Thesis (Ph. D.)--Cornell University, 1920. / "Reprinted from the American journal of psychology, April 1920, vol. XXXI."

Space-derived data lies untouched in data vaults, while many potential use cases for space applications are not exploited by the space industry. This gap may exist because the conceptualisation of the user in the satellite industry is too narrow, and yet influences the architecture and thence outcomes of a satellite mission. Assumptions about users and markets are not made on the basis of data and market research, in itself typically difficult to obtain, especially in Africa. This results in a lack of understanding of the end user and their social and economic context which feeds back to inadequately scoped requirements in satellite design. The reasons for this are not solely the limited imaginations and culture of practice of satellite engineers, but the structure of the space industry itself and its design frameworks. This limitation has impact especially for developing country applications, where the user and beneficiary concept elide in often unexamined and unchallenged ways. The satellite industry, part of the wider space industry, could borrow usefully from the IT industry in its relationship to the user and methods of deriving user requirements; in fact could consider itself part of the IT/data industry. This study explores the relationship between satellite design and the users of space-derived data, and how this is being affected by new disruptors to the traditional space industry. The implications for potential users in Africa are considered.

Outer space is a hazardous environment for satellites as they are continuously exposed to harsh space radiation in the form of cosmic rays and high-energy electrically charged particles (protons, electrons and alpha particles). Mission-critical electronic components are especially susceptible to space radiation as high-velocity charged particle impacts on molecular-sized circuitry can cause significant device upsets or permanent damage, compromising a satellite's functional integrity. In order to mitigate this radiation hazard, electronic components are carefully selected and tested prior to deployment. Part of this process involves consulting a space radiation model in order to be able to estimate the type of radiation environment the electronics will be exposed to. There are many different environmental models to choose from and the output from the models will influence whether a certain device will be selected or not. Due to this, the model selection process should be very well understood and all parameters carefully chosen. This project aims to describe the radiation environment in low Earth orbit, and to provide guidelines for using the space radiation models found on the Space ENVironment Information System (SPENVIS). By going through the modelling process in detail, we have found that the trapped radiation models are completely independent of the date specified when describing the orbit of interest. We found that all long-term solar proton models (except King) assume a zero flux for solar minimum dates. The accuracy of the model output for a specific orbit depends on the duration of the model's time span. For instance, we found that for certain low Earth orbits, the accuracy of the model output could be easily improved by increasing the number of days in the orbit generator from one to three. For the low Earth orbits we selected to analyse, we found that a one-year mission delay at any point on the solar cycle will not have great enough an effect on the output to warrant a re-calculation. It is important to consider both trapped and non-trapped radiation when calculating an upset rate and, lastly, the upset rate calculation could be altered by a factor of 1000 simply by selecting different models for the exact same device and orbit. We conclude this study with some guidelines for the use of SPENVIS for radiation modelling during mission planning.

The Square Kilometre Array Project is a multi-national venture attempting to build the world's largest radio telescope. Australia and South Africa (together with other African countries), will be host to the SKA site. Both countries are building pre-cursor radio telescopes to demonstrate their ability to successfully host the project. Square Kilometre Array South Africa (SKA SA) is currently constructing the MeerKAT Radio Telescope in the Karoo Desert. Radio telescopes are conventionally designed to have the signal Digitiser located in the pedestal of the radio telescope antenna structure to shield the incoming radio signal from being contaminated by the electromagnetic interference (EMI)/radio frequency interference (RFI) noise created by the Digitiser electronics. However, if a Digitiser could be placed near the antenna feed, this would decrease the length of the signal path between the receiver and the Digitiser, which would decrease noise on the signal. The aim of this thesis is to present a viable thermal design for an externally, near-feed mounted, passively cooled Digitiser on the MeerKAT Radio Telescope. This has never been done before. Through calculation, simulation and design iteration this aim was achieved, resulting in an operational Digitiser system which is being used on the MeerKAT Radio Telescope and could potentially also be used in SKA Phase 1.

Small satellites are being launched by a multitude of private and public organizations around the world. They are innately cheaper than their large counterparts. This attribute, and additional ones, such as their easy-to-assemble nature and the convenience of using commercially available off-the-shelf parts to build them has enhanced their popularity. Now that getting into space has become more accessible there is an influx of information available from small satellites, however the information is not being utilized too efficiently on Earth. One reason as to why this is evident is because traditional ground stations, which are largely hardware dependent, are expensive to develop. However, with the introduction of Software Defined Radios (SDRs) many of the operations formerly done using hardware can now be implemented in software. Using a SDR can substantially reduce the cost of a traditionally hardware-based ground station. A number of universities and other organizations have or are developing SDR ground stations to communicate with satellites in different orbits. The ability to receive or transmit signals is important because it displays the capability to develop and operate satellites to various stakeholders. This dissertation attempted to enhance the movement towards satellite communication using SDR technology by developing a low cost, portable, easy to assemble and extendable ground station at the University of Cape Town in order to make contact with one or more small satellites in Low Earth Orbit (LEO), to encourage data usage, national and international collaboration and education. The ground station was constructed and tested based on its objectives, requirements and constraints. The commissioning tests were conducted in the SpaceLab at the University of Cape Town. The ground station was able to make contact with two small satellites in LEO successfully. Packets were received from two satellites that clearly stated who they were. The information contained in the packets was decoded into ASCII text and Hex code. They were compared with other successful amateur ground station results from all over the world to verify their authenticity. The main conclusion was that the SDR ground station was able to make contact with small satellites in LEO operating in the 70-cm band.

his dissertation serves to report on the novel use of a geodetic-grade, dual-frequency Global Positioning System (GPS) Ionospheric Scintillation and Total Electron Content Monitor (GISTM), in an attempt to identify instances of ionospheric scintillation over the South Atlantic Magnetic Anomaly (SAMA) while located aboard the moving polar research vessel SA Agulhas II. The SAMA is a region in the South Atlantic Ocean where the Earth’s magnetic field is weakest in relation to other regions at comparable latitudes, resulting in the precipitation of high-energy particles into the ionosphere during geomagnetic storms. Ionospheric scintillations are rapid fluctuations in the phase and amplitude of trans-ionospheric radio signals resulting from electron density variations along the ray path. As a result, spacebased navigation systems can encounter increased errors in position accuracy or complete loss of lock. These are risk factors for modern aircraft and ocean vessels which rely on access to accurate Position, Navigation and Timing (PNT) services to operate safely. In this research, only the radio signals from GPS satellites are specifically used to measure these fluctuations. Traditional scintillation measurements are done using dedicated dual-frequency GPS receivers at fixed terrestrial locations. Most of the SAMA lies beyond the reach of the land-based sensors. The South African National Space Agency (SANSA) operates several GISTM stations in Southern Africa, at Marion Island, Gough Island, and the SANAE-IV base in Antarctica. The NovAtel GSV4004B GPS Ionospheric Scintillation and Total Electron Content Monitor (GISTM) installed on board the SA Agulhas II in 2012 has enabled for the first time the terrestrial measurement of scintillation from within the SAMA region. In this project, the amplitude scintillation (S4) and phase scintillation (σφ) indices from 50 Hz L1 GPS signals recorded during the 2014 and 2015 voyages of the SA Agulhas II were analysed for the first time. The scintillation effects are characterised in terms of position and motion data, carrierto-noise-density ratio, number of satellites, and satellite lock time. The goal is to develop an understanding of the effect of motion on the quality of data recorded by the receiver. The roll angle thresholds for the SA Agulhas II are calculated and it is shown that multipath errors are unlikely to be experienced. Significant data challenges were identified stemming from the incorrect setup of the SA Agulhas II GISTM. Data from elevations below 10° were missing because of hard-coded limitations within the GISTM on-board software. The data underwent significant reprocessing before being used. Comparisons were done in-harbour and out at sea with data from the nearest stationary GISTM receivers. It was shown that the movement of the receiver induces significant noise in the data. The noise levels are proportional to the velocity of the ship. An attempt to filter out the noise was unsuccessful. The motion-induced noise in the ship data masked the presence of any potential scintillations. With the ability to detect scintillation compromised, it was decided that a comparison with a land-based receiver within the SAMA would be necessary. Only one identical GISTM receiver met these requirements, located on Gough Island, at 40°20’ 58.90" S, 9°52’ 49.35" W. Data was isolated from both the SA Agulhas II GISTM and Gough Island GISTM for a period where the separation between the two receiver locations was less than 100 km. The Symmetric-Horizontal disturbance index (SYM-H) was used to identify geomagnetic storm conditions. GPS visibility maps were used to identify any potential signal obstructions. No correlation could be seen between position error and the number of satellites locked due to the high number of GPS satellites available at all times. It was discovered that the high noise levels had no effect on the position accuracy of the moving receiver, but that rapid changes in the instantaneous velocity coincided with peaks in the position error. No scintillation events were identified using the SA Agulhas II GISTM as a result of masking by the noise, however, the Gough Island GISTM data showed that no scintillation events occurred during the period in question anyway. Wind was identified as a potential contributing factor to the motion noise effect. This study provided justification for the purchase and installation of a newly developed motion-compensated GISTM receiver on board the SA Agulhas II, running off the same antenna and thus the same received signals. These data sets can be used for a direct receiver comparison in future work.

The Alan Cousins Telescope is a 0.75-m automatic photoelectric telescope situated at the South African Astronomical Observatory, in Sutherland. The telescope was designed and built to execute a range of photometry programmes, but is used mainly for the long-term monitoring of variable stars. In addition, there is the potential for target-of-opportunity observations of unanticipated events, such as gamma ray bursts, and anticipated events such as occultations. Ultimately the telescope is intended to be a fully robotic telescope with limited operational support needs. Some advance toward this goal has been made by a full hardware interface to allow queue executions of observations. The next phase is the implementation of an automated scheduler that will generate a queue of valid observations for each night of observation. Queue scheduling algorithms are widely used in astronomy and the aim of this dissertation is to present a strawman scheduler that will generate the nightly observation queue. The main design of the scheduler is based on a merit-based system implemented at the STELLA robotic observatory, paired with the scheduling algorithms used by SOFIA. The main drawback of the telescope is that it does not currently accommodate dynamically changing weather conditions. As a consequence, the main scheduling constraints are observation parameters, instrument ability, and for monitoring type observations, observation time window constraints.

specialcollections@tulane.edu / With the age of discovery in the 15th century, mankind’s view of the known world was changed forever. Nations and private entities scrambled to attain a foothold in this emerging frontier, bringing with them new technologies, cultures, economies, societies and architecture. In the late 19th century, numerous experimental communities planted their flags on American soil, often with utopian visions for their new way of life. Due to social rifts, economic collapse, or unforeseen outside events, nearly all failed. However, these settlements became a testament to what human ingenuity could achieve with only ambition and a blank slate on the other side of a daunting voyage. This same opportunistic spirit still exists today in the imaginations of futurists, architects, and science-fiction writers but in this period, the new frontier is Mars. Human voyages to other planets are inevitable, and the movement of doing so is not unlike the establishment of colonial settlements in the early Americas. Missions to Mars will need a human touch and the settlements to follow will bring with them unforeseen problems for architects. The fate of extraterrestrial colonization is impossible to explicitly predict, therefore, speculation and learning from historical narratives it vital. By using architecture to speculate on plausible futures, we as architects can help predict and solve what it would take not only to survive but endure. / 1 / Max Warshaw

In the last few years, there has been a considerable increase of low cost space mission. Almost every small satellite has appendages like Solar Panels OR Antennas. These appendages have large inertial forces with low structural rigidity and mass to size ratio. These appendages are in stowed position in launcher to accommodate the whole satellite in the Launcher. However after launching these appendages are deployed to obtain the required power and the pointing of antennas. Their power producing capability is directly related to their area of exposure to sun, that is why these panels are available in different sizes and configurations. The requirement for the deployment mechanism for these appendages need to be cost effective, compact, lighter in weight and simple. It is entirely dependent on the structural designer to create such a robust mechanism that conforms to the requirements of the mission. In order to deploy the solar panels, it is mandatory that some sort of actuating system is employed. In this regard, we are aiming to use the torsional spring to induce the required torque for the deployment. There has been a considerable amount of research work [1-4] for a robust deployment mechanism to deploy the solar panel reliably without compromising on the overall cost and strength of the system. To realize the practical utility of Torsion Springs [5] for solar panel deployment, with the deficiency of locking after deployment and hold down mechanism when stowed. We propose a simple actuation scheme of designing the mechanism using Spiral Torsional spring for small satellite with its Zero 'g' testing and mitigation of expected Risks.

Perhaps no other field of scientific endeavor has been more influenced by the arts than space exploration. The artistic visions of yesteryear are the technological realities of today. These realities in turn create new possibilities for artistic expression. However, Space Art and Space Science have shared a convoluted history. Their forerunner disciplines of the Humanities and Natural Sciences and their practitioners were entrenched as polar opposites for centuries. Recent research, however, has revealed the reverse; that the psychological profile and the creative processes of artists and scientists are actually similar, often to the point of the practitioners being polymathic. Moreover, it has been discovered that polymathic ability nurtures two qualities essential for the survival of both Space Art and Space Science: that of creativity and innovation. Current literature has taken note of the commonality of polymathic ability between the practitioners of the arts and sciences. Academic and industry think tanks have examined the virtues of artists as space researchers, and conversely, scientists developing an artistic approach as a design strategy. Thought leaders have expressed faith in trans-disciplinary collaboration as the way forward in the global affairs of space. Yet, therein lies the problem. These various studies individually lack a cohesive strategy to leverage their findings and transform the Art/Sci dialogue into a disruptive force that sustains a paradigm shift in the arts, space and society agendas going forward. The impetus for this dissertation is the unique opportunity to amalgamate those disparate studies by utilizing the momentum of New Space culture, and its focus on societal inclusion and environmental concerns to serve as anchors for space research and sustainability. Further, we argue that the next logical step is to inculcate a fundamental Art/Sci paradigm shift within the space community to exploit the unprecedented global drive towards space exploration and colonization, thereby solidifying the influence of the space art and space science agendas in the service of the global commons on Earth and in space.