Communication satellite power amplifiers: current and future SSPA and TWTA technologies

This study captures the state of current satellite transponder technology, specifically, solid-state power amplifiers (SSPAs) and traveling wave tube amplifiers (TWTAs), and describes expected future advances, including GaN SSPAs. The findings of five previous SSPA and TWTA studies, including the 1991 European Space and Technology Center study, the 1993 National Aeronautics and Space Administration study, and three Boeing studies conducted in 2005, 2008, and 2013, are tabulated and summarized. The results of these studies are then compared with new analyses of two validated sources of amplifier data: a commercially licensed database, Seradata's Spacetrak, and a publicly available database, Gunter's Space Page. The new analyses consider a total of 18,902 amplifiers (6428 TWTAs, 2158 SSPAs, and 10,316 unspecified amplifiers) onboard 565 communications satellites launched from 1982 to 2016. This new study contains the largest number of satellites and amplifiers to date and compares output power, redundancy, and bandwidth capabilities. We find an increase in output power from the 1993 study of >200% for Ku-band TWTAs and C-band SSPAs, and >1000% increase for C-band TWTAs. The ratio of operational to redundant amplifiers is 10 times higher for TWTAs than SSPAs, and the majority of amplifiers over the past 30 years operate with bandwidth less than 100 MHz. A second analysis is conducted using failure records and telemetry of 16 geostationary satellites equipped with 659 amplifiers: 535 SSPAs and 124 TWTAs. We find that <2% of TWTAs and 5% of SSPAs experience anomalies. Overall, this research was performed to update and clarify how the power and bandwidth needs and redundancy trends of the SatCom community have evolved over the past 30 years

Causal relationships between solar proton events and single event upsets for communication satellites

In this work, we analyze a historical archive of single event upsets (SEUs) maintained by Inmarsat, one of the world's leading providers of global mobile satellite communications services. Inmarsat has operated its geostationary communication satellites and collected extensive satellite anomaly and telemetry data since 1990. Over the course of the past twenty years, the satellites have experienced more than 226 single event upsets (SEUs), a catch-all term for anomalies that occur in a satellite's electronics such as bit-flips, trips in power supplies, and memory changes in attitude control systems. While SEUs are seemingly random and difficult to predict, we correlate their occurrences to space weather phenomena, and specifically show correlations between SEUs and solar proton events (SPEs). SPEs are highly energetic protons that originate from solar coronal mass ejections (CMEs). It is thought that when these particles impact geostationary (GEO) satellites they can cause SEUs as well as solar array degradation. We calculate the associated statistical correlations that each SEU occurs within one day, one week, two weeks, and one month of 10 MeV SPEs between 10 - 10,000 particle flux units (pfu). However, we find that SPEs are most prevalent at solar maximum and that the SEUs on Inmarsat's satellites occur out of phase with the solar maximum. Ultimately, this suggests that SPEs are not the primary cause of the Inmarsat SEUs. A better understanding of the causal relationship between SPEs and SEUs will help the satellite communications industry develop component and operational space weather mitigation techniques as well as help the space weather community to refine radiation models.International Maritime Satellite OrganizationNational Science Foundation (U.S.)Massachusetts Institute of Technolog

Data management of geostationary communication satellite telemetry and correlation to space weather observations

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from department-submitted PDF version of thesis.Includes bibliographical references (p. 86-89).To understand and mitigate the effects of space weather on the performance of geostationary communications satellites, we analyze sixteen years of archived telemetry data from Inmarsat, the UK-based telecommunications company, and compare on-orbit anomalies with space weather observations. Data from multiple space weather sources, such as the Geostationary Operational Environmental Satellites (GOES), are compared with Inmarsat anomalies from 1996 to 2012. The Inmarsat anomalies include 26 solid-state power amplifier (SSPA) anomalies and 226 single event upsets (SEUs). We first compare SSPA anomalies to the solar and geomagnetic cycle. We find most SSPA anomalies occur as solar activity declines, and when geomagnetic activity is low. We compare GOES 2 MeV electron flux and SSPA current for two weeks surrounding each anomaly. Seventeen of the 26 SSPA anomalies occur within two weeks after a severe space weather event. Fifteen of these 17 occur after relativistic electron events. For these fifteen, peak electron flux occurs a mean of 8 days and standard deviation of 4.7 days before the anomaly. Next, we examine SEUs, which are unexpected changes in a satellite's electronics, such as memory changes or trips in power supplies. Previous research has suggested that solar energetic protons (SEPs) cause SEUs. However, we find that SEUs for one generation of satellites are uniformly distributed across the solar cycle. SEUs for a second generation of satellites, for which we currently have only half a solar cycle of data, occur over an order of magnitude more often than the first, even during solar minimum. This suggests that SEPs are not the primary cause of SEUs, and that occurrence rates differ substantially for different satellite hardware platforms with similar functionality in the same environment. These results will guide design improvements and provide insight on operation of geostationary communications satellites during space weather events.by Whitney Quinne Lohmeyer.S.M

Telemetry Fault-Detection Algorithms: Applications for Spacecraft Monitoring and Space Environment Sensing

Algorithms have been developed that identify unusual behavior in satellite health telemetry. Telemetry from solid-state power amplifiers and amplifier thermistors from 32 geostationary Earth orbit communications satellites from 1991 to 2015 are examined. Transient event detection and change-point event detection techniques that use a sliding window-based median are used, statistically evaluating the telemetry stream compared to the local norm. This approach allows application of the algorithms to any spacecraft platform because there is no reliance in the algorithms on satellite- or component-specific parameters, and it does not require a priori knowledge about the data distribution. Individual telemetry data streams are analyzed with the event detection algorithms, resulting in a compiled list of unusual events for each satellite. This approach identifies up to six events of up to six events that affect 51 of 53 telemetry streams at once, indicative of a spacecraft system-level event. In two satellites, the same top event date (4 December 2008) occurs over more than 10 years of telemetry from both satellites. Of the five spacecraft with known maneuvers, the algorithms identify the maneuvers in all cases. Event dates are compared to known operational activities, space weather events, and available anomaly lists to assess the use of event detection algorithms for spacecraft monitoring and sensing of the space environment.The authors would like to acknowledge the U.S. Air Force Office of Sponsored Research grant FA9550-13-1-0099 and NASA for funding this work through NASA Space Technology and Research Fellowship grant NNX16AM74H

Quantifying the average and the likelihood of increases in space weather indices and in situ measurements during Solar Cycles 20–23

It is known that space weather harshly affects spacecraft performance, yet spacecraft operations and understanding the cause of anomalies can be challenging due to the complexity of environmental metrics. In this work, we analyse five metrics and in-situ measurements (Kp, Dst, and AE index, and high-energy proton and electron flux) throughout Solar Cycles 20–23 (1964 to 2008), and provide a baseline for the environment during the phases of the solar cycles (maximum, minimum, declining or ascending). We define increased activity as activity greater than two median absolute deviations (MADs) above the average activity for each phase. MAD is used, rather than standard deviation, because it is more resilient to outliers. The average and MAD values are tabulated in Table 3 to Table 6. We determine the probability that increased activity occurs 3, 14 or 30 days before a random day to distinguish between increased/quiet activities and to aid in correlating intensifications of the environment and anomalous satellite performance

The Design, Analysis and Testing of Low Cost Dual Deployable Solar Panels for Small Satellite Missions

The National Science Foundation (NSF) funded university small satellite mission, Space Weather Atmospheric Reconfigurable Multiscale Experiment (SWARM-EX) is designed to address outstanding aeronomy and space weather questions while demonstrating swarm behavior in constellations of six to twelve 3U CubeSats. SWARM-EX is limited in power, which requires the use of dual-deployable solar panels in order to maximize the number of solar cells powering the small satellite. Commercial off the shelf (COTS) dual-deployable solar panel options tend to be expensive, necessitating the creation of custom-built, dual-deployable solar panels. The design of the dual-deployable solar panels is constrained in volume, manufacturability, and survivability of the launch conditions. In the stowed launch configuration, the full smallsat assembly must fit in an 88 mm by 326.1 mm by 9 mm space. The dual-deployable solar panel assembly must also be able to withstand the vibroacoustic launch environment. The launch environment requires withstanding a vibroacoustic load of 10 Grms for one minute in each axis. The solar panel assembly underwent testing in order to ensure the system operates as expected during the mission. Deployment testing will be conducted, and vibrational testing is planned for six months before launch

FCC Five Year Deorbit Compliance Tools for Standard Low Earth Orbiting SmallSats Employing Passive Re-Entry Techniques

On September 29, 2022, the Federal Communications Committee (FCC) adopted a regulation to address the growing issue of orbital debris, requiring spacecraft in orbits of 2,000 km or less to deorbit as soon as possible, but within no more than five years after the end of the mission. These regulations will be enforced starting in 2024 and will apply to network providers both licensed in the United States and foreign-licensed seeking U.S. market access. Given the updated legislation, various communications providers may find that their traditional system architectures are not compliant with the five-year rule. In this work, the authors assess the outputs of Orbital Debris Assessment Reports (ODARs) operators have submitted to the FCC and then utilize NASA’s Debris Assessment Software (DAS) and Ansys’s Systems Toolkit (STK) to determine deorbit lifetime for standard bus sizes. From the data analysis, the relationship between different parameters (such as apogee, area-to-mass ratio, and mission end year) and their respective deorbit time is mapped to create a predictive, accessible reference intended to provide both commercial satellite providers and academic small satellite operators with an efficient method to initially gauge whether the design of their systems will comply with the updated legislations

Response of geostationary communications satellite solid-state power amplifiers to high-energy electron fluence.

The key components in communications satellite payloads are the high-power amplifiers that amplify the received signal so that it can be accurately transmitted to the intended end user. In this study, we examine 26 amplifier anomalies and quantify the high-energy electron environment for periods of time prior to the anomalies. Building on the work of Lohmeyer and Cahoy (2013), we find that anomalies occur at a rate higher than just by chance when the >2 MeV electron fluence accumulated over 14 and 21 days is elevated. To try to understand “why,” we model the amplifier subsystem to assess whether the dielectric material in the radio frequency (RF) coaxial cables, which are the most exposed part of the system, is liable to experience electrical breakdown due to internal charging. We find that the accumulated electric field over the 14 and 21 days leading up to the anomalies is high enough to cause the dielectric material in the coax to breakdown. We also find that the accumulated voltages reached are high enough to compromise components in the amplifier system, for example, the direct current (DC) blocking capacitor. An electron beam test using a representative coaxial cable terminated in a blocking capacitor showed that discharges could occur with peak voltages and energies sufficient to damage active RF semiconductor devices

CubeSat Radiation Hardness Assurance Beyond Total Dose: Evaluating Single Event Effects

Radiation poses known and serious risks to smallsat survivability and mission duration, with effects falling into two categories: long-term total ionizing dose (TID) and instantaneous single event effects (SEE). Although literature exists on the topic of addressing TID in smallsats, few resources exist for addressing SEEs. Many varieties of SEEs exist, such as bit upsets and latch ups, which can occur in any electronic component containing active semiconductors (such as transistors). SEE consequences range from benign to destructive, so mission reliability can be enhanced by implementing fault protection strategies based on predicted SEE rates. Unfortunately, SEE rates are most reliably estimated through experimental testing that is often too costly for smallsat-scale missions. Prior test data published by larger programs exist, but may be sparse or incompatible with the environment of a particular mission. Despite these limitations, a process may be followed to gain insights and make informed design decisions for smallsats in the absence of hardware testing capabilities or similar test data. This process is: (1) Define the radiation environment; (2) identify the most critical and/or susceptible components on a spacecraft; (3) perform a search for compatible prior test data and/or component class data; (4) evaluate mission-specific SEE rates from available data; (5) study the rates alongside the mission requirements to identify high-risk areas of potential mitigation. The methodology developed in this work is based on the multi-institutional, National Science Foundation (NSF) Space Weather Atmospheric Reconfigurable Multiscale Experiment (SWARM-EX) mission. The steps taken during SWARM-EX’s radiation analysis alongside the detailed methodology serve as a case study for how these techniques can be applied to increasing the reliability of a university-scale smallsat mission

Data Sharing in Satellite Systems: Review of the Past and Opportunities in the Age of Large LEO Constellations

Since 1957, more than 14,000 satellites have been launched into space; 2022 marks a record year with the launch of 2,163 satellites [1]. The increased number of satellites in combination with technological advancements in satellite communications has enabled operators to collect vast amounts of science data and satellite telemetry. These large data sets can be utilized to ensure coexistence between the ever-increasing number of satellite systems, potentially reducing both the risk of harmful interference and in-orbit collisions. Additionally, they can act as decentralized information sources, improving our understanding of the space environment and increasing the reliability of satellites. Modern data sharing practices for space mission data can be categorized into either post-mission or real-time analysis. Post-mission analysis can lead to detecting anomalies that occurred during a mission by correlating data points from individual or different satellites. In contrast, real-time data sharing can also help avoid harmful communication interference events and in-orbit collisions. This paper provides a review of data collection and sharing practices across three types of satellite systems: university smallsat missions, federal government missions, and private sector/commercial missions. In this review and synthesis, the utility of those datasets is identified along with challenges associated with moving towards standard structures and stakeholder sharing practices