space tug
spacecraft vehicle designed to move the payload from a reference orbit to the target orbit, or direct it to an interplanetary trajectory
Shuttle-Centaur
proposed Space Shuttle upper stage
Mission Extension Vehicle
type of space tug
Agena D
American rocket upper stage
Centaur
family of rocket stages which can be used as a space tug
Volga
rocket upper stage designed in Russia
Blok D
upper stage used on Soviet and later Russian expendable launch systems
Altair
family of American solid-propellant upper stages
Delta Cryogenic Second Stage
rocket stage used in Delta rockets
Payload Assist Module
single-stage solid-fueled booster stage
Transfer Orbit Stage
single-stage solid-fueled booster rocket
STAR
family of American rocket stages developed by Thiokol
satellite dispenser
spacecraft designed to release smaller payloads into their designated orbit
Inertial Upper Stage
two-stage solid-fueled booster rocket developed by the U.S. Air Force