Ronald Hatcher.

Introduction

The Baby rocket was a foundational milestone in Japan’s postwar space development. Baby followed the success of the Pencil Rocket, Japan’s first experimental rocket flown in 1954. In the words of Itokawa himself, “We had nothing after the war — no rockets, no knowledge, no funding. But we had spirit and curiosity.”¹

Launched from a beach in Akita Prefecture, the Baby rocket series included three variants—Baby-S, Baby-T, and Baby-R—each focusing on a critical experimental function. Though small (1.2 metres long), Baby’s achievements paved the way for Japan’s future launch vehicles like the Kappa and Lambda series.

Background

After the success of the Pencil Rocket in 1954, Itokawa’s team sought to build a larger test vehicle capable of reaching higher altitudes. The Baby rocket was conceived as Japan’s first practical sounding rocket and was designed in anticipation of the International Geophysical Year² (1957–1958). Baby used solid propellant, had two stages, and was launched at an angle over the Sea of Japan from a rail launcher.

Variants

Variant	Purpose	Notable Feature
S	Stability	Smoke generator for optical tracking
T	Telemetry	First Japanese rocket with a transmitter
R	Recovery	Parachute + camera; recovered at sea

Design

The design was guided by simplicity and improvisation. “The Baby was small enough to be carried by one person and fired from a wooden sled,” Itokawa wrote in a 1955 newspaper article.³

• Length: 1.2 metres
• Diameter: 80 mm
• Weight: ~10 kg
• Staging: Two-stage solid fuel
• Stabilisation: Fin-stabilised
• Guidance: None

Each Baby rocket used a high-thrust booster for initial ascent and a sustainer stage for continuation. Baby-T’s nose housed Japan’s first FM-FM telemetry system, developed by Meisei Electric⁴.

Launch History

The Baby series saw nine launches in 1955. Launches took place at Michikawa Beach, Akita, using a portable inclined launch rail.

Flight No.	Variant	Date	Apogee	Notes
1	Baby-S	6 Aug 1955	~6 km	First flight; smoke generator used for tracking.
2	Baby-S	Aug 1955	~6 km	Stability test flight.
3	Baby-S	Aug 1955	~6 km	Demonstrated stage separation.
4	Baby-T	17 Sep 1955	~6 km	First telemetry-equipped flight.
5	Baby-T	19 Sep 1955	~40 m	Second stage failed; rocket fell near pad and was disarmed manually by Toda while venting gas.5
6	Baby-T	Sep 1955	~6 km	Partial telemetry success.
7	Baby-T	Sep 1955	~6 km	Full telemetry data transmitted.
8	Baby-R	Oct 1955	~6 km	Parachute deployed; camera failed.
9	Baby-R	4 Dec 1955	~6 km	Successful recovery; payload and charm retrieved from sea.

Sources: JAXA History, JAXA Interview

Legacy

The Baby rocket programme was more than a stepping stone — it was a declaration of Japan’s renewed scientific ambitions after World War II. Though Baby stood just 1.2 metres tall, it carried the hopes of a country rebuilding its technical infrastructure from near-zero. It demonstrated for the first time in Japan the coordinated success of multistage propulsion, telemetry, and recovery.

Baby led directly to the development of the Kappa sounding rocket series, which reached altitudes exceeding 200 km by the early 1960s. The lessons from Baby also shaped the Lambda series, culminating in the launch of Ōsumi, Japan’s first satellite, in 1970 — making Japan the fourth nation to place a satellite into orbit with its own technology.

The team behind Baby, including figures like Hideo Itokawa, Yasuaki Toda, and Yasunori Matogawa, would go on to lead generations of space engineers and scientists. Many of their students and colleagues later contributed to Japan’s planetary missions, including Sakigake, Hayabusa, and the H-II launch vehicle series.

The Baby rocket’s influence extended beyond sounding rockets. It laid the groundwork for Japan’s first orbital-class rocket, the Lambda 4S, which launched the Ōsumi satellite. Technologies and development strategies initiated during Baby’s era reappeared in the Mu series, particularly the Mu-3H and Mu-5 used for scientific satellite launches. Baby also influenced the methodology behind the H-IIA and H-IIB launch vehicles developed by JAXA, and inspired miniature launch platforms like SS-520, which drew on early solid-fuel principles proven in Baby. Even Japan’s planetary missions — including Sakigake, Suisei, Nozomi, and Hayabusa — carry traces of the experimental, iterative spirit established by Itokawa’s team in 1955.

The Baby rocket has also become an enduring symbol of postwar ingenuity. Its story is still taught in aerospace engineering courses, and a preserved Baby-T rocket is displayed at the National Museum of Nature and Science in Tokyo. There, visitors can see its charred nosecone and finned tail — silent witnesses to the moment Japan’s space ambitions began to take flight.

Most importantly, Baby’s legacy lives on in the culture of Japanese aerospace. The rocket’s development model — rapid iteration, small teams, and emphasis on learning through doing — continues to inform Japan’s approach to experimental spacecraft and planetary science today.

As Matogawa once reflected, “It wasn’t just about building a rocket. It was about building the people who would shape the future of Japan’s science and technology.”

Stories and Reflections

The early days of Japan’s rocket development were marked by modest tools and enormous ambition. On remote beaches, young engineers launched fragile vehicles they had built by hand, guided more by intuition and courage than equipment. These moments — equal parts scientific and deeply personal — gave rise to a national space programme. The following stories offer a glimpse into the human side of the Baby rocket era.

“We had nothing after the war — no rockets, no knowledge, no funding. But we had spirit and curiosity.”
— Hideo Itokawa¹

Professor Itokawa’s words encapsulate the spirit behind the Baby rocket programme. Launched just a decade after Japan's defeat in World War II, Baby was more than a research vehicle — it was a statement of resilience. The team had no radar, no telemetry infrastructure, and little funding. But they had ideas, enthusiasm, and a willingness to take risks on the edge of a beach in Akita.

“Everyone was nervous. We didn’t know if it would blow up on the rail or soar into the sea — but we were determined to learn either way.”
— Yasunori Matogawa, on the first Baby-T launch²

Before the Baby-T flight, tension ran high. The rocket carried Japan’s first FM-FM telemetry system — a marvel packed into a body shorter than a broom handle. The team huddled inside the so-called kamaboko hut, a corrugated metal shelter barely large enough for a few engineers and a field radio. They counted down with a stopwatch and waited. When the rocket leapt from the rail, it felt like Japan itself had taken its first scientific step skyward.

“It looked like a fish cake. It was cramped, hot, and filled with anticipation.”
— Matogawa, describing the kamaboko hut²

The launch facility at Michikawa Beach was little more than a rail launcher, some optical tracking gear, and this makeshift hut. Inside, engineers took shelter from their own experiments, sweating in silence during countdowns, then erupting in cheers or quiet sighs when the rocket disappeared into the sky. Their equipment was handmade, their expertise self-taught, and yet they achieved results that rivalled more experienced programmes abroad.

“Everyone else was rooted in place, but he just acted.”
— Matogawa, recalling Yasuaki Toda³

When the Baby-T rocket failed to ignite its second stage and crash-landed back on the beach, panic hung thick in the air. Smoke hissed from the rocket casing. No one moved — except Yasuaki Toda. Without orders or hesitation, he crawled through the sand to reach the still-live projectile and disconnected the igniter by hand. It wasn’t just bravery. It was instinct, trust in his training, and an unspoken bond shared by a team pushing the limits of what was possible.

“Even science needs its share of luck and rituals.”
— Hideo Itokawa⁴

For the final Baby-R flight, the engineers added a small omamori — a traditional Japanese good luck charm — from Itokawa’s car. It flew alongside a film camera, and though the camera failed, the payload was recovered from the sea intact, the charm still dry inside its casing. This blend of science and superstition underscored their work: empirical, but deeply human.

Footnotes

1. Hideo Itokawa, quoted in ISAS Rocket History Archive, 1955. ↩ ↩²

2. Yasunori Matogawa, “Pencil Rocket Story”, JAXA Global Interview: https://global.jaxa.jp/article/interview/sp1/episode-5_p1_e.html ↩ ↩² ↩³

3. “Professor Itokawa's essay in Mainichi News”, January 3, 1955. ISAS Archive. ↩ ↩²

4. JAXA Global Interview Series, Matogawa recounting Toda’s actions: https://global.jaxa.jp/article/interview/sp1/episode-5_p1_e.html ↩ ↩²

5. JAXA Global Interview Series, Matogawa recounting Toda’s actions: https://global.jaxa.jp/article/interview/sp1/episode-5_p1_e.html ↩