With the support of NANOSTAR, our partner Universidade da Beira Interior (UBI, Portugal) is now developing a student CubeSat project called CUBISat. The objective is to develop a 1U CubeSat technology demonstrator for an Attitude and Dynamics control System.


Magnetic attitude determination and control devices are one of the cheapest most reliable, small and lightweight attitude systems. However, they have limitations, in particular a relatively low accuracy and actuation capability requiring other attitude sensors and actuators. Theoretical studies demonstrate that a solely magnetic Attitude Determination and Control system might be capable of providing three-axis orbital attitude for nanosatellites. To test the proposed algorithms for future space missions a technology demonstrator is needed.

In this activity, the students are performing a health check on a CubeSat reaction wheel that would be used in the CUBISAT.

Students involved:

Supervisor: Jorge Monteiro

 

Design of a set of orbital platforms to raise and lower the orbit of nanosatellites efficiently without using propellant, as a major piece of infrastructure for a space-based nanosatellite economy.

Author: Juan José García Ortiz
University Carlos III Madrid (Spain)

Space activities and attainability are constrained nowadays due to the high cost of rocketry employed put payloads in orbit. This study aims to design, analyze and optimize a network of orbital relay stations that can act as orbital energy accumulators to support other space missions.

The sustainability of such network lies in a balance between payloads being orbited and deorbited.

To test the viability of the proposed network, simulated missions are implemented in a programming environment in a way that can reproduce numerically the behaviour of the network in missions of increasing complexity. The design optimization of such missions is then performed assisted with a built-in genetic algorithm.

The results gathered prove that the energetic balance can be achieved providing an operation with minimal degradation. Proper mission design and station orbit spacing are key in defining suitable design conditions that yield the best case performance and the genetic algorithm is applicable to reduce the losses in off-design operating conditions.

 

Design and fabrication of a thrust balance to measure a pulsed plasma thruster thrust force. This permits to verify the operation of the developed PPT thruster and identify potential improvements.

Author: Andrés Cabello López
University Carlos III Madrid (Spain)

A design of a torsional thrust stand has been developed to test a µPPT at Carlos III University facilities. The proposed design is able to measure single impulses in the range of 5 − 100 µNs and thrust forces in repetitive shot operation of 1 − 100 µN with a sensitivity of 0.776 µm/s/µNs and 6.365 µm/µN respectively. The resolution is estimated in 400 nNs and 100 nN. Two approaches have been faced to model the response of the balance: a simple pendulum analysis, and a flexible beam study. The contribution of both models allows covering the effects induced on the deflection by damping, the different punctual masses and the harmonic normal modes that arise due to the excitation of the thruster.

After an analysis of the requirements imposed and considering the different alternatives for all the subsystems and sensors needed, a complete design has been provided, searching for a convenient, simple, accurate and economical solution. The asymmetrical swing-gate configuration proposed employs a pair of flexural pivots and fits in the prescribed vacuum chamber. The linear displacement response is measured with a confocal chromatic optical pen and the damping is introduced with an eddy current system that can be manually regulated. The calibration method proposed is performed with a parallel plate capacitor to generate electrostatic forces and impulses in the range of the ones exerted by the PPT. A levelling system and alternatives as coaxial liquid connectors or batteries to
decouple the power supply lines from the exterior are also described to improve the performance of the stand and reduce the overall error. Finally, a complete CAD model has been developed.

 

Author: Hugo Miguel Martins Marques
Instituto Superior Técnico, Lisboa (Portugal)

The Attitude Determination and Control System (ADCS) of a nanosatellite is a key subsystem to provide precise attitude knowledge and pointing for the on-board payload and necessary maneuvers. Its design has serious constraints in terms of mass, volume, size, cost and power. The main goal of this dissertation is to provide the NANOSTAR project with a grounded study in terms of attitude determination algorithms and sensors that can be employed in the missions designed under the scope of the project. For that, a simulation platform that realistically describes the nanosatellite environment, allowing orbit generation and propagation, as well as data creation to feed the ADCS was developed.

Then, three representative attitude determination algorithms, namely the Quaternion Estimator (QUEST), the Multiplicative Extended Kalman Filter (MEKF), and a recently developed Globally Exponentially Stable Cascade Attitude Nonlinear Observer, were studied and implemented on the platform developed, using vector measurements provided by a star tracker, Sun sensor, magnetometer and rate gyroscope. Finally, the comparison of the three algorithms in terms of computational resources efficiency, steady-state performance and performance in the case of faults is done, using realistic simulation scenarios. The results obtained provide meaningful insight on the advantages, disadvantages, complexity, computational resources efficiency and performance of the three algorithms,
providing the project with a grounded analysis that can be used for future decision making in terms of
the ADCS design.

Setup of a plant growing system, with the goal of testing growing strategies with A.I. (with uncertainty and machine learning). In fact, plant growing is a repetitive and time-consuming task, which can be automated to some extent, saving space, optimizing resources and reducing pesticide use.

ISAE-SUPAERO (France)

Implementation on real robotic systems (e.g. sensors and actuators) is pursued, with the following main goals:

  1. complete a state of the art of vegetable growing systems, given the constraints identified,
  2. propose a prototype (e.g. https://farm.bot/),
  3. propose an experimental setup and implementation (graphical interface, data recording, etc.), and
  4. optimize and deploy growing strategies for the platform.

Development of antennas, supported by the Astre’nogs association, that will be part of an open source global network of satellite ground-stations named SatNOGS and made available to the scientific community. The final outcome is an antenna what can receive both UHF and VHF frequencies.

ISAE-SUPAERO (France)

Design, analysis and manufacturing of an inertia morphing nanosatellite prototype, capable of controlling a less than 5 seconds periodic Dzhanibekov’s effect.

University Carlos III Madrid (Spain)

The final outcome is a prototype that could be tested in microgravity conditions using parabolic flight, incrementing the TRL of this technology.

The Dzhanibekov’s effect, or tennis racket theorem, is a fast, periodic, controllable and customizable 180 degrees attitude change (obtained when rotation happens around the intermediate inertia axis) that can be used as a passive heat dissipation system or to perform attitude changes in combination with Reaction Wheels in an efficient way.

Inertia control can also allow small satellites to stably spin around a preferred orientation, while maintaining their angular momentum invariant.

The challenge, apart from directly involving 4 students at UC3M, also features the participation of the DZH Dynamics research group, created in the early 2019, with the goal of developing small satellites with inertia morphing properties. A full control of the inertia properties of a solid rigid allows to implement novel attitude control techniques.

 

Refurbishment of an unused vacuum chamber for nanosatellite components testing under vacuum conditions (in accordance to ECSS  standards). The activities include the design and fabrication of a support structure for the vacuum chamber, the definition and purchasing of all necessary chamber components and the vacuum testing of a nanosatellite component.

University Carlos III Madrid (Spain)

Design of deployment mechanisms that manage to reduce the amount of energy that, during deployment, is transmitted to the solar panels. The most common mechanisms in the deployment of panels are studied, as well as dealing with this problem, to choose the ones that best adapt to the requirements. Less conventional mechanisms, unusual in satellites or simply never used, are also studied. This type of mechanism is also analyzed in terms of its viability for use in space.

Polytechnic University of Madrid (UPM), Spain

Feasibility analysis of a space mission and determination of the high-level requirements derived from mission objectives and scientific goals. The set of requirements is approved at the MRR (Mission Requirement Review) at the end of the challenge. Furthermore, different design concepts that meet the requirements are explored, identifying those concepts whose performance could give the maximum scientific return.

Polytechnic University of Madrid (UPM), Spain