MADISON, Wis. (AP) – Scientists at the University of Wisconsin-Madison are helping search for alien life forms. But they aren’t looking into space. They’re studying rocks here on Earth.  The rocks are billions of years old. The scientists are looking for information that can be used to guide the search for life on Mars one day. And their research is also telling us more about Earth’s history.  They’ve already found new details about microbial life that dates back more than 2 billion years, before Earth’s atmosphere contained oxygen.  They are working with scientists from around the world as part of the Wisconsin Astrobiology Research Consortium.  NASA approved a $7 million, five-year grant that started in January, which continued on research from a similar five-year grant.