Feasibility study of a PocketQube platform to host an ionospheric impedance probe

Since the advent of CubeSat spacecraft, universities and private entities have been successfully designing and launching satellites at a fraction of the traditional cost. These satellites still accommodate useful scientific payloads. Another recently established satellite format is the PocketQube (PQ) - one eighth the size of a CubeSat – with the aim of further reducing launching costs. However, this brings with it the challenge of working with substantially smaller power, mass and volume budgets. Accurate ionospheric modelling requires the use of electron density measurements at the topside of the ionosphere which could be obtained via distributed in-situ sensing. This makes a low cost PQ constellation ideal for this application. In order to assess the feasibility of the PQ format, a preliminary study was conducted about the design of a PQ technology demonstrator capable of carrying a scientific payload. In this paper, the design approaches are discussed, keeping in mind the design budget restrictions as well as the constraints imposed by the ionospheric sensor.The research work disclosed in this publication is funded by the ENDEAVOUR Scholarship Scheme (Malta). The scholarship is part-financed by the European Union – European Social Fund (ESF) under Operational Programme II – Cohesion Policy 2014-2020, “Investing in human capital to create more opportunities and promote the well-being of societypeer-reviewe

Feasibility study of a PocketQube platform to host an ionospheric impedance probe

Since the advent of CubeSat spacecraft, universities and private entities have been successfully designing and launching satellites at a fraction of the traditional cost. These satellites still accommodate useful scientific payloads. Another recently established satellite format is the PocketQube (PQ) - one eighth the size of a CubeSat – with the aim of further reducing launching costs. However, this brings with it the challenge of working with substantially smaller power, mass and volume budgets. Accurate ionospheric modelling requires the use of electron density measurements at the topside of the ionosphere which could be obtained via distributed in-situ sensing. This makes a low cost PQ constellation ideal for this application. In order to assess the feasibility of the PQ format, a preliminary study was conducted about the design of a PQ technology demonstrator capable of carrying a scientific payload. In this paper, the design approaches are discussed, keeping in mind the design budget restrictions as well as the constraints imposed by the ionospheric sensor.The research work disclosed in this publication is funded by the ENDEAVOUR Scholarship Scheme (Malta). The scholarship is part-financed by the European Union – European Social Fund (ESF) under Operational Programme II – Cohesion Policy 2014-2020, “Investing in human capital to create more opportunities and promote the well-being of societypeer-reviewe

Cortical Gyrification and Sulcal Spans in Early Stage Alzheimer's Disease

Alzheimer's disease (AD) is characterized by an insidious onset of progressive cerebral atrophy and cognitive decline. Previous research suggests that cortical folding and sulcal width are associated with cognitive function in elderly individuals, and the aim of the present study was to investigate these morphological measures in patients with AD. The sample contained 161 participants, comprising 80 normal controls, 57 patients with very mild AD, and 24 patients with mild AD. From 3D T1-weighted brain scans, automated methods were used to calculate an index of global cortex gyrification and the width of five individual sulci: superior frontal, intra-parietal, superior temporal, central, and Sylvian fissure. We found that global cortex gyrification decreased with increasing severity of AD, and that the width of all individual sulci investigated other than the intra-parietal sulcus was greater in patients with mild AD than in controls. We also found that cognitive functioning, as assessed by Mini-Mental State Examination (MMSE) scores, decreased as global cortex gyrification decreased. MMSE scores also decreased in association with a widening of all individual sulci investigated other than the intra-parietal sulcus. The results suggest that abnormalities of global cortex gyrification and regional sulcal span are characteristic of patients with even very mild AD, and could thus facilitate the early diagnosis of this condition

A miniaturized impedance probe for ionospheric sensing

Space weather refers to “conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and the thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health” [National Space Weather Program, 1995]. Of particular interest are the effects caused by the ionosphere, which is an ionised region of the upper atmosphere, ranging from approximately 90 to 1500 km. The ionosphere can degrade the performance of many radio systems; these include satellite navigation systems (i.e. GPS), satellite communications and space based radar. Measurements of the electron density in the ionosphere can be used to improve empirical ionospheric models or as inputs into assimilative ionospheric models, thereby permitting the development of better techniques to mitigate the impact of the ionosphere on radio systems. Ground-based radar systems may be used to make measurements of the bottom-side of the ionosphere (i.e. below the height of the peak density), and GPS provides a means of making integrated measurements of total electron content between a satellite and a receiver. However, for measurements of the top-side of the ionosphere, satellite based instrumentation is required. A radio frequency ionospheric impedance probe (ImP) is being developed by the Space Environment and Radio Engineering group at the University of Birmingham, UK, to provide in-situ measurements of the top-side electron density. ImP will measure this density by exciting an antenna embedded in the ionosphere – the frequencies at which the antenna resonates can then be used to estimate the electron density. ImP can be hosted on a dedicated very small spacecraft, such as a PocketQube. A PocketQube is a small spacecraft typically measuring 5x5x5 cm. Alternatively, it could be hosted as a secondary payload on a larger platform, such as a CubeSat or larger. Effective ionospheric measurements will require several ImPs to be installed on satellite constellations to provide measurements with high spatial and temporal resolution. A PocketQube platform is being developed by the Astrionics group at the University of Malta, with a target of launching a complete spacecraft with an ImP in March 2018. The platform is being developed to meet the design constraints imposed by ImP. ImP requires both orbital positioning data and attitude determination, which is to be provided by the platform. ImP measurements also require a magnetically clean environment as it is susceptible to local magnetic fields. This poster paper will describe the principle of operation behind ImP, as well as the design of the instrument itself. It will also describe the challenges involved in designing a versatile PocketQube spacecraft architecture that can accommodate a scientific payload.peer-reviewe