From the 21st Annual International Mars Society Convention, held at the Pasadena Convention Center in Southern California from Aug 23-26, 2018.
You have to launch 226 kilograms from Earth for every 1 kilogram of material that you get onto Mars.
You need to produce water and oxygen on Mars. These can be used for energy, fuel, life support and agriculture.
There is a drilling system that weighs 100 kilograms that can drill to 2 kilometers of depth in 100 days.
With SpaceX BFR we should change the way we are thinking and not scaling missions for small rovers. If we will put 100 tons on Mars, then we will have tens of kilowatts or hundreds of kilowatts or megawatts. We can make massive drilling and construction on Mars.