What does the term "terraforming" refer to?

Terraforming refers to the process of modifying a planet's environment to make it suitable for human habitation and life as we know it. This involves altering various environmental factors, such as the atmosphere, temperature, surface topography, and other conditions to create an ecology that can support human life and possibly other Earth-based organisms.

The concept of terraforming is often discussed in the context of planets like Mars, where scientists explore the potential for transforming the planet's thin, inhospitable atmosphere into one that could support human life. This could involve techniques such as introducing specially designed bacteria that can produce oxygen, heating the planet to melt ice caps, or even creating artificial structures to hold in heat and gases.

The other choices focus on different aspects of space exploration that do not directly involve altering a planet's environment to make it livable. For instance, creating artificial satellites pertains to the deployment of technology in orbit, establishing colonies focuses on habitation without necessarily changing planetary conditions, and mining resources deals with extracting materials from celestial bodies rather than modifying them for life.