Ever wondered why there isn’t life on Mars?
Except for that giant head in the sand, Mars has been pretty dead for a very long time. But it wasn’t always like this.
Around 4 billion years ago there was water on Mars, an essential ingredient for life. But why didn’t life begin?
When the little Mars rover came back from its long journey, it brought with it a mystery. The red planet had lots and lots of rocks on it which were made up of 8-10% sulphur, but no limestone.
Now, if anyone remembers their carbon cycle they’ll know that as silicate rocks remove CO2 from the atmosphere it turns into limestone, in the presence of water. We know there was water, but there isn’t any limestone. Weird.
Scientists discovered that Mars’ atmosphere lacked oxygen and carbon dioxide, therefore in order for there not to have been any limestone, the gaseous atmosphere may have been sulphur dioxide – a greenhouse gas, produced by volcanoes. On Earth our sulphur dioxide is removed from the atmosphere by oxidation, which is what led scientists to formulate that there were and still are vast quantities of sulphur present on “the red planet,” due to the fact that atmospheric sulphur dioxide wasn’t oxidised by oxygen.
As vast quantities of the greenhouse gas, Sulphur dioxide were present, Mars may have had a climate and been warmer than today. Logically, it must have smelled rotten (rotten eggs to be precise) thanks to all that sulphur. So perhaps the reason life didn’t begin on Mars was that it just smelled too bad, and as this was life’s first appearance in the solar system it wasn’t going to begin until it could be sure that it smelled sweet.