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

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 3Cat-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 3Cat-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 3Cat-4 mission was selected by the ESA Academy to be launched in Q4 2021

3Cat-4: combined GNSS-R, L-Band radiometer with RFI mitigation, and AIS receiver for a I-Unit Cubesat based on software defined radio

The 3 Cat-4 mission aims to demonstrate the capabilities of nano-satellites plus the versatility of a Software Defined Radio for passive Earth Observation. Three different microwave payloads are integrated into a single unit CubeSat platform: a multi-constellation (GPS and Galileo) and a dual-band (L1 and L2) Global Navigation Satellite System - Reflectometer receiver, a total power radiometer including a novel Radio Frequency Interference (RFI) detection and mitigation technique, and an Automatic Identification System receiver for vessels tracking. Being able to validate these technologies in a CubeSat enables their fast adoption as hosted payloads or in more performing dedicated platforms in the future. This paper shows a novel approach for embedding multiple passive microwave payloads in a single platform.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

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-1 project: a multi-payload CubeSat for scientific experiments and technology demonstrators

This article introduces 3Cat-1, the first project of the Technical University of Catalonia to build and launch a nano-satellite. Its main scope is to develop, construct, assemble, test and launch into a low Earth orbit a CubeSat with seven different payloads (mono-atomic oxygen detector, graphene field-effect transistor, self-powered beacon, Geiger radiation counter, wireless power transfer (WPT), new topology solar cells and WPT experiment), all fitted in a single-unit CubeSat. On one hand, this is mainly an educational project in which the development of some of the subsystems is carried out by undergraduate and postgraduate students. The satellite demonstrates its capabilities as a cost-effective platform to perform small scientific experiments and to demonstrate some of the new technologies that it incorporates

3Cat-1 project: a multi-payload CubeSat for scientific experiments and technology demonstrators

This article introduces 3 Cat-1, the first project of the Technical University of Catalonia to build and launch a nano-satellite. Its main scope is to develop, construct, assemble, test and launch into a low Earth orbit a CubeSat with seven different payloads (mono-atomic oxygen detector, graphene field-effect transistor, self-powered beacon, Geiger radiation counter, wireless power transfer (WPT), new topology solar cells and WPT experiment), all fitted in a single-unit CubeSat. On one hand, this is mainly an educational project in which the development of some of the subsystems is carried out by undergraduate and postgraduate students. The satellite demonstrates its capabilities as a cost-effective platform to perform small scientific experiments and to demonstrate some of the new technologies that it incorporates

3Cat-1 project: a multi-payload CubeSat for scientific experiments and technology demonstrators

This article introduces 3 Cat-1, the first project of the Technical University of Catalonia to build and launch a nano-satellite. Its main scope is to develop, construct, assemble, test and launch into a low Earth orbit a CubeSat with seven different payloads (mono-atomic oxygen detector, graphene field-effect transistor, self-powered beacon, Geiger radiation counter, wireless power transfer (WPT), new topology solar cells and WPT experiment), all fitted in a single-unit CubeSat. On one hand, this is mainly an educational project in which the development of some of the subsystems is carried out by undergraduate and postgraduate students. The satellite demonstrates its capabilities as a cost-effective platform to perform small scientific experiments and to demonstrate some of the new technologies that it incorporates