International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This student paper was produced as part of the team design competition in the University of Arizona course ECE 485, Radiowaves and Telemetry. It describes a telemetering system design recommendation for a small satellite capable of conducting scientific research regarding atmospheric water content. This paper focuses on the cross-link subsystem required to make the scientific measurements and on the power generation and distribution subsystem for the satellite. A companion paper (Cramer, et. al.) focuses on the subsystems required to send the scientific data and monitored operational conditions from the satellite to, and commands to the satellite from, a ground station. The central objective is to validate a new technique for precisely measuring water vapor profiles of clouds throughout the troposphere. This method involves the detection of 4 SHF tones sent out from the International Space Station (ISS), providing high-resolution amplitude and phase delay data.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This student paper was produced as part of the team design competition in the University of Arizona course ECE 485, Radiowaves and Telemetry. It presents a telemetering system proposed for UASat, a small satellite being designed for launch in the year 2004. The overall system architecture is described, including the transducers used by each subsystem, the command and telemetry packet formats, the antennas and modulation schemes, the link budget, and some hardware recommendations. A discussion of the data analysis is also included.

Wildlife habitat mapping strongly supports applications in natural resource management, environmental conservation, impacts of anthropogenic activity, perturbed ecosystem restoration, species-at-risk recovery and species inventory. Remote sensing has long been identified as a feasible and effective technology for large-area wildlife habitat mapping. However, existing and future uncertainties in remote sensing will definitely have a significant effect on relevant scientific research, such as the limitation of Landsat-series data; the negative impact of cloud and cloud shadows (CCS) in optical imagery; and landscape pattern analysis using remote sensing classification products. This thesis adopted a manuscript-style format; it addresses these challenges (or uncertainties) and opportunities through exploring the state-of-the-art optical and radar remotely sensed data for large-area wildlife habitat mapping, and investigating their feasibility and applicability primarily by comparison either on the level of direct remote sensing products (e.g. classification accuracy) or indirect ecological model (e.g. presence/absence and frequency of use model based on landscape pattern analysis). A framework designed to identify and investigate the potential remotely sensed data, including Disaster Monitoring Constellation (DMC), Landsat Thematic Mapper (TM), Indian Remote Sensing (IRS), and RADARSAT-2, has been developed. The chosen DMC and RADARSAT-2 imagery have acceptable capability of addressing the existing and potential challenges (or uncertainties) in remote sensing of large-area habitat mapping, in order to produce cloud-free thematic maps for the study of wildlife habitat. A quantitative comparison between Landsat-based and IRS-based analyses showed that the characteristics of remote sensing products play an important role in landscape pattern analysis to build grizzly bear presence/absence and frequency of use models.

Wildlife habitat mapping strongly supports applications in natural resource management, environmental conservation, impacts of anthropogenic activity, perturbed ecosystem restoration, species-at-risk recovery and species inventory. Remote sensing has long been identified as a feasible and effective technology for large-area wildlife habitat mapping. However, existing and future uncertainties in remote sensing will definitely have a significant effect on relevant scientific research, such as the limitation of Landsat-series data; the negative impact of cloud and cloud shadows (CCS) in optical imagery; and landscape pattern analysis using remote sensing classification products. This thesis adopted a manuscript-style format; it addresses these challenges (or uncertainties) and opportunities through exploring the state-of-the-art optical and radar remotely sensed data for large-area wildlife habitat mapping, and investigating their feasibility and applicability primarily by comparison either on the level of direct remote sensing products (e.g. classification accuracy) or indirect ecological model (e.g. presence/absence and frequency of use model based on landscape pattern analysis). A framework designed to identify and investigate the potential remotely sensed data, including Disaster Monitoring Constellation (DMC), Landsat Thematic Mapper (TM), Indian Remote Sensing (IRS), and RADARSAT-2, has been developed. The chosen DMC and RADARSAT-2 imagery have acceptable capability of addressing the existing and potential challenges (or uncertainties) in remote sensing of large-area habitat mapping, in order to produce cloud-free thematic maps for the study of wildlife habitat. A quantitative comparison between Landsat-based and IRS-based analyses showed that the characteristics of remote sensing products play an important role in landscape pattern analysis to build grizzly bear presence/absence and frequency of use models.

This research outlines a low-cost, low-power, arc-minute accurate star tracker that is designed for use on a CubeSat. The device is being developed at the University of Texas at Austin for use on two different 3-unit CubeSat missions. The hardware consists of commercial off-the-shelf parts designed for use in industrial machine vision systems and employs a 1024x768 grey-scale charge coupled device (CCD) sensor. The software includes the three standard steps in star tracking: centroiding, star identification, and attitude determination. Centroiding algorithms were developed in-house. The star identification code was adapted from the voting method developed by Kolomenkin, et al. Attitude determination was performed using Markley's singular value decomposition method. The star tracker was then tested with internal simulated star-fields. The resulting accuracy was less than an arcminute. It was concluded that this system is a viable option for CubeSats looking to improve their attitude determination. On-orbit demonstration of the system is planned when the star tracker flies on the planned CubeSat missions in 2013 or later. Further testing with external simulated star fields and night sky tests are also planned. / text

With the growing accessibility of space, this thesis work sets out to explore space-based swarms to do multipoint magnetometer measurements of current systems embedded within the Aurora Borealis as an initial foray into concepts for space physics applications using swarms of small spacecraft. As a pathfinder, ANDESITE---a 6U CubeSat with eight deployable picosatellites---was built as part of this research. The mission will fly a local network of magnetometers above the Northern Lights. With the spacecraft due to launch on an upcoming ELaNa mission, here we discuss the details of the science motivation, the mathematical framework for current field reconstruction, the particular hardware implementation selected, the calibration procedures, and the pragmatic management needed to realize the spacecraft. After describing ANDESITE and defining its capability, we also propose a follow-on that uses propulsive nodes in a swarm, allowing measurements that can adaptively change to capture the physical phenomena of interest. To do this a flock of satellites needs to fall into the desired formation and maintain it for the duration of the science mission. A simple optimal controller is developed to model the deployment of the satellites. Using a Monte Carlo approach for the uncertain initial conditions, we bound the fuel cost of the mission and test the feasibility of the concept. To illustrate the system analysis needed to effectively design such swarms, this thesis also develops a framework that characterizes the spatial frequency response of the kilometer-scale filter created by the swarm as it flies through various current density structures in the ionospheric plasma. We then subjugate a nominal ANDESITE formation and the controlled swarm specified to the same analysis framework. The choice of sampling scheme and rigorous basic mathematical analysis are essential in the development of a multipoint-measurement mission. We then turn to a novel capability exploiting current trends in the commercial industry. Magnetometers deployed on the largest constellation to date are leveraged as a space-based magnetometer network. The constellation, operated by Planet Labs Inc., consists of nearly 200 satellites in two polar sun-synchronous orbits, with median spacecraft separations on the order of 375 km, and some occasions of opportunity providing much closer spacing. Each spacecraft contains a magneto-inductive magnetometer, able to sample the ambient magnetic field at 0.1 Hz to 10 Hz with <200 nT sensitivity. A feasibility study is presented wherein seven satellites from the Planet constellation were used to investigate space-time patterns in the current systems overlying an active auroral arc over a 10-minute interval. Throughout the this work advantages, limitations, and caveats in exploiting networks of lower quality magnetometers are discussed, pointing out the path forward to creating a global network that can monitor the space environment.

Small satellites, and CubeSats in particular, have quickly become a hot topic in the aerospace industry. Attitude determination is currently one of the most intense areas of development for these miniaturized systems and future Cal Poly satellite missions will depend heavily on magnetometers. In order to utilize magnetometers as a viable source of attitude knowledge, precise calibration is required to ensure the greatest accuracy achievable. This paper outlines a procedure for calibrating and testing magnetometers on the next generation of Cal Poly CubeSates, utilizing a Helmholtz cage to simulate any desired orbital magnetic field that would be experienced by a spacecraft around Earth, as well as investigation of magnetic interference as a result of on-board electrical activity.

Small satellites refer to a new breed of smaller and computationally capable satellites, which serve as a ?faster, better, cheaper? means of realizing space missions. To ensure success of a small satellite mission, it is important that systems engineering be applied at the initial stages of the program formalization to provide a basis for defining mission strategies, managing requirements, risk analysis, performing design trades and estimating cost. The objective of this thesis is to formalize a small satellite mission plan while providing recommendations in areas involving design optimization, systems engineering, project management, cost modeling, subsystem design and selection. Finally, this thesis details the preliminary design of a conceptual ?MSUSAT? small satellite, using Commercial Off The Shelf (COTS) components, from a systems engineering perspective. It explains the choice of orbit, payload and other subsystem components that are necessary to ensure that the mission fulfils its objective.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / An increasing number of satellite users and manufacturers are looking to lightweight, inexpensive satellites as substitutes to traditional large, expensive satellites with multiple payloads. Neither the Department of Defense nor the commercial sector can bear the financial or reputational consequences associated with massive program failures. With the low cost and weight of these new satellites, users can achieve mission success without great risk. One example of this new class of inexpensive spacecraft is the RADCAL (RADar CALibration) satellite. Detachment 2, Space & Missile Systems Center at Sunnyvale, CA operates the satellite. RADCAL is a 200-pound polar orbiting satellite with an average altitude of 450 miles. It is primarily used by 77 worldwide radars to calibrate their systems to within five meter accuracy. Also flying on board RADCAL is a communication payload for remote field users with small radios. The RADCAL program has satisfied all mission requirements. However, with the limited size and cost come certain challenges, both in the satellite and on the ground. Pre-launch testing was not as comprehensive as with more expensive programs; anomalies have arisen that require extensive workarounds. Data management is not a straightforward task, and it is sometimes difficult and inexact to track satellite performance. These challenges are presented with their solutions in the following discussion; this paper addresses the functional, operational, and testing aspects associated with the RADCAL satellite.

This thesis presents the design of a working and testable satellite with particular emphasis on the electrical, mechanical, and thermal modelling and performance issues for the ECOSat project in the framework of the Canadian Satellite Design Competition. In order of importance, based on the design challenges for the satellite structure were the dynamics modelling and analysis, thermal modeling and analysis, and assembly and integration modeling. Both the dynamics and thermal modeling of the satellite were completed using Finite Element Analysis (FEA) in NX with the NASTRAN solver. The dynamic analysis study was performed first since it has the primary design driver for the structure. These frequencies are of concern due to the 90 Hz or greater fundamental frequency requirement for each axis. The dynamic modes of the satellite structure had the largest influence not only on the design of the structure but also its interface to the electronic systems as these had to meet the required testing qualification levels. It was found that the first fundamental frequency appeared near 200 Hz in the XY plane of the structure. The second study performed was on the thermal modeling of the satellite both for extreme operating conditions in “Hot” and “Cold” cases. Operational limiting cases were identified for the batteries in the cold and hot case study, and the power amplifier for the transmitter was identified for the hot case study. For the batteries to perform satisfactorily for the cold and hot case problem, a metal bracket with an electric heater was added to the design. The heaters were added to the design as a resistive heating element, the additional thermal coupling from the bracket improved heat transfer during the hot case. A trade study analysis was conducted for the power amplifier. Here, a bi directional heat spreader made of pyrolytic graphite attached to a frame member with high thermal inertia was chosen as the optimal solution. Finally, the third study performed tested the interface and clearance requirements of the satellite. The synergistic integration of the electrical and mechanical systems required significant attention in order to ensure the successful assembly, integration, and testing of the two systems. The investigation focused on the cabling assemblies of the satellite. Several design iterations were required for the power regulation, transmitter, receiver, modem, and onboard computer systems. Detailed assembly drawings were created for the cabling assembly fabrication prior to the final integration of the electrical and mechanical systems. The performance simulations show that the satellite systems meet or exceed the required launch qualification tests as well as the thermal cycling requirements for all systems and their components to operate within the manufacturer specified values. Once completely assembled and launched into orbit, the satellite should be able to perform and within its operational and mission requirements in both a sun synchronous or polar orbit at a range of altitudes. / Graduate / 0538 / 0544 / 0548 / jtcurran@uvic.ca