Mars’ surface, as seen through Curiosity’s eyes.

Scientists have made great strides in predicting what will happen to Earth’s climate, but there is a fundamental problem: We only have one climate to test our hypotheses in. We can’t irreversibly hack Earth’s climate (by pumping it full of toxic gases, for example) to test whether our assumptions are right or wrong — that, obviously, would be disastrous for Earth’s inhabitants. That means climate models are loaded with historical and empirical data to make them function.

If only we could take the model to another planet to really test the underpinning physics!