The N-I rocket[1]
FunctionCarrier rocket
ManufacturerMcDonnell Douglas (design)
Mitsubishi Heavy Industries (production)
Country of originUnited States (design)
Japan (production)
Height34 metres (112 ft)[1]
Diameter2.44 metres (8.0 ft)
Mass131,330 kilograms (289,530 lb)[1]
Stages2 or 3
Payload to LEO
Mass1,200 kilograms (2,600 lb)[1]
Payload to GTO
Mass360 kilograms (790 lb)[1]
Associated rockets
Launch history
Launch sitesLA-N, Tanegashima
Total launches7
Partial failure(s)1
First flight9 September 1975
Last flight3 September 1982
Boosters – Castor 2
No. boosters3[2]
Powered by1 TX-354-3
Maximum thrust258.9 kilonewtons (58,200 lbf)
Specific impulse262 sec
Burn time37 seconds
First stage – Thor-ELT
Powered by1 MB-3-3
Maximum thrust866.7 kilonewtons (194,800 lbf)
Specific impulse290 sec
Burn time270 seconds
Second stage
Powered by1 LE-3
Maximum thrust52.9 kilonewtons (11,900 lbf)
Specific impulse290 sec
Burn time246 seconds
Third stage (optional) – Star-37N
Powered by1 solid
Maximum thrust45 kilonewtons (10,000 lbf)
Specific impulse290 sec
Burn time42 seconds
Mock up of N-1

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.

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
1(F) 9 September 1975
Tanegashima Engineering Test Satellite I "KIKU-1"(ETS-I) 82.5kg[10] LEO Success
2(F) 29 February 1976
Tanegashima Ionosphere Sounding Satellite "UME"(ISS) 139kg[11] LEO Success
3(F) 23 February 1977
Tanegashima Engineering Test Satellite II "KIKU-2"(ETS-II) 130kg[12] GTO Success
3rd stage used
4(F) 16 February 1978
Tanegashima Ionosphere Sounding Satellite "UME-2"(ISS-b) 141kg[11] LEO Success
5(F) 6 February 1979
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
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
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


  1. ^ a b c d e Wade, Mark. "Delta". Encyclopedia Astronautica. Archived from the original on 17 August 2013. Retrieved 3 September 2008.
  2. ^ a b "JAXA Digital Archives". Japan Aerospace Exploration Agency. Archived from the original on 9 September 2009. Retrieved 1 October 2009.
  3. ^ "N-Iロケット開発の歩み". Yukihiko Takenaka, NASDA. Retrieved 10 February 2011.
  4. ^ "三菱重工 名古屋誘導推進システム製作所 事業所紹介 沿革". Mitsubishi Heavy Industries. Archived from the original on 4 July 2011. Retrieved 10 February 2011.
  5. ^ "第1部 創造性豊かな科学技術を求めて 第2章 自主技術開発への展開 第3節 先導的・基盤的科学技術分野における自主技術開発の展開 2.宇宙開発". Ministry of Education, Culture, Sports, Science and Technology. Archived from the original on 15 June 2008. Retrieved 10 February 2011.
  6. ^ Krebs, Gunter. "N-1". Gunter's Space Page. Retrieved 31 August 2008.
  7. ^ Pearlman, Robert (29 February 2016). "Space Station Command Change Is One Giant Leap (Day) for Space History". Space.com. Retrieved 2 November 2017.
  8. ^ "JAXA | N-I Launch Vehicle". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
  9. ^ a b c d e f g McDowell, Jonathan. "Thor". Orbital and Suborbital Launch Database. Jonathan's Space Report. Archived from the original on 1 August 2020. Retrieved 31 August 2008.
  10. ^ a b "JAXA | Engineering Test Satellite I "KIKU-1" (ETS-I)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
  11. ^ a b c "JAXA | Ionosphere Sounding Satellite "UME" (ISS)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
  12. ^ a b "JAXA | Engineering Test Satellite II "KIKU-2" (ETS-II)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
  13. ^ a b c "JAXA | Experimental Communications Satellites "Ayame" (ECS)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
  14. ^ a b "JAXA | Engineering Test Satellite III "KIKU-4" (ETS-III)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
  15. ^ "ISS a, b (Ume 1, 2)". Gunter's Space Page. Retrieved 18 February 2024.