The Sun Shines At Night

A Real-Life Fantasy

 
While fantasies of this sort tend to inhabit a future we can only dream of, today we can find a tangible basis for even the most fantastic projects.

Imagine that a reflector capable of casting sunlight on our planet is launched into artificial satellite orbit around the Earth. The reflected beam of sunlight can illuminate one or several areas in various time zones.

The idea of creating a space reflector was first dreamed up by a German physicist named Hermann Oberth in 1929. It was further developed by the American scientist Krafft Ehricke. Today we are very close to seeing the practical implementation of these projects, which seemed fantastic at one time.

Let’s first address the question of why we need artificial moons.

Man-made space reflectors have the potential to be beneficial in a variety of economic sectors. Using satellite reflectors to prolong daylight for a few hours in a big city will ensure high-quality (shadow-free) and cost-effective illumination of streets, highways and construction sites. For instance, the cost of satellite illumination for five cities the size of Moscow would be recovered within four or five years through energy savings alone. It would also be possible to illuminate other cities using the same reflector system at virtually no additional expense.

Another potential application is providing illumination for sites where work goes on at night, such as large construction sites at high latitudes or agricultural regions during seed and harvest seasons.

For years, our country has studied how altering the duration and specter of illumination affects crop yields. Research indicates that illumination of fields in specific specter ranges can result in more intensive growth of plants and provide a way to control short-term freezing temperatures at night. This type of controlled illumination can be achieved using reflector satellites. Another of the many potentially useful applications of reflectors is providing light for rescue operations at the sites of major earthquakes and other natural calamities.

But what are the technical requirements for implementing these projects? The main difficulty is the task of orbit launching reflecting surfaces with an area of dozens of hectares. In addition, the profitability of such systems suffers as the satellite throw-weight increases. For these reasons, super-light constructions should be created requiring no assembly in orbit. At the same time, lighter constructions are less rigid, which means poorer accuracy in targeting the light flux. An efficient management system can partially offset these drawbacks.

Research engineers have already outlined a design for the economically viable orbital illumination systems of the future. It appears that they can be assembled using groups of independent reflector satellites traveling in advantageous orbits. Each reflector will look like an ordinary folded umbrella which opens automatically after being launched into orbit. The light-reflecting surface on these satellites will be made of polymer metalized film. The light flux will be directed by a multi-point control system that compensates for the structure’s vibrations.

A well-organized programme of research and experimental development for building the structures and studying the operating principles could give us pilot space reflectors. The USSR Academy of Sciences and several ministries believe that steps should be taken to organize such a programme immediately. It would be practicable to draw on the substantial scientific potential of the Higher School, all the more so because the necessary preparatory work has already been done.             

For instance, the Moscow Aviation Institute named after Sergo Ordzhonikidze (MAI) is designing an orbital experiment with a reflector satellite weighing not more than 200 kg and having a reflecting surface of 110 m². The goal of this experiment is to test the technical solutions based on which future space reflectors will be constructed. Light intensity at the earth receiver over an area with a diameter of 10 km should be seven times that of a full moon (approximately 1.5 Lux).   

Researchers and students at MAI have already created pilot on-ground facilities demonstrating how to unfold and control the surface of a space reflector. The process would benefit if the USSR State Committee for Science and Technology and the Ministry of Higher Education approve the creation of a research base.

In parallel, we must study the environmental impact of using space reflectors and formulate recommendations to efficiently use these systems in an environmentally friendly manner.   

The sun, the most powerful of all existing energy sources, can provide even more efficiently for people’s energy needs.    

Academician Zhores Alferov

Vice Chairman, Scientific Council on new applications

for solar energy at the Russian Academy of Science

Viatcheslav Kantor, Ph.D.