Mercury-Scout 1
Function	Expendable launch system Sounding rocket
Manufacturer	Vought
Country of origin	United States
Size
Height	24 metres (79 ft)
Diameter	1.02 metres (3 ft 4 in)
Mass	16,874 kilograms (37,201 lb)
Stages	Four
Capacity
Payload to LEO
Mass	30 kilograms (66 lb)
Associated rockets
Family	Scout
Launch history
Status	Retired
Launch sites	Canaveral LC-18B
Total launches	3
Success(es)	2
Failure(s)	1
First flight	1961-03-03
Last flight	1961-11-01
First stage – Algol 1B
Powered by	1 solid
Maximum thrust	471 kilonewtons (106,000 lbf)
Specific impulse	236 sec
Burn time	40 seconds
Propellant	Solid
Second stage – Castor 1A
Powered by	1 solid
Maximum thrust	286 kilonewtons (64,000 lbf)
Specific impulse	247 sec
Burn time	27 seconds
Propellant	Solid
Third stage – Antares 1A
Powered by	1 X-254
Maximum thrust	60 kilonewtons (13,000 lbf)
Specific impulse	256 sec
Burn time	39 seconds
Propellant	Solid
Fourth stage – Altair 1A
Powered by	1 X-248A
Maximum thrust	14 kilonewtons (3,100 lbf)
Specific impulse	255 sec
Burn time	40 seconds
Propellant	Solid
[edit on Wikidata]

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.

v t e Scout rockets
Main articles	Scout family List of Scout launches
Rockets	Scout X Scout X Scout X-1 Scout X-1A Scout X-2 Scout X-2B Scout X-2M Scout X-3 Scout X-3A Scout X-3C Scout X-3M Scout X-4 Scout X-4A Scout X-5C Blue Scout Blue Scout Junior Blue Scout I Blue Scout II Later Series Scout A Scout A-1 Scout B Scout B-1 Scout D-1 Scout E-1 Scout F-1 Scout G-1 Scout 2 Test Vehicle Cancelled Scout A-2 Scout B-2 Scout C Scout 2 Other RAM-B
Launch sites	Arguello LC-A LC-D Canaveral LC-18 San Marco Vandenberg SLC-5 Wallops LA-3
Components	Alcyone Algol Altair Antares Castor MG-18 NOTS-17