Deployment mechanism for an L-Band Helix antenna on-board the 3Cat-4 1U CubeSat

Earth Observation (EO) is key for climate and environmental monitoring at global level, and in specific regions where the effects of global warming are more noticeable, such as in polar regions, where ice melt is also opening new commercial maritime routes. Soil moisture is also useful for agriculture and monitoring the advance of desertification, as well as biomass and carbon storage. Global Navigation Satellite System - Reflectometry (GNSS-R) and L-band microwave Radiometry are passive microwave remote sensing techniques that can be used to perform these types of measurements regardless of the illumination and cloud conditions, and -since they are passive- they are well suited for small satellites, where power availability is a limiting factor. GNSS-R was tested from space onboard the UK-DMC and the UK TechDemoSat-1, and several missions have been launched using GNSS-R as main instrument, as CyGNSS, BuFeng-1, or the FSSCAT [1] mission. These missions aim at providing soil moisture [2], ocean wind speed [3], and flooding mapping of the Earth. L-band microwave radiometry data has also been retrieved from space with SMOS and SMAP missions, obtaining sea ice thickness, soil moisture, and ocean salinity data [4]. The 3Cat-4 mission was selected by the ESA Academy "Fly your Satellite" program in 2017. It aims at combining both GNSS-R and L-band Microwave Radiometry at in a low-power and cost-effective 1-Unit (1U) satellite. Moreover, the 3Cat-4 can also detect Automatic Identification System (AIS) signals from vessels. The single payload is the Flexible Microwave Payload 1 (FMPL-1) [5] that performs the signal conditioning and signal processing for GNSS-R, L-Band microwave radiometry and AIS experiments. The spacecraft has three payload antennas: (1) a VHF monopole for AIS signals; (2) an uplooking antenna for the direct GPS signals; (3) a downlooking antenna that captures reflected GPS signals, and for the Microwave Radiometer. The downlooking antenna is a deployable helix antenna called the Nadir Antenna and Deployment Subsystem (NADS) which has a volume of less than 0,3U when stowed, achieving an axial length of more than 500 mm when deployed. As part of this mission, the design of the NADS antenna, its RF performance, as well as the environmental tests performed in terms of structural and thermal space conditions will be presented

RITA: a 1U multi-sensor Earth observation payload for the AlainSat-1

The Remote sensing and Interference detector with radiomeTry and vegetation Analysis (RITA) is one of the Remote Sensing payloads selected as winners of the 2nd GRSS Student Grand Challenge in 2019, to fly on board of the 3U AlainSat-1. This CubeSat is being developed by the National Space Science and Technology Center (NSSTC), United Arab Emirates University. RITA has been designed as an academic mission, which brings together students from different backgrounds in a joint effort to apply very distinct sensors in an Earth Observation mission, fusing their results to obtain higher-accuracy measurements. The main payload used in RITA is a Total Power Radiometer such as the one on board the FSSCat mission. With these radiometric measurements, soil moisture and ice thickness will be obtained. To better characterize the extensive Radio-Frequency Interferences received by EO satellites in protected bands, several RFI Detection and Classification algorithms will be included to generate a worldwide map of RFI. As a novel addition to the 3Cat family of satellites and payloads, a hyper-spectral camera with 25 bands ranging from 600 to 975 nm will be used to obtain several indexes related to vegetation. By linking these measurements with the soil moisture obtained from the MWR, pixel downscaling can be attempted. Finally, a custom- developed LoRa transceiver will be included to provide a multi-level approach to in-situ sensors: On-demand executions of the other payloads will be able to be triggered from ground sensors if necessary, as well as simple reception of other measurements that will complement the ones obtained on the satellite. The antennas for both the MWR and the LoRa experiments have been developed in-house, and will span the entirety of one of the 3U sides of the satellite. In this work, the latest development advances will be presented, together with an updated system overview and information about the operations that will be conducted. Results obtained from the test campaign are also presented in the conference

Implementation and verification of cubeSat subsystems

The TFG is involved in the Nano-Satellite and Payload Laboratory (NanoSat Lab) activity to develop a 1U CubeSat in the ESA Academy program. In particular, it is expected that the student implements different subsystems, in terms of Hardware, and verify them following a specific testing procedure. The analysis of the test results will also provide an additional point of view of the system.Increasingly, the nanosatellites are becoming a versatile platform to send experiments to space, since their cost is relatively cheaper in relation to conventional satellites. The NanoSat Lab, from the Polytechnic University of Catalonia, develops innovative applications using nanosatellites for experimenting into space. The mission 3Cat-4, selected by the European Space Agency (ESA) for "Fly Your Satellite" program, aims to design and implement a nanosatellite to send three experiments to space. The applications involved in these experiments are a GNSS receiver, an AIS receiver and an L-band radiometer. In order to test the different satellite?s subsystems, during the different phases of the implementation, a series of tools have been developed. This project aims to design and implement some of these necessary tools.Cada vez más, los nanosatélites se están convirtiendo en una plataforma versátil para poder enviar experimentos al espacio, ya que su coste es relativamente económico en relación con los satélites convencionales. El Nanosat Lab, de la Universidad Politécnica de Catalunya, desarrolla aplicaciones innovadoras y utiliza los nanosatélites para poder experimentar estas aplicaciones en el espacio. La misión 3Cat-4, seleccionada dentro del programa "Fly Your Satellite" de la Agencia Espacial Europea (ESA) pretende diseñar e implementar un nanosatélite que llevará tres experimentos al espacio. Las aplicaciones que forman parte de estos experimentos son: un receptor de GNSS, un receptor AIS y un radiómetro de banda L. Para poder testear los diferentes subsistemas que conforman el satélite, durante las diferentes etapas de su implementación, se ha desarrollado una serie de herramientas. Este trabajo pretende diseñar e implementar algunas de estas herramientas necesariasCada vegada més, els nanosatèl·lits s'estan convertint en una plataforma versàtil per poder enviar experiments a l'espai, ja que el seu cost es relativament econòmic en relació amb els satèl·lits convencionals. El NanoSat Lab, de la Universitat Politècnica de Catalunya, desenvolupa aplicacions innovadores i utilitza nanosatèl·lits per tal de poder experimentar-les a l'espai. La missió 3Cat-4, seleccionada dins del programa "Fly Your Satellite" de l'Agencia Espacial Europea (ESA) pretén dissenyar i implementar un nanosatèl·lit que portarà tres experiments a l'espai. Les aplicacions que formen part d'aquest experiment són: un receptor de GNSS, un receptor AIS i un radiòmetre de banda L. Per tal de poder testejar els diferents subsistemes que conformen el satèl·lit, durant les diferents etapes de la implementació, s'han de desenvolupat un seguit d'eines. Aquest treball pretén dissenyar i implementar algunes d'aquestes d'eines necessàries

Implementation and verification of cubeSat subsystems

The TFG is involved in the Nano-Satellite and Payload Laboratory (NanoSat Lab) activity to develop a 1U CubeSat in the ESA Academy program. In particular, it is expected that the student implements different subsystems, in terms of Hardware, and verify them following a specific testing procedure. The analysis of the test results will also provide an additional point of view of the system.Increasingly, the nanosatellites are becoming a versatile platform to send experiments to space, since their cost is relatively cheaper in relation to conventional satellites. The NanoSat Lab, from the Polytechnic University of Catalonia, develops innovative applications using nanosatellites for experimenting into space. The mission 3Cat-4, selected by the European Space Agency (ESA) for "Fly Your Satellite" program, aims to design and implement a nanosatellite to send three experiments to space. The applications involved in these experiments are a GNSS receiver, an AIS receiver and an L-band radiometer. In order to test the different satellite?s subsystems, during the different phases of the implementation, a series of tools have been developed. This project aims to design and implement some of these necessary tools.Cada vez más, los nanosatélites se están convirtiendo en una plataforma versátil para poder enviar experimentos al espacio, ya que su coste es relativamente económico en relación con los satélites convencionales. El Nanosat Lab, de la Universidad Politécnica de Catalunya, desarrolla aplicaciones innovadoras y utiliza los nanosatélites para poder experimentar estas aplicaciones en el espacio. La misión 3Cat-4, seleccionada dentro del programa "Fly Your Satellite" de la Agencia Espacial Europea (ESA) pretende diseñar e implementar un nanosatélite que llevará tres experimentos al espacio. Las aplicaciones que forman parte de estos experimentos son: un receptor de GNSS, un receptor AIS y un radiómetro de banda L. Para poder testear los diferentes subsistemas que conforman el satélite, durante las diferentes etapas de su implementación, se ha desarrollado una serie de herramientas. Este trabajo pretende diseñar e implementar algunas de estas herramientas necesariasCada vegada més, els nanosatèl·lits s'estan convertint en una plataforma versàtil per poder enviar experiments a l'espai, ja que el seu cost es relativament econòmic en relació amb els satèl·lits convencionals. El NanoSat Lab, de la Universitat Politècnica de Catalunya, desenvolupa aplicacions innovadores i utilitza nanosatèl·lits per tal de poder experimentar-les a l'espai. La missió 3Cat-4, seleccionada dins del programa "Fly Your Satellite" de l'Agencia Espacial Europea (ESA) pretén dissenyar i implementar un nanosatèl·lit que portarà tres experiments a l'espai. Les aplicacions que formen part d'aquest experiment són: un receptor de GNSS, un receptor AIS i un radiòmetre de banda L. Per tal de poder testejar els diferents subsistemes que conformen el satèl·lit, durant les diferents etapes de la implementació, s'han de desenvolupat un seguit d'eines. Aquest treball pretén dissenyar i implementar algunes d'aquestes d'eines necessàries

Demonstration of the federated satellite systems concept for future earth observation satellite missions

In the last years, the need to access Earth Observation high spatial resolution data with very low latency, ideally in near-real-time, has increased. Distributed Satellite Systems have emerged as an effective and efficient architecture to deal with these tight requirements. One of these systems is the Federated Satellite Systems which explore the benefits of sharing unused and available resources between satellites, such as memory storage or downlink opportunities. This interaction is known as satellite federations. Additional downlink contacts may enable low-latency communications and increase the downlink capacity. Therefore, the deployment of federations would allow satisfying current Earth Observation community demands. This work contributes to establish this promising paradigm by presenting a proof-of-concept of a federated system, called FSS Experiment payload. This payload is boarded into three stratospheric balloons, and it provides them communications means to create federations. The design of the payload, and the flight campaign results are presented in this work. These results demonstrate the feasibility of deploying federations, as well as the benefits of deploying them in future EO missions.This work has been funded by “CommSensLab” Excellence Research Unit Maria de Maeztu (MINECO grant MDM-2016-0600), and the Spanish Ministerio MICINN and EU ERDF project (RTI2018-099008-B-C21) “Sensing with pioneering opportunistic techniques” by the grant FI-DGR 2015 of AGAUR - Generalitat de Catalunya (FEDER). The authors would like to acknowledge Skoltech and all the students that with their passion have made possible this balloon campaign.Peer ReviewedPostprint (published version

Deployment mechanism for a L-band helix antenna in 1-Unit Cubesat

Recently, there is a renewed interest in Earth Observation (EO) of the cryosphere as a proxy of global warming, soil moisture for agriculture and desertification studies, and biomass for carbon storage. Global Navigation Satellite System-Reflectometry (GNSS-R) and L-band microwave Radiometry have been used to perform these measurements. However, it is expected that the combination of both can largely improve current observations. Cat-4 mission aims at addressing this technology challenge by integrating a combined GNSS-R and Microwave Radiometer payload into a 1-Unit CubeSat. One of the greatest challenges is the design of an antenna that respects the envelope and stowage requirements of 1-Unit CubeSat, being able to work in the different frequency bands: Global Positioning System (GPS) L1-band (1575 MHz), GPS L2-band (1227 MHz), and microwave radiometry at 1400–1427 MHz. After a trade-off analysis, a helix antenna was found to be the most suitable option. This antenna has 11 turns equally distributed with 68.1 mm of diameter. This design generates an antenna with 506 mm of axial length, providing the maximum radiation gain in the endfire direction. Additionally, a counterweight is added at the tip of the antenna to enhance the directivity, and it is used as gravity gradient technique. The deployment of this antenna in vacuum and extreme temperature conditions is the greatest mechanical challenge that needs to be addressed for the success of the mission. This work presents a mechanical solution that enables to deploy the helix antenna from 25.5 mm (stowed configuration) to the final 506 mm (deployed configuration). By sequentially deploying different parts of the antenna, the final configuration is reached without impacting the attitude pointing of the CubeSat. This is accomplished using dyneema lines that are melted sequentially by commands. In addition, the deployment velocity, acceleration, and waving are presented as part of its characterization. The current test results in a Thermal Vacuum Chamber indicate also that the deployment can be achieved in -35 °C. The Cat-4 CubeSat, with the L-band helix antenna, will be launched in Q4 2020 as part of the “Fly Your Satellite!” program of the European Space Agency (ESA).This work was supported in part by the ‘‘CommSensLab’’ ExcellenceResearch Unit Maria de Maeztu Ministerio de asuntos Económicos y transformación digital (MINECO) under Grant MDM-2016-0600; in part by the Spanish Ministerio de Ciencia e Innovación (MICINN) and European Union - European Regional Development Fund (EUERDF) project ‘‘Sensing with pioneering opportunistic techniques’’ un-der Grant RTI2018-099008-B-C21; and in part from FI-2019 grant from AGAUR-Generalitat de Catalunya.Peer ReviewedPostprint (author's final draft

Proof-of-concept of a federated satellite system between two 6-unit cubeSats for distributed earth observation satellite systems

During these years, novel Distributed Satellite Systems (DSS) have addressed the new Earth Observation (EO) requirements (e.g. near-real time access to data, or multi-point observations). One of the DSS proposals is the concept of Federated Satellite System (FSS) which has explored the benefits of sharing available and unused resources between satellite to maximize the system utility. The possibility to use additional downlink opportunities thanks to federations is a resource that could improve current EO missions, and thus achieving the required performance. For that reason, the FSS Experiment payload has been implemented as a FSS proof-of-concept between 6-Unit CubeSats in the FSSCAT mission. This article presents the design, and the test results of this payload demonstrating its feasibility for future EO missions.Peer ReviewedPostprint (published version

Design and Testing of a Helix Antenna Deployment System for a 1U CubeSat

CubeSats have revolutionized Earth Observation and space science, although their small size severely restricts satellite performance and payload. Antenna deployment from a stowed configuration in these small-satellites remains a great challenge. This paper presents the design, optimization, and testing of an L-band helix antenna deployment system for the 3 Cat-4, a 1U CubeSat developed at the NanoSat Lab (UPC). The 506-mm-long antenna is packed into a 26.8 mm gap together with a tip mass that provides a gravity gradient for nadir-pointing. The 3 Cat-4 Nadir Antenna Deployment Subsystem (NADS) melts dyneema strings to release the antenna in successive steps. PTFE coated fiberglass ensures the helix’s nominal diameter and pitch while a security locking mechanism serves as a redundant system for holding it in place before deploying. Our novel methodology optimizes the number and length of the NADS deployment steps. A slow-motion camera and image recognition software track the velocity and acceleration of the antenna sections by means of tracking dots. Kinematic analysis of the antenna resulted in a final design of four length steps: 90, 300, 420 and 506 mm. Our methodology for calculating these values can be widely applied for measuring many deployment system’s kinematic properties. The NADS performance is tested by characterizing antenna rigidity, analyzing helix behavior after one year in stowed configuration, and by testing the deployment mechanism in a thermal vacuum chamber at -35°C, the most critical temperature stress scenario. All test results are satisfactory. The final design of the NADS deployment mechanism is light, stable, reliable, affordable, highly scalable, and can be used in many antenna configurations and geometries. The 3 Cat-4 mission was selected by the ESA Academy to be launched in Q4 2021.Postprint (published version

³Cat-4 Mission: a 1-unit cubesat for earth observation with a L-band radiometer and a GNSS-reflectometer using software defined radio

Global Navigation Satellite System Reflectometry and L-band microwave radiometry have been used for soil moisture, biomass, and cryosphere studies. Combining both technologies in a low-power and cost-effective solution could largely improve current Earth observations. 3 Cat-4 mission is a 1-Unit CubeSat technology demonstrator of the Flexible Microwave Payload - 1, a reduced size payload that combines these two technologies. This work presents the objectives of the 3 Cat-4 mission and the details of the spacecraft architecture and performance. Each spacecraft subsystem is detailed at hardware and software levels. In addition, the presented results indicate that the current spacecraft design will survive the flight conditions (i.e. thermal and structural ones).Peer ReviewedPostprint (published version