Spacecraft in the outer solar system versus spacecraft in the inner solar system. Spacecraft operating in the inner Solar System usually rely on the use of photovoltaic solar panels to generate electricity from sunlight. In the outer solar system, where sunlight is too weak to produce sufficient energy, radioisotope thermoelectric generators (RTGs) are used as a power source. For example, the radioisotope Plutonium-238 is a very powerful alpha emitter making it suitable for use in RTGs. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original EssayFuture Developments of Space PhotovoltaicsFor future missions, it is desirable to reduce the mass of solar panels and increase the power generated per unit area. This will reduce the overall mass of the spacecraft and could make it feasible to operate solar-powered spacecraft at greater distances from the sun. The mass of solar panels could be reduced with thin-film photovoltaic cells, flexible substrates and composite support structures. Flexible solar panels are being explored for use in space. The “Roll Out Solar Array” (also known as ROSA) was launched to the International Space Station in July 2017. The efficiency of solar panels could be improved by using new photovoltaic cell materials and solar concentrators that intensify incident sunlight. Photovoltaic concentrator solar panels for spacecraft primary energy are devices that intensify sunlight on photovoltaics. This design uses a flat lens, called a Fresnel lens, which captures a large area of ​​sunlight and focuses it onto a smaller spot. The same principle is used to light a fire with a magnifying glass on a sunny day. Solar concentrators place one of these lenses on each solar cell. This focuses light from the large area of ​​the concentrator towards the smaller cell area. This allows you to reduce the amount of expensive solar cells by the amount of concentration. Concentrators work best when there is a single light source and the concentrator can be pointed directly at it. This is ideal in space, where the Sun is a single source of light. Solar cells are the most expensive part of solar panels, and solar panels are often a very expensive part of the spacecraft. This technology can significantly reduce costs by using less material. Using Space Photovoltaics in Space Solar Power Space-based solar power (SBSP) is the concept of collecting solar energy in space and distributing it on Earth. Space solar power is the energy of the future. It is generated via solar satellites, otherwise known as “powersats,” and the energy is transmitted wirelessly to receiving stations on the Earth's surface. There are both advantages and disadvantages associated with this means of power generation. The SBSP concept is attractive because space has several important advantages over the Earth's surface for harvesting solar energy: It is always solar noon in space and full sun. This means that solar energy harvesting is virtually unaffected by the sun's day and night cycles. On the earth's surface, solar panels can only collect solar energy for a maximum of 9 hours per day, and in case of cloud cover this number is even lower. Collecting surfaces could receive much more intense sunlight, due to the lack of obstacles such as atmospheric gases, clouds, dust and other events.