Kaguya (SELENE)

Kaguya (SELENE)
Name	Kaguya (SELENE)
Mission type	Lunar orbiter
Operator	JAXA
COSPAR ID	2007-039A
SATCAT	32272
Mission duration	Planned: 1 year, Final: 1 year, 8 months
Spacecraft	SELENE
Manufacturer	NEC, Mitsubishi Electric
Launch mass	2,914 kg
Dry mass	1,984 kg
Power	3,486 watts
Launch date	14 September 2007, 01:31:01 UTC
Launch rocket	H-IIA (H-IIA2022)
Launch site	Tanegashima Space Center, Yoshinobu Launch Complex
Disposal type	Controlled impact
Impacted	10 June 2009, 18:25 UTC
Impacted site	Gill crater region
Orbit reference	Selenocentric orbit
Orbit regime	Polar orbit
Orbit periapsis	100 km
Orbit apoapsis	100 km
Orbit inclination	90°
Orbit period	~118 minutes
Apsis	selene
Programme	SELENE program
Previous mission	Hiten
Next mission	SELENE-2

Kaguya (SELENE). The **SELenological and ENgineering Explorer**, known as **Kaguya**, was a flagship lunar orbiter mission developed and operated by the Japan Aerospace Exploration Agency. Launched in 2007, it was Japan's largest and most sophisticated lunar probe since the Hiten mission, designed to conduct comprehensive scientific observations of the Moon's surface, interior, and environment. Its successful operation yielded a wealth of data that significantly advanced global selenology and influenced subsequent international lunar exploration programs.

Overview

The mission was a cornerstone project for JAXA, representing a major technological leap for the nation's deep space capabilities following earlier missions like Nozomi. Named after a lunar princess from the Japanese folktale *The Tale of the Bamboo Cutter*, the spacecraft aimed to provide a detailed global understanding of the Moon to address key questions in planetary science. Its development involved major Japanese aerospace contractors including NEC and Mitsubishi Electric, and it was launched from the Tanegashima Space Center aboard a powerful H-IIA rocket.

Mission objectives

Primary scientific goals included investigating the Moon's origin and evolution, its surface composition, and the structure of its interior. Key objectives were to create high-resolution topographical and mineralogical maps, study the lunar gravity field in unprecedented detail, and characterize the lunar plasma environment and electromagnetic field. The mission also carried technology demonstration payloads, such as a high-definition television camera system provided by NHK, to support future exploration planning and public engagement.

Spacecraft design and instruments

The main orbiter, weighing nearly three metric tons, was accompanied by two smaller satellites: the Okina relay satellite and the Ouna Very Long Baseline Interferometry satellite. Its suite of fifteen scientific instruments included the Terrain Camera, the Lunar Radar Sounder to probe subsurface structures, the Spectral Profiler for mineralogy, and the Lunar Magnetometer. Other critical payloads were the Differential VLBI Radio Source for precise gravity measurements and the X-ray spectrometer developed in collaboration with agencies like the European Space Agency.

Mission profile and timeline

Launched on 14 September 2007, the spacecraft performed a phasing orbit maneuver before entering a nominal 100 km circular polar orbit around the Moon in October 2007. The **Okina** satellite was deployed into a higher elliptical orbit to facilitate precise gravity measurements of the lunar far side. The primary mission lasted one year, after which an extended phase lowered the orbit for higher-resolution observations. The mission concluded on 10 June 2009 with a planned controlled impact into the Gill crater region near the lunar south pole, observed by telescopes like the Hawaiian-based Canada-France-Hawaii Telescope.

Scientific discoveries and results

**Kaguya** provided the first global, high-resolution topographic map of the Moon using its Laser Altimeter, revealing complex structures like the massive South Pole–Aitken basin. Its gravity data, particularly from the far side, offered new insights into the lunar crust's thickness and the presence of mascons. The mission detected uranium and thorium signatures across the surface, identified possible olivine-rich sites, and captured the first high-definition video of an Earthrise from lunar orbit. It also made detailed observations of the tenuous lunar atmosphere and its interaction with the solar wind.

Legacy and impact

The mission's extensive dataset, archived with organizations like the Planetary Data System, remains a fundamental resource for lunar science, informing missions such as NASA's Lunar Reconnaissance Orbiter and Chandrayaan-1. Its technological heritage directly contributed to Japan's subsequent lunar and planetary missions, including the planned Martian Moons eXploration mission and the **SELENE-2** lander project. **Kaguya**'s public outreach, especially its stunning imagery, played a significant role in revitalizing global public and political interest in lunar exploration during the early 21st century.

Category:Spacecraft launched in 2007 Category:Japanese Lunar probes Category:JAXA space probes