1. Along time,people are more and more curious about the issue that whether there exists extraterrestrial lifes.
2. From ancient times, humans on the Moon from superstition to detect other galaxies which have been working with the living conditions for life to explore whether the planet is suitable for living.
3. With the development of technology,the human exploration of the process has bee nmoving forward.
4.At the same time,human beings are hoping to find another "Earth" fitting for human habitation.
5 From the Soviet Union's satellite first launched in 1957, humans have officially declared into the space.
6.1969, American astronaut Neil Armstrong left the first human footprints on the lunar surface.