Space satellite network design and operation have become more challenging following emerging advanced applications and the increased number of satellites launched into the Earth orbit each year. This has also occasioned an obvious concern for space situational awareness management, interplanetary communications, post-launch reengineering and post-mission reapplications of spacecraft; these all require adaptive, reconfigurable and multifunctional space systems and networks. Enormous advances aimed at making spacecraft systems reconfigurable, reliable, broadband, and multifunctional have been patented. Consequently, recent space technology patents in reconfigurable and autonomous system designs and architectures have been studied and qualified. This paper presents a reconfigurable space satellite network design that uses cooperative space-borne systems to complement ground-based enhancements. Each network node employs the deterministic multifunctional architecture with packet router interface switch matrix platforms. The reconfigurable cooperative intelligent control (RCIC) design exploits the deterministic and reconfigurable property of field programmable gate array to offer in-situ autonomous control. Four reliable and adaptive space control capability modes have been identified for a robust space satellite network. Furthermore, the control capability has been analysed with recourse to satellite generations. Consequently, a case study reconfigurable space network covering femtosatellites to minisatellites has been designed. The analysis presented in this work promises to enhance small satellite formation and constellations designs and applications. It also enables real-time space surveillance and provides platforms for the reuse of decommissioned satellite systems.
The navigation techniques for spacecrafts are based on different systems or sensors, depending on the specific mission. The spacecrafts operating near the Earth surface (LEO missions for example) can use GPS to estimate position, speed and, in more advanced applications, attitude too. For interplanetary missions, GPS is unsuitable, thus other systems have to be applied. In both cases, inertial sensors are always applicable for navigation and attitude determination, even if they have some disadvantages. In the field of spacecrafts navigation, several algorithms and systems have been developed and patented in recent years. In this paper, the most relevant patents presented in recent years, concerning spacecraft navigation, have been reviewed. The following fields have been covered: i) application of GPS for spacecraft navigation, ii) application of stars trackers, or more in general celestial sensors for attitude determination, iii) application of video and radio systems for navigation and control purposes. Furthermore, some proposals of integration among different navigation systems will be presented. This review considers various applications, emphasizing main advantages and weaknesses of the proposed solutions and suggesting some possible future developments.
Tethered satellite technology has the potential to revolutionize our presence in space. This paper provides an overview of the dynamics and applications of tethers in space. Experiments, patents, and papers are reviewed to provide an overview of the current status of tether technology. Key application areas that are reviewed include deployment, electrodynamics, momentum-exchange, and the space elevator. Among the most promising applications for near-term exploitation are electrodynamic orbital maneuvering of satellites with little or no propellant, and momentum-exchange tethers capable of injecting payloads into different orbits. This paper illustrates that these applications have a solid theoretical basis, as well as supporting empirical flight data.
There are numerous phenomena in the space, biological and ecological sciences whose discrete evolution can be effectively modeled by exponentially decaying discrete dynamical systems, which can be represented as follows: Let F : Rn x P → Rn be a smooth map, where Rn is Euclidean n-space representing the state variables x and P is a subset of Rm representing the parameter space comprised of m-vectors denoted by µ . The discrete dynamics of the system is given by the iterates of the map fµ : Rn → Rn , where fµ (x) := F(x,µ), with the exponentially decaying behavior embodied in the property that there exists a positive constant M such that |f µ(x)| ≤ Me -|x| for all (x,µ ) ∈ Rn x P. It is not difficult to show that these exponentially decaying dynamical systems have attracting sets that can have remarkable properties. For example, the attractor may be a strange attractor – a set with non-integer fractal dimension on which the dynamics is chaotic - and variations in the parameter can cause bifurcations that change the fundamental nature of the chaotic regimes. Known results on these strange attractors will be discussed, several new developments will be presented and some challenging open problems will be outlined. AMS Subject Classification: 37C05; 37G10; 37N25; 92D25.
The energy balance of Earth is influenced by many factors such as temperature, wind, the amount of water vapor in the air as well as surface albedo and emittance. Radiative transfer is the transfer of electromagnetic radiation in scattering, absorbing and emitting media. Instruments deployed on weather balloons, aircrafts, and satellites are used to collect data to characterize the atmosphere including its scattering and absorption properties, either locally or by remote sensing. Radiative transfer models (RTMs) are developed and used extensively for a wide range of applications in remote sensing and space technology. This paper is intended to provide a coherent summary of RTMs and associated databases publicly available, as well as some patents and publications related directly or indirectly to the field of radiative transfer and the use of RTMs in remote sensing applications. The computer codes described in this paper reflect some of the latest advancements in the analysis of data related to Earths radiation budget and their use to enhance understanding of climate change and global warming. The applications of radiative transfer occur mainly in areas of climate modeling, atmospheric science, ocean science, remote sensing, astronomy, astrophysics, hydrodynamics, and optics. Radiative transfer codes are used in this broad range of applications, including many related to weather, climate and satellite meteorology. This paper concludes with a description of the future developments expected in the subject covered.
This research paper presents two algorithms that will be able to determine the aerodynamic angles, that is, the angles of attack and sideslip, of a symmetric capsule-type spacecraft during atmospheric entry with the use of a 3-axis accelerometer. The algorithms are conceived only for emergency entry situations in which no attitude from the primary and backup navigation systems is available. The aerodynamic angles are provided in both methods with different degrees of accuracy and with different processing requirements. Both methods will increase the probabilities of flying a successful emergency ballistic entry that will, in turn, increase the probabilities of crew survival. Navigation reliability and tolerance to failures is traditionally achieved through the implementation of redundant elements. The algorithms presented in this paper increase reliability of the overall system through the utilization of a navigation instrument, the 3-axis accelerometer, for a use other than that for which it is designed. The algorithms presented in this research paper are documented in the NASA Disclosure of Invention and New Technology Number 5022510. They have been submitted to the U.S. Patent and Trademark Office with U.S. Provisional Application Number 61/212996.
Planning principles are considered for a permanent three-dimensional complex in space (space-town) protecting the inhabitants from harmful cosmic impacts for several generations at least as effectively as on Earth. The complex includes habitable structures and life-supporting facilities, as well as workshops, services and institutions; the entire complex is interconnected by a system of passages for people and transportation. An axiomatic approach to spacetown planning and a self-consistent set of design rules are suggested. On this basis, the town structure is conceptually, approximately developed and its basic structural parameters, including total mass, are quantitatively defined for three generations of a “minimal city” in free space. Conservatively realistic estimates of anticipated timeframes are given as well. The relevant recent patents are reviewed in the first part of the article.