Abstract:Numerous recent studies have been performed on space exploration missions to develop and identify optimal methods and technologies that will increase payload mass to destination within time and budget constraints [1–3].§ This paper presents a comparative study of a new concept in which space tugs are used for orbit raising to store energy at highly elliptical rendezvous orbits (HEROs) [3]. A detailed case study involving missions to Venus, Mars, and Jupiter is also presented. The study results show that this concept greatly simplifies the overall boil off problem associated with cryogenics and increases the change in velocity increment (ΔV) to the departing payload.