Deep Space Telecommunications Research Articles

Mission to Earth–Moon Lagrange Point by a 6U CubeSat: EQUULEUS

EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) will be the world's smallest spacecraft to explore the Earth-Moon Lagrange point. It is being jointly developed by JAXA (Japan Aerospace Exploration Agency) and the University of Tokyo, and will be launched by NASA's Space Launch System Exploration Mission-1. The spacecraft will fly to a libration orbit around the Earth-Moon L2 point (EML2) and will demonstrate low-energy trajectory-control techniques within the Sun-Earth-Moon region for the first time by a nano-class spacecraft. EQUULEUS also carries three scientific observation missions: imaging of Earth's plasmasphere by extreme ultraviolet wavelength, lunar impact flash observation on the far side of the moon, and micrometeoroid flux measurements in the cis-lunar region. While all these missions have their own scientific objectives, they will also contribute to future human activity and/or infrastructure development in the cis-lunar region. Most parts of the spacecraft system use commercial off-the-shelf components, or are designed based on the experiences of various past space missions, with the exception of the newly developed water resistojet propulsion system. EQUULEUS uses X-band frequency for deep space telecommunication. Japanese deep space antennas (64-m and 34-m) will be nominally used for spacecraft operation, and support from the deep space network of JPL (Jet Propulsion Laboratory) is also being planned, especially for the initial phase of operation. The spacecraft will fly to EML2 in less than one year, and will remain there for scientific observations until shortly before the depletion of the onboard propellant, when the spacecraft will leave the orbit for space-debris compliance.

High Gain UWB Four Elements Antenna Array for C-Band and X-Band Application

The C-band is allocated for commercial telecommunications via satellites. Amateur satellite operations in the frequency range 5.830 to 5.850 GHz for down-links and 5.650 to 5.670 GHz for up-links are allowed by International Telecommunication Union. The X-band is used for terrestrial broadband communication, radar applications, and portions of the X-band are assigned for deep space telecommunications. In this paper, a design of 4 × 1 Ultra Wide Band (UWB) antenna array for C-band and X-band applications is introduced. Metamaterial sixteen-unit cells are incorporated into each antenna element for radiation characteristics enhancement purposes. Permeability and permittivity of metamaterial unit cells are obtained all over the operating bandwidth. UWB unequal power divider is used to feed the proposed four elements antenna array based on Chebyshev excitation method. The proposed antenna has a suitable 3 dB beam width and gains all over the operating bandwidth which extends from 5.6 GHz to 10.9 GHz. The proposed antenna covers 60% and 72.5% of the C-band and X-band, respectively. The proposed antenna is fabricated, measured, and good agreement is obtained between simulated and measured results. The obtained performance ensures the suitability of the proposed antenna array for C-band and X-band applications.

Developing Future Deep-Space Telecommunication Architectures: A Historical Look at the Benefits of Analog Research on the Development of Solar System Internetworking for Future Human Spaceflight.

Exploration analog field tests, missions, and deployments enable the integration and validation of new and experimental concepts and/or technologies through strategic experimental design. The results of these operations often create new capabilities for exploration and increase confidence in, and credibility of, emerging technologies, usually at very low cost and risk to the test subjects involved. While these experiments resemble missions 10–30 years into the future, insights obtained are often of immediate value. Knowledge gained in the field translates into strategic planning data to assist long-range exploration planners, and planners influence the experimental design of field deployments, creating a synergistic relationship. The Biologic Analog Science Associated with Lava Terrains (BASALT) communication architecture is a high-fidelity analog program that emulates conditions impacting future explorers on the martian surface. This article provides (1) a brief historical review of past analog operations that deliberately used elements of a flight-like telecommunication infrastructure to add fidelity to the test, (2) samples of the accomplishments made through analog operations, and (3) potentially significant deep-space telecommunication insights gained from the BASALT program in support of future extravehicular activity exploration of Mars. This article is paired with and complements Miller et al. in this issue which focuses on the telecommunication infrastructure utilized by the BASALT team during the field deployment.

A Flexible Telecommunication Architecture for Human Planetary Exploration Based on the BASALT Science-Driven Mars Analog.

There is a synergistic relationship between analog field testing and the deep space telecommunication capabilities necessary for future human exploration. The BASALT (Biologic Analog Science Associated with Lava Terrains) research project developed and implemented a telecommunications architecture that serves as a high-fidelity analog of future telecommunication capabilities for Mars. This paper presents the architecture and its constituent elements. The rationale for the various protocols and radio frequency (RF) link types required to enable an interdisciplinary field mission are discussed, and the performance results from the BASALT field tests are provided. Extravehicular Informatics Backpacks (EVIB) designed for BASALT and tested by human subjects are also discussed, and the proceeding sections show how these prototype extravehicular activity (EVA) information systems can augment future human exploration. The paper concludes with an aggregate analysis of the data product types and data volumes generated, transferred, and utilized by the ground team and explorers over the course of the field deployments.

Polarization in Bistatic Radar Probing of Planetary Surfaces: Application to Mars Express Data

Spacecraft-to-ground bistatic radar provides a straightforward method for surveying planetary surfaces on scales of importance to landers and rovers. Centimeter wavelengths, currently in use for deep-space telecommunications, interact with surface structure of similar to somewhat larger scales. For the quasi-specular component of scattering and for surfaces uniformly illuminated by monochromatic signals from an orbiting or flyby vehicle, the echo Doppler dispersion is proportional to the root mean square (rms) surface slope. When the specular condition occurs within 10°-20° of the Brewster angle, the surface dielectric constant can be derived from relative echo power measured simultaneously in orthogonal polarizations and the Fresnel reflection laws. Cross spectra, computed from outputs of the orthogonally polarized receivers, may be used to calculate a complete description of the polarization properties of the scattered fields. Application to planetary studies requires accurate amplitude and phase calibration of the polarization channels, including correction for any leakage between the two receiving paths, such as from imperfectly isolated antenna feeds. We illustrate these techniques using Mars Express results from “Stealth” (Medusae Fossae), a region on Mars that has not previously been detected by Earth-based radar, and from a long profile including Acidalia Planitia. Single-location Stealth observations support previous conclusions that the surface is rough and porous (dielectric constant ≈ 1.4). But the longest experiment (in which the specular point was followed for an hour) yields relatively high dielectric constants (2.8), suggesting that the model is incomplete. The surface of Acidalia Planitia has low dielectric constants ( ≈2.6) over 60-90 W at 50 N and higher values (≈3.6) as the specular point moves south and crosses the equator.

Weak Solar Scintillation Effects on Deep Space Communication

摘要: 行星聚合和太阳闪烁是影响深空通信的重要因素. 分析了行星聚合和太阳闪烁的物理特性, 建立了弱太阳闪烁条件下深空通信信道的Rician 模型, 并得出了当Rician 因子大于10 dB 时近似为高斯信道的结论. 对弱太阳闪烁下X 波段和Ka 波段的通信性能进行了仿真, 这对建立可靠的深空通信链路具有十分重要的意义. 关键词: 太阳闪烁 / 行星聚合 / 深空通信

Enabling Antenna Systems for Extreme Deep-Space Mission Applications

Two NASA deep-space probes, Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) and New Horizons (NH), are moving towards the extremes of our solar system (Mercury and Pluto). The delivery of the science in these extreme environments is a challenge, and the missions require unique approaches. MESSENGER'S antenna system utilizes the first electronically scanned high-gain array for a deep-space telecommunication application. The array, which provides the high-data-rate downlink, is scanned in one dimension and is circularly polarized. Although a linearly polarized array would have satisfied the minimum mission science data rate requirements, MESSENGER'S circularly polarized array doubles it. To achieve this, the Johns Hopkins University/Applied Physics Laboratory (JHU/APL) developed an innovative technique to produce circular polarization from a narrow-wall slotted waveguide array. The new technique uses short parasitic monopoles mounted to the exterior of the waveguides. The result is a simple, lightweight, and all-metal circularly polarized array capable of operating at +300 OC, and a variety of measurement techniques were used to verify phased-array antenna system performance during qualification. The NH antenna system is a stack arrangement of a high-gain antenna (HGA), medium-gain antenna (MGA), and low-gain antenna (LGA). To minimize mission operating costs, the spacecraft is spin stabilized at times except during encounters to maintain a fixed spacecraft attitude. This approach and application for a narrow beamwidth antenna is unique for a deep-space mission, resulting in new approaches to accurately measure the gain and radio-frequency (RF) boresight direction in a compact range facility. Because of the importance of the HGA function to overall mission success, testing of the HGA system at operational temperatures of -200 OC was also performed. Recent in-flight measurement of the NH HGA pattern verified ground alignments. The RF design of the NH antenna also forms the baseline RF design for a deployable antenna system JHU/APL is developing called the Hybrid Deployable Antenna (HDA). The HDA combines a fixed parabolic dish with a deployable/inflatable reflector annulus that greatly increases antenna area after launch. This concept provides a high-payoff deployable antenna system that is being developed to address the all or nothing risk by providing a viable backup capability. This paper discusses some of the challenges to advance this concept for a future deep-space mission.

Testing of the MESSENGER spacecraft phased-array antenna

The MESSENGER spacecraft, designed to orbit the planet Mercury, uses the first electronically scanned phased-array antenna for a deep-space telecommunication application. Two lightweight phased arrays, mounted on opposite sides of the spacecraft, provide the high-gain downlink coverage. Techniques for measurement of the phased-array antenna system include ambient temperature measurements in a compact antenna range, thermal vacuum testing, and spacecraft-level testing. There have been two novel developments in the characterization of the phased-array system. The first is a envelope response, which is a measurement of the gain of the array at the intended scan angle as the array is electrically scanned in 1/spl deg/ increments. This response was produced through a combination of hardware and test software to synchronize the gain measurement with the mechanical and electrical scanning. The second is a phase-steering verification test that utilizes couplers in each steered element in conjunction with previously measured element patterns to confirm that the antenna beam is steered property. This method allows functional verification of the phased-array system while radiating into an RF-absorber-lined hat during spacecraft-level tests.

Advances in deep-space telecommunications technology at the Applied Physics Laboratory

This paper reviews recent advances in RF telecommunications technology at the Applied Physics Laboratory. These advances, which address the miniaturization and high data rate needs of NASA, fall into three major areas: (1) transceiver-based systems, (2) antennas, and (3) solid-state power amplifiers. In the transceiver area, a deep-space transceiver system being developed for the Comet Nucleus Tour (CONTOUR) spacecraft is described. In addition, the development progress of a low-power S/X-band digital receiver and an advanced ultrastable oscillator quartz resonator are described. In the antenna area, an X-band phased array system being developed for the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft is described, along with the concept for a K a -band hybrid inflatable antenna. In the solid-state power amplifier area, the development of X- and K a-band amplifiers suitable for phased array applications is described.

Communications technologies for space exploration

Deep-space telecommunications over the next several decades will face continuing challenges to technological innovation. In the current era of going often, landing, and returning samples, the challenges are driven by the larger number of missions, each with much smaller mass and power. In the next era, the challenges may be driven by permanent robotic outposts, wide bandwidth telecommunications, and virtual presence at a variety of sites in the solar system, leading to eventual human exploration. Even more challenging will be the interstellar missions as we take the first steps in the journey beyond our solar system into interstellar space.

Microtechnology in telecommunications for spacecraft cost and mass reduction

This paper examines the incorporation of both microelectronics and micromachining (termed microtechnologies) as applied to deep space telecommunication subsystems. Using the Pluto Fast Flyby Pre-Project as a main case study we have reduced the subsystem mass by 50%. This was accomplished via the use of advanced packaging {RF and digital multichip modules (MCMs) and Monolithic Microwave Integrated Circuits (MMICs) for the transponder and advanced GaAs power device technology for solid state power amplifiers}. Micromachined diplexers, filters, and switches using membrane-supported transmission line-technology (MIST-T) provide the potential to reduce subsystem form factor. Another way to reduce mission costs is in the use of both 32 GHz (at Goldstone Deep Space Network {DSN} facility) and 8.4 GHz (at Canberra and Madrid DSN facilities) downlink frequencies. This allows the data to be returned faster, thereby saving both DSN and Mission Operation costs.

Ground antennas in NASA's deep space telecommunications

Ground antennas are the major visible components of NASA's Deep Space Network (DSN). The role, key characteristics, and performance of these antennas in deep-space telecommunications are described. The system analyses and tradeoffs to optimize the overall ground-to-spacecraft link and to define future missions are elaborated from an antenna perspective. Overall performance of receiving systems is compared using the widely accepted G/T figure-of-merit, i.e., net antenna gain divided by the operating system noise temperature. Performance of past, present, and future antennas and receiving systems is discussed, including the planned development of a world-wide network of 34-m diameter beam-waveguide antennas. The need for multifrequency operation, presently in the S- and X-bands, and in the future in the Ka-band, is discussed. The resulting requirements placed on antenna technology are highlighted. Beam-waveguide antenna performance to further improve performance and operational advantages is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Precision DSN radiometer systems: impact on microwave calibrations

The NASA Deep Space Network (DSN) has a long history of providing large parabolic dish antennas with precision surfaces, low-loss feeds, and ultra-low noise amplifiers for deep-space telecommunications. To realize the benefits of high sensitivity, it is important that receiving systems are accurately calibrated and monitored to maintain peak performance. A method is described to measure system performance and to calibrate the receiving system using procedures, software, and commercial instruments that are easy to implement and efficient to use. The utility of the measurement procedures and the precision of the receiver calibration technique were demonstrated by performing tests at Ka-band (32 and 33.68 GHz) frequencies at Goldstone on a 34-m beam-waveguide antenna. Observations of multiple calibration radio sources are used to measure the dependence of antenna gain and system noise temperature on source elevation and derive the performance parameters. The experimental results described illustrate some of the ways that receiving system nonlinearity can negatively impact system performance. A simple radiometer calibration technique and analysis provide quantitative information that enables the system engineer to adjust and linearize the receiving system. When that is not practical, the experimenter or the operator can apply connection coefficients to the measured values of system noise temperature and thereby compensate for the receiving system nonlinearity. >

Ruby masers for maximum G/T/sub op/

The Deep-Space Network (DSN) includes world-wide networks of 26-, 34- and 70-m antennas in Australia, Spain, and the USA. Ruby masers are used on the 34and 70-m antennas to maximize the system operating noise temperature and thereby maximize the DSN receiving system figure of merit, antenna gain divided by system operating noise temperature. These systems are used for deep-space telecommunications, solar system radar, and radio astronomy. Cavity, traveling-wave, and reflected-wave maser designs and performance characteristics from 960 MHz to 34 GHz are summarized. Effective noise temperatures of ruby masers are addressed with emphasis on a 33.68-GHz maser where quantum noise is a major source of noise.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Microwave systems applications in deep space telecommunications and navigation: Space Exploration Initiative architectures

The US Space Exploration Initiative (SEI) calls for the charting of a new and evolving manned course to the Moon, Mars, and beyond. The fundamental SEI support objectives are to provide the mission with means to monitor and control mission elements, acquire engineering, science, and navigation data, compute state vectors and navigate, and move these data efficiently and automatically between mission nodes for timely analysis and decision-making. Microwave links provide the means to communicate between system nodes, and the essential radio metrics to navigate; later, these probably will be augmented with optical links. The general mission telecommunications and navigation support requirements and resulting architectures for SEI mission support are described, and then the implications of these on the role of microwave technology in these architectures, particularly for Mars exploration support, are discussed. >

Deep space telecommunications, navigation, and information management: Support of the space exploration initiative

The United States Space Exploration Initiative (SEI) calls for the charting of a new and evolving manned course to the Moon, Mars, and beyond. This paper discusses key challenges in providing effective deep space telecommunications, navigation, and information management (TNIM) architectures and designs for Mars exploration support. The fundamental objectives are to provide the mission with means to monitor and control mission elements, acquire engineering, science, and navigation data, compute state vectors and navigate, and move these data efficiently and automatically between mission nodes for timely analysis and decision-making. Although these objectives do not depart, fundamentally, from those evolved over the past 30 years in supporting deep space robotic exploration, there are several new issues. This paper focuses on summarizing new requirements, identifying related issues and challenges, responding with concepts and strategies which are enabling, and, finally, describing candidate architectures, and driving technologies. The design challenges include the attainment of: 1) manageable interfaces in a large distributed system, 2) highly unattended operations for in-situ Mars telecommunications and navigation functions, 3) robust connectivity for manned and robotic links, 4) information management for efficient and reliable interchange of data between mission nodes, and 5) an adequate Mars-Earth data rate.

Book reviews: Deep space telecommunications systems engineering

Book reviews: Deep space telecommunications systems engineering

Power requirements for deep-space telecommunication links

The signal-to-noise ratio in a given equivalent bandwidth must be maintained above a minimum value during a deep-space mission in order to provide predictable performance, and in order to maintain effective telemetry communications with spacecraft at interplanetary distances it is necessary for earth stations to use maximum antenna gain. One solution is to extend telecommand range by reducing system noise temperature in the spacecraft receiver and reducing the bandwidth of the receiver's phase-lock loop. Low-noise preamplifiers have not yet been applied in planetary spacecraft in order to maintain simplicity and reliability. An answer to the problem seems to be high-power transmitters (earth-based) with outputs in the 1000-GW range.