The field of on-orbit servicing of space systems has been studied extensively, and techniques for performing satellite resupply and repair functions have been developed in detail. They are covered extensively in the literature. Based on this background, Microcosm has performed design studies, partly under NASA/MSFC contract, of a small-size, 300 kg-class multifunction Orbital Transfer Vehicle (OTV) that can provide servicing and resupply functions for the International Space Station (ISS). It carries the required payload from a launch vehicle upper stage to the Station, and after berthing it supports servicing activities of the ISS crew members. The vehicle has a payload-carrying capability of 350 kg. The current design includes grappling fixtures specifically designed for ISS berthing which can be eliminated for servicing other satellites. The very strict safety requirements involving ISS access were taken into account in the servicing vehicle design. Repeated ISS servicing sorties to be performed by the OTV are of particular interest, to meet tight revisiting schedules. Extended reuse of the same OTV, once in orbit, allows substantial launch and operational cost savings. Propellant requirements for the servicing sorties are very modest, allowing an extended on-orbit life of this vehicle, with at least 3, but more likely 6 to 8 ISS revisits. The OTV discussed here can be utilized for low-cost servicing of other spacecraft as well. The paper discusses the vehicle’s maneuver sequences and propellant requirements, and describes its design features and its interactions with the ISS. The OTV’s total recurring cost is estimated at less than $35 Million. It would nominally be carried by a light-lift launcher, such as Microcosm’s planned Sprite vehicle, at a projected cost of the order of $2.5 Million.
Collins, J., H.F. Meissinger, R. Bell. 15th Annual AIAA/USU Conference on Small Satellites, Utah State University, Logan, Utah. August 13–16, 2001.