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). The vehicle used a Long Tank Thor first stage derived from the PGM-17 Thor intermediate-range ballistic missile, a Mitsubishi Heavy Industries-designed LE-3 engine on the second stage,[3][4][5] and three Castor 2 solid rocket motors. An optional third stage, the Star-37N solid motor, was used on three of the seven launches.
Seven N-I rockets were launched between 1975 and 1982, after which the vehicle was replaced by the N-II. Six launches were successful. The fifth flight failed after the payload and third stage collided shortly after separation.
On 29 February 1976, the second N-I launch conducted the only orbital launch on a leap day, as of February 2024.[6]
Launch history

| Flight | Date (UTC) | Launch site | Payload[7] | Payload mass | Orbit | Outcome |
|---|---|---|---|---|---|---|
| F1 | 9 September 1975 05:30[8] |
Tanegashima, Osaki | ETS-I | 82.5 kg (182 lb)[9] | LEO | Success |
| ETS-I (Engineering Test Satellite I, nicknamed Kiku-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.[9] It ceased operations on 28 April 1982. | ||||||
| F2 | 29 February 1976 03:30[8] |
Tanegashima, Osaki | ISS | 139 kg (306 lb)[10] | LEO | Success |
| ISS (Ionosphere Sounding Satellite, nicknamed UME) was used to monitor radio waves in the ionosphere and forecast conditions for shortwave communications.[10] A power supply issue caused Ume to stop functioning one month after launch.[11] | ||||||
| F3 | 23 February 1977 08:50[8] |
Tanegashima, Osaki | ETS-II | 130 kg (290 lb)[12] | GTO | Success |
| 3rd stage used. ETS-II (Engineering Test Satellite II, nicknamed 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. | ||||||
| F4 | 16 February 1978 04:00[8] |
Tanegashima, Osaki | ISS-b | 141 kg (311 lb)[10] | LEO | Success |
| ISS-b (Ionosphere Sounding Satellite b, nicknamed 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. | ||||||
| F5 | 6 February 1979 08:46[8] |
Tanegashima, Osaki | ECS | 130 kg (290 lb)[13] | GTO | Failure |
| 3rd stage used. ECS (Experimental Communications Satellite, nicknamed Ayame). Satellite and third stage collided shortly after separation.[13] The satellite had the intention of conducting millimeter wave experiments. | ||||||
| F6 | 22 February 1980 08:35[8] |
Tanegashima, Osaki | ECS-b | 130 kg (290 lb)[13] | GTO | Success |
| 3rd stage used. ECS-b (Experimental Communications Satellite b, nicknamed Ayame-2). Repeat of the ECS mission. Satellite stopped transmitting shortly after separation. | ||||||
| F9[a] | 3 September 1982 05:00[8] |
Tanegashima, Osaki | ETS-III | 385 kg (849 lb)[14] | LEO | Success |
| ETS-III (Engineering Test Satellite III, nicknamed Kiku-4) was developed to acquire data on designing earth observation satellites with high power requirements.[14] ETS-III 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. | ||||||
- ↑ Flights 7 and 8 used the N-II rocket
See also
References
- 1 2 3 4 5 Wade, Mark. "Delta". Encyclopedia Astronautica. Archived from the original on 17 August 2013. Retrieved 3 September 2008.
- ↑ "JAXA Digital Archives". Japan Aerospace Exploration Agency. Archived from the original on 9 September 2009. Retrieved 1 October 2009.
- ↑ Takenaka, Yukihiko. "N-Iロケット開発の歩み" [The Development History of the N-I Rocket] (in Japanese). NASDA. Retrieved 10 February 2011.
- ↑ "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, Ltd. — Nagoya Guidance & Propulsion Systems Works: Site Overview — History] (in Japanese). Mitsubishi Heavy Industries. Archived from the original on 4 July 2011. Retrieved 10 February 2011.
- ↑ "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" [Part 1: In Pursuit of Creative Science and Technology — Chapter 2: Advancing Independent Technology Development — Section 3: The Development of Independent Technology in Leading and Fundamental Scientific and Technological Fields — 2. Space Development] (in Japanese). Ministry of Education, Culture, Sports, Science and Technology. Archived from the original on 15 June 2008. Retrieved 10 February 2011.
- ↑ Pearlman, Robert (29 February 2016). "Space Station Command Change Is One Giant Leap (Day) for Space History". Space.com. Retrieved 2 November 2017.
- ↑ "N-I Launch Vehicle". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
- 1 2 3 4 5 6 7 McDowell, Jonathan. "Thor". Orbital and Suborbital Launch Database. Jonathan's Space Report. Archived from the original on 1 August 2020. Retrieved 31 August 2008.
- 1 2 "Engineering Test Satellite I "KIKU-1" (ETS-I)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
- 1 2 3 "Ionosphere Sounding Satellite "UME" (ISS)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
- ↑ "ISS a, b (Ume 1, 2)". Gunter's Space Page. Retrieved 18 February 2024.
- 1 2 "Engineering Test Satellite II "KIKU-2" (ETS-II)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
- 1 2 3 "Experimental Communications Satellites "Ayame" (ECS)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.
- 1 2 "Engineering Test Satellite III "KIKU-4" (ETS-III)". JAXA | Japan Aerospace Exploration Agency. Retrieved 18 February 2024.