ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / The CNES (French Space Agency) has studied memoryless predistortion techniques for power amplifier nonlinearity of satellite payload telemetry. These techniques are applied to high order modulations taken from the DVB-S2 standard and the associated CCSDS blue book. An easy-to-implement calibration method was also developed. The predistortion was implemented at two times the symbol rate after Square Root Raised Cosine shaping on a breadboard model of a 16APSK modulator associated to a Solid State Power Amplifier. It allows to reduce the amplifier back-off and thus to increase the power added efficiency for an equivalent signal quality.

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University-built satellite programs are prone to failure because these projects are performed by inexperienced student-engineers during the early parts of the satellite-building “learning curve”. However, with sufficient attention on risk management, students should be able to identify what risk avoidance actions should be taken, and when. By applying risk mitigation strategies, university built satellite programs will not only contribute students to learn space systems engineering, but also accomplish their scientific missions with higher rates of success. This thesis study is aimed to provide risk management guidelines that could be adapted to university built satellite programs to increase the risk awareness. Besides indicating the key strategies for risk mitigation, a set of risk management procedures are prepared to help students during the university-built satellite projects. / text

Geosynchronous (GEO) satellites are essential for modern communication networks. If communication to a GEO satellite is lost and a malfunction occurs upon orbit insertion such as a solar panel not deploying there is no direct way to observe it from Earth. Due to the GEO orbit distance of ~36,000 km from Earth's surface, the Rayleigh criteria dictates that a 14 m telescope is required to conventionally image a satellite with spatial resolution down to 1 m using visible light. Furthermore, a telescope larger than 30 m is required under ideal conditions to obtain spatial resolution down to 0.4 m. This dissertation evaluates a method for obtaining high spatial resolution images of GEO satellites from an Earth based system by measuring the irradiance distribution on the ground resulting from the occultation of the satellite passing in front of a star. The representative size of a GEO satellite combined with the orbital distance results in the ground shadow being consistent with a Fresnel diffraction pattern when observed at visible wavelengths. A measurement of the ground shadow irradiance is used as an amplitude constraint in a Gerchberg-Saxton phase retrieval algorithm that produces a reconstruction of the satellite's 2D transmission function which is analogous to a reverse contrast image of the satellite. The advantage of shadow imaging is that a terrestrial based redundant set of linearly distributed inexpensive small telescopes, each coupled to high speed detectors, is a more effective resolved imaging system for GEO satellites than a very large telescope under ideal conditions. Modeling and simulation efforts indicate sub-meter spatial resolution can be readily achieved using collection apertures of less than 1 meter in diameter. A mathematical basis is established for the treatment of the physical phenomena involved in the shadow imaging process. This includes the source star brightness and angular extent, and the diffraction of starlight from the satellite. Atmospheric effects including signal attenuation, refraction/dispersion, and turbulence are also applied to the model. The light collection and physical measurement process using highly sensitive geiger-mode avalanche photo-diode (GM-APD) detectors is described in detail. A simulation of the end-to-end shadow imaging process is constructed and then utilized to quantify the spatial resolution limits based on source star, environmental, observational, collection, measurement, and image reconstruction parameters.

Satellite cells (SCs) are muscle stem cells that stay in a metabolically and mitotically quiescent state in adult skeletal muscle until activated. In mammals, SCs are activated and enter into the cell cycle for growth and regeneration. The mechanism initiating SC activation in vivo and in vitro, mediated by nitric oxide (NO) and hepatocyte growth factor (HGF) is described in the mouse model, but not in other species. Here, we assessed SC activation by counting bromodeoxyuridine (BrdU)-immuno-positive cells, and found that SC activation in zebrafish single muscle-fibre cultures is also NO and HGF dependent, peaking at 1 mM isosorbide dinitrate (ISDN, an NO donor drug) and 10 ng/mL HGF respectively, using dose-response experiments. Moreover, HGF signalling via the c-Met receptor is involved in the SC activation pathway and is considerably affected by temperature (i.e., 21 °C). Overall, understanding NO-HGF-c-Met signalling in SC activation gives new insights on fish muscle growth and conservation of regulatory pathways between species.

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Satellite capabilities greatly enhance both the military and civilian sectors of society. Anti-satellite (ASAT) weapons pose a serious risk to all satellites. Chapter One of this thesis discusses current satellite capabilities. Chapter Two, details the wide variety of ASAT weapons. Chapter Three turns to the intentions of various States to employ ASATs. Chapter Four analyzes the legal implications of using force against satellites---beginning with the laws relating to the use of force in general, including the right of self-defense, and then progressing through relevant provisions of the laws of armed conflict. It also addresses the debate over the militarization and weaponization of outer space and past efforts at non-proliferation that relate to space activities. Chapter Five addresses the creation of space debris---a side effect of ASAT use. I will conclude with a short discussion regarding the potential for a new international agreement restricting the use of ASATs.

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