Overview of the Advanced High Frequency Branch

This presentation provides an overview of the competencies, selected areas of research and technology development activities, and current external collaborative efforts of the NASA Glenn Research Center's Advanced High Frequency Branch

Cube Laser Communication Terminal state of the Art

Based on the increasing need for higher data rates in CubeSat missions primarily for Earth observation and communication missions mainly focused on Direct-to-Earth (DTE) applications, DLR started the development of a highly compact laser communication payload for CubeSats. In parallel TESAT has used its experience for preparing and developing this technology for volume production. At the same time to ensure the compatibility with the ground stations, DLR started and lead the CCSDS working group for Optical On-Off-Keying (O3K) to further extend the commercial use of CubeLCT terminals. This cooperation between industry and research center has been very successful. The PIXL-1 mission was accomplished in a very agile new space approach, developing and demonstrating the technology in record time. Moreover, in order to enable the potential customers to deploy a complete end-to-end system, TESAT in cooperation with GSOC has specified the interface requirements for developing the first demonstrator for DTE optical system mission planning, mainly focused on the link planning challenges. This concept can be applied to current missions, and allows identifying the needs also for further applications. In addition to DTE links, the increasing demand for higher data rates and low latency communication in upcoming constellations of CubeSats also drives the need to extend the CubeLCT terminal with Inter-Satellite-Linkfunctionality. In continuation to the first development, IKN, RSC3 and TESAT, are currently developing a CubeLCT for intra-plane communication capable of transferring 100 Mbps over 1800 km. The upcoming challenges in operation of inter-satellite-links on CubeSats combined with the possibilities of enabling DTE are also covered in this paper

Quantum channels from reflections on moving mirrors

Light reflection on a mirror can be thought as a simple physical effect. However if this happens when the mirror moves a rich scenario opens up. Here we aim at analyzing it from a quantum communication perspective. In particular, we study the kind of quantum channel that arises from (Gaussian) light reflection upon an accelerating mirror. Two competing mechanisms emerge in such a context, namely photons production by the mirror's motion and {\blu interference between modes}. As consequence we find out a quantum amplifier channel and quantum lossy channel respectively below and above a threshold frequency (that depends on parameters determining mirror's acceleration). Exactly at the threshold frequency the channel behaves like a purely classical additive channel, while it becomes purely erasure for large frequencies. In addition the time behavior of the channel is analyzed by employing wave packets expansion of the light field.Comment: 12 pages, 3 figure

Unconstrained distillation capacities of a pure-loss bosonic broadcast channel

Bosonic channels are important in practice as they form a simple model for free-space or fiber-optic communication. Here we consider a single-sender two-receiver pure-loss bosonic broadcast channel and determine the unconstrained capacity region for the distillation of bipartite entanglement and secret key between the sender and each receiver, whenever they are allowed arbitrary public classical communication. We show how the state merging protocol leads to achievable rates in this setting, giving an inner bound on the capacity region. We also evaluate an outer bound on the region by using the relative entropy of entanglement and a `reduction by teleportation' technique. The outer bounds match the inner bounds in the infinite-energy limit, thereby establishing the unconstrained capacity region for such channels. Our result could provide a useful benchmark for implementing a broadcasting of entanglement and secret key through such channels. An important open question relevant to practice is to determine the capacity region in both this setting and the single-sender single-receiver case when there is an energy constraint on the transmitter.Comment: v2: 6 pages, 3 figures, introduction revised, appendix added where the result is extended to the 1-to-m pure-loss bosonic broadcast channel. v3: minor revision, typo error correcte

資源に制約のある小型衛星における自由空間光通信に関する研究

Presently, the farthest CubeSats have gone into deep space was via a piggy-back ride to the orbit of planet Mars where a twin-6U CubeSats (MarCO-A & B) in formation provided X-band (8.425GHz) radio-frequency (RF) communication relay support between the Insight Lander spacecraft and the NASA Deep Space Network (DSN) receiving system on Earth at about 8Kbps data rate. Subsequent planned interplanetary CubeSat missions (such as the ESA Asteroid Impact and Deflection Assessment collaborative mission) seeks to leverage on and improve the capacity. The increasing demand for higher network bandwidth and system data-throughput has led to the utilization of higher frequency bands in the electromagnetic spectrum and increase in transmitter power for long range scenarios. Operating at higher frequencies (or shorter wavelengths) provides an expanded channel capacity and reduction in the transceiver components sizes comparable to the lower frequencies (VHF, UHF) counterparts. However, RF signals are highly susceptible to divergent spreading, atmospheric absorption and attenuation, severely limiting the communication system performance and efficiency. The RF spectrum is also fast becoming congested with severe signal interference problems especially in collocated and multi-node systems. On the contrary, the optical bands are currently underexplored, less regulated and without licensing complications. Free-space laser communication represents a paradigm shift in modern high-rate data link and information processing capability enhancement. Laser signals have very high directivity, significantly increasing the transmitter’s effective isotropic radiated power (EIRP) and improving the received signal to noise ratio in a long distance link such as direct deep-space satellite to ground communication system. Compactness of opto-electronic components is likewise attractive for very low-resource (size, weight and power) small satellite platforms, especially CubeSats. On the contrary, the suiting benefits of the narrow laser beamwidth simultaneously give rise to misalignment challenges, pointing and acquisition, tracking (PAT) problems, resulting to pointing errors between the communicating nodes. Platform disturbances and micro-vibrations from satellite onboard subsystems and deployable appendages also contribute to the laser signal pointing instability. A small satellite in deep space establishing an optical link with the ground will require a very strictly precise attitude determination and control system working together with a rapid response beam stabilization system having a high level of reliability and accuracy. Lean or small (commonly used interchangeably) satellite philosophy is gaining prominence in defining the current and future architecture of space exploration missions. In recognition of this, the International Academy of Astronautics constituted a Study Group to define the industry standards and requirements of small satellites. The lean satellite approach seeks cheaper, quick development and delivery of small satellite missions, utilizing commercial-off-the-shelf components, smaller human resource and faster mission turn-around time. CubeSats are getting more roles and are consistently been considered for demanding tasks which were once the domain of traditional satellites. However, there exists a number of technology gaps that must be filled before the full potentials of CubeSat applications for very high throughput missions and deep space exploration can be fully harnessed. Gigabytes rate communication transceivers, compact propulsion system, interplanetary guidance and navigation systems are a few of the current technological gaps. This research is focused on tackling the problems of laser communication adaptability on small satellites in considerable range with Earth-bound optical ground systems. To this end, the systematic design of an example theoretical mission described in this thesis adapts lean satellite initiative, use of COTS components and scalability. A new approach of utilizing Photodiode Array (PDA) as an optical feedback sensor applicable to a MEMS Fine Steering Mirror (FSM) based laser beam fine pointing and control system is introduced in this thesis. Analyses and experiments demonstrated that the PDA have a much improved frame rate, eliminating the feedback delay experienced in the use of CCD cameras for laser beam position control. This presents a useful improvement in the performance of optical beacon tracking and fine pointing systems for laser communication modules in small satellites. Experiments on characterization of platform jitter spectrum and beam steering system mitigating the jitter effects in a 6U CubeSat platform is also presented in this thesis. CubeSats and Unmanned Aerial Vehicles (UAV) are identical in terms of “leanness” or “scarcity” of onboard resources and are both considered as viable host platforms for laser communication devices in a ubiquitous optical communication regime. As a derivation of this research, the activities of the Japanese’ National Institute of Information and Communications Technology, NICT-Kyutech collaboration on the development of a Drone 40Gbps lasercom fine pointing system is discussed. The Drone lasercom project sought to advance the state-of-the-art in UAV communication capabilities, with the agile optical coarse tracking, acquisition and fine pointing system playing a very critical role. In conclusion, the work done and reported in this thesis contributes to the advancement of free-space laser communication technology on small satellites in both near-Earth and deep space scenarios.九州工業大学博士学位論文 学位記番号：工博甲第537号 学位授与年月日：令和3年12月27日1. Introduction |2. Background and Literature Review |3. Lunar Cubesat Lasercom Design Reference Mission |4. Photodiode Array Aided Laser Beam Steering Experiment |5. Cubesat Jitter Effects on Lasercom Beam Pointing Stability |6. Drone 40gbps Lasercom Project |7. Conclusion and Recommendations九州工業大学令和3年

Generation and analysis of correlated pairs of photons on board a nanosatellite

Satellites carrying sources of entangled photons could establish a global quantum network, enabling private encryption keys between any two points on Earth. Despite numerous proposals, demonstration of space-based quantum systems has been limited due to the cost of traditional satellites. We are using very small spacecraft to accelerate progress. We report the in-orbit operation of a photon pair source aboard a 1.65 kg nanosatellite and demonstrate pair generation and polarization correlation under space conditions. The in-orbit photon correlations exhibit a contrast of 97+/-2%, matching ground-based tests. This pathfinding mission overcomes the challenge of demonstrating in-orbit performance for the components of future entangled photon experiments. Ongoing operation establishes the in-orbit lifetime of these critical components. More generally, this demonstrates the ability for nanosatellites to enable faster progress in space-based research