Juno II

Juno II missile launched in Cape Canaveral

Juno II launched on April 27, 1961 with Explorer 11

Upper stages of the Juno II missile

The Juno-II - rocket went out of the medium-range missile PGM-19 Jupiter forth. This formed the basic level of Juno II and had been extended by 0.91 m for this purpose. A gimbal-mounted Rocketdyne S-3D was used as the engine, which was later used only slightly modified in the Thor . On the first stage, two or three were Sergeant -Feststoffoberstufen that already in the I Juno were used. After the first stage had burned out (182 s after takeoff), these were ignited by a radio pulse from the control center, which caused the Explorer S-46 to be lost due to radio interference . The variant with only two upper stages was used only once for the unsuccessful launch of the Beacon-2 satellite.

The Juno II was launched exclusively from Cape Canaveral between 1958 and 1961 . Out of a total of ten starts, only four were successful.

Rockets of this type transported two Pioneer moon probes (one false start due to premature burnout of the first stage), seven Explorer satellites (four false starts) and one beacon satellite (false start).

The Juno II could carry 41 kg in low earth orbit or 6 kg in interplanetary orbit. Due to their poor performance, no further development of this type of missile took place.

Technical specifications

	Juno-2
length	23.85 m
diameter	2.67 m
Takeoff mass	55.0 t
stages	4th
1st stage
Engine	North American Rocketdyne LR-79-NA-9
Start thrust	667.2 kN
fuel	Kerosene and LOX
Burn time	182 s
Takeoff / empty mass	54.43 / 4.53 t
length	18.38 m
diameter	2.67 m
2nd stage
Engine	11 Thiokol baby sergeant
thrust	73.4 kN
fuel	TPH
Takeoff / empty mass	327/90 kg
Burn time	6.5 s
length	1.07 m
diameter	1.22 m
3rd stage
Engine	3 Thiokol baby sergeant
thrust	24.0 kN
fuel	TPH
Takeoff / empty mass	94/28 kg
Burn time	6.5 s
length	1.07 m
diameter	1.22 m
4th stage
Engine	1 Thiokol baby sergeant
thrust	8.0 kN
fuel	TPH
Takeoff / empty mass	27/5 kg
Burn time	6.5 s
length	1.07 m
diameter	1.22 m

Start list

This is a complete launch list for the Juno II missile.

Serial No.	Date ( UTC )	Ser.-No.	stages	Launch site	payload	Type of payload	Payload in kg (gross 1 )	Orbit 2	Remarks
1	December 6, 1958	AM-11	4th	CC LC-5	Pioneer 3	Probe to fly by the moon	5.9 kg	Rises before at 102,200 km height it falls back and after 38 hours burn up	Partial success First stage switched off too early.
2	March 3, 1959	AT THE 14TH	4th	CC LC-5	Pioneer 4	Probe to fly by the moon	5.9 kg	Heliocentric	success
3	July 16, 1959	AT 16	4th	CC LC-5	Explorer S-1	Research satellite	42 kg	planned: LEO	Failure to lose control of the missile after about 5 seconds.
4th	August 14, 1959	AM-19B	3	CC LC-26B	Beacon 2	Balloon satellite	5 kg	planned: LEO	Failure First stage shut down too soon. No control over the upper levels.
5	October 13, 1959	AM-19A	4th	CC LC-5	Explorer 7 (S-1a)	Research on cosmic rays	42 kg	LEO	success
6th	March 23, 1960	AM-19C	4th	CC LC-26B	Explorer (8) (S-46)	Exploration of the radiation belt	16 kg?	planned: LEO	Failure defect in the second stage. Third stage did not ignite, loss of contact with the ground station.
7th	November 3, 1960	AM-19D	4th	CC LC-26B	Explorer 8 (S-30)	Ionospheric research	41 kg	LEO	success
8th	February 25, 1961	AM-19F	4th	CC LC-26B	Explorer (10) (S-45)	Ionospheric research	34 kg	planned: LEO	Third stage failure did not ignite.
9	April 27, 1961	AM-19E	4th	CC LC-26B	Explorer 11 (S-15)	Gamma ray research	37 kg	LEO	success
10	May 24, 1961	AM-19G	4th	CC LC-26B	Explorer (12) (S-45a)	Ionospheric research	34 kg	planned: LEO	Second stage failure failed.

¹ Gross weight = (satellites + adapter, housing etc.)

² NOT necessarily the target orbit of the payload - but the path on which the payload is to be deployed from the upper stage.

Web links

Commons : Juno II  - collection of pictures, videos and audio files

• Juno II in the Encyclopedia Astronautica (English)

Individual evidence

1. ↑ http://www.bernd-leitenberger.de/pioneer.shtml