Spacecraft Communications Research Articles

Performance Analysis of Ranging Techniques for the KPLO Mission

In this study, the performance of ranging techniques for the Korea Pathfinder Lunar Orbiter (KPLO) space communication system is investigated. KPLO is the first lunar mission of Korea, and pseudo-noise (PN) ranging will be used to support the mission along with sequential ranging. We compared the performance of both ranging techniques using the criteria of accuracy, acquisition probability, and measurement time. First, we investigated the end-to-end accuracy error of a ranging technique incorporating all sources of errors such as from ground stations and the spacecraft communication system. This study demonstrates that increasing the clock frequency of the ranging system is not required when the dominant factor of accuracy error is independent of the thermal noise of the ranging technique being used in the system. Based on the understanding of ranging accuracy, the measurement time of PN and sequential ranging are further investigated and compared, while both techniques satisfied the accuracy and acquisition requirements. We demonstrated that PN ranging performed better than sequential ranging in the signal-to-noise ratio (SNR) regime where KPLO will be operating, and we found that the T2B (weighted-voting balanced Tausworthe, voting v = 2) code is the best choice among the PN codes available for the KPLO mission.

The youth technical program in long beach delights participants

The Sue Archambeault Youth Technical Program (YTP) for the 2018 IEEE Symposium on Electromagnetic Compatibility, Signal and Power Integrity brought together 25 Junior Conference Companions, ages 6 to 16, to learn the basic principles of EMI/EMC, about the role of the Deep Space Network in spacecraft communication, and to practice circuit prototyping skills. All participants succeeded in constructing a motor-driven model of a Deep Space Network (DSN) antenna dish.

Предварительный анализвоз можности построения терагерцевой линии связи между космическими аппаратами

Предварительный анализвоз можности построения терагерцевой линии связи между космическими аппаратами

Сравнительная оценка решений системы дифференциальных уравнений в задаче изгиба прямых участков волноводов космических аппаратов связи

Сравнительная оценка решений системы дифференциальных уравнений в задаче изгиба прямых участков волноводов космических аппаратов связи

METHOD OF INCREASING FAULT TOLERANCE OF SATELLITE COMMUNICATION NETWORKS UNDER INFORMATION TECHNOLOGY INTERFERENCE

Aim. The aim of the paper is to develop a method that would allow for integrated experimental, computational, analytical and expert assessment of the vulnerabilities of satellite communication networks, feasibility of information technology interference by intruders against such vulnerabilities and probability of fault tolerance under the chosen information protection solutions, trusted information technologies and fault tolerance sensors. The paper shows the relevance and importance of the method of increasing fault tolerance of satellite communication networks under information technology interference in service control channels and satellite equipment data. The authors examine targeted information technology interference that causes malfunction of satellite modems, control stations and connected user computer networks. The paper shows the unique nature of satellite communication networks operation due to the global operating range, availability of broadband radio signals from communication and retransmission spacecraft for technical analysis and processing within the operating range, potential possibility of unauthorized connection to communication services. The primary direction of development of procedural and process engineering guidelines on protection and fault tolerance of satellite communication networks are defined. Methods. A method has been developed that is based on three components: model of experimental identification of satellite communication network vulnerabilities; simulation, computational and analytical model of detection and identification of threats of information technology interference; decision-making algorithm for improvement of the fault tolerance of a satellite communication network under information technology interference. The model of experimental detection of satellite communication network vulnerability allows, as part of bench tests, establishing connections between existing vulnerabilities of the hardware and software of satellite modems, control stations, user networks and the potential information technology interferences by intruders. As part of the vulnerability model the authors describe the certificates of vulnerable radio technical and information technology parameters of the satellite communication network signals, as well as suggest an analytic expression for calculating the probability of detection of such network vulnerabilities. The paper presents a computational and analytical model of detection and identification of information technology interference threats as a structure of advanced means of detection, prevention and elimination of the consequences of information technology interference in satellite communication networks and the mathematical expression for identification of conditional probability of materialization of the threat of information technology interference in satellite communication networks. An algorithm is considered for improvement of fault tolerance of satellite communication networks under information technology interference, including preparation of parameters and evaluation of the fault tolerance of a satellite communication network, adjustment of the parameters of satellite communication network, information security facilities and fault tolerance sensors, situational adjustment of satellite communication network fault tolerance solutions. Conclusions. It is noted that the developed method enables improved fault tolerance of satellite communication networks under information technology interference based on a set of interconnected procedures of the model of experimental detection of satellite communication network vulnerabilities on testbed; simulation, computational and analytical models of detection and identification of information technology interference threats; application of the decision-making algorithm of improvement of satellite communication network fault tolerance.

Space Radiator Optimization for Single-Phase Mechanical Pumped Fluid Loop

Advances in the design and development of communication spacecraft are associated with an increase in power consumption and heat dissipation in the spacecraft. As a consequence, advanced thermal control technologies like mechanical pumped fluid loop (MPFL) are increasingly being considered for spacecraft temperature management. These technologies generally use radiative sinks (often deployable) to reject heat. Since mass is a critical parameter in space applications, mass-optimized radiator design is paramount. This paper presents semi-analytical approach to evolve design of a mass-optimized space radiator panel for single-phase MPFL.

Navigation strategy with the spacecraft communications blackout for Mars entry

Future Mars missions require precision entry navigation capability, especially in the presence of communications blackout. On the mission of Mars Science Laboratory (MSL), there was a 70-s communications blackout period during atmospheric entry phase. In allusion to the spacecraft communications blackout encountered, this paper predicts an upper-bound for any possible blackout period firstly, improves the default integrated navigation measurements based on IMU and surface radiometric beacons, and proposes innovative attitude observation model based on IMU and range observation model based on orbiters finally. To verify the accuracy and effectiveness of the proposed observation models in the presence of communications blackout, unscented Kalman filter is utilized to demonstrate the navigation performance. The results show that navigation errors based on improved observation models proposed in this paper degrade an order of magnitude compared with the default observation models even if the communications blackout takes place, which satisfies the requirements of future Mars landing missions.

Research on the Applications and Measurements of the Microwave Technology

Microwave technology is extensively used for point-to-point telecommunications. Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower frequencies because antenna size is inversely proportional to transmitted frequency. Microwaves are used in spacecraft communication, and much of the world’s data, TV, and telephone communications are transmitted long distances by microwaves between ground stations and communications satellites. Microwaves are also employed in microwave ovens and in radar technology. The prefix “micro-” in “microwave” indicates that microwaves are “small” compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared light, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study.

Inflatable antenna for cubesats: Motivation for development and antenna design

CubeSats and small satellites have potential to provide means to explore space and to perform science in a more affordable way. As the goals for these spacecraft become more ambitious in space exploration, moving from Low Earth Orbit (LEO) to Geostationary Earth Orbit (GEO) or further, the communication systems currently implemented will not be able to support those missions. One of the bottlenecks in small spacecraft communication systems is represented by antennas' size, due to the close relation between antenna gain and dimensions. Current antennas for CubeSats are mostly dipole or patch antennas with limited gain. Deployable (not inflatable) antennas for CubeSats are currently being investigated, but these solutions are affected by the challenge of packaging the whole deployable structure in a small spacecraft.The work that we propose represents the first attempt to develop an inflatable antenna for CubeSats. Inflatable structures and antennas can be packaged efficiently occupying a small amount of space, and they can provide, once deployed, large dish dimension and correspondent gain. Inflatable antennas have been previously tested in space (Inflatable Antenna Experiment, STS-77). However they have never been developed for small spacecraft such as CubeSats, where the packaging efficiency, the deployment, and the inflation represent a challenge.Our study explores for the first time the possibility of developing such antenna in a way compatible with CubeSat dimensions and constraints. The research provides answers on the possible dimensions for an inflatable antenna for small satellites, on the gain and resolution that can be achieved, and on the deployment and inflation mechanism compatible with CubeSat. Future work in the development of the antenna will include the test of the antenna in flight during a specific technical demonstration mission.The article is structured as follows: context and motivation for Cubesat inflatable antenna are described; then a study to design the antenna which achieves the required performance metrics, while respecting the constraints imposed by CubeSat structure, is presented.

D01 初期角運動量を有する宇宙機のホイール故障時における劣駆動姿勢制御(M-OS14-1:非線形制御理論とその応用I,M-OS14 非線形制御理論とその応用,「海を越え,国を越え,世代を超えて!」)

The attitude of a spacecraft is usually controlled by more than 3 reaction wheels. However, it is important to consider the attitude control by only 2 wheels for a fail safe. When the angular momentum of the body is not 0, it is known that the attitude cannot be controlled arbitrarily. Therefore, the purpose of this research is to control the direction of spacecraft's communication antenna. We separate the control law into two cases by the configuration of wheels; (1) One of the the wheel is set along the antenna, and (2) Both wheels are not set along the antenna. In the case (1), by using partial linearization and idea of equal ratio divergence, it can control the direction of antenna and stop rotation of the body. In the case (2), by using the output zeroing control, it can control the direction of the antenna and keep rotation around the antenna.

Attitude & Orbit Digital and Pulse-width Control of Large-scale Communication Spacecraft

New results on both the attitude gyromoment digital control and the orbit electro-reaction pulse-width control of the large-scale communication satellites with precise pointing the large-scale flexible antennas, are presented.

Investigation of factors contributing depolarization in offset reflector antenna and trimmed-reflector offset parabolic antenna with lower cross-polarization

This article outlines impact of various factors on cross-polarization characteristics of offset reflector antenna for communication spacecraft with smaller sized bus at C band. Effects of different parameters are considered in rigorous analysis of the antenna. Measured and predicted performances are found in agreement. To fulfill specific requirement of higher edge-of-coverage gain (>26 dBi) and higher cross-polarization discrimination (XPD > 30 dB) over a wider coverage and dual linear polarization under the imposed constraints, a novel trimmed-reflector offset parabolic antenna (TROPA) is devised. This interesting configuration is obtained by trimming both sides parallel to symmetrical plane of a parabolic offset reflector antenna. Parametric study of trimming distance versus its impact on cross-polarization is also presented. The TROPA acquires wider bandwidth, simplification in its mechanical design and manufacturing, and offers low weight and compactness. It is also shown that trimmed reflector has almost even RF performance in presence of spacecraft body and other antenna. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.

Research on Attenuation Effects of Plasma to Electromagnetic Waves and Influences to the Spacecraft Communication

Electromagnetic waves will be attenuation when through plasma because of absorption and refraction efferts. Active application of plasma attenuation effect has good application prospect, such as aircraft stealth. But at the same time, the attenuation effect oneself will also bring some problems. For exzample, as the power system of the spacecraft, electric thruster plasma jet is possiblly to cause some problem on the communication between spacecraft and ground stations [1] .

Research on Attenuation Effects of Plasma to Electromagnetic Waves and Influences to the Spacecraft Communication

Electromagnetic waves will be attenuation when through plasma because of absorption and refraction efferts. Active application of plasma attenuation effect has good application prospect, such as aircraft stealth. But at the same time, the attenuation effect oneself will also bring some problems. For exzample, as the power system of the spacecraft, electric thruster plasma jet is possiblly to cause some problem on the communication between spacecraft and ground stations [1] .

The Moon Mineralogy Mapper (M3) imaging spectrometer for lunar science: Instrument description, calibration, on-orbit measurements, science data calibration and on-orbit validation

[1] The NASA Discovery Moon Mineralogy Mapper imaging spectrometer was selected to pursue a wide range of science objectives requiring measurement of composition at fine spatial scales over the full lunar surface. To pursue these objectives, a broad spectral range imaging spectrometer with high uniformity and high signal-to-noise ratio capable of measuring compositionally diagnostic spectral absorption features from a wide variety of known and possible lunar materials was required. For this purpose the Moon Mineralogy Mapper imaging spectrometer was designed and developed that measures the spectral range from 430 to 3000 nm with 10 nm spectral sampling through a 24 degree field of view with 0.7 milliradian spatial sampling. The instrument has a signal-to-noise ratio of greater than 400 for the specified equatorial reference radiance and greater than 100 for the polar reference radiance. The spectral cross-track uniformity is >90% and spectral instantaneous field-of-view uniformity is >90%. The Moon Mineralogy Mapper was launched on Chandrayaan-1 on the 22nd of October. On the 18th of November 2008 the Moon Mineralogy Mapper was turned on and collected a first light data set within 24 h. During this early checkout period and throughout the mission the spacecraft thermal environment and orbital parameters varied more than expected and placed operational and data quality constraints on the measurements. On the 29th of August 2009, spacecraft communication was lost. Over the course of the flight mission 1542 downlinked data sets were acquired that provide coverage of more than 95% of the lunar surface. An end-to-end science data calibration system was developed and all measurements have been passed through this system and delivered to the Planetary Data System (PDS.NASA.GOV). An extensive effort has been undertaken by the science team to validate the Moon Mineralogy Mapper science measurements in the context of the mission objectives. A focused spectral, radiometric, spatial, and uniformity validation effort has been pursued with selected data sets including an Earth-view data set. With this effort an initial validation of the on-orbit performance of the imaging spectrometer has been achieved, including validation of the cross-track spectral uniformity and spectral instantaneous field of view uniformity. The Moon Mineralogy Mapper is the first imaging spectrometer to measure a data set of this kind at the Moon. These calibrated science measurements are being used to address the full set of science goals and objectives for this mission.

Enhancing Reliability of LEDs and other Display Devices

Organic materials have played significant role in advancing sensor & display technologies for the past couple of years. Reliability and protection of various electronic components that are used in aircraft, artificial satellites and spacecraft for communications, navigation and the display and management of multiple systems are becoming more challenging due to their long-term performance requirements. In the recent years, organic polymers, particularly those deposited through vapor phase polymerization, have found an increasing role in the fabrication of display devices (including LED, OLED and FOLED), sensors, MEMS and optical windows and enhancing their overall reliability. Para-xylylene family of vapor phase polymers, particularly fluorinated Parylene (Parylene HT) offers unique characteristics for sensor, optical windows and display applications that are not available by other polymeric materials. This presentation describes a new development in the area of Parylenes and its role to advance the effectiveness of various types of LEDs, sensors, optical windows and display electronics. In addition, it highlights some characteristics for protection of various LEDs, sensors and their packaging components from solvent, gasoline, corrosive vapors, moisture and other harsh environmental effects including high temperature environments.

电推力器等离子体喷流对航天器通讯电磁波信号衰减效应

电推力器等离子体喷流对航天器通讯电磁波信号衰减效应

OWLS: a ten-year history in optical wireless links for intra-satellite communications

The application of Optical Wireless Links to intra- Spacecraft communications (OWLS) is presented here. This work summarizes ten years of developments, ranging from basic optoelectronic parts and front-end electronics, to different inorbit demonstrations. Several wireless applications were carried out in representative environments at ground level, and on in-flight experiments. A completely wireless satellite will be launched at the beginning of 2010. The benefits of replacing standard data wires and connectors with wireless systems are: mass reduction, flexibility, and simplification of the Assembly, Integration and Tests phases (AIT). However, the Aerospace and Defense fields need high reliability solutions. The use of COTS (Commercial-Off-The- Shelf) parts in these fields require extensive analyses in order to attain full product assurance. The current commercial optical wireless technology needs a deep transformation in order to be fully applicable in the aforementioned fields. Finally, major breakthroughs for the implementation of optical wireless links in Space will not be possible until dedicated circuits such as mixed analog/digital ASICs are developed. Once these products become available, it will also be possible to extend optical wireless links to other applications, such as Unmanned Air and Underwater Vehicles (UAV and UUV). The steps taken by INTA to introduce Optical Wireless Links in the Space environment are presented in this paper.

Spacecraft engineering and research at Saint Louis University

Parks College of Engineering and Aviation of Saint Louis University has a tradition of offering an outstanding aerospace engineering education to prepare students at the undergraduate and graduate level for careers in commercial aviation, defense systems, and space systems fields. Courses are offered across the engineering spectrum (aerospace, electrical and computer engineering, and physics departments) ranging from an introduction to aerospace engineering to spacecraft design, spacecraft communications, and space physics. Students participate in courses that include orbital mechanics, space dynamics, spacecraft engineering, and space systems. Senior capstone project work is also included. A separate Astronautics Engineering track as well as a Minor in Space Systems Engineering for non-aerospace engineering students is currently being developed. A, number of student-driven space systems projects are in process that involve design, development, and test of small satellites similar to those recently highlighted in the March 2009 Systems article entitled The First one Hundred University-Class Spacecraft 1981 - 2008. Reference identifies student spacecraft launched over the past 27 years.

Entry, Descent, and Landing Communications for the2007 Phoenix Mars Lander

This paper addresses NASA's requirement on the 2007 Phoenix Mars Lander to provide spacecraft communications during entry, descent, and landing on Mars to allow the identification of probable root cause should any mission failure occur. The Phoenix mission launched on 4 August 2007 and will land on 25 May 2008 on the northern plains of Mars to conduct a three-month study of the Martian environment. The paper discusses the architectural trades in designing a communications link and surveys the entry, descent, and landing communications approaches taken by previous missions. It then discusses the Phoenix-specific constraints and degrees of freedoms and presents a novel and robust implementation approach to entry, descent, and landing communications. The overall methodology and conclusions described herein can serve as a pathfinder for the entry, descent, and landing communications architecture and implementation of future Mars landed missions.