Astronomy:Three-stage-to-orbit

The three-stage-to-orbit launch system is a commonly used rocket system to attain Earth orbit. The spacecraft uses three distinct stages to provide propulsion consecutively in order to achieve orbital velocity.

Examples of three stage to orbit systems

• Saturn V
• Vanguard
• Ariane 4 (optional boosters)
• Ariane 2
• Ariane 1 (four stages)
• GSLV (three stages and boosters)
• PSLV (four stages)
• Proton (optional fourth stage)
• Long March 5 (optional boosters and optional third stage)
• Long March 1, Long March 1D
• Zenit-3SL
• Minotaur IV (four stages)
• Minotaur V (five stages)
• Unha-3
• KSLV-2 "Nuri"

Examples of two stages with boosters

Other designs (in fact, most modern medium- to heavy-lift designs) do not have all three stages inline on the main stack, instead having strap-on boosters for the "stage-0" with two core stages. In these designs, the boosters and first stage fire simultaneously instead of consecutively, providing extra initial thrust to lift the full launcher weight and overcome gravity losses and atmospheric drag. The boosters are jettisoned a few minutes into flight to reduce weight.

• US Space Shuttle — SRB first stage ; External Tank + SSME second stage ; OMS on internal tanks third stage ;
• Angara A5
• Ariane 5
• Atlas V 551
• Delta II (optional third stage)
• Delta III
• Delta IV-Medium+ and -Heavy
• Falcon Heavy
• Geosynchronous Satellite Launch Vehicle Mk III (However, like the Titan IIIC, the GSLV MkIII is launched solely by the side boosters. The main core only ignites a few minutes into flight, shortly before the boosters are jettisoned.)
• H-IIA, H-IIB
• Soyuz
• Space Launch System
• Titan IV
• Long March 2E, Long March 2F, Long March 3B

See also

• SSTO - Single-stage-to-orbit
• TSTO - Two-stage-to-orbit