And the temperature on the ground is boiling! It's so hot is can melt lead.
The Express will use the same designs as the Mars Express probe which will take off to the Red Planet in 2003.
But the mission has been on and off. Earlier in the year, plans were put on hold because more studies needed to be done.
Then Italy - one of the Esa countries - did not know if they would be able to afford the mission. But a plan where they just provide spare parts and some money has been worked out for them.