FunctionExpendable launch system
Sounding rocket
Country of originUnited States
Height24 metres (79 ft)
Diameter1.02 metres (3 ft 4 in)
Mass16,874 kilograms (37,201 lb)
Payload to LEO
Mass30 kilograms (66 lb)
Associated rockets
Launch history
Launch sitesCanaveral LC-18B
Total launches3
First flight1961-03-03
Last flight1961-11-01
First stage – Algol 1B
Powered by1 solid
Maximum thrust471 kilonewtons (106,000 lbf)
Specific impulse236 sec
Burn time40 seconds
Second stage – Castor 1A
Powered by1 solid
Maximum thrust286 kilonewtons (64,000 lbf)
Specific impulse247 sec
Burn time27 seconds
Third stage – Antares 1A
Powered by1 X-254
Maximum thrust60 kilonewtons (13,000 lbf)
Specific impulse256 sec
Burn time39 seconds
Fourth stage – Altair 1A
Powered by1 X-248A
Maximum thrust14 kilonewtons (3,100 lbf)
Specific impulse255 sec
Burn time40 seconds

The RM-90 Blue Scout II was an American sounding rocket and expendable launch system which was flown three times during 1961. It was used for two HETS test flights, and the launch of the Mercury-Scout 1 satellite for NASA. It was a member of the Scout family of rockets.

The Blue Scout II was a military version of the NASA-operated Scout X-1.


All three launches occurred from Launch Complex 18B at the Cape Canaveral Air Force Station, the same launch pad used for the Blue Scout I.

The first two launches were successfully conducted on 3 March and 12 April 1961 respectively, using vehicles D-4 and D-5. They both carried HETS A2 plasma research experiments on suborbital trajectories.

The third launch was conducted on 1 November, using vehicle D-8, with the Mercury-Scout 1 satellite for NASA, which was intended to reach low Earth orbit. The launch failed after the rocket went out of control, and was destroyed by the range safety officer 43 seconds after liftoff.


  • Wade, Mark. "Scout". Encyclopedia Astronautica. Archived from the original on September 17, 2008. Retrieved 2009-06-20.
  • Krebs, Gunter. "Scout". Gunter's Space Page. Retrieved 2009-06-20.
  • McDowell, Jonathan. "Scout". Orbital & Suborbital Launch Database. Jonathan's Space Page. Retrieved 2009-06-20.
  • Heyman, Jos; Parsch, Andreas (2007-07-09). "LTV SLV-1 Scout". Appendix 3: Space Vehicles. Directory of U.S. Military Rockets and Missiles. Retrieved 2009-06-20.