"We are running out of space and the only places to go to are other worlds... Spreading out maybe the only thing that can save us from ourselves. I believe that humans need to leave Earth. "These are the words of the famous scientist Stephen Hawking, spoken at a science festival in 2017.
▲ Many experts also think that the only way for humans to go far into the future is to take control of other planets. Mars(火星) is one of the most attractive places humans have thought about. NASA, the United Arab Emirates, the private company SpaceX, and the organization Mars One all have plans to send humans there. "Either we spread out to other planets, or we risk dying out, "SpaceX founder Elon Musk said.
But not everyone agrees that moving to Mars or other planets is such a great plan. The most common argument against spreading is that it's just too expensive or dangerous. It will take a lot of money and other effort just to get people there, let alone set up a place for them to live. It's not even clear if humans could survive(生存) on Mars.
Maybe all the time and money people would pour into a Mars program would be better spent on more urgent ones here on Earth, like dealing with environmental protection. Some experts argue that dealing with a problem while staying here on Earth would be much easier and less expensive than surviving on a new planet.
What's more, moving to a new planet could harm or destroy(破坏) anything that already lives there. Mars seems deserted, but it could possibly have microbial life. Human visitors may destroy this life or change or damage the environment on Mars forever. Some feel it's too much of a risk to leave Earth.
