Japan launched the Kaguya spacecraft on Sept. 13, 2007, initiating a lunar exploration effort designed to map the moon’s surface and study its gravitational field, according to mission records. Formally designated as SELENE, which stands for SELenological and ENgineering Explorer, the probe lifted off from the Tanegashima Space Center aboard a Japanese H-IIA rocket, marking the nation’s second overall moon mission and its first spacecraft to enter lunar orbit.
Mission Architecture and Spacecraft Components
The Kaguya mission relied on a trio of spacecraft to gather comprehensive data about Earth’s nearest neighbor. According to mission parameters, the assembly included a main orbiter, a small communications satellite named Okina, and a third small satellite dedicated to gravity mapping named Ouna. The spacecraft carried 14 distinct science instruments. Following a 20-day transit after its launch—which occurred at 10:31 a.m. on Sept. 14 at the local launch site—the fleet arrived in lunar orbit to begin roughly a year of planned observations.
Technological Evolution from Hiten to Kaguya
Kaguya represented a technological leap forward compared to Japan’s earlier lunar endeavors. Japan’s previous lunar probe, Hiten, launched in 1990 and utilized a highly elliptical Earth orbit to execute 10 lunar flybys before crashing into the surface in 1993, alongside its small accompanying probe, Hagoromo. While Hiten and Hagoromo tested foundational technologies, Kaguya put those systems into operational practice. Shortly after liftoff, the main probe was renamed Kaguya after the moon princess Kaguya-hime from a traditional Japanese folktale, following a public polling process.
Did you know? Kaguya captured the first-ever high-definition video and images of the moon, including rare views of Earthrise—a phenomenon not documented visually since NASA’s Apollo missions.
Scientific Discoveries and Public Impact
Beyond capturing high-definition footage of the lunar horizon and Earthrises, the spacecraft achieved several cartographic and geological milestones. According to a NASA review of the mission, Kaguya generated a complete topographical map of the moon, identified gravity anomalies on both the near and far sides, and recorded the first optical observations inside the permanently shadowed interior of Shackleton Crater near the lunar south pole. Additional analysis of data from the probe also indicated the presence of oxygen originating from Earth on the lunar surface, as reported by mission scientists.
Mission Conclusion and Impact of Mechanical Failure
Kaguya successfully completed its primary mission objectives in October 2008. Although mission planners at the Japan Aerospace Exploration Agency (JAXA) hoped to extend operations through early 2009, a faulty reaction wheel forced teams to cut the extension short. Operators directed the spacecraft into a planned crash landing on the lunar surface near Gill Crater on Feb. 12, 2009, concluding its active observational career.
Frequently Asked Questions
When was the Kaguya spacecraft launched?
Kaguya launched on Sept. 13, 2007, Eastern Time, which corresponded to the morning of Sept. 14 at the Tanegashima Space Center in Japan.
What does SELENE stand for?
SELENE stands for SELenological and ENgineering Explorer, which was the formal designation for Japan’s Kaguya moon mission.
How did the Kaguya mission end?
The mission concluded with a planned impact on the lunar surface near Gill Crater on Feb. 12, 2009, after a faulty reaction wheel prompted JAXA to end the mission early.
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