Search

In the last years the S5Lab (Sapienza Space Systems and Space Surveillance Laboratory) from Sapienza University of Rome has given to the students the opportunity to gather knowledge on stratospheric payloads by supporting the design and development of two experiments selected for the participation in the REXUS/BEXUS educational Programme, managed by three european space institutions. The insights and lessons learned gathered during the participations in the REXUS/BEXUS educational programme gave the possibility to the student to take part in the development of a third experiment in the frame of the professional research programme HEMERA and complete it successfully. STRATONAV (STRATOspheric NAVigation experiment) was a stratospheric experiment based on Software Defined Radios (SDRs) technology whose aim was the testing of the VOR (VHF Omnidirectional Range) navigation system, evaluating its performance above the standard service volume, which was launched on BEXUS 22 in October 2016. TARDIS (Tracking and Attitude Radio-based Determination In Stratosphere) was developed as a follow up of STRATONAV between 2018 and 2019. Similarly to its predecessor TARDIS was a stratospheric experiment aimed at exploiting the VOR signal, with the aid of SDRs, to perform in-flight attitude and position determination, and was launched on BEXUS 28 in October 2019. After the launch of TARDIS, a team composed both by former STRATONAV and TARDIS students was formed for the development of a third stratospheric experiment going by the name of STRAINS (Stratospheric Tracking Innovative Systems), conceived by Sapienza University of Rome and ALTEC and supported by ASI. STRAINS main objective was the proof of concept of the possibility of achieving the Time Difference of Arrival (TDOA) and the Frequency Difference of Arrival (FDOA) for navigation purposes with the aid of SDRs. The experiment was developed between 2020 and 2021 exploiting the lessons learned from the former team members of the two BEXUS campaigns and was launched on board of the Hemera H2020 stratospheric balloon in September 2021 from Esrange Space Center, Kiruna, Sweden. After a brief description of the stratospheric payloads design and manufacturing, the paper will present the major lessons learned from the previous stratospheric experiments, STRATONAV and TARDIS, and their application to the development and manufacturing of the latest launched stratospheric experiment STRAINS, as well as their educational return to the students involved in the projects.

The LEDSAT 1U Cubesat, a satellite roughly 10x10x11cm, was developed between late 2016 and 2021 by students of Sapienza University of Rome. The project was conceived with the help of the University of Michigan and started being developed by space engineering master students of Sapienza in a class context. The team of the S5Lab (Sapienza Space System and Space Surveillance Laboratory) continued the project and applied for the Fly Your Satellite! Programme of ESA Education, which has followed the development of the CubeSat, providing important expert support and periodic reviews. The approach brought to the students an invaluable educational experience as they participated actively in the development of a spacecraft with the typical milestones of satellite projects. The mission objectives of LEDSAT include the use of onboard LEDs for improved orbit determination, experimental attitude determination and backup light communication. Each of the six sides of the CubeSat houses an LED board of a different color (red, green, and blue) with opposite sides with paired color. The LEDs can flash a pattern predefined by radio telecommand and the light is observed using ground telescopes. The design of the spacecraft started in late 2016 and was presented at the selection workshop of the Fly Your Satellite! Programme in May 2017. Final assembly took place in mid-2020 after which the team performed functional and environmental testing between October and December 2020, with the objective of ensuring the survivability of the spacecraft in the space environment and characterization of its behavior. After successful testing, the spacecraft was integrated inside the deployer in July 2021 in Brno, Czech Republic and was launched from Kourou, French Guiana on August 17th, 2021, aboard the Vega VV19 launcher. The spacecraft is now in orbit and operating nominally, with the LED flashes having been observed several times. The development of the spacecraft was not without difficulty, with preventable issues arising through testing that imposed design changes and further analysis - the paper will walk through the project since its conception, throughout the development, the functional and environmental testing of the payload and at system level, emphasizing the lessons learned by the students.

The in-orbit cultivation of vegetables, fruits, and edible plants is of paramount importance for the development of long-term manned space mission Environmental Control and Life Support Systems (ECLSS) and for the improvement of bio-regenerative systems. GreenCube is a 3U CubeSat mission aimed at demonstrating the functionalities of an autonomous cultivation laboratory that stems from a collaboration between the Sapienza University of Rome, the Italian Space Agency, University of Naples "Federico II", and ENEA. The satellite will cultivate microgreens in a pressurized vessel containing support systems and monitoring instrumentation for the plant growth. This paper describes the GreenCube mission and the instrumentation used for the growth support and monitoring.

This paper reports the results from the thermal analysis, the steady state analysis and the thermal vacuum testing from the LEDSAT 1U CubeSat environmental qualification. While the thermal analysis has been computed to state the compliance of the CubeSat to the orbital environment, the steady state analysis has been performed to confirm the suitability of the selected thermal vacuum test levels for the survivability and operational ranges of the satellite components. The spacecraft system-level thermal vacuum testing has given satisfying results, with perfect functionalities of the spacecraft and with a successful qualification of the PFM for spaceflight.

This paper presents the HORUS mission, aimed at multispectral and multiangle (nadir and off-nadir) planetary optical observation, using Commercial Off-The-Shelf (COTS) instruments on-board a 6-Unit CubeSat. The collected data are characterized by a sub-kilometer resolution, useful for different applications for environmental monitoring, atmospheric characterization, and ocean studies. Latest advancements in electro-optical instrumentation permit to consider an optimized instrument able to fit in a small volume, in principle without significant reduction in the achievable performances with respect to typical large-spacecraft implementations. CubeSat-based platforms ensure high flexibility, with fast and simple components’ integration, and may be used as stand-alone system or in synergy with larger missions, for example to improve revisit time. The mission rationale, its main objectives and scientific background, including the combination of off-nadir potential continuous multiangle coverage in a full perspective and related observation bands are provided. The observation system conceptual design and its installation on-board a 6U CubeSat bus, together with the spacecraft subsystems are discussed, assessing the feasibility of the mission and its suitability as a building block for a multiplatform distributed system.

This paper presents the results of STRATONAV experiment to test the precision of the VOR (VHF Omni Range) aircraft navigation system in stratosphere. The experiment has been conducted by the S5Lab research group at Sapienza University of Rome in the framework of the REXUS/BEXUS Programme. STRATONAV has been successfully launched on-board the BEXUS 22 stratospheric balloon from Esrange Space Center in Kiruna, Sweden, in 2016. The main payload was composed by two typologies of VOR receivers, a commercial portable receiver and a Software Defined Radio (SDR), alongside the bus and positioning, attitude and temperature sensors. STRATONAV succeeded in collecting VOR radials for the whole duration of the balloon flight. The results prove that VOR can be used as back-up navigation system for stratospheric platforms, ensuring a reliability improvement, while being applied to smaller payloads as primary system for a cost and complexity reduction of experiment developments. The paper analyzes the collected VOR data during the balloon flight. Accuracy and performance plots with respect to distance from the VOR stations and altitude are presented and discussed. The mean errors and standard deviations from all stations for both the receivers are shown with an analysis over the recorded errors. Finally, future perspectives, analyses and applicability of the research are exposed.

With the increasing number of satellite launches, especially in Low Earth Orbit (LEO), optical tracking can offer a convenient enhancement of tracking precision and availability. Spaceborne active illumination devices, such as LED payloads, can offer a significant improvement to optical observations, extending the observability interval to the whole eclipse time and performing optimized flash sequences for identification, orbit determination, attitude reconstruction or low data rate communication. The main features of LED panels for optical tracking mounted on small satellites platforms (and with particular regards to nano-satellite platforms) are outlined in this paper, along with the description of the design drivers. The analysis of the performance is referred to Sun-Synchronous (at 700 km of altitude) and International Space Station (400 km) orbits, while the ground segment and the optical link budget reference design relies on a standard university space debris observation station architecture. The paper also outlines the advantages of using different observation techniques and the variety of flashing patterns. The LEDSAT 1U CubeSat, aiming at demonstrating the effectiveness of an LED-based payload for observation and tracking, is used as a study case for examples of the LED payloads and related operations that are reported and described in this paper.

While Electro-Magnetic Compatibility testing is not often considered for CubeSat projects, the increasing complexity of nano-satellite platforms is suggesting to include such tests in their standard verification processes. This paper reports the followed approach and measurements set-up for an EMC anomaly regarding the LEDSAT 1U CubeSat Proto-Flight Model on-board GPS antenna. The anomaly was discovered and solved during functional testing campaign in 2020 and the satellite has been successfully qualified for flight.

The new concept aerospace mission profiles, such as stratospheric airships or suborbital vehicles, impose new requirements for the tracking and surveillance systems, with particular regards to manned missions. New technologies and innovative tracking systems can be supporting such operations. The STRAINS (Stratospheric Tracking Innovative Systems) Experiment, conceived by Sapienza University of Rome and ALTEC (Aerospace Logistics Technology Engineering Company) and supported by ASI (Italian Space Agency), to be launched in Q3/Q4 2021, is aiming at demonstrating TDOA (Time Difference of Arrival), FDOA (Frequency Difference of Arrival) and single station tracking for a Zero-Pressure Balloon Flight in the framework of the HEMERA H2020 balloon launch infrastructure. This paper describes the design of the STRAINS stratospheric experiment, including the stratospheric and the ground segment, the analyses carried out for optimizing the experiment functionalities, the mission analysis for defining the multi-lateration stations locations and the performance evaluation for the designed TDOA tracking system.

Optical observations are intensively applied to space debris monitoring for the achievement of orbit determination and for gathering information on their attitude motion, even if constrained by light conditions. Light Emitting Diodes (LEDs) installed on the external surfaces of a satellite could increase the visibility interval to the whole eclipse time. LEDSAT (LED-based small SATellite) is a 1-Unit CubeSat aimed at demonstrating the effectiveness of LEDs for the improvement of space debris optical monitoring algorithms. The LEDSAT experimental mode includes flashing patterns that will allow the CubeSat attitude reconstruction and the testing of a back-up light-based communication method. This paper will describe the features of the LEDSAT experimental mode, by describing the needed measurements for achieving the satellite LED-based attitude reconstruction and the features of the back-up LED communication.

Binary or multiple stellar systems, constituting almost a third of the content of the Milky Way, represent a high priority astronomical target due to their repercussions on the stellar dynamical and evolutionary parameters. Moreover the spectral study of such class of stars allows to better constrain the evolutionary theories of the Galactic stellar populations. By resolving the members of stellar systems through photometric observations we are able to perform more detailed measurements to infer their mass. In this paper we investigate the feasibility of a cubesat based mission including an optical payload to directly optically discriminate the members of a selected sample of binary systems. The scientific targets, consisting 11 M class dwarf stars binary systems, have been extracted from the already studied Riaz catalogue. These subset has been selected considering the star distance, the members angular separation, and the distance from the Galactic plane (due to limit the background and foreground contamination). The satellite concept is based on a 6 unit Cubesat embedding some commercial off the shelf components and an ad hoc designed optical payload occupying almost 4 units. The optical configuration has been chosen in order to fit the angular resolution requirements, as derived from the target characteristics. Moreover, according to the optical analysis and the computed field of view some requirements on the attitude control system have been inferred and fulfilled by the component selection. The paper is organized as in the following: a brief scientific introduction is made; consequently the project is described with particular attention to the optical design and the standard sub-systems; finally the conclusions are drawn and the future perspectives are investigated.

LEDSAT (LED-based small SATellite) is a 1-Unit CubeSat that will mount Light Emitting Diodes (LEDs) on its six faces, in order to validate, verify and improve the current methodologies for optical orbit determination. The LEDs will also support the CubeSat identification after deployment from the ISS. The satellite is being produced by the S5Lab research group at Sapienza – University of Rome, and it has been accepted for the European Space Agency Fly Your Satellite! Programme. Currently, the on-board LEDs have been tested for the UV and gamma-ray radiations, proving their survivability in the space environment. This paper describes the aims, the design, the LED-based payload and the expected results of LEDSAT.

The stratosphere is the highest layer of Earth's atmosphere where aircraft can still fly. Today, the potential of stratospheric vehicles is largely unexploited, but in the future, they will compete with spacecraft in a huge variety of applications. In fact, stratospheric vehicles can provide a valid alternative in several scientific and commercial applications. The extension and validation of radio “Navaids” for the stratospheric flight could set a significant increase in reliability for high altitude navigation system receivers, and a reduction of the stratospheric navigation system development cost. STRATONAV (STRATOspheric NAVigation) experiment is developed by a team of Italian students from Sapienza — University of Rome and Alma Mater Studiorum — University of Bologna. The main goal of the experiment is to test the VOR (VHF Omnidirectional Range) navigation system by evaluating its accuracy above the estimated Standard Service Volume through an in-situ testing campaign. The STRATONAV team has been selected to participate to the 2016 REXUS/BEXUS Programme cycle 09 by a panel of ESA (European Space Agency) experts. This paper deals with the STRATONAV Experiment concept and its main features, focusing on the main technical and scientific objectives, the expected results, the mechanical set-up and the environmental and structural analyses and testing campaigns.