Robert Zubrin,a rocket scientist, thinks humans should colonize space .He wants to start with Mars.Why? There are several advantages:for one , sending people to the moon and Mars will allow us to learn a lot - for example,whether living on other planets is possible . Then ,we can eventually create new human societies on other planets. In addition, the advances we make for space travel in the fields of science ,technology,medicine, and health can also benefit us here on Earth