Experimental bearings stiffness verification of the pointing assembly for optical inter-satellite link

Předložená diplomová práce se zabývá zjištěním tuhosti předepnutého dvouřadého ložiska s kosoúhlým stykem v relevantních podmínkách. V úvodu práce jsou popsány základní znalosti týkající se dvouřadých ložisek s kosoúhlým stykem a souvislosti vnitřní vůle, předpětí a dalších vlivů na tuhosti. V práci je uveden přehled studií zabývajících se tuhostí ložisek a přehled zařízení, která slouží pro experimentální zjištění tuhosti. Následně je popsáno vlastní řešení, ve kterém prvně proběhl teoretický výpočet tuhosti ložiska. K zjištění experimentálních hodnot bylo nutné navrhnout a zkonstruovat experimentální zařízení pro testování ložiska v relevantních podmínkách. Z naměřených dat a teoretických výpočtů byl zjištěn vliv materiálu a teploty na tuhosti ložiska. Výstupem práce je funkční vzorek, se kterým proběhlo testování ložiska.This master´s thesis deals with the determination of the stiffness of a preloaded double-row bearing with an angular contact in the relevant conditions. The introduction describes the basic knowledge about double row angular contact bearings and the relationship between internal clearance, preload and other effects on stiffness. An overview of studies dealing with bearing stiffness and an overview of devices used for experimental stiffness determination is given. Subsequently, the solution itself is described, in which the theoretical calculation of the bearing stiffness was performed first. To determine the experimental values, it was necessary to design and construct experimental device for testing the bearing in the relevant conditions. The effect of material and temperature on the stiffness of the bearing was determined from the measured data and theoretical calculations. The result of this thesis is a functional device, which was used to test the bearing in the thermal chamber.

Recent Status of Small Satellite Study in Japan

This paper describes the recent status of small satellite study in Japan focusing on the activities of the Small Payload WorkShop (SPWS) which was established in January, 1990. The objectives of SPWS are to review the development of small satellite and its launching system, to study the possible mission, to exchange information, to pick up and study the issues to be solved and to contribute to the good and efficient development of the future plan of small satellite utilization in Japan. The discussion to initiate the SPWS is reviewed briefly. The paper describes the recent studies of small satellites missions and launching systems as well as the Japanese small satellites which have been launched so far

Communication satellite technology trends

A chronology of space-Earth interconnectivity is presented. The Advanced Communications Technology Satellite (ACTS) system, Land Mobile Satellite, space-Earth antennas, impact of antenna size on coverage, intersatellite links are outlined. This presentation is represented by graphs and charts only

Parameterized analysis of optical inter-satellite links for high resolution satellite communication

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 151-154).The use of antenna arrays to exploit spatial information in single and multi-user RF communication receivers is well established for reducing interference and enabling frequency reuse. Antenna arrays have been deployed in single satellite applications but arrays have not been exploited in multi-satellite constellations where increased array size enables high spatial selectivity between ground transmitters. One requirement for these array systems is sufficient fidelity in transporting the received RF signals at each antenna to the array processor. Optical inter-satellite link architectures for signal transport are investigated and parameterized models to compare the performance of each are synthesized. Both analog and digital modulation schemes for the link are considered. A two-channel receiver with both low and high interference is analyzed. It is shown that high resolution satellite array receivers are practical with low required optical power. The optimum selection of transport architecture is shown by selecting for lowest error probability or minimum required optical power. A satellite-to-satellite distance threshold is found for selecting the optimum inter-satellite link architecture for a given application.by James Bernard Glettler.S.M

UPC NanoSat-Lab - Past, present and future activities

The Universitat Politècnica de Catalunya UPC NanoSat Lab is part of the CommSensLab-UPC Specific Research Center of the Department of Signal Theory and Communications, and counts with the support of the School of Telecommunications Engineering (Telecom Barcelona, ETSETB). It is located in the UPC Campus Nord. The lab was originally created in 2007 to promote the testing of novel remote sensors and techniques in space, taking advantage of CubeSats. Over time, the lab has also started the study of Earth-to-space IoT and RF intersatellite link communications, as key enabling technologies for the next revolution of Earth Observation. At the time of writing this abstract, the UPC NanoSat Lab has developed and launched four CubeSats, and is working in three new missions that will be launched in Q4 2022 - Q1 2023. At present, the Lab is developing an "Open PocketQube Kit" for IEEE as a low-cost educational platform on space-related technologies. The lab has also a Class 8 clean room equipped with a shaker and thermal vacuum chamber, and Helmholtz coils, air bearing system, and Sun simulator for attitude determination and control system testing to conduct the environmental tests. Finally, in the MontSec Astronomical Observatory (OAdM),which is managed and operated by IEEC, hosts the UPCNanoSat Lab VHF/UHF and S-band ground station [3], where the data from the 3Cat-5/A satellite where downloaded. Since its inception in 2007, about 300 students have been trained in the lab, either as undergraduate students in the "Advanced Engineering Project" of the ETSETB, as Final Degree or Master Thesis projects, as graduate students, or just for an internship. This paper presents a quick overview of the past, present and future activities of the UPC NanoSat La

Investigation and analysis of inter-satellite- optical wireless communication system based on dense-wavelength-division multiple-access

Optical wireless communication offers high data rates applications due to license-free and wide-bandwidth access techniques and cost-effective implementations. Recently, the world introduced to a revolutionary technology called Inter-satellite optical communication that aims to establish transmission among satellites. However, transmitting pointing errors is the main issue in creating an inter-satellite link, which leads turbulences in the connection. This article aims to study the implementation of an optical wireless communication system in satellite communication. In this work, we investigate and analysis of data rate of 16-channel in inter-satellite optical wireless communication systems (Is-OWC) based on dense-wavelength-division multiple-access (DWDM) with standard downlink channel spacing DWDM (ITU grid specification). Computer simulations are carried using Opti-system over different wavelengths between two satellites transmit 160 Gbps over 7000 km. This evaluation performance is based on eye diagrams, BER, optical spectrum and Q-Factor with minimum input power under turbulences of transmitter pointing error angl

Secure Space Mesh Networking

Innoflight’s Secure Space Mesh Networking development and prototyping efforts started at its incorporation over 15 years ago with a vision of establishing end-to-end Internet Protocol (IP) connectivity in and through space. A number of space industry trends have accelerated the demand for space networking: (a) the widespread adoption of enterprise-grade and cloud-based, IP-centric ground system architectures; (b) the accelerated growth of both commercial and government proliferated Low Earth Orbit (pLEO) constellations leveraging small satellites (SmallSats); (c) the maturation, miniaturization and commoditization of high-speed Radio Frequency (RF), Free Space Optical (FSO) Inter-Satellite Links (ISLs), and high-performance flight processors for aforementioned SmallSats; and (d) the need for All-Domain Operations (ADO) seamlessly and autonomously integrating space, airborne, terrestrial, maritime and underwater networks. Furthermore, data encryption, for reasons of either National Security or monetized mission data protection, creates additional challenges to effectively switch/route and encrypt/decrypt ciphertext data across a mesh network. Lastly, with the projection of multiple and multi-national pLEO constellations, it is critical to negotiate link security real-time for dynamic, trusted nodes, and prevent inadvertent or intentional networking with unknown/untrusted nodes. Innoflight will discuss the aforementioned relevant space industry trends and commercial and government initiatives, including DARPA (Defense Advanced Research Projects Agency) Blackjack and Space Development Agency’s (SDA) National Defense Space Architecture (NDSA), and then identify the technical challenges for secure space mesh networking and decompose these challenges with two popular frameworks: (a) the individual layers, especially Layer 2 (data/link layer) and Layer 3 (network layer), within the Open Systems Interconnection (OSI) model; and (b) the control and data planes within the Software Defined Networking (SDN) model. Innoflight will present its development and prototyping efforts, specific to these challenges, including recent work funded under a 2019 Space Pitch Day award and leveraging its general-purpose processing and networking CFC-400X platform, and conclude by identifying remaining gaps: including technical, commercial and policy; to fully realize interoperable secure space mesh networking.

A Small Satellite Constellation for Monitoring of the Aurora

As part of the European Space Agency\u27s D3S (Distributed Space Weather Sensor System), a small satellite constellation is currently being designed by OHB Sweden which will observe space weather impacts in Earth\u27s vicinity by monitoring of the auroral oval. The primary objective of the Aurora mission is to observe the Aurora Borealis and Australis continuously and as complete as possible. The auroral emissions are the result of interactions of the Solar Wind and Coronal Mass Ejections with the Earth which drive the location and strength of electron precipitation on the ionosphere. Such observations will thereby allow the identification, characterization and nowcasting of geomagnetic storms and sub-storms. Observation of the auroral emissions is expected to enable improved and new services relevant for critical infrastructures such as communication, satellite navigation, satellite operation, aviation, transport, power network operation, and resource utilization. The core instruments of the Aurora mission are the optical and far UV wide-field imagers. Furthermore, a radiation monitor and a magnetometer are baselined as a secondary payload to monitor magnetic field dynamics and the radiation environment. The availability of additional resources for other payloads relevant for D3S is under investigation. To minimize the number of satellites, while ensuring continuous and guaranteed coverage of the auroral oval, a constellation of four satellites in MEO orbit is envisaged. Such orbit however poses significant challenges for small satellites in terms of accessibility, sustainability, and radiation dose. The heritage microsatellite platform from OHB Sweden, InnoSat (designed for LEO), will thus undergo several upgrades in terms of maneuverability, shielding, communication, and reliability. Of particular importance is the low latency requirement which may favor an Inter-Satellite Link. In a first step ESA is implementing a demonstrator mission that shall be launched in 2027 with the aim of optimizing the performance and preparing the operational satellite constellation considered for implementation in a second step. We will report about the status of the satellite design and the mission architecture