N-I (rocket)

This article is about the Japanese rocket. For the Soviet rocket, see N1 (rocket).

The N-I or N-1 was a derivative of the American Thor-Delta rocket, produced under license in Japan. The N stood for "Nippon" (Japan). It used a Long Tank Thor first stage, a Mitsubishi Heavy Industries-designed LE-3 engine on the second stage,^[3][4][5] and three Castor SRMs.^[2][6] Seven were launched between 1975 and 1982, before it was replaced by the N-II. Six of the seven launches were successful, however on the fifth flight, there was recontact between the satellite and the third stage, which caused the satellite to fail.

N-I

The N-I rocket[1]
Function	Carrier rocket
Manufacturer	McDonnell Douglas (design) Mitsubishi Heavy Industries (production)
Country of origin	United States (design) Japan (production)
Size
Height	34 metres (112 ft)[1]
Diameter	2.44 metres (8.0 ft)
Mass	131,330 kilograms (289,530 lb)[1]
Stages	2 or 3
Capacity
Payload to LEO
Mass	1,200 kilograms (2,600 lb)[1]
Payload to GTO
Mass	360 kilograms (790 lb)[1]
Associated rockets
Family	Delta
Launch history
Status	Retired
Launch sites	Tanegashima, Osaki
Total launches	7
Success(es)	6
Partial failure(s)	1
First flight	9 September 1975
Last flight	3 September 1982
Boosters – Castor 2
No. boosters	3[2]
Powered by	1 TX-354-3
Maximum thrust	258.9 kilonewtons (58,200 lbf)
Specific impulse	262 sec
Burn time	37 seconds
Propellant	Solid
First stage – Thor-ELT
Powered by	1 MB-3-3
Maximum thrust	866.7 kilonewtons (194,800 lbf)
Specific impulse	290 sec
Burn time	270 seconds
Propellant	RP-1/LOX
Second stage
Powered by	1 LE-3
Maximum thrust	52.9 kilonewtons (11,900 lbf)
Specific impulse	290 sec
Burn time	246 seconds
Propellant	NTO/A-50
Third stage (optional) – Star-37N
Powered by	1 solid
Maximum thrust	45 kilonewtons (10,000 lbf)
Specific impulse	290 sec
Burn time	42 seconds
Propellant	Solid

Mock up of N-1

On 29 February 1976, the second N-I conducted the only orbital launch, as of 17 February 2024, to occur on a leap day.^[7]

Launch history

Flight No.	Date / time (UTC)	Launch site	Payload[8]	Payload mass	Orbit	Launch outcome
1(F)	9 September 1975 05:30[9]	Tanegashima	Engineering Test Satellite I "KIKU-1"(ETS-I)	82.5kg[10]	LEO	Success
2(F)	29 February 1976 03:30[9]	Tanegashima	Ionosphere Sounding Satellite "UME"(ISS)	139kg[11]	LEO	Success
3(F)	23 February 1977 08:50[9]	Tanegashima	Engineering Test Satellite II "KIKU-2"(ETS-II)	130kg[12]	GTO	Success
	3rd stage used
4(F)	16 February 1978 04:00[9]	Tanegashima	Ionosphere Sounding Satellite "UME-2"(ISS-b)	141kg[11]	LEO	Success
5(F)	6 February 1979 08:46[9]	Tanegashima	Experimental Communications Satellites "Ayame"(ECS)	130kg[13]	GTO	Partial failure
	3rd stage used; Recontact between satellite and upper stage.
6(F)	22 February 1980 08:35[9]	Tanegashima	Experimental Communications Satellites "Ayame-2"(ECS-b)	130kg[13]	GTO	Success
	3rd stage used; Satellite failed shortly after separation.
9(F)	3 September 1982 05:00[9]	Tanegashima	Engineering Test Satellite III "KIKU-4"(ETS-III)	385kg[14]	LEO	Success

Payload Descriptions

Engineering Test Satellite I "KIKU-1" (ETS-1)

ETS-1 was the first satellite launched by the NASDA. It had the objective of acquiring information on N-series launch vehicles, orbit injection, and tracking and control.^[10] It ceased operations on 28 April 1982.

Ionosphere Sounding Satellite "UME" (ISS)

UME was Japan's first Ionosphere Sounding Satellite.^[11] It was used to monitor radio waves in the ionosphere and forecast conditions for shortwave communications. A power supply issue caused Ume to stop functioning one month after launch.^[15]

Engineering Test Satellite II "KIKU-2" (ETS-2)

KIKU-2 was NASDA's first satellite launched to GEO.^[12] It was intended to gather data on geostationary satellite launch, tracking, control, orbit maintenance, and attitude control as well as carrying out experiments on communications equipment. KIKU-2 ceased operations on 10 December 1990, leaving GEO.

Ionosphere Sounding Satellite "UME-2" (ISS-b)

UME-2 had similar goals to the original UME satellite, but was much more successful in carrying them out. While it was originally intended to gather data for only a year and a half, UME-2 ceased operations on 23 February 1983.

Experimental Communications Satellites "Ayame/Ayame-2" (ECS/ECS-b)

Both ECS satellites were unsuccessful in completing their mission. During the first ECS launch, the third stage rocket collided with the satellite shortly after separation. During the ECS-2 launch, the satellite stopped transmitting shortly after separation. The satellites had the intention of conducting millimeter wave experiments. The JAXA website states that "we learned some valuable lessons on satellite separation technology and apogee engine from this experience".^[13]

About Engineering Test Satellite III "KIKU-4" (ETS-III)

KIKU-4 was developed to acquire data on designing earth observation satellites with high power requirements.^[14] KIKU-4 completed testing of three-axis attitude control, deployable solar panels, movable heat control, and ion engine operation. On 8 April 1985, the satellite ran out of fuel and ceased operation.

See also

• Comparison of orbital launchers families
• Delta rocket
• H-I
• H-II
• H-IIA
• N-II (rocket)
• PGM-17 Thor