Military Wiki
RM-86 Exos
Exos PWN-4A.jpg
Function Sounding rocket
Manufacturer University of Michigan
Country of origin United States
Height 12.941 metres (42 ft 5.5 in)
Diameter 580 millimetres (22.9 in)
Mass 2,660 kilograms (5,870 lb)
Stages Three
Launch history
Status Retired
Launch sites Eglin AFB
Total launches 10
Successes 9
Failures 1
First flight June 26, 1958
Last flight November 2, 1965

The Exos, originally designated RM-86 and later PWN-4, was a sounding rocket developed by the University of Michigan and NACA for use by the United States Air Force.


Developed by the University of Michigan for use by the Air Force Cambridge Research Center, Exos used a three-stage configuration, consiting of a first stage rocket from an Honest John rocket, a second stage from a Nike-Ajax surface-to-air missile, and a Thiokol XM19 upper stage.[1] It was designated XRM-86 in April 1959, and redesignated PWN-4A in June 1963.[2]

Utilising a rail launcher, the first launch of a full Exos vehicle took place in June 1958,[2] launched from the Wallops Flight Facility.[3] Eight operational launches took place between 1960 and 1965, launched from Eglin Air Force Base.[4]

Launch history

Date/Time (GMT) Rocket Launch site Outcome Apogee Mission[4]
1958-06-26 Exos Wallops Island Sucess 370 kilometres (230 mi) Test launch
1958-09-25 Exos Wallops Island Sucess 460 kilometres (290 mi) Test launch
1960-02-19 Exos Eglin AFB Failure Apogee 37 kilometres (23 mi) Chemical release research
1961-08-11 Exos Eglin AFB Success Apogee 114 kilometres (71 mi) Ionospheric research
1962-08-03 Exos Eglin AFB Success Apogee 365 kilometres (227 mi) Bipolar Probe ionospheric research
1962-10-25 Exos Eglin AFB Success Apogee 669 kilometres (416 mi) Ionospheric research
1963-07-25 Exos Eglin AFB Success Apogee 623 kilometres (387 mi) Ionospheric research
1965-05-25 Exos Eglin AFB Success Apogee 488 kilometres (303 mi) Ionospheric research
1965-11-02 Exos Eglin AFB Success Apogee 686 kilometres (426 mi) International Quiet Sun Year aeronomy mission


  1. Skoog and Hall 1990, p.214.
  2. 2.0 2.1 Parsch 2002
  3. Shortal 1978, p.581.
  4. 4.0 4.1 Wade, Mark. "Exos". Encyclopedia Astronautica. Accessed 2014-05-11.
  • Parsch, Andreas (2002). "University of Michigan RM-86/PWN-4 Exos". Directory of U.S. Military Rockets and Missiles. Retrieved 2014-05-11. 
  • Shortal, Joseph Adams (1978). A New Dimension, Wallops Island Flight Test Range: The First Fifteen Years. Hampton, VA: National Aeronautics and Space Administration. ASIN B004VJHCKC. 
  • Skoog, Å. Ingemar and R. Cargill Hall, ed (1990). History of Rocketry and Astronautics: Proceedings of the Twelfth, Thirteenth and Fourteenth History Symposia of the International Academy of Astronautics. AAS History Series. 10. Springfield, Virginia: American Astronautical Society. ISBN 978-0877033295. 

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