The future of Earth observation in hydrology

In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smart-phones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3-5 m) resolution sensing of the Earth on a daily basis. Start-up companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions. With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via high-altitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the "internet of things" as an entirely new measurement domain. Such global access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparent is that the tools and techniques afforded by this array of novel and game-changing sensing platforms present our community with a unique opportunity to develop new insights that advance fundamental aspects of the hydrological sciences. To accomplish this will require more than just an application of the technology: in some cases, it will demand a radical rethink on how we utilize and exploit these new observing systems

Millimeter and sub-millimeter wave radiometers for atmospheric remote sensing from CubeSat platforms

2018 Fall.Includes bibliographical references.To view the abstract, please see the full text of the document

Nanosatellites and Applications to Commercial and Scientific Missions

In the past two decades, a silent revolution has taken place in the space domain, leading to what today is known as “New Space.” We have passed from a selected group of countries, space agencies, and big industries building, launching, and operating satellites and other spacecrafts, of a scenario in which many universities and research institutes can do it. The key of this was the definition of the “CubeSat” standard, back to 1999. In 2013, it all took off on the commercial Earth Observation sector with the first launches from two companies that are now running 100+ CubeSat constellations for optical imaging or weather prediction, with very low revisit times. Today, the same revolution is taking place in the fields of Telecommunications, and Astronomical Scientific missions. In this chapter, the evolution of the space sector is briefly revised until the arrival of the CubeSats. Then, the CubeSat intrinsic limitations are discussed as they are key to understand the development and current situation of the CubeSat sector. NASA and ESA strategies are also presented. The chapter concludes with a summary of the technology roadmap to enable the next generation of CubeSat-based missions, including satellite constellations or federations, formation flying, synthetic apertures

Selection of the key earth observation sensors and platforms focusing on applications for Polar Regions in the scope of Copernicus system 2020-2030

An optimal payload selection conducted in the frame of the H2020 ONION project (id 687490) is presented based on the ability to cover the observation needs of the Copernicus system in the time period 2020–2030. Payload selection is constrained by the variables that can be measured, the power consumption, and weight of the instrument, and the required accuracy and spatial resolution (horizontal or vertical). It involved 20 measurements with observation gaps according to the user requirements that were detected in the top 10 use cases in the scope of Copernicus space infrastructure, 9 potential applied technologies, and 39 available commercial platforms. Additional Earth Observation (EO) infrastructures are proposed to reduce measurements gaps, based on a weighting system that assigned high relevance for measurements associated to Marine for Weather Forecast over Polar Regions. This study concludes with a rank and mapping of the potential technologies and the suitable commercial platforms to cover most of the requirements of the top ten use cases, analyzing the Marine for Weather Forecast, Sea Ice Monitoring, Fishing Pressure, and Agriculture and Forestry: Hydric stress as the priority use cases.Peer ReviewedPostprint (published version

Small satellite earth-to-moon direct transfer trajectories using the CR3BP

The CubeSat/small satellite field is one of the fastest growing means of space exploration, with applications continuing to expand for component development, communication, and scientific research. This thesis study focuses on establishing suitable small satellite Earth-to-Moon direct-transfer trajectories, providing a baseline understanding of their propulsive demands, determining currently available off-the-shelf propulsive technology capable of meeting these demands, as well as demonstrating the effectiveness of the Circular Restricted Three Body Problem (CR3BP) for preliminary mission design. Using the CR3BP and derived requirements from NASA\u27s Cube Quest Challenge, five different trajectory scenarios were analyzed for their propulsive requirements. Results indicate that the CR3BP is an effective means for preliminary mission design; however, limitations were noted in its ability to account for the lunar orbit eccentricity with respect to the Earth. Additionally, two available options of off-the-shelf propulsion systems are identified that can achieve the ΔV necessary for lunar capture, but have not yet been demonstrated in-flight --Abstract, page iii

Gaps analysis and requirements specification for the evolution of Copernicus system for polar regions monitoring: addressing the challenges in the horizon 2020-2030

This work was developed as part of the European H2020 ONION (Operational Network of Individual Observation Nodes) project, aiming at identifying the technological opportunity areas to complement the Copernicus space infrastructure in the horizon 2020–2030 for polar region monitoring. The European Earth Observation (EO) infrastructure is assessed through of comprehensive end-user need and data gap analysis. This review was based on the top 10 use cases, identifying 20 measurements with gaps and 13 potential EO technologies to cover the identified gaps. It was found that the top priority is the observation of polar regions to support sustainable and safe commercial activities and the preservation of the environment. Additionally, an analysis of the technological limitations based on measurement requirements was performed. Finally, this analysis was used for the basis of the architecture design of a potential polar mission.Peer ReviewedPostprint (published version

2016 Annual Report of the Graduate School of Engineering and Management, Air Force Institute of Technology

The Graduate School\u27s Annual Report highlights research focus areas, new academic programs, faculty accomplishments and news, and provides top-level sponsor-funded research data and information

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

Fluid Phase Separation via Nanochannel Array

Microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) generate ideas and techniques for creating new devices at the micro/nano scale. This dissertation study designed a gas generator system utilizing nanochannels for phase separation that is useful for micro-pneumatic actuators, micro-valves, and micro-pumps. The new gas generator has the potential to be an integral part of a propulsion system for small-scale satellites. Nano/picosatellites have limited orientation capability partly due to the current limitations of microthruster devices. Development of a self-contained micro propulsion system enables dynamic orbital maneuvering of pico- and nano-class satellites. Additionally, the new gas generator utilizes a high efficiency, green propellant that is less harmful to the environment. This dissertation study tested aqueous antifreeze solutions to verify vapor pressures and establish previously unknown kinematic viscosities. A viscometer, developed expressly for this study, measured kinematic viscosity values between 1E-2 and 1E-4 m2/s for water solutions mixed with propylene glycol, ethylene glycol, methanol, and glycerol. CubeSats, 10-centimeter cube satellites, are volume limited, and high strain expansion of water during crystallization could destroy the structure. Validation of the freezing point depression and measurement of previously unknown percent expansion with increasing concentration are valuable for setting safe design specifications. A 7.5 %w/w propylene glycol-water solution reduces the overall expansion by 2% while 20 %w/w PG reduces the expansion 4%. Potassium hydroxide etched silicon micro/nanochannels regulated vaporization of aqueous propylene glycol to a vacuum environment. Sequential still images captured with a Basler Scout camera were used to measure mass flow rates, representative of Washburn capillary flow. Magnitude of single channel flow rates ranged from 1E-10 mol/s to 1E-8 mol/s for 600nm channels up to 12μm channels, respectively. Although the flow rate increased using nanochannel arrays, it was 35% slower than expected based on single nanochannel measurements. A system utilizing nanochannel arrays for fluid phase separation, with propylene glycol as the propellant, is feasible in a low-cost, green, non-toxic, and non-pressurized CubeSat propulsion system. Depressing the freezing point of water by adding antifreeze creates a wider liquid working range, decreases power requirements, but also maintains appreciable flow rates for thrust generation (micro-millinewton). Successful nanofluidic research on an aqueous antifreeze solution is foundational for future propulsion system research and pushes CubeSats in the right direction