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Solar Electric Systems
Published in Robert K. McMordie, Mitchel C. Brown, Robert S. Stoughton, Solar Energy Fundamentals, 2021
Robert K. McMordie, Mitchel C. Brown, Robert S. Stoughton
Solar photovoltaic (PV) systems use solar cells to convert sunlight directly into electrical energy. Solar cells produce direct current and usually the direct current is inverted to alternating current. The most common solar cell material is silicon. PV systems vary greatly in size and complexity. Small systems with fixed solar panels (solar cell arrays) of one or two square feet are commonly seen along highways powering signs, telephones, etc. Almost all spacecraft have solar arrays that provide the spacecraft with electrical power. At Denver International Airport, there is a PV system covering 7.5 acres that produces approximately 3.5 million kW-hr of electricity annually. This system is a one axis tilt angle tracking system. PV systems have an application in residential electrical power. The usual arrangement is to mount the solar arrays on the roof and invert the direct current to alternating current. If the PV system produces more electrical power than the residence requires, the excess is returned to the power grid and the home owner is credited for this power. In Colorado, the state requires that the credit is the same as the original cost of the power.
Launch Vehicles, Propulsion Systems, and Payloads
Published in Janet K. Tinoco, Chunyan Yu, Diane Howard, Ruth E. Stilwell, An Introduction to the Spaceport Industry, 2020
Janet K. Tinoco, Chunyan Yu, Diane Howard, Ruth E. Stilwell
Spacecraft is a term used to specify a “vehicle or device designed for travel outside the Earth’s atmosphere” (spacecraft, NASA Jet Propulsion Laboratory 2018). Depending on the design, it can be separate from the payload, can hold the payload, or be considered part of the payload. Note that there is an important distinction to be made between satellites and spacecraft. Satellites observe orbital trajectories while spacecraft may or may not orbit the Earth. If a spacecraft orbits the Earth, it is often referred to as an artificial satellite. This is the case of the International Space Station (ISS), shown in Figure 3.1, as well as other man-made satellites such as those used for ommunications, weather observation, remote sensing, etc. Conversely, Voyager, the spacecraft launched in 1977 from Cape Canaveral, Florida, was not a satellite (Harvard-Smithsonian Center for Astrophysics 2008; NASA Jet Propulsion Laboratory 2018). Thus, a man-made satellite is a spacecraft, but a spacecraft is not necessarily a satellite. Our Moon is a natural satellite as it orbits Earth. Finally, it is noted that a probe is an unmanned spacecraft that collects scientific information for study (United States NASA 2018).
Investigation of CHEM Space Applications
Published in Witold M. Sokolowski, Cold Hibernated Elastic Memory Structure, 2018
There is a demand and need for precise, reliable, safe, low-cost landing systems for small, single landers as well as for large multi-probe missions for planetary and small-body exploration. Current spacecraft use complex systems such as aeroshells coupled with parachutes, solid rockets, and ultimately airbags to minimize the impact of landing or use all propulsive soft-landing approaches. Airbags are being used for intermediate-sized landers, but they are too complicated and expensive for small (1- to 50-kg-class) landers [2]. As lander mass increases, airbag systems become too heavy. Airbags have other problems as well. On first impact, they produce lander bounce, making it difficult to land within a small, scientifically interesting target area. Also, past mission experience indicates that the lander platform is not sufficiently stable to perform some precision operations even after airbag deflation. In addition, airbags do not provide sufficient thermal insulation against heat loss from the lander body to the cold ground.
Shielding Analysis for a Moderated Low-Enriched-Uranium–Fueled Kilopower Reactor
Published in Nuclear Technology, 2022
Jeffrey C. King, Leonardo de Holanda Mencarini
In spacecraft design, radiation shielding is frequently required to protect the astronaut crew, the payload, and/or any radiation-sensitive spacecraft equipment. Radiation shielding will almost always be a necessary subsystem of a space nuclear reactor power system. In orbital or deep space applications, the absence of a surrounding gaseous medium or atmosphere that could scatter neutrons back toward the system makes it feasible to place the radiation-sensitive portion of the spacecraft within a protected cone provided by a radiation shadow shield located between the reactor and other elements of the spacecraft. The design of shielding for space nuclear reactors needs to be a balance between limiting the mass of the reactor and the shield while meeting appropriate dose limits for the remainder of the spacecraft.
Robust attitude tracking control for a rigid spacecraft under input delays and actuator errors
Published in International Journal of Control, 2019
Alireza Safa, Mehdi Baradarannia, Hamed Kharrati, Sohrab Khanmohammadi
The spacecraft is equipped with gyros and attitude sensors, such as Sun, star tracker and magnetometer sensors, that provide inertial and non-inertial measurements, respectively. Namely, the angular velocity (inertial) and attitude (non-inertial) measurements are both available in feedback control design.