SELENE

SELENE (/ˈsɛlɪniː/; Selenological and Engineering Explorer), better known in Japan by its nickname Kaguya (かぐや), was the second Japanese lunar orbiter spacecraft following the Hiten probe.[2] Produced by the Institute of Space and Astronautical Science (ISAS) and the National Space Development Agency (NASDA), the spacecraft was launched on September 14, 2007. After successfully orbiting the Moon for a year and eight months, the main orbiter was instructed to impact on the lunar surface near the crater Gill on June 10, 2009.[3]

For the second SELENE series lunar spacecraft, see SELENE-2. For other uses, see Selene (disambiguation).

Kaguya
Mission typeLunar orbiter
OperatorJAXA
COSPAR ID2007-039A
SATCAT no.32054
Mission duration1 year and 9 months (launch date to decay date)
Spacecraft properties
ManufacturerNEC Toshiba Space Systems
Launch mass2,914 kilograms (6,424 lb)
Power3,486 watts
Start of mission
Launch dateSeptember 14, 2007, 01:31:01 (2007-09-14UTC01:31:01Z) UTC
RocketH-IIA 2022 F13
Launch siteTanegashima Yoshinobu 1
ContractorMitsubishi
End of mission
Decay dateJune 10, 2009, 18:25 (2009-06-10UTC18:26Z) UTC
Orbital parameters
Reference systemSelenocentric
Periselene altitude281 kilometres (175 mi)[1]
Aposelene altitude231,910 kilometres (144,100 mi)[1]
Inclination29.9 degrees[1]
Period7109.28 seconds[1]
EpochSeptember 29, 2007[1]
Lunar orbiter
Orbital insertionOctober 3, 2007
Instruments
  • X-ray Spectrometer (XRS)
  • gamma-ray spectrometer (GRS)
  • Multi-band Imager (MI)
  • Spectral Profiler (SP)
  • Terrain Camera (TC)
  • Lunar Radar Sounder (LRS)
  • Laser Altimeter (LALT)
  • Lunar Magnetometer (LMAG)
  • Charged Particle Spectrometer (CPS)
  • Plasma energy Angle and Composition Experiment (PACE)
  • Radio Science (RS)
  • Upper-atmosphere and Plasma Imager (UPI)
  • Relay Satellite aboard Okina (RSAT)
  • VLBI Radio source aboard Okina and Ouna (VRAD)
  • High Definition Television cameras (HDTV)
 

Nickname

The orbiter's nickname, Kaguya, was selected by the general public. It comes from the name of a lunar princess in the ancient Japanese folktale The Tale of the Bamboo Cutter.[4] After their successful release, its sub-satellites, Rstar and Vstar, were named Okina and Ouna, also derived from characters in the tale.[5]

Mission objectives

The main scientific objectives of the mission were to:

Launch
Launch of H-IIA F13 carrying SELENE (Photo by Narita Masahiro)

SELENE launched on September 14, 2007 at 01:31:01 UTC on an H-IIA (Model H2A2022) carrier rocket from Tanegashima Space Center into a 281.55-kilometre (174.95 mi) (perigee) / 232,960-kilometre (144,750 mi) (apogee) geocentric parking orbit.[6][7] The total launch mass was 3,020 kilograms (6,660 lb).[8]

The SELENE mission was originally scheduled to launch in 2003, but rocket failures on another mission and technical difficulties delayed the launch until 2007.[9] Launch was planned for August 16, 2007, but was postponed when some electronic components were found to be installed incorrectly.[10]

Lunar operations

On October 3, it entered an initial 101-to-11,741-kilometre (63 to 7,296 mi) polar lunar orbit.[11] On October 9, the relay satellite was released into a 100-to-2,400-kilometre (62 to 1,491 mi) orbit, while on October 12 the VLBI satellite was released into a 100-to-800-kilometre (62 to 497 mi) one.[5] Finally, by October 19, the orbiter was in a circular 100-kilometre (62 mi) orbit.[12] The nominal mission duration was one year plus possible extensions.

On October 31, 2007, Kaguya deployed its Lunar Magnetometer, Lunar Radar Sounder, Earth-looking Upper Atmosphere and Plasma Imager. On December 21, 2007, Kaguya began regular operations after all fifteen observation experiments had been satisfactorily verified.

Kaguya completed the planned operation by the end of October 2008 and began extended operations planned to continue through March 2009. It would then be sent into a circular 50-kilometre (31 mi) orbit, and finally to an elliptical 20-to-100-kilometre (12 to 62 mi) one, with a controlled impact occurring by August 2009.[13] Because of a degraded reaction wheel, the plan was changed so that on February 1, 2009, the orbit was lowered to 50 kilometres (31 mi) ± 20 kilometres (12 mi),[14] and impact occurred at 18:25 UTC on June 10, 2009.[3]

Design

The mission featured three separate spacecraft:

Main orbiter[8]

Okina (small relay satellite)

Okina (formerly Rstar) and Ouna (formerly Vstar) were octagonal prisms to support radio science. Okina relayed radio communications between the orbiter and the Earth when the orbiter was behind the Moon. This allowed, for the first time, the direct Doppler shift measurements needed to precisely map the gravitational field of the lunar farside; previously, the farside gravity field could only be inferred by nearside measurements. The relay satellite impacted the lunar farside near the Mineur D crater at 19:46 JST (10:46 UTC) on February 12, 2009.[14]

  • Function: two-way radio science relay, orbiter-earth
  • Mass: 53 kilograms (117 lb)[8]
  • Size: 1.0 x 1.0 x 0.65 m (3.3 x 3.3 x 2.1 ft)
  • Attitude control: spin-stabilized
  • Power: 70 W
  • Initial orbit: 100 to 2,400 kilometres (62 to 1,491 mi)
  • Inclination: 90 degrees

Ouna (VLBI satellite)

Ouna used Very Long Baseline Interferometry as a second way to map the Moon's gravity field. It was especially useful at the lunar limb, where the gravitational acceleration is perpendicular to the line of sight to earth, making Doppler measurements unsuitable.

  • Function: VLBI radio science
  • Mass: 53 kilograms (117 lb)
  • Size: 1.0 x 1.0 x 0.65 m (3.3 x 3.3 x 2.1 ft)
  • Attitude control: spin-stabilized
  • Power: 70 W
  • Initial orbit: 100 to 800 kilometres (62 to 497 mi)
  • Inclination: 90 degrees

Payload

SELENE carried 13 scientific instruments "to obtain scientific data of the lunar origin and evolution and to develop the technology for the future lunar exploration":[15]

  • Terrain camera (TC) (resolution 10 meters [33 ft] per pixel)[16]
  • X-Ray fluorescence spectrometer (XRS)
  • Lunar magnetometer (LMAG)
  • Spectral profiler (SP) (resolution per pixel: 562 x 400 m [1840 x 1310 ft)
  • Multi-band imager (MI) (resolution of visible light 20 [66 ft] meters per pixel, near-infrared 62 meters [200 ft] per pixel)
  • Laser altimeter (LALT)
  • Lunar radar sounder (LRS)
  • Gamma ray spectrometer (GRS)
  • Charged particle spectrometer (CPS)
  • Plasma analyzer (PACE)
  • Upper atmosphere and plasma imager (UPI)
  • Radio wave repeater (RSAT) aboard Okina
  • Radio wave source for VLBI (VRAD) aboard Okina and Ouna

Two 2.2 megapixel CCD HDTV cameras, one wide-angle and one telephoto, were also on board, primarily for public relations purposes.[17]

JAXA collected names and messages that were carried on SELENE through their "Wish Upon the Moon" campaign.[18] 412,627 names and messages were printed on a sheet measuring 280 mm x 160 mm (11 x 6.3 in) at 70 µm (0.0003 in) per character. The sheet was installed under the photovoltaic modules and cooling panels beneath the multi-layered insulation.[19]

Results

Major results include:

  • Improved lunar global topography maps.[20] This detailed altitude and geological data is provided to Google for free to make Google Moon 3-D.
  • Detailed gravity map of the far side of the Moon.[21]
  • First optical observation of the permanently shadowed interior of the crater Shackleton at the lunar south pole.[22]
  • Evidence of earth's oxygen being transported to the moon via magnetospheric ions.[23]

Other lunar probes
Map of the lunar south pole showing the SELENE craft at the left.

SELENE was part of a renewed global interest in lunar exploration; it was "the largest lunar mission since the Apollo program".[24] It followed Japan's first lunar probe, Hagoromo, launched in 1990.[2][25] China launched its Chang'e 1 lunar explorer on October 24, 2007, followed by India's October 22, 2008 launch of Chandrayaan-1 and the United States Lunar Reconnaissance Orbiter in June 2009. The United States, European countries (ESA), Russia, Japan, India and China are planning future manned lunar exploration missions or lunar outpost construction on the Moon between 2018 and 2025.[26]

See also

References
  1. McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 2018-05-03.
  2. "Kaguya – Another Chapter for the Lunar Saga". Red Orbit. 2007-09-14. Retrieved 2007-09-14.
  3. "KAGUYA Lunar Impact". JAXA. Retrieved 2009-06-24.
  4. ""KAGUYA" selected as SELENE's nickname". Retrieved 2007-10-13.
  5. "KAGUYA (SELENE) / Result of the Separation of the VRAD Satellite (Vstar)" (Press release). 2007-10-12. Retrieved 2007-10-13.
  6. Emily Lakdawalla (2007-09-14). "Kaguya Rockets Toward the Moon". Retrieved 2007-09-15.
  7. MHI / JAXA. "H-IIAロケット13号機による月周回衛星「かぐや」の打上げ結果について（速報）" (PDF) (in Japanese). Retrieved 2007-09-19.
  8. "平成19年度夏期ロケット打ち上げおよび追跡管制計画書 (Rocket Launch and Tracking Control Plan, Summer 2007)" (PDF) (in Japanese). MHI / JAXA.
  9. "Japan launches first lunar probe". BBC News. 2007-09-14. Retrieved 2007-09-14.
  10. "Launch Postponement of the KAGUYA (SELENE)". 2007-07-20. Retrieved 2007-08-15.
  11. "KAGUYA (SELENE) Result of the Lunar Orbit Injection Maneuver (LOI1) - Lunar orbit injection was confirmed -" (Press release). JAXA. 2007-10-05. Retrieved 2007-10-05.
  12. "かぐや/H-IIA13号機　打上げ特設サイト" (in Japanese). Retrieved 2007-10-01.
  13. "月周回衛星「かぐや（SELENE）」の定常運用終了と後期運用計画について" (PDF) (in Japanese). 2008-11-05. Retrieved 2008-11-05.
  14. "月周回衛星「かぐや（SELENE）」の 状況について" (PDF) (in Japanese). 2009-02-18. Retrieved 2009-02-22.
  15. "Kaguya (SELENE)". JAXA. Retrieved 2007-06-25.
  16. "LISM [TC, MI, SP]". Kaguya (SELENE). JAXA. Retrieved 2007-06-25.
  17. "KAGUYA (SELENE) - Mission Instruments - HDTV". Retrieved 2009-03-01.
  18. "Send a New Year's Message to the Moon on Japan's SELENE Mission: Buzz Aldrin, Ray Bradbury and More Have Wished Upon the Moon" (Press release). The Planetary Society. 2007-01-11. Retrieved 2007-07-14.
  19. "セレーネ「月に願いを!」(SELENE "Wish Upon the Moon!")" (in Japanese). JAXA. 2007. Archived from the original on 2007-04-04. Retrieved 2007-07-14.
  20. H. Araki; et al. (2009-02-13). "Lunar Global Shape and Polar Topography Derived from Kaguya-LALT Laser Altimetry". Science. 323 (5916): 897–900. Bibcode:2009Sci...323..897A. doi:10.1126/science.1164146. PMID 19213910.
  21. N. Namiki; et al. (2009-02-13). "Farside Gravity Field of the Moon from Four-Way Doppler Measurements of SELENE (Kaguya)". Science. 323 (5916): 900–905. Bibcode:2009Sci...323..900N. doi:10.1126/science.1168029. PMID 19213911.
  22. J. Haruyama; et al. (2008-11-07). "Lack of Exposed Ice Inside Lunar South Pole Shackleton Crater". Science. 322 (5903): 938–939. Bibcode:2008Sci...322..938H. doi:10.1126/science.1164020. PMID 18948501.
  23. Terada, Kentaro; Yokota, Shoichiro; Saito, Yoshifumi; Kitamura, Naritoshi; Asamura, Kazushi; Nishino, Masaki (2017-01-30). "Biogenic oxygen from Earth transported to the Moon by a wind of magnetospheric ions". Nature Astronomy. 1 (2): 0026. Bibcode:2017NatAs...1E..26T. doi:10.1038/s41550-016-0026.
  24. "SELENE: The largest lunar mission since the Apollo program". Retrieved 2008-04-21.
  25. "Hiten". NASA. Retrieved 2007-09-14.
  26. "NASA Authorization Act of 2008 - Section 404 - Lunar Outpost". Library of Congress. 2008-10-22.
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