http://apcnasa3ozl2j74htizuzba5b6nhugbg2qze2nrz43siunkct555fpid.onion
Staging is also highly advantageous for vehicles that must lift off from a planet's surface. First of all, large high-thrust engines are required to overcome the gravitational attraction of the planet. Smaller, lower-thrust engines can be used for inter-orbital transfers once the vehicle is moving so the large engines can be discarded after lift-off.