Space Launch Report Pegasus Data Sheet
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Vehicle Configurations

Vehicle Components

Pegasus Launch Log

Pegasus, the world's only winged, drop-launched space launch vehicle, was developed during the late 1980s and early 1990s by Orbital Sciences Corporation and Hercules Aerospace. The original design that first flew in 1990 was upgraded to a heavier, more powerful Pegasus XL model in 1994.

Pegasus consists of three solid-fuel stages with an optional HAPS (Hydrazine Auxiliary Propulsion Stage) monopropellant fourth stage. Alliant Tech Systems (formerly Hercules Aerospace) builds the graphite composite motor case solid fuel stages. Burt Rutan's Scaled Composites, Inc manufactures the graphite composite clipped delta wing and tail surfaces that provide lift and aerodynamic flight control during the vehicle's first stage flight.

Pegasus is drop launched at Mach 0.8 and an alititude of 11.9 km from a modified Lockheed Tristar L-1011 owned by Orbital Sciences named "Stargazer". Pegasus falls for five seconds until its first stage ignites. It then flies a shallow ascent to first stage burn-out, which occurs at a speed of Mach 8.7 and an altitude of 40-65 km, depending on the mission type. The first stage engine has a fixed nozzle. All flight control is provided by the elevator and rudder control surfaces.

The air launch technique reduces total delta-V requirements by 10-15%.

The second and third stages use steerable nozzles to provide pitch and yaw thrust vector control. Roll control is provided by cold gas thrusters. When flown as a three-stage vehicle, the third stage coasts to apogee for several minutes before igniting.

Pegasus suffered teething problems. Five of the first 14 launches performed by the end of 1996 failed. But by the end of 2013, Pegasus had recovered with 28 consecutive successes. By then, Pegasus had flown 42 times from five different launch zones with payloads for commercial, defense, and civil space customers. In addition, three suborbital Pegasus first stages had boosted NASA's Hyper-X hypersonic research test missions.

Pegasus may ultimately fly more often as a traditional, no-wings rocket. Pegasus stages have been combined with Minuteman and Peacekeeper ICBM stages to create Mintotaur and Taurus space launchers. A complete no-wings version of Pegasus, called Orbital Boost Vehicle, has been developed to support missile defense technology development.

Launch Sites

Pegasus is integrated at Vandenberg Air Force Base, then ferried to its launch site by the L-1011 carrier aircraft. Launches have been conducted from Vandenberg, Cape Canaveral, Wallops Island, the Canary Islands, and from Kwajalien in the South Pacific.

NASA's famed B-52 No. 008 "Mother Ship" was used to launch the first dozen or so Pegasus rockets.  The L-1011 entered service to handle the heavier Pegasus XL variant.

Vehicle Configurations

(metric tons)
400 km x
28.5 deg
(metric tons)
400 km x
90 deg
Configuration Liftoff
(metric tons)
Pegasus 0.36 t 0.27 t 3 Stage Pegasus (Orion 50S, Orion 50, Orion 38) 15 m 18.6 t
Pegasus XL 0.40 t 0.3 t 3 Stage Pegasus XL (Orion 50SXL, Orion 50XL, Orion 38) with optional HAPS 4th stg 16.9 m 23.13 t

Vehicle Components

  Stage 1
Orion 50S
Stage 1
Orion 50SXL
Stage 2
Orion 50
Stage 2
Orion 50XL
Stage 3
Orion 38
Stage 4
Diameter (m) 1.28 m 1.28 m 1.28 m 1.28 m 0.97 m .97
Length (m) 9.39m 10.27 m 3.84 m 4.29 m 1.34 m .3
Propellant Mass (tons) 12.15 t 15.01 t 3.02 t 3.93 t 0.77 t 0.07 t
Total Mass (tons) 14.02 t 16.38 t 3.37 t 4.35 t 0.89 t 0.09 t
Engine Orion 50S Orion 50SXL Orion 50 Orion 50XL Orion 38 HAPS
Engine Mfgr ATK ATK ATK ATK ATK Olin
Fuel Solid Solid Solid Solid Solid Hydrazine
Oxidizer Solid Solid Solid Solid Solid  
(SL tons)
(Vac tons, avg)
59.5 t 74.03 t 12.65 t 20.03 t 3.66 t 0.07 t
ISP (SL sec)            
ISP (Vac sec) s 295 s s 289 s 287 s 236 s
Burn Time (sec) 72 s 68.6 s 75.9 s 69.4 s 68.5 s 241 s
No. Engines 1 1 1 1 1 3

Pegasus Launch Log


DATE     VEHICLE           ID      PAYLOAD                 MASS(t) SITE*      ORBIT**
04/05/90 Pegasus           F1      SECS/Pegsat             0.246   ED NB52B  LEO/P
02/09/93 Pegasus HAPS      F2      Microsat 1-7            0.159   ED NB52B [LEO][1] 
02/09/93 Pegasus           F3      SCD 1/Orbcomm-CDS 1     0.129   CC NB52B  LEO
04/25/93 Pegasus           F4      ALEXIS/Orbcomm-CDS 2    0.129   ED NB52B  LEO   
05/19/94 Pegasus HAPS      F5      STEP 2 (P91-2, SIDEX)   0.180   ED NB52B [LEO][2]    
06/28/94 Pegasus-XL        F6      STEP 1 (P90-1)          0.352   VA L1011 [FTO][3]      
08/03/94 Pegasus           F7      APEX                    0.260   ED NB52B  EEO [4] 
04/03/95 Pegasus-H         F8      Orbview 1/Orbcomm 1-2   0.148   VA L1011  LEO   
06/22/95 Pegasus-XL        F9      STEP 3 (P92-2)          0.268   VA L1011 [FTO][5]    
03/09/96 Pegasus-XL        F10     REX 2 (P94-2)           0.110   VA L1011  LEO/P    
05/17/96 Pegasus-H         F11     MSTI 3                  0.211   VA L1011  LEO/S
07/02/96 Pegasus-XL        F12     TOMS-EP                 0.295   VA L1011  LEO/S   
08/21/96 Pegasus-XL        F13     FAST (SMEX 2)           0.191   VA L1011  EEO [6]   
11/04/96 Pegasus-XL        F14     SAC-B / HETE 1          0.309   WI L1011 [LEO][7]    
04/21/97 Pegasus-XL        F15     Minisat 1/Celestis 1    0.195   GA L1011  LEO/R[8]
08/01/97 Pegasus-XL        F16     OrbView 2               0.309   VA L1011  LEO/S
08/29/97 Pegasus-XL        F17     FORTE (P94-1)           0.215   VA L1011  LEO
10/22/97 Pegasus-XL        F18     STEP 4 (P95-1)          0.403   WI L1011  LEO [9]
12/23/97 Pegasus-XL HAPS   F19     Orbcomm 5-12            0.320   WI L1011  LEO
02/26/98 Pegasus-XL        F20     SNOE / BATSAT (T1)      0.235   VA L1011  LEO/S   
04/02/98 Pegasus-XL        F21     TRACE (NASA)            0.213   VA L1011  LEO/S
08/02/98 Pegasus-XL/HAPS   F22     Orbcomm FM 13-20        0.320   WI L1011  LEO      
09/23/98 Pegasus-XL/HAPS   F23     Orbcomm FM 21-28        0.320   WI L1011  LEO  
10/23/98 Pegasus-XL        F24/P33 SCD 2                   0.117   CC L1011  LEO     
12/06/98 Pegasus-XL        F25/M22 SWAS (NASA)             0.213   VA L1011  LEO
03/05/99 Pegasus-XL        F26     WIRE (NASA)             0.254   VA L1011  LEO/S[10] 
05/18/99 Pegasus-XL HAPS   F27     TERRIERS/MUBLCOM        0.173   VA L1011  LEO/S 
12/04/99 Pegasus-XL HAPS   F28     Orbcomm FM 29-35        0.315   VA L1011  LEO  
06/07/00 Pegasus XL        F29     TSX-5                   0.250   VA L1011  EEO [11]
10/09/00 Pegasus           F30/P35 HETE-2                  0.124   KW L1011  LEO [12]
02/05/02 Pegasus XL        F31     HESSI (NASA)            0.304   CC L1011  LEO
01/25/03 Pegasus-XL        F32     SORCE                   0.315   CC L1011  LEO
04/28/03 Pegasus XL        F33     GALEX                   0.312   CC L1011  LEO
06/26/03 Pegasus XL        F34     Orbview 3               0.360   CC L1011  LEO/S
08/13/03 Pegasus XL        F35     SciSat 1                0.150   VA L1011  LEO
04/15/05 Pegasus XL HAPS   F36     DART                    0.300   VA L1011  LEO/P
03/22/06 Pegasus XL        F37     SpaceTech 5             0.075   VA L1011  EEO/P[13]
04/25/07 Pegasus XL        F38     AIM                     0.200   VA L1011  LEO/S
04/16/08 Pegasus XL        F39     C/NOFS                  0.395   KW L1011  LEO
10/19/08 Pegasus XL        F40     Star 27/IBEX            0.462   KW L1011  LEO
06/13/12 Pegasus XL        F41     NuStar                  0.350   KW L1011  LEO
06/28/13 Pegasus XL        F42     IRIS                    0.180   VA L1011  LEO/S
12/15/16 Pegasus XL        F43     CYGNSS                  0.229   CC L1011  LEO

[1] 1st stg sep delay caused low, 356 x 454 km x 82 deg orbit.  719 km x 82 deg 
     planned.  Satellites decayed after only six months.  1st HAPS.

[2] Incorrect (low) orbit, 606 x 834 km x 81.9 deg versus planned 830 km circular.  
     Possible HAPS issue.  Satellite mission successful.  
[3] 1st stg wing structure fail.   

[4] 933 x 2,555 km x 70 deg orbit.  Final B-52 launch.

[5] 2nd stg failed, RSO.  Planned 450 km polar orbit.

[6] 350  4,200 km x 83 deg.  Fast Auroral Snapshot Explorer.

[7] 3rd stg battery failure prevented payload deployment.

[8] Staged from Gando, Canary Islands.  570 x 577 km x 151 deg.

[9] 430  500 km x 45 deg.  Solar panels failed to deploy.  Satellite mission 
     declared a failure.

[10] Upon reaching orbit, WIRE's cryogenic coolant evaporated prematurely, leaving 
      main telescope useless.  Onboard star tracker subsequently used to monitor 
      stars for astroseismology. 

[11] 410 x 1,750 km x 69 deg orbit.

[12] 598  641 km x 1.9 deg near-equatorial orbit.

[13] 301 x 4,568 km x 105.6 deg. Three x 25 kg microsatellites.

*Site Code:

CC = Cape Canaveral, FL, USA 
ED = Edwards AFB, California, USA
GA = Gando, Canary Islands, Spain
KC = Kennedy Space Center, FL, USA
KW = Kwajalein, Marshall Is.
WI = Wallops Island 
VA = Vandenberg AFB, CA, USA

**Orbit Code:

EEO = Elliptical Earth Orbit
EEO/M = Molynia (12-hr) Elliptical Earth Orbit
FTO = Failed to Orbit
FSO = Failed Suborbital
GTO = Geosynchronous Transfer Orbit
GTO+ = Supersynchronous or High Perigee Transfer Orbit
GTO- = Subsynchronous Transfer Orbit
GTOi = Inclined GTO
GEO = Geosynchronous Orbit
HCO = Heliocentric (solar) Orbit
HTO = High Earth Transfer Orbit
LEO = Low Earth Orbit
LEO/R = Retrograde LEO
LEO/S = Sun Synchronous Low Earth Orbit
LEO/P = Polar Low Earth Orbit
MEO = Medium Earth Orbit
MTO = Medium Earth Transfer Orbit 
SUB = Suborbital


Pegasus User's Guide, Release 4.0, Oribital Sciences Corp, 1998

Last Update: July 6, 2016