Frameless structures of space solar power systems

V.M.Melnikov, V.A.Komkov

Moscow Aviation Institute (STU)

Russia, 125993, Moscow, Volokolamskoe schosse, 4

B.N.Kharlov

S.P.Korolev RKK "Energia"

Russia, 141017, MO, Korolev

 

Of all the problems that face the whole Earth, energy is the most crucial. The Earth resources, such as oil and gas, will be exhausted in the nearest future. Their exploration, production, and transportation costs are constantly increasing. Beyond, there is a whole class of problems, such as pollution of the environment and the greenhouse effect, associated with utilization of traditional energy sources. All that, right now, raises a question of how to decrease sharply their consumption during transition to alternative power sources. By solving the problem of energy crisis via space-based technologies, the man-caused effects on the environmental ecology, causing the weather destabilization, would be simultaneously removed. The founding father of cosmonautics, K.E. Tsiolkovsky, started cosmonautics development more than 100 years ago and came up with the idea of how to solve precisely the problems of energy and ecology crises via solar power engineering. To develop large space-based power systems of low cost and high efficiency, high-technology scientific achievements, development of new trends, and wide international cooperation are required. It will be impossible to enter the next Millennium with many traditional approaches framed in the last century. The goal pursued by the authors of this article is to show new ways of coping with the problem. It is natural that, to develop large space-based power systems, the practical experience in developing space power systems of smaller sizes must be gained. This is why, as steps towards the final goal, the proposed structures must be employed on small and medium satellites, in the Martian mission power system and during the Moon exploration, requiring scaled power stations capable of operating under deep vacuum and low gravity which must be fast deployed and stowed in cases of dislocation and repair.

The ground-based solar arrays are 5-7 times less efficient than in space because of the lighting modes "day-night" and "winter-summer", absorption in the atmosphere due to rains, snow, dust storms, and local latitude. There are no all these factors in space.

In mid-80s of the past century, research was established in the USSR within the framework of state research programs to outline the reason for the most advisable applications of large space structures and to define their configuration. A comparative analysis has been carried out on mass-dimension properties, development and production costs, transport configurations, and efficiency of framed and frameless structures deployed by centrifugal forces, as well as inflatable structures and structures deployed by electrostatic forces. Following a set of parameters and potential applications, the frameless structures deployed by centrifugal forces were recognized as offering the most promise. Such structures gain the weight advantages over analogs in low cost and mass because of absence of a frame, space-saving transport configuration, automatic deployment in orbit with low power consumption, capability of non-propulsive re-orientation, etc. The principal drawback of an inflatable structure is the complexity of maintaining its required configuration because of inevitable structure irregularities of material in the process of hardening that is necessary for further utilization of the originally soft structure. The reviewed adaptive electrostatic structures required a rigid frame and a rather expensive electronic control system. Within the program "Znamya", a space experiment has been scheduled to test the structures deployed by centrifugal forces and to gain experience in their development. The film structure model of solar sail of 20 m Æ ("Znamya 2" space-based experiment) was for the first time ever deployed on the transportation vehicle Progress on 04.02.93, including the structure re-pointing maneuver in space.

The experiment pursued the goal to employ the structure in the capacity of a reflector, beaming sunlight to the Earth. The experiment proved the validity of design solutions and future benefits. To prepare the experiment, that took 6 years, a large number of specialists from rocket and space companies and institutes were involved. The milestones accomplished by then are explained before. Next years, applications of such structures in the capacity of sunlight reflectors for a local weather control and increase of crop and seafood capacity have been investigated. Since 2000, because of insufficient funding, a spectrum of applications under consideration has been restricted to the development of most promising thin-film amorphous silicon solar arrays.

The article gives the results of frameless structures research as the most promising for space power engineering problems. The works were fulfilled within the framework of the Agreement with the International Science & Technology Center (Project ISTC ї2620 a-Si polymeric thin-film solar arrays deployed by centrifugal forces for communication and remote Earth sensing satellites>. The Project was initiated on 01.01.2004 and completed on 30.06.2006).

In conclusion, the authors, who have worked for more than 30 years as leading experts in the area of space power engineering, cite that, unless this technology was developed, such a potentially effective trend, with such multiple applications (small and medium spacecraft, Martian mission, Lunar bases, space-based power plants of 1 - 10 GW to resist energy crisis and to stabilize weather) could not seem feasible. The proposed technology for deployment of a large power plant by joining in orbit with a deployment mechanism, using a "pulling roller", of SA segments delivered to orbit on separate reels is a rare engineering finding that would outperform all possible alternatives (e.g. nuclear thermoemission power plants). The use of amorphous silicon photovoltaics can be considered only as a step to transform to semiconductor structures generating not direct current, but the waves directly in SHF band. This gives the ability to radically overcome difficulties which developers of power systems are currently facing and to solve power problem for a long time. The company which will apply this technology will undoubtedly become a world-wide leader in the market of space power systems that will inevitably grow fast on the verge of energy crisis

 

V.M. Melnikov, Professor of Theory of Machines and Mechanisms department of MAI-STU; Dr. Sci. Tech; graduated from Moscow Aviation Institute; Full Member of K.E. Tsiolkovsky Russian Academy of Astronautics; Manager of ISTC ї2620 Projects. Previously, he was a scientific manager and senior investigator in "Znamya 2" space experiment. The experiment results made a basis of his doctoral thesis (1996). Scientific interests area: space power systems.

V.A. Komkov, Professor, Head of Theory of Machines and Mechanisms department of MAI-STU; graduated from Moscow Aviation Institute; Full Member of K.E. Tsiolkovsky Russian Academy of Astronautics; an expert in durability of structure materials. He took an active part in "Znamya 2" experiment. His doctoral thesis (2000), besides engineering aspects of large space structures developing, addresses the possibility to increase crop capacity in different regions of Russia through beaming additional sunlight from a space-based reflector. Scientific interests area: space power systems.

B.N. Kharlov, Chief Designer (ZEM RKK "Energia"); graduated from Moscow Aviation Technological Institute; he contributed much in designing and manufacturing SA deployment mechanisms, including the ones for "Znamya 2" experiment, and cable system deployment device capable of compensating the kinetic moment. Scientific interests area: electromechanics.