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.[4] 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 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.[5]
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)
Nicknameedit
The orbiter's nickname, Kaguya, was selected by the general public. It comes from the name of a lunar princess in the ancient Japanese folktaleThe Tale of the Bamboo Cutter.[6] After their successful release, its sub-satellites, Rstar and Vstar, were named Okina and Ouna, also derived from characters in the tale.[7]
Mission objectivesedit
The main scientific objectives of the mission were to:
The SELENE mission was originally scheduled to launch in 2003, but rocket failures on another mission and technical difficulties delayed the launch until 2007.[10] Launch was planned for August 16, 2007, but was postponed when some electronic components were found to be installed incorrectly.[11]
Lunar operationsedit
On October 3, it entered an initial 101-to-11,741-kilometre (63 to 7,296 mi) polar lunar orbit.[12]
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.[7] Finally, by October 19, the orbiter was in a circular 100-kilometre (62 mi) orbit.[13] 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.[14] 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),[15]
and impact with lunar surface occurred at 18:25 UTC on June 10, 2009.[5]
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.[15]
Function: two-way radio science relay, orbiter-earth
Initial orbit: 100 to 2,400 kilometres (62 to 1,491 mi)
Inclination: 90 degrees
Ouna (VLBI satellite)edit
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
Instrumentsedit
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":[17]
Terrain camera (TC) (resolution 10 meters [33 ft] per pixel)[18]
Radio wave source for VLBI (VRAD) aboard Okina and Ouna
Two 2.2 megapixel CCD HDTVcameras, one wide-angle and one telephoto, were also on board, primarily for public outreach.[19] The HDTV system, developed by NHK (Japan Broadcasting Corporation), produced over 1.3 TB of video and stills over 19 months.[20]
JAXA collected names and messages that were carried on SELENE through their "Wish Upon the Moon" campaign.[21] 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.[22]
Resultsedit
Major results include:
Improved lunar global topography maps.[23] This detailed altitude and geological data was provided to Google for free to make Google Moon 3-D.
First optical observation of the permanently shadowed interior of the crater Shackleton at the lunar south pole.[25]
Evidence of Earth's oxygen being transported to the Moon via magnetospheric ions.[26]
Other lunar probesedit
SELENE was part of a renewed global interest in lunar exploration; it was "the largest lunar mission since the Apollo program".[27] It followed Japan's first lunar probe, Hagoromo, launched in 1990.[4][28] 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 crewed lunar exploration missions or lunar outpost construction on the Moon between 2018 and 2025.[29]
^""KAGUYA" selected as SELENE's nickname". Retrieved 2007-10-13.
^ ab"KAGUYA (SELENE) / Result of the Separation of the VRAD Satellite (Vstar)" (Press release). 2007-10-12. Archived from the original on 2012-03-20. Retrieved 2007-10-13.
^Emily Lakdawalla (2007-09-14). "Kaguya Rockets Toward the Moon". Archived from the original on 2012-02-06. Retrieved 2007-09-15.
^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.
^"Japan launches first lunar probe". BBC News. 2007-09-14. Retrieved 2007-09-14.
^"Launch Postponement of the KAGUYA (SELENE)". 2007-07-20. Retrieved 2007-08-15.
^"KAGUYA (SELENE) Result of the Lunar Orbit Injection Maneuver (LOI1) – Lunar orbit injection was confirmed" (Press release). JAXA. 2007-10-05. Archived from the original on 2012-05-14. Retrieved 2007-10-05.
^"かぐや/H-IIA13号機 打上げ特設サイト" (in Japanese). Retrieved 2007-10-01.
^"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.
^ ab"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.
^"Results of High-Definition Television System (HDTV) on Board SELENE (KAGUYA)" (PDF). 40th Lunar and Planetary Science Conference (2009). Retrieved 2022-12-09.
^"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. Archived from the original on 2012-02-12. Retrieved 2007-07-14.
^"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.
^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. S2CID 2115707.
^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. S2CID 5306227.
^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. S2CID 20749838.
^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. S2CID 85560607.
^"SELENE: The largest lunar mission since the Apollo program". Archived from the original on 2013-10-24. Retrieved 2008-04-21.
^"NASA Authorization Act of 2008 – Section 404 – Lunar Outpost". Library of Congress. 2008-10-22. Archived from the original on 2016-07-04. Retrieved 2008-10-22.
External linksedit
Wikinews has related news:
Japan's lunar probe performing 'smoothly' after successful launch
(in English) Official project site, JAXA
(in English) Official launch information site, JAXA
SELENE Mission Profile by NASA's Solar System Exploration
(in English) SELENE overview, ISAS/JAXA
(in English) Official YouTube channel, JAXA
(in English) June 10th impact location Archived 2013-07-18 at the Wayback Machine