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Defense Information, Communication, and Space Technology
Published in Anna M. Doro-on, Handbook of Systems Engineering and Risk Management in Control Systems, Communication, Space Technology, Missile, Security and Defense Operations, 2023
LEO is the term applied to the region below about 5000 km altitude. Most scientific satellites and many weather satellites are in a nearly circular LEO. The satellite’s inclination depends on what the satellite was launched to monitor (NASA 2017b). The tropical rainfall measuring mission (TRMM) satellite was launched to monitor rainfall in the tropics (NASA 2017b). Therefore, it has a relatively low inclination (35 degrees), staying near the equator (NASA 2017b). Orbits there have periods ranging from 90 minutes to a few hours. Other orbits which are finding increased use in recent years are the LEOs may be at altitude up to 1500 km and have application for surveillance, earth resources, scientific, microgravity experiments, and possible communications (Patton 1993).
Space Situational Awareness & Space Traffic Management
Published in M. Madi, O. Sokolova, Space Debris Peril: Pathways to Opportunities, 2020
The basic constituents of space sustainability are clear. We must prevent predictable collisions (prevention), minimize the creation of new debris (mitigation), and remove massive derelict LEO objects (remediation), as shown in Fig. 2.12a. If space were a school playground, the rules would be “don’t hit each other, play nicely, don’t litter, and put your toys away.” the relative size of each constituent piece is meant to notionally convey the authors’ view of its relative importance in the overall scheme of ensuring long-term sustainability. What has become increasingly evident based upon space population long-term evolution studies is that successfully disposing of spacecraft and mission-released debris once their mission is completed is the most important step we can take.
Advanced Topic: A Moon-Based Imaging of Earth’s Surface
Published in Kun-Shan Chen, Radar Scattering and Imaging of Rough Surfaces, 2020
Earth observation from remote sensing satellites orbiting in a low Earth orbit provides a continuous stream of data that can enable a better understanding of the Earth with respect to climate change [1]. Recently, the concept of observing the Earth from the Moon-based platform was proposed [2–4]. The Moon, as the Earth’s only natural satellite, is stable in periodic motion, making an onboard sensor unique in observing large-scale phenomena that are related to the Earth’s environmental change [5,6]. Synthetic aperture radar (SAR), an active sensor, provides effective monitoring of the Earth with all-time observation capabilities [7,8]. A SAR placed in the lunar platform was proposed [3], in which the configurations and performance of The Moon-Based SAR system was thoroughly investigated. Also, the concept of the Moon-based Interferometric SAR (InSAR) were analyzed by Renga and Moccia [4]. Later, the performance and potential applications of the Moon-Based SAR were characterized by Moccia and Renga [5], and the scientific and technical issues in the application of lunar-based repeat track and along-track interferometry in [6]. Following this stream of development, an L-band Moon-Based SAR for monitoring large-scale phenomena related to global environmental changes was discussed [9]. These studies are focused on the performance analysis and potential applications with some assumptions, such as a regular spherical Earth, an orbicular circular lunar orbit, a fixed earth’s rotational velocity, and a stationary Moon. By so doing, the SAR onboard Moon can be viewed as an inverse SAR (ISAR) or an equivalent sliding spotlight SAR [6,10].
Uncertainty and disturbance-observer based robust attitude control for satellites
Published in International Journal of Control, 2023
Shilpee Kumar, Sarbani Chakraborty
In this work, modelling is done for generalised satellite, however, the proposed controller strategy is verified for a nanosatellite. Nanosatellites have evolved and grown much in demand since the last decade. The purpose of space missions in LEO has extended from science and military to education, environment monitoring, research, and commercial utilities. The highly efficient nanosatellites are advantageous over heavier satellites in terms of low weight, cost, and feasibility (Foreman et al., 2016; Nag et al., 2014). In course of time, an application-based cluster of small satellites is also proving to be a suitable replacement for larger satellites in space missions.
Satellite delivery of high-accuracy GNSS precise point positioning service: an overview for Australia
Published in Journal of Spatial Science, 2019
The altitude of LEO satellites ranges between 200 and 1200 km above the Earth’s surface. The advantage of LEO is that the path length between the satellite and users is shorter, therefore reducing the path losses (as compared to other high-orbit altitude satellites such as GEO).