This topic reminds me of the three greatest quetions : who are we？ where are we from？ Where are we going to? These questions have been cofusing human beings since the first man appeared on earth. So, people kept looking for the answers generation by generation. Until technology rapidly developed in recently a few decades, people could make some traveling machines to leave the earth and have a limited space travel. Though 50 years have passed, the Voyager 1 is still flying alone in the solar system. It told us that the whole solar system was full of silence and dark besides the earth. We feel frustrated after not finding other lives in the solar system,but we never give up. Human beings still try their best to make more powerful aircrafts to get to further spaces. Whether finding aliens or not, the spirit of never giving up promotes human beings get more stronger in the universe.