Slide 9 of 99
Notes:
NASA originally hoped to develop a space tug in the 1990s for manned missions to geostationary orbit and beyond. This modular design (from 1984) was proposed by General Dynamics who investigated space station/space tug integration issues in the early 1980s. Spherical tanks contain liquid hydrogen and oxygen propellant for the engines; three sets would be carried for manned or heavy-lift missions while one set would suffice for delivering smaller unmanned payloads. Note Shuttle and space station in the background.
