GEM 63
GEM 63 is Northrop Grumman’s fixed-nozzle, graphite-epoxy strap-on booster for Atlas V. It first flew on NROL-101 in November 2020. The 2025 manufacturer sheet specifies 20.09 m total length, 1.60 m motor diameter, 97.6 s burn time and 370,835 lbf maximum thrust. Loaded mass is 49,300 kg, including 44,200 kg propellant. These are whole-booster loaded values, distinct from dry motor mass.
Identity
- Domains
- spaceflight
- Identity Level
- variant
- Kind
- solid-rocket-motor
- Name
- GEM 63
- Status
- active
Details
- Description
- GEM 63 is Northrop Grumman’s fixed-nozzle, graphite-epoxy strap-on booster for Atlas V. It first flew on NROL-101 in November 2020. The 2025 manufacturer sheet specifies 20.09 m total length, 1.60 m motor diameter, 97.6 s burn time and 370,835 lbf maximum thrust. Loaded mass is 49,300 kg, including 44,200 kg propellant. These are whole-booster loaded values, distinct from dry motor mass.
- Developers
- Family
- Length
- …
- Lineage
- Note
- Northrop Grumman identifies GEM 63 as the fourth generation, using designs and materials developed across earlier GEM motors.
- Related Propulsion System
- Relationship
- technology-derived-from
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- Northrop Grumman
- Title
- GEM Motor Series Propulsion Products Catalog
- Manufacturers
- Rocket Specs
- Burn Time
- …
Links
Assets & Meta
- Creation Time
- July 29, 2026 at 08:34:19 UTC
- Updated Time
- October 29, 2026 at 15:55:38 UTC
Other
- Diameter
- …
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- Northrop Grumman
- Title
- GEM 63 and GEM 63XL
- Accessed Date
- 2026-07-29
- Publisher
- Northrop Grumman
- Title
- GEM Motor Series Propulsion Products Catalog
- Accessed Date
- 2026-10-29
- Note
- Page 2 table visually inspected. Total length, motor diameter and burn time; masses are loaded, thrust is maximum with ambient condition unspecified. No dry mass or nominal/vacuum thrust inferred.
- Publisher
- Northrop Grumman
- Title
- GEM 63 and GEM 63XL — 2025 product sheet