From BEXUS to HEMERA: The application of lessons learned on the development and manufacturing of stratospheric payloads at S5Lab

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 automation of the EQUO on-ground observatory at broglio space center for space surveillance

The arrangement of an equatorial observatory fully dedicated to orbital debris observation significantly increase Italian and European capability to deliver support to operative spacecraft both in LEO (Low Earth Orbit) and GEO (Geostationary Earth Orbit) impact risk management and in orbital maneuver measurement. The presented paper describes the installation and the operations of the fully remote controlled EQUO (Equatorial Observatory) On-Ground at Broglio Space Center (BSC) in Malindi (Kenya) for orbital debris observation. The project is developed in the framework of the Italian Space Agency (ASI) - University of Rome "La Sapienza" Agreement for scientific cooperation at the BSC. The observatory has been developed by Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) research group in order to increase space debris observation potential and it is characterized by a 200mm diameter f/4 telescope in Newtonian configuration and it is equipped with a CCD sensor with a wide Field of View (FOV) of about 9 degrees squared. The results of the observatory installation campaign at BSC concerning the firsts operations of the whole system are shown. Special focus is dedicated on how remote operations are performed in order to acquire data from different observing strategies (tracking, beam park and follow-up) at different orbital regimes and the results of the observing campaigns performed

Thermal and mechanical design and test campaign results of a single-piece structure for the URSA MAIOR nanosatellite

The Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) of La Sapienza University of Rome is involved in the development and manufacturing of the nano-satellite URSA MAIOR (University of Rome la SApienza Micro Attitude In ORbit testing), a 3U CubeSat selected in the framework of QB50 mission, an FP7 project led by the Von Karman Institute of Fluid Dynamics with the aim to demonstrate the possibility of launching a network of 50 CubeSats intended for measuring and analyzing the lower thermosphere. The nano-satellite, scheduled for launch from July 2016 on, carries a multi Needle Langmuir Probe (mNLP) science unit, used to determine the electron temperature and density and the electric potential of plasma, an Attitude Determination and Control System (ADCS) realized by Surrey Space Centre and two experiments: a polymeric drag sail for nano-satellites deorbiting and an innovative cold-gas MEMS (Micro Electro Mechanical System) micro-thruster for attitude control of nano-satellites, developed at the Sapienza Aerospace Research Centre (CRAS). Both the on-board computers and the structure have been designed, manufactured and tested at the local facilities. The structure subsystem is realized from a 100mm × 100mm square aluminium profile to enhance the thermal conductivity and the mechanical properties. The profile le is properly machined to reduce the overall weight while preserving the thermal conductivity features and the structural stiffness. This paper outlines and compares the results from thermal and mechanical analysis and test campaigns. In particular, a PSD (Power Spectral Density) frequency analysis, used to evaluate the stress suffered by the satellite during the launch, is performed. Furthermore, a (1g) sine sweep 5-400Hz test allows evaluating the natural frequency of the structure and a random vibration test allows comparing real results to FEM analysis

An innovative multi-spectral and multi-angle based CubeSat for Earth Observation applications

Small satellites are widely used for Earth Observation applications. CubeSats in formation flight can improve low-cost environmental monitoring as track natural disasters with a resolution of few meters and daily revisit capability. The main missions commonly use a nadir-pointing sensor, not always able to quantify atmospheric properties. In order to obtain these data, an off-set nadir sensor is necessary, providing a multiple angle observation. This architecture scheme is similar to the MISR sensor (Multi-angle Imaging SpectroRadiometer) successfully flown on the EOS NASA's TERRA satellite. The paper describes the feasibility study of a CubeSat-based multi-angle and multi-spectral Earth Observation system able to collect multi angle and multispectral data. As opposite to large satellite EO platforms, the observation payload is split among several spacecraft, by splitting the optical observation capabilities into a cluster of small satellites based on four 6U CubeSats in formation flight. The main technical and scientific objectives of the mission and the main system requirements are outlined and the paper gives a description of the main key performance parameters and expected results of the designed sensor and mission

Testing vor performances in the stratosphere: The stratonav experiment

The VOR (VHF Omnidirectional Range) system has been used for decades as primary navigation aid to civil aviation and is used nowadays by commercial aircraft as back-up for GNSS (Global Navigation Satellite Systems). The STRATONAV (STRATOspheric NAVigation) experiment purpose is to test the VOR system in stratosphere during a stratospheric balloon flight in order to evaluate the performances of this radio-navigation system above its standard service volume. The experiment, developed by an Italian student team from Sapienza - University of Rome and Alma Mater Studiorum - University of Bologna, has been proposed during the 2015 call of REXUS/BEXUS (Rocket and Balloon EXperiments for University Students) Programme and selected for BEXUS 22 flight from Kiruna, Sweden, scheduled in October 2016. The VOR stations service volume estimation is based on the International Civil Aviation Organization (ICAO) prescribed radiated power rates: a high altitude VOR navigation station shall ensure its service at least until 18 km in height with prescribed precision rates of 1.4 degrees in radial evaluation. The flight of the BEXUS balloon will reach an altitude of at least 20 km above ground level during the floating phase. STRATONAV experiment is designed to tune its on-board receiver to the optimal VOR station frequency by evaluating the estimated service volumes and the GPS balloon positioning data in order to collect VOR radial data. BEXUS will be launched from the Esrange Space Center in Kiruna (Sweden) and the area nearby is equipped with multiple VOR high altitude navigation stations. The expected balloon flight path has been computed by analyzing previous BEXUS flight and the results show that intersections of two or more VOR standard service volumes are revealed for the whole flight. The presented paper shows the experiment design and system studied to investigate the accuracy of the VOR system in stratosphere and to perform a stand-alone VOR positioning by interfacing two or more VOR radials evaluated from different ground stations in order to compute the balloon ground track. Moreover, the methodology that will be performed to analyze the post-flight collected VOR radials will be presented

Student CEF at Sapienza - University of Rome. Preliminary design of LEDSAT CubeSat

Students attending the Spacecraft Design course for the MSc Degree in Space and Astronautical Engineering at Sapienza – University of Rome, had the chance to take part in a Concurrent Engineering activity for the preliminary design of the LEDSAT 1U CubeSat. The mission aims to use a LED-based technology as main payload to allow the nanosatellite orbit and attitude determination by means of ground-based optical observations. Starting from the mission concept, the involved students had to merge the activity related to the CubeSat design to the development of dedicated tools to define the main features of each subsystem. In this way, they created their own Concurrent Engineering tools in a Concurrent Engineering Facility environment. During the course, the whole class was split into subgroups, each one taking care of a subsystem or a mission aspect. Starting from the main design drivers and key performance parameters, each student team defined the main features of their subsystem, the realization procedures, and needed timing and costs. Furthermore, this activity contributed in increasing the students cooperative skills by giving the opportunity to put into practice the theoretical knowledge gather during their academic career. At the end, the final configuration, reached by following a design iteration procedure based on the contributions coming from each team, was presented during the “3rd Space Debris Student Opportunities Workshop” at Sapienza – University of Rome. In this occasion the students were called to give a public presentation about their work and achieved results. Moreover, the LEDSAT mission design has been further improved and proposed for the ESA “Fly your Satellite!” programme. This paper outlines the LEDSAT preliminary design, the development of the low cost CEF made by students and how this experience allowed them to understand and practice how a satellite design process is worked ou

Sapienza space debris observatory network (SSON): a high coverage infrastructure for space debris monitoring

Optical observations represent a passive method for space debris tracking and monitoring. Although being con- strained to limited time intervals, e.g. when the target is in sunlight and the observatory is in darkness, a debris observatory network distributed over multiple locations can improve the observational interval and favor the data integration for more consistent and significant results. The Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) At Sapienza University of Rome has established Sapienza Space debris Observatory Net- work (SSON), an international network of optical observatories addressed at debris surveillance. The network is composed of six observatories owned and controlled by Sapienza, plus five observational sites controlled by collaborators (mainly University of Michigan and the University of Bern). The network operations have been carried out during several observations campaign, including the Tiangong-1 space station re-entry campaign per- formed in support of the Inter-Agency space Debris Committee (IADC). The heterogeneous capabilities of the different observatories represent an advantage for acquiring a wider set of debris monitoring data with different techniques. A strong synergy between our institution and the Italian specialized industry has also revealed to be very productive in the context of the network establishment. The present paper will describe the SSON infrastructure and the opportunities, improvements and future perspectives for research institutions or space industry of this wide observatories network will be discussed