... Rectangular Ridges on Mars . ... What could cause rectangular ridges on Mars? As data flows in from the two spacecraft currently orbiting Mars, surface structures are seen that are not immediately understood. ... D rad Bacteria: Candidate Astronauts . ... These bacteria could survive on another planet. ... The graceful spiral structure seen in this computer visualization does not portray winding spiral arms in a distant galaxy of stars. ... Have you ever seen the band of our Milky Way Galaxy? ...