A dent is similar to a Crater, but it exists upon impact of a space station. It cannot be constructed. Dents are typically created after a Supply pod expires on the station. Supply pods are typically used to give emergency extra storage to a Space Station.
Making a Space Station
Space Stations are functional only after you are in an alliance. It is intended for an alliance to work together to maintain the stations as it will require votes of your alliance to build and upgrade the different plans/modules being added to the station.
Space Station Hull
You need a level 20 embassy to build a Space Station hull.