1: NASA scientist confirms alien life exists

2: Evidence of alien life in our Solar System

3: Possibility of extraterrestrial organisms on Mars

4: Enceladus and Europa: potential alien habitats

5: Methane on Titan: a sign of alien life?

6: Searching for signs of life on Venus

7: Probing the oceans of Enceladus for aliens

8: NASA missions hunting for alien life

9: The search for extraterrestrial life in our backyard