By: http://news.discovery.com/space/are-we-infecting-mars-with-our-germs.htm
Life on Mars?
Scientists found evidence of small roundish objects that could be bacteria. Plus some minerals and organic molecules that might have been made by bacteria. There is also some evidence that there used to be water on mars a long time ago.
Some things we have to deal with:
The problem is we don't know if there will be any life on mars so we have to make sure we are sanitary so we don't spread Earth germs around or with mars germs. We also don't want to spread Earth viruses