Read this excerpt from "Mars: Landscape of the Red Planet." NASA and its European equivalent, ESA, currently have spacecraft orbiting Mars, delivering pictures and weather reports back to Earth. On January 3 and 24, 2004, NASA landed two robotic rovers named Spirit and Opportunity on the Martian surface. The twin rovers have spent the last nine years exploring Mars, taking pictures, video, and geological samples. This excerpt is most likely to appear in which part of a scientific text? introduction methods results conclusion