Hello! I took a look at the ship and the asteroid's scenes. In the asteroid script, you check if the collided area is in the "ship" group (which is correct), but the ship scene does not have any groups set.
If you go to the root of the ship scene, and click on the "Node" tab on the top right corner, and assign the ship group to it, does the asteroid collision work? Remember that the name of the group must be exactly the same name you are checking on the asteroid script.
Hope this helps!