After NASA found evidence of primitive life deep inside a meteorite from Mars discovered in Antarctica, a look at the story of rock ALH844001 that asks if we alone in the universe.
For centuries people have speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth. Serious searches for evidence of life began in the 19th century, and continue via telescopic investigations and landed missions. While early work focused on phenomenology and bordered on fantasy, modern scientific inquiry has emphasized the search for chemical biosignatures of life in the soil and rocks at the planet's surface, and the search for biomarker gases in the atmosphere. Fictional Martians have been a recurring feature of popular entertainment of the 20th and 21st centuries, and it remains an open question whether life currently exists on Mars, or has existed there in the past.