The European Space Tug: a Reappraisal

The European Space Tug system studies established in conjunction with NASA the preliminary definition for a third stage vehicle that was reusable, adaptable, economic, and had a high mission capture. A 12-ton Tug was derived, capable of operating in either a one or two stage configuration at 6000 Kgl thrust and 460 s of specific impulse. The Tug model has since been updated by technological developments in composite structures, avionics, and new hardware. A mismatch between payload capabilities and the available space for its accommodation has to be corrected, and the Tug model must be reappraised to meet with current projections. The Tug study confirms that initial project design should be constrained, the hardware objectives set as simple as possible and then refined with the evolution of new technologies. Cost comparisons show, however, that the updated Tug model is still a cost-effective option for the space Tug under development.