Observations and models don't match, so there is some input that is missing. In this case it seems to be a heavier atmosphere (which has later blown away). Thei

Observations and models don't match, so there is some input that is missing. In this case it seems to be a heavier atmosphere (which has later blown away). Their hopes are that this added assumption will reconcile the observations and models, and thus give a more complete picture on how Mars developed.