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Encyclopedia entry

GEM

Program

Original archive entry. The text, images and links below are kept as they were written.

Family of stages.

Subtopics

  • GEM (abbreviation) Abbreviation for Giotto Extended Mission
  • GEM 40 Hercules solid rocket engine. Air-ignited versions have nozzle ratio of 16:1, specific impulse of 283.4 sec. Used on Delta 7925 launch vehicle. First flight 1990.
  • GEM 60 Hercules solid rocket engine. In production. Used as strap-on boosters for Delta 3 , Delta IV Medium. First flight 2002. Solid propellant rocket stage. 90.5 bar chamber pressure, 11.0 nozzle expansion ratio. Figures for TVC version. Fixed nozzle version is 599 kg lighter.
  • GEM 46 Hercules solid rocket engine. Air-ignited versions have nozzle ratio of 24.8:1, specific impulse of 284 sec. First flight 1998. Solid propellant rocket stage. Nine 1168-mm (46 in.) diameter Alliant graphite epoxy motors (GEM LDXLs) (strap-on solid rocket motors - SSRMs) augment the first-stage performance of the Delta III and were a direct evolution from the GEMs used on Delta II.