Overview

“Kaguya” (SELENE) is a lunar exploration mission led by the Japan Aerospace Exploration Agency (JAXA), aimed at elucidating the origin and evolution of the Moon. It was launched on September 14, 2007, and concluded operations on June 10, 2009. This mission was designed to conduct detailed observations of the lunar surface, internal structure, magnetic and plasma environments, and gravity field. “Kaguya” was placed into lunar orbit and was equipped with various observation instruments.

“Kaguya” consists of a main satellite orbiting in a polar circular orbit at an altitude of approximately 100 km and two sub-satellites (“Okina” relay satellite and “Ouna” VRAD satellite) in higher elliptical orbits. The main satellite measures about 2.1m x 2.1m x 4.8m and weighs approximately 3 tons. At the end of the mission, it was deliberately impacted on the near side of the Moon on June 11, 2009.

Observation Instruments

XRS (X-Ray Fluorescence Spectrometer)

XRS is an instrument that observes fluorescent X-rays emitted from the lunar surface. This allows for the analysis of the elemental composition of the lunar surface. XRS is capable of detecting elements such as magnesium, aluminum, and silicon.

GRS (Gamma-Ray Spectrometer)

GRS is an instrument that observes gamma rays emitted from the lunar surface. This enables a detailed analysis of the elemental composition of the lunar surface. GRS can detect radioactive elements such as uranium, thorium, and potassium.

MI (Multiband Imager)

MI is a camera that captures images of the lunar surface in multiple wavelength bands. This facilitates detailed analysis of the lunar mineral composition and geological structures. MI covers wavelengths from visible light to near-infrared.

SP (Spectral Profiler)

SP is an instrument that performs high-resolution spectral observations of the lunar surface. This allows for detailed analysis of the lunar mineral composition. SP covers wavelengths from visible light to near-infrared.

TC (Terrain Camera)

TC is a camera that captures high-resolution images of the lunar surface. This enables detailed mapping of the lunar terrain and geological structures. TC can also perform stereoscopic imaging to create three-dimensional topographic maps of the Moon.

LRS (Lunar Radar Sounder)

LRS is a radar instrument designed to probe the lunar subsurface structure. This allows for detailed analysis of subsurface layers and lava flow distributions. LRS uses VHF band radio waves.

LMAG (Lunar Magnetometer)

LMAG is an instrument that observes the lunar magnetic field. This helps elucidate the internal structure and origin of the lunar magnetic field. LMAG uses a high-sensitivity magnetometer.

LALT (Laser Altimeter)

LALT is a laser altimeter used to measure the altitude of the lunar surface. This enables the creation of detailed topographic maps of the Moon. LALT measures altitude by emitting laser light to the lunar surface and analyzing the reflected light.

PACE (Plasma energy Angle and Composition Experiment)

PACE is an instrument that observes the magnetic and plasma environment around the Moon. This allows for detailed analysis of the plasma density and temperature around the Moon. PACE measures the energy distribution of ions and electrons.

CPS (Charged Particle Spectrometer)

CPS is an instrument that observes high-energy particles around the Moon. This enables detailed analysis of the radiation environment around the Moon. CPS can measure the effects of solar wind and cosmic rays.

RS (Radio Science)

RS is an instrument used to precisely measure the lunar gravity field. This helps elucidate the internal structure and mass distribution of the Moon. RS measures the gravity field by utilizing the Doppler shift of radio waves.

UPI (Upper Atmosphere and Plasma Imager)

UPI is an instrument that observes the upper atmosphere and plasma around the Moon. This allows for detailed analysis of the dynamics of the atmosphere and plasma around the Moon. UPI uses ultraviolet and visible light for observations.

VRAD (VLBI Radio Source)

VRAD is an instrument that uses VLBI (Very Long Baseline Interferometry) to measure the position of the Moon with high precision. This allows for detailed analysis of the lunar orbit and internal structure. VRAD conducts observations in collaboration with multiple ground stations.

HDTV (High-Definition Television Camera)

HDTV transmits high-definition images of the Earth and lunar surface from lunar orbit. This provides educational and public outreach opportunities by sharing these images alongside other scientific results.

Achievements

The “Kaguya” mission has provided a wealth of important data on the origin and evolution of the Moon. Significant achievements include detailed topographic maps and mineral composition mapping of the lunar surface, elucidation of the lunar subsurface structure, and precise measurements of the lunar magnetic field and gravity field. These data have greatly contributed to understanding the formation processes and internal structure of the Moon.