http://apcnasa3ozl2j74htizuzba5b6nhugbg2qze2nrz43siunkct555fpid.onion
For example, the Apollo Lunar Module had a T/W of 0.3, or about twice the local lunar gravity (1/6 gee). Low T/W propulsion systems, like electric-ion systems (T/W less than about 1/100), can only be used for inter-orbit transfers; even a good-sized asteroid has a high enough surface gravity to prevent lift-off by an electric-ion propulsion system.