Introduction:
Artificial satellites and space probes are crucial for various space exploration and communication purposes. These devices require a reliable and sustainable source of energy to operate effectively in the harsh conditions of outer space. Among the options given, solar energy is the primary source of power for artificial satellites and space probes.

Explanation:
Solar Energy:
Solar energy is the conversion of sunlight into electrical energy using photovoltaic cells or solar panels. These panels consist of semiconductors that absorb sunlight and convert it into electricity. Solar energy is the most suitable and widely used source of power for satellites and space probes due to the following reasons:

1. Availability: Solar energy is readily available in space as the sun is a constant and abundant source of light and heat. Satellites and space probes can capture this energy and convert it into electricity to power their systems.

2. Lightweight and Compact: Solar panels are lightweight and compact, making them ideal for space missions where weight and space constraints are crucial factors. They can be easily integrated into the design of satellites and space probes without adding significant mass.

3. Reliability: Solar energy is a reliable source of power as long as the satellite or space probe remains in sunlight. Since most satellites and space probes orbit the Earth or other celestial bodies, they continuously receive sunlight, ensuring a steady supply of energy.

4. Low Maintenance: Solar panels require minimal maintenance in the vacuum of space. They have no moving parts, reducing the chances of mechanical failure. This makes solar energy an efficient and cost-effective choice for powering satellites and space probes.

5. Longevity: Solar panels have a long lifespan, typically lasting for several years without significant degradation in performance. This allows satellites and space probes to operate for extended periods without the need for frequent replacements or repairs.

6. Environmental Friendliness: Solar energy is a clean and renewable energy source, producing no harmful emissions or waste products. It aligns with the principles of sustainable development and helps reduce the environmental impact of space missions.

Conclusion:
In conclusion, artificial satellites and space probes primarily depend on solar energy as their source of power. Solar energy offers numerous advantages such as availability, lightweight design, reliability, low maintenance, longevity, and environmental friendliness. These factors make solar energy the most suitable and widely used option for powering satellites and space probes in outer space.