of being the core attitude estimation equipment of the European Moon Student Orbiter. This development goes on since several years and is currently in phase B. We intend to start building an integrated breadboard for the end of the academic year. The STR is composed of several sub-systems: the optical and detection sub-system, the electronics, the mechanics and the software. The optical detection part is based on an in-house developed new generation of APS detectors. The optical train is made of several lenses enclosed in a titanium tube. The electronics includes a FPGA for the pre-processing of the image and a microcontroller in order to manage the high level functions of the instrument. The mechanical part includes the electronics box, as well as the sensor baffle. The design is optimized to minimize the thermo-elastic noise of the assembly. Embedded on ESMO platform, this Star Tracker will be able to compute the satellite‘s attitude, taking into account the specific requirements linked to a Moon mission (illumination, radiation requirements and baffle adaptation to lunar orbit). In order to validate the design, software end-to-end simulation will include a complete simulation of the STR in its lunar dynamic environment. Therefore, we are developing a simple orbital model for the mission (including potential dazzling by celestial bodies)

The evolution of oscillatory behavior in age-structured species

A major challenge in ecology is to explain why so many species show oscillatory population dynamics and why the oscillations commonly occur with particular periods. The background environment, through noise or seasonality, is one possible driver of these oscillations, as are the components of the trophic web with which the species interacts. However, the oscillation may also be intrinsic, generated by density-dependent effects on the life history. Models of structured single-species systems indicate that a much broader range of oscillatory behavior than that seen in nature is theoretically possible. We test the hypothesis that it is selection that acts to constrain the range of periods. We analyze a nonlinear single-species matrix model with density dependence affecting reproduction and with trade-offs between reproduction and survival. We show that the evolutionarily stable state is oscillatory and has a period roughly twice the time to maturation, in line with observed patterns of periodicity. The robustness of this result to variations in trade-off function and density dependence is tested

Sampling-based optimal kinodynamic planning with motion primitives

This paper proposes a novel sampling-based motion planner, which integrates in RRT* (Rapidly exploring Random Tree star) a database of pre-computed motion primitives to alleviate its computational load and allow for motion planning in a dynamic or partially known environment. The database is built by considering a set of initial and final state pairs in some grid space, and determining for each pair an optimal trajectory that is compatible with the system dynamics and constraints, while minimizing a cost. Nodes are progressively added to the tree {of feasible trajectories in the RRT* by extracting at random a sample in the gridded state space and selecting the best obstacle-free motion primitive in the database that joins it to an existing node. The tree is rewired if some nodes can be reached from the new sampled state through an obstacle-free motion primitive with lower cost. The computationally more intensive part of motion planning is thus moved to the preliminary offline phase of the database construction at the price of some performance degradation due to gridding. Grid resolution can be tuned so as to compromise between (sub)optimality and size of the database. The planner is shown to be asymptotically optimal as the grid resolution goes to zero and the number of sampled states grows to infinity

QKD hardware on small satellites

Quantum Key Distribution (QKD) enables the exchange of secret keys by which, based on the laws of quantum physics, eavesdropping attempts can be detected and their maximum information can be determined. By using satellites equipped with QKD hardware and an optical communication terminal, fundamental limitations for fber based QKD networks regarding the distance between the communicating parties can be overcome. In this thesis, a compact and robust QKD sender module, which has been designed, built, and qualifed for the integration into the 3-unit (30 × 10 × 10 cm3) Cube-Satellite QUBE, is presented. The goal of QUBE is to test and verify the suitability of QKD senders based on two different technologies under real space conditions. Our sender implements the BB84 QKD protocol with polarization encoding of weak coherent pulses (WCPs). Its compactness and its low power consumption is reached by the usage of mostly passive micro-optical components. Colleagues of the MPL in Erlangen provide a further payload which features the phase encoding of WCPs based on photonic integrated circuits. The harsh environmental infuences in space (radiation, thermal cycles, vacuum) and the mechanical vibration loads during the rocket launch require considerable tests of the hardware, which were performed on devices identical to the ones later integrated as fight models in the satellite. Promising results were achieved, which for example show a good quality of the prepared polarization states and a low quantum bit error ratio (QBER) of only 2.2% of the light emitted by the fully integrated satellite

Statistical Properties of the Quantile Normalization Method for Density Curve Alignment

We present a proof for the quantile normalization method proposed by \citet{Bolstad-03} which has become one of the most popular methods to align density curves in microarray data analysis. We prove consistency of this method which is viewed as an application to density curve registration of the new method proposed in \citet{Dupuy-Loubes-Maza-11}, the structural expectation. Moreover, when this method fails in some case of mixture, we propose a new methodology to cope with this issue

Design of a flatsat for the AlbaSat mission

openThis thesis presents the design of a FlatSat for the AlbaSat mission. AlbaSat is a 2U CubeSat with four mission objectives: (1) to collect in-situ measurements of the sub-mm space debris environment in LEO, (2) to study the micro-vibration environment on the satellite throughout different mission phases, (3) to do orbit and attitude determination through laser ranging; (4) to investigate alternative systems for possible Satellite Quantum Communication applications on nanosatellites. Firstly, an overview of CubeSats state of art and of the AlbaSat mission is provided, illustrating the main mission objectives and the importance of testing and verifying the satellite performance before launch using, for instance, FlatSat. Subsequently, the objectives of the FlatSat in the AlbaSat mission are defined. These objectives include creating a test and verification platform to evaluate the satellite's functionalities, verifying the proper interaction between subsystems, and achieving performance and reliability requirements. The design of the FlatSat is described in detail, including component selection, functional architecture, subsystem arrangement, and interfaces between them. Aspects such as power supply, attitude control, data acquisition, and communication are considered. Special attention is given to subsystem integration to ensure proper connection and interaction. The tests programmed on the FlatSat are presented, including functional tests, integration tests, and communication tests. In addition, the Electro-magnetic Compatibility (EMC) of the satellite components is addressed. Aspects related to electromagnetic interference and protective measures are analyzed to ensure immunity to external electromagnetic disturbances and non-interference with other systems or devices. The thesis is developed in the framework of the Alba CubeSat project, which participate to the European Space Agency’s (ESA) Fly Your Satellite! – design booster program. The thesis provides the guidelines to assembly and integrate and test the FlatSat of AlbaSat, contributing to the development of the mission. The results and experiences gained from this research can be applied to future satellite development projects

Validation of a test platform to qualify miniaturized electric propulsion systems

Miniaturized electric propulsion systems are one of the main technologies that could increase interest in CubeSats for future space missions. However, the integration of miniaturized propulsion systems in modern CubeSat platforms presents some issues due to the mutual interactions in terms of power consumption, chemical contamination and generated thermal and electro-magnetic environments. The present paper deals with the validation of a flexible test platform to assess the interaction of propulsion systems with CubeSat-technologies from mechanical, electrical, magnetic, and chemical perspectives. The test platform is a 6U CubeSat hosting an electric propulsion system and able to manage a variety of electric propulsion systems. The platform can regulate and distribute electric power (up to 60 W), exchange data according to several protocols (e.g. CAN bus, UART, I2C, SPI), and provide different mechanical layouts in 4U box completely dedicated to the propulsion system. Moreover, the data gathered by the onboard sensors are combined with the data from external devices and tools providing unprecedented information about the mutual behavior of a CubeSat platform and an electric propulsion system