TOPIC: O1 Space Communications and Navigation

• Highly phase-stable RF ground systems are critical to high accuracy radiometric tracking. Present systems rely upon analog transmission over 0.5 to 10 km distances of a broadband (100 - 600 MHz) spectrum. Transmission induced phase errors could be greatly reduced by developing highly phase stable digital sampling and time tagging systems that can be placed near (~10m) to the RF feedhorn without measurably degrading the RF signal capture with spurious tones and noise. Phase stability goals are given above. The sampler should Nyquist sample the 100 - 600 MHz band with at least 8-bit resolution and be capable of digitally transmitting the resulting samples over fiber optic lines;
  
• The VLBI parameter estimation software used to build the radiometric reference frames used for precise tracking relies on a Square Root Information Filter that makes use of Householder transformation techniques. These solutions often take several days of CPU time on a modern workstation. Block matrix techniques have the potential to optimize the interaction of the CPU and cache memory thereby greatly reducing the CPU time needed for solutions. The goal is a factor of three improvement in total solution time for problems with 7 million data points and 500,000 parameters, which include at least 5000 parameters that are active over the entire data set;
  
• Microwave radiometry of atmospheric emission lines (22 GHz H₂O, 60 GHz O₂) has been successful in demonstrating 1 mm level calibration of tropospheric path delay. However, the usefulness of this technique has been limited by the large mass and size of the instrument packages. Identifying/developing low mass, low cost implementations of this technique without significantly sacrificing accuracy would greatly enhance precise tracking;
  
• Develop low mass, (Less than 1 kg) low cost onboard radio frequency standards for generating highly phase-stable onboard radio signals which achieve Allan standard deviations of 1 x 10^-15 at 1000 seconds and drift of less than 10^-15/day;
  
• Develop innovative tracking technologies using new wavelengths (X-ray, Infra-red, etc.), such as systems using celestial and planetary emissions and reflections (not limited to the visible spectrum) that can produce three-dimensional absolute and relative position and velocity in regions where Earth-based GPS measurements are not available. The technologies can exploit either ground based or on-board techniques;
  
• Develop innovative technologies for improving the state-of-the-art in terms of cost and performance in making spacecraft-to-spacecraft measurements, such as omni-directional range and bearing sensors and robotic-vision-based systems;
  
• Develop innovative navigation algorithms and software supporting analysis, design, and mission operations that will reduce operations costs and support multiple systems in simultaneous, tightly-coupled, non-quiescent operations, such as robotic servicing, formation flying, or surface mobility.
  
• Systems and technologies for providing an EVA crewmember with real-time navigation and position information while traversing on foot or on a rover. This system will be especially useful when the suited crewmember is traversing on foot and cannot rely on the rover system and markers for walk-back navigation.
  
• Develop a highly integrated Ultra Wide Band (UWB) communications and tracking solution to reduce costs and provide robust performance, multipath immunity, long range one-way tracking, high precision short range tracking, high (broadband) capacity, and a transmit-only tag tracking system. RFID tags using UWB technology have been shown to provide sub-inch accuracy for close-in tracking. This precision tracking can be used to allow astronauts and robonauts to work in close proximity with reduced risk of collisions. The same UWB equipment can be used for long range tracking/wideband communications and the precise tracking at close ranges. Because of its mitigation properties, this impulse radio technology is well-suited for surface mobile area networks and reliable for simultaneous target tracking and high data rate communications in and around lunar craters. Commercial applications include precise tracking of moving oil-drill equipment, medical imaging, automobile collision-avoidance and surveillance through walls.
  

• Low power consumption;
  
• Low mass/volume;
  
• Compliance with range safety standards;
  
• Flexible tracking loop programmability;
  
• Programmable output formats; and
  
• Operability in high G environments.
  

• Minimizing the life-cycle cost of an array that produces a given EIRP by selecting the optimum combination of antenna size, transmitter power, and number of antennas. This becomes much more difficult if the option of using the same antenna for both uplink and downlink is considered.
  
• Identifying/developing low-cost, highly reliable, easily serviceable components for key systems. This could include highly integrated RF and digital signal processing electronics, including mixed-signal ASICs. It could also include low-cost, high-volume antenna manufacturing techniques. (For the receiving array, another key component is a cryogenic refrigerator for the 15 - 25K temperature range.) Also, low-cost transmitters, including medium-power of the order of 100's of watts amplifiers, are desirable.
  
• Phase calibration techniques are required to ensure coherent addition of the signals from individual antennas at the spacecraft. It is important to understand whether space-based techniques are required or ground-based techniques are adequate. In general, a target spacecraft in deep space cannot be used for calibration because of the long round-trip communication delay.
  
• Design of ultra phase-stable electronics to maintain the relative phase among antennas. These will minimize the need for continuous, extensive and/or disruptive calibrations.
  
• Understanding the effect of the medium (primarily the Earth's troposphere) on the coherence of the signals at the target spacecraft. Generally, turbulence in the medium tends to disrupt the coherence in a way that is time-dependent and site-dependent. A quantitative understanding of this is needed.
  
• Techniques for integrating a very low-noise, cryogenically-cooled receiver with a medium power (1W to 200W) transmitter. If transmitters and receivers are combined on the same antenna, the performance of each should be compromised as little as possible, and the low cost and high reliability should be maintained.
  

• Innovative methods of using X-ray or radio pulsar signals for precise navigation or positioning of spacecraft.
  
• Small, low mass, reliable detectors, improvements in position accuracy, digital signal processing advances for time of arrival, drift estimation, and position estimation.
  
• Development of nano-scale communication devices and systems (e.g., FET arrays, nano-antennas, nano-transceivers, etc.), which can enable nano-spacecraft applications.
  
• Quantum entanglement or other innovative breakthroughs in quantum information physics to specifically address curious effects and critical unknowns relevant to revolutionary improvements in communicating data, information or knowledge between independent entities across space-time are sought.
  
• Methods and techniques to demonstrate extremely novel means of effectively packaging, storing, encrypting, and/or transferring information or knowledge.
  
• Breakthrough power-efficiency in communications brought about through the use of natural phenomenon (e.g., soliton pulse/wave/energy propagation).
  
• RF Micro Electro-Mechanical Systems (MEMS) devices. Besides low spatial volume, lightweight, and low-power consumption, these devices are also attractive to operate as high Q components and perform frequency selectivity - namely, agile pre-selectors, multi-couplers, and diplexers. Selectivity, or Q, for band pass filters currently comes at an unacceptably high penalty in size and mass. For example, most high rejection diplexers for space-based radios are almost as enormous as the modern radio package itself. To build and design high performance, tightly coupled, low volume space radios, compact selectivity-determining devices are a critical enabler. Most high Q filters above 400MHz, such as inter-digital filters and others involving resonant cavities, are wholly mechanical assemblies which can be "folded" in their design and lend themselves to micro machining techniques
  
• Other rich areas of investigation may lie within the area between MEMS and Micro-Machined devices, including electromechanically tuned filters, 3D micro machined RF resonators, filter configurations consisting of cantilevered structures, as well as carbon nano-tube waveguides. Develop, apply and demonstrate advantages of RF MEMS circuitry that proliferate the implementation of next-generation lightweight communications systems (e.g., extravehicular activity (EVA) radios).
  

• Systems and technologies relating to acquisition, tracking and sub-microradian pointing of the optical communications beam under typical deep-space ranges (to 40 AU) and spacecraft micro-vibration environments.
  
• Uncooled photon counting imagers with >1024 x 1024 formats, ultra low dark count rates and 400 - 2000 nm sensitivity.
  
• Ultra-low (<0.1%) fixed pattern non-uniformity NIR imagers with large format (1024 x 1024), low noise (<1 e- read, <1ke/pix/sec dark) and high QE (>0.7).
  
• Nutating fiber pointing mechanisms with high precision (<0.01 urad) and high bandwidth (> 3 kHz).
  
• Compact, lightweight, low power, broad bandwidth (0 - 3 kHz) disturbance rejection and/or isolation platforms.
  
• Space-qualifiable, > 20% wall plug efficiency, lightweight, 20-500 psec pulse-width (10 to > 100 MHz PRF), tunable (± 0.1 nm) pulsed 1064-nm or 1550-nm laser transmitter fiber MOPA sources with >1 kW of peak power per pulse (over the entire pulse-repetition rate), with Stimulated Brillouin Scattering (SBS) suppression and > 10 W of average power, near transform limited spectral width, and <10 psec pulse rise and fall times. Description of approaches to achieve the stated efficiency is a must.
  
• > 2-m diameter, <30-nm bandpass optical filters on a membrane substrate to pass center. Wavelengths in the 1000 to 1600 nm band with >90% transmission.
  
• > 2-m diameter f/1.1 primary mirror and Cassegrain focus of ~f/6 optical communication receiver telescopes. Maximum RMS surface figure error of 1-wave at 1000 nm wavelength. Telescope is positioned with a 2-axis gimbal capable of 0.25 mrad pointing. Combined telescope and gimbal shall be manufacturable in quantity (tens) for <$400k each.
  
• Daytime atmospheric compensation techniques capable of removing all significant atmospheric turbulence distortions (tilt and higher-order components) on an uplink laser beam; and/or for a 2-m diameter downlink receiver telescope. Also of interest are technologies to compensate for the static and dynamic (gravity sag and thermal) aberrations of 2-m diameter telescopes with a surface figure of 10's of waves.
  
• Ground-based, relatively low-cost diode-pumped laser technology capable of reaching 100 kW average power levels in a TEM₀₀ mode, for uplink to spacecraft.
  
• Photon counting Si, InGaAs, and HgCdTe detectors and arrays for the 1000 to 1600 nm wavelength range with single photon detection efficiencies > 60% and output jitters less than 20 psec, active areas > 20 microns/pixel, and 1 dB saturation rates of at least 100 megaphotons (detected) per pixel and dark count rates of < 1 MHz / mm².
  
• Radiation hard (100 Mrad level) photon counting detectors and arrays for the 1000 to 1600 nm wavelength range with single photon detection efficiencies > 40% and 1 dB saturation rates of at least 30 megaphotons/pixel and operational temperatures above 220 K and dark count rates of < 10 MHz / mm.
  
• Single-photon-sensitive, high-bandwidth (1 GHz), linear mode, high gain (> 1000), low-noise (< 1 kcps), large diameter (200 micron), HgCdTe avalanche photodiode and/or (small diameter) arrays for optical detection at 1060 nm or 1550 nm.
  

• Ultra-small, light-weight, low-cost, low-power, modular deep-space transceivers, transponders and components, incorporating MMICs and Bi-CMOS circuits;
  
• MMIC modulators with drivers to provide large linear phase modulation (above 2.5 rad), high-data rate (10 - 200 Mbps), BPSK/QPSK modulation at X-band (8.4 GHz), and Ka-band (26 GHz, 32 GHz and 38 GHz);
  
• High-efficiency (> 60%) Solid-State Power Amplifiers (SSPAs), of both medium output power (10 W - 50 W) and high-output power (150 W - 1 KW), using power combining techniques and/or wide-bandgap semiconductor devices at X-band (8.4 GHz) and Ka-band (26 GHz, 32 GHz and 38 GHz);
  
• Epitaxial GaN films with threading dislocations less than 1e6 per cm2 for use in wide band-gap semiconductor devices at X- and Ka-Band;
  
• Utilization of nanomaterials and/or other novel materials and techniques for improving the power efficiency or reducing the cost of reliable vacuum electronics amplifier components (e.g., TWTAs and Klystrons);
  
• Long lifetime, radiation hard SSPAs, modulators and MMICs for 26 GHz Ka-band (lunar communication);
  
• TWTAs operating at higher millimeter wave frequencies (e.g., W-Band) and at data rates of 10 Gbps or higher;
  
• Ultra low-noise amplifiers (MMICs or hybrid) for RF front-ends (< 50 K noise temperature); and
  
• MEMS-based RF switches and photonic control devices needed for use in reconfigurable antennas, phase shifters, amplifiers, oscillators, and in-flight reconfigurable filters. Frequencies of interest include VHF, UHF, L-, S-, X-, Ka-, V-band (60 GHz) and W-band (94 GHz). Of particular interest is Ka-band from 25.5 - 27 GHz and 31.5 - 34 GHz.
  

• Low power, space-rated Application-Specific Integrated Circuits (ASICs) and Field Programmable Gate Arrays (FPGAs) for wireless network products: short range (< 1 km) access point, base stations, and wireless router bridges for extending surface network coverage;
  
• Fixed, long range (< 50 km) wireless network terminals for extending high data rate communications which are designed to be cycled for years through the extreme lunar temperature variations;
  
• Integrated tracking, timing, and navigation services which will determine locations of human and robotic assets on the lunar surface, providing them to relevant entities;
  
• Self-healing, ad hoc, disruption tolerant network protocols for intelligent, autonomous link management and reliability;
  
• Non-line-of-sight communication between stationary and moving assets, outside or inside lunar craters;
  
• Autonomous surface navigation and hazard avoidance systems for robotic and fixed assets;
  
• Analog voice-only radio service to the lunar outpost and the lunar relay satellite at the highest network priority for HF, UHF, or S-band.
  

• Technical challenges posed by the design considerations enumerated above and assess tradeoffs of disruption, load, storage, topology, and delivery ratio;
  
• Demonstrate adaptive DTN routing via simulations;
  
• Develop proof-of-concept nodes complete with the networking algorithms developed as part of the funded work;
  
• Demonstrate unique communications in networks that suffer from severe disruptions and delays with adaptive routing developed in Phase 1;
  
• Develop a prototype convergence layer adapter plug-in for an Extra-Vehicular Activity (EVA) radio.
  

• Autonomously reconfigurable receivers capable of automatic link configuration and management;
  
• Microwave ranging hardware built into the communication system for rendezvous and collision avoidance;
  
• Ad hoc, long-range spacecraft-to-spacecraft network protocols to initialize links on demand such that each node can route data through to another node.
  

• Antennas for surface and orbital access communications required for the aforementioned goals shall be developed under subtopic O1.04.
  
• Radios for surface and orbital communications required for the aforementioned goals shall be developed under subtopic O1.06.
  
• Optical transceivers required for the aforementioned goals shall be developed under subtopic O1.08.
  
• Any high rate, low power, efficient amplifiers or transponders required for the aforementioned goals shall be developed under subtopic O1.09.
  

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