A lucky accident aboard the Curiosity Rover has confirmed that there is life on Mars. A life-detection experiment conducted by the Viking lander in 1976 generated a pattern of responses that fulfilled criteria for the presence of life on the planet, but the results were dismissed by JPL experts. Over the years that followed, this conclusion came into serious question, and a paper published in the International Journal of Aeronautical and Space Sciences in March of 2012 presented convincing evidence that the earlier analysis of the data was flawed. Now the leak in Curiosity’s wet chemistry test has confirmed the presence of gasses that can only be created by living organisms. The final confirmation of the existence of microbial life on the planet would be actually observing living microbes in the soils that are emitting these gasses.

Other observations suggesting the presence of sedimentary structures similar to those left by ancient bacteria on Earth mean that there could have been bacterial life present on Mars as long as 3.7 billion years ago. The earliest similar structures found on Earth are 3.48 billion years old. NASA recently announced the discovery that a sea the size of the Atlantic Ocean existed on Mars for millions of years, and that the planet had standing water for 1.5 billion years. Complex creatures such as trilobites swam Earth’s oceans 500 million years ago, so it seems possible that higher forms may have evolved on Mars prior to the time when its atmosphere thinned and its oceans escaped into space. It this is true, then future Mars missions should search likely areas of the old sea bed for fossils of more complex plants and animals.