SELENE

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This article is about the lunar spacecraft. For other uses, see Selene (disambiguation).
 This article or section documents a current or recent spaceflight.
Details may change as the mission progresses.
Kaguya (かぐや ?) (SELENE)
Image:kaguya mark.jpg
The mission mark of KAGUYA
Organization JAXA
Mission type Orbiter
Satellite of Moon
Launch date 01:31:01, 14 September 2007 UTC
Launch vehicle H-IIA
NSSDC ID 2007-039A
Home page SELENE page
Mass 2,914 kg (Main Orbiter, launch mass)
Power 3,486 W
Orbital elements
Inclination 90°
Orbital period 2h
Apoapsis 100 km
Periapsis 100 km

SELENE (Ancient Greek: Σελήνη, moon), better known in Japan by its nickname Kaguya (かぐや ?), is the second Japanese lunar orbiter spacecraft.[1] Produced by the Institute of Space and Astronautical Science and NASDA (both organizations that are now part of the Japan Aerospace Exploration Agency, or JAXA), the spacecraft was launched September 14, 2007.

The name stands for Selenological and Engineering Explorer; Selene was a lunar deity in Greek mythology. The orbiter's nickname, Kaguya, which was selected by the general public, derives from the name of a lunar princess in the ancient Japanese folktale The Tale of the Bamboo Cutter.[2] After the successful release of its sub-satellites Rstar and Vstar, they were named Okina and Ouna, also from folklore.[3]

SELENE comes as part of a renewed interest in lunar exploration, being "the largest lunar mission since the Apollo program",[4] and following up on Japan's first lunar probe, Hagoromo, launched in 1990.[1][5] China launched its Chang'e 1 lunar explorer on October 24, 2007, followed by India's 22 October 2008 launch of Chandrayaan-1, the United States is also planning to launch its Lunar Reconnaissance Orbiter in April 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.[6]

Contents

[edit] Mission objectives

The main scientific objectives of the mission are:

[edit] Launch

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

SELENE launched at 01:31:01, September 14, 2007 UTC on an H-IIA (Model H2A2022) carrier rocket from Tanegashima Space Center into a 281.55 km (perigee) / 232960 km (apogee) geocentric parking orbit.[7] [8] The total launch mass was 3020 kg.[9]

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 due to the discovery that some electronic components were installed incorrectly.[11]

[edit] Lunar operations

On October 3, it reached the moon and entered an initial 101 by 11741 km polar orbit.[12] On October 9, the relay satellite was released to an approximately 100 by 2400 km orbit, and on October 12 the VLBI satellite was released to an approximately 100 by 800 km orbit.[3] Finally, by October 19, the orbiter moved to an approximately 100 km circular orbit.[13] The nominal operation of the mission is one year, with extension if possible.

JAXA announced on October 31, 2007 that Kaguya deployed its Lunar Magnetometer, Lunar Radar Sounder, as well as the Earth-looking Upper Atmosphere and Plasma Imager.

JAXA announced on December 21, 2007 that the operation mode of the lunar explorer, KAGUYA, was shifted to regular operations from its initial verification on December 21, 2007 (Japan Standard Time) as they were able to acquire satisfactory verification results for all fifteen observation missions.

By the end of October 2008, Kaguya completed the planned operation, and entered an extended operation phase. It was planned to continue through March 2009, then lower the orbit to 50 km height circular orbit, and to 20 km - 100 km elliptic orbit, and by August 2009, the controlled collision to the lunar surface.[14] Due to the degraded performance of a reaction wheel, the plan was changed so that from February 1, 2009, the orbit was lowered to 50 km ± 20 km, and the lunar surface impact is expected in June.[15]

[edit] Design

There are three separate units comprising the spacecraft.

[edit] Main orbiter

The main orbiter is a rectangular box measuring about 2.1 m by 4.2 m, with a launch mass of about 2,914 kg.[9]

  • Mass: 2,914 kg
  • Size: 2.1 x 2.1 x 4.8 m
  • Attitude control: Three-axis stabilized
  • Power: 3.5 kW (Max.)
  • Mission period: 1 year
  • Mission orbit: Circular orbit
  • Altitude 100 km
  • Inclination 90 degree

[edit] Okina (small relay satellite)

Okina, a small relay satellite (formerly called Rstar) and Ouna, a VLBI satellite (formerly called Vstar) are both octagonal prisms. The relay satellite relays the radio wave from the Earth to the orbiter and also the opposite direction, when the orbiter is hidden behind the moon, to measure the Doppler shift. The relay satellite impacted into the lunar farside, around Mineur D crater, at 19:46(JST), February 12, 2009[15].

  • Mass: 53 kg[9]
  • Size: 1.0 x 1.0 x 0.65 m
  • Attitude control: spin-stabilized
  • Power: 70 W
  • Orbit (initial orbit):
  • Elliptical orbit (100 km x 2,400 km)
  • Inclination 90 degrees

[edit] Ouna (VLBI satellite)

The Vstar (Very Long Baseline Interferometry satellite) will be used to measure the moon's gravity field, especially of the lunar limb area, where the Doppler shift method cannot be used.

  • Mass: 53 kg
  • Size: 1.0 x 1.0 x 0.65 m
  • Attitude control: spin-stabilized
  • Power: 70 W
  • Orbit (initial orbit):
  • Elliptical orbit (100 km x 800 km)
  • Inclination 90 degrees

[edit] Payload

SELENE carries 13 scientific instruments, including imagers, a radar sounder, a laser altimeter, an X-ray fluorescence spectrometer and a gamma ray spectrometer. Their objectives are "to obtain scientific data of the lunar origin and evolution and to develop the technology for the future lunar exploration", according to the official website.[16]

  • Terrain camera (TC) (resolution 10 meters per pixel)[17]
  • X-Ray fluorescence spectrometer (XRS)
  • Lunar magnetometer (LMAG)
  • Spectral profiler (SP) (resolution per pixel is 562 by 400 m)
  • Multi-band imager (MI) (resolution of visible light 20 meters per pixel, near-infrared 62 meters 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

Also, two HDTV cameras with 3*CCD 2.2 megapixels, one wide-angle camera and one telephoto camera are on board, primarily for public relations purposes.[18]

Along with scientific instruments, JAXA collected names and messages to be carried on SELENE through their "Wish Upon the Moon" campaign.[19] The 412,627 names and messages collected were printed on a sheet measuring 280 mm × 160 mm, at a size of 70 µm per character. The sheet was installed under the photovoltaic modules and the cooling panels for the instruments, beneath the multi-layered insulation.[20]

[edit] Results

Major results include:

[edit] References

  1. ^ a b "Kaguya – Another Chapter for the Lunar Saga". Red Orbit. 14 September 2007. http://www.redorbit.com/news/space/1066163/kaguya__another_chapter_for_the_lunar_saga/index.html. Retrieved on 2007-09-14. 
  2. ^ ""KAGUYA" selected as SELENE's nickname". http://www.jaxa.jp/countdown/f13/special/nickname_e.html. Retrieved on 2007-10-13. 
  3. ^ a b KAGUYA (SELENE) / Result of the Separation of the VRAD Satellite (Vstar). Press release. 2007-10-12. http://www.jaxa.jp/press/2007/10/20071012_kaguya_e.html. Retrieved on 2007-10-13. 
  4. ^ "SELENE: The largest lunar mission since the Apollo program". http://www.jaxa.jp/projects/sat/selene/index_e.html. Retrieved on 2008-04-21. 
  5. ^ "Hiten". NASA. http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1990-007A. Retrieved on 2007-09-14. 
  6. ^ "NASA Authorization Act of 2008 - Section 404 - Lunar Outpost". Library of Congress. 2008-10-22. http://thomas.loc.gov/cgi-bin/query/z?c110:H.R.6063:. 
  7. ^ Emily Lakdawalla (2007-09-14). "Kaguya Rockets Toward the Moon". http://planetary.org/news/2007/0914_Kaguya_Rockets_Toward_the_Moon.html. Retrieved on 2007-09-15. 
  8. ^ 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）" (in Japanese) (PDF). http://www.jaxa.jp/press/2007/09/20070919_sac_h2a-f13.pdf. Retrieved on 1997-09-19. 
  9. ^ a b c "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)" (in Japanese) (PDF). MHI / JAXA. http://www.jaxa.jp/press/2007/06/20070613_sac_h2a-f13.pdf. 
  10. ^ "Japan launches first lunar probe". 14 September 2007. http://news.bbc.co.uk/2/hi/asia-pacific/6994272.stm. Retrieved on 2007-09-14. 
  11. ^ "Launch Postponement of the KAGUYA (SELENE)". 2007-07-20. http://www.jaxa.jp/press/2007/07/20070720_kaguya_e.html. Retrieved on 2007-08-15. 
  12. ^ JAXA (2007-10-05). KAGUYA (SELENE) Result of the Lunar Orbit Injection Maneuver (LOI1) - Lunar orbit injection was confirmed -. Press release. http://www.jaxa.jp/press/2007/10/20071005_kaguya_e.html. Retrieved on 2007-10-05. 
  13. ^ "かぐや/H-IIA13号機　打上げ特設サイト" (in Japanese). http://www.jaxa.jp/countdown/f13/index_j.html. Retrieved on 2007-10-01. 
  14. ^ "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" (in Japanese) (PDF). 2008-11-05. http://www.jaxa.jp/press/2008/11/20081105_sac_kaguya.pdf. Retrieved on 2008-11-05. 
  15. ^ a b "月周回衛星「かぐや（SELENE）」の 状況について" (in Japanese) (PDF). 2009-02-18. http://www.jaxa.jp/press/2009/02/20090218_sac_kaguya.pdf. Retrieved on 2009-02-22. 
  16. ^ "Kaguya (SELENE)". JAXA. http://www.selene.jaxa.jp/index_e.htm. Retrieved on 2007-06-25. 
  17. ^ "LISM [TC, MI, SP"]. Kaguya (SELENE). JAXA. http://www.selene.jaxa.jp/en/equipment/tc_e.htm. Retrieved on 2007-06-25. 
  18. ^ "KAGUYA (SELENE) - Mission Instruments - HDTV". http://www.kaguya.jaxa.jp/en/equipment/hdtv_e.htm. Retrieved on 2009-03-01. 
  19. ^ The Planetary Society (2007-01-11). 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. http://www.planetary.org/about/press/releases/2007/0111_Send_a_New_Years_Message_to_the_Moon.html. Retrieved on 2007-07-14. 
  20. ^ "セレーネ「月に願いを!」(SELENE "Wish Upon the Moon!")" (in Japanese). JAXA. 2007. http://www.isas.jaxa.jp/j/new/event/selene_camp/topics.shtml. Retrieved on 2007-07-14. 
  21. ^ H. Araki et al (February 13, 2009). "Lunar Global Shape and Polar Topography Derived from Kaguya-LALT Laser Altimetry". Science (5916): pp. 897 - 900. doi:10.1126/science.1164146. 
  22. ^ N. Namiki et al (February 13, 2009). "Farside Gravity Field of the Moon from Four-Way Doppler Measurements of SELENE (Kaguya)". Science (5916): pp. 900 - 905. doi:10.1126/science.1168029. 
  23. ^ J. Haruyama et al (November 7, 2008). "Lack of Exposed Ice Inside Lunar South Pole Shackleton Crater". Science (5903): pp. 938 - 939. doi:10.1126/science.1164020. 

[edit] See also

[edit] External links

Sister project Wikinews has related news: Japan's lunar probe performing 'smoothly' after successful launch
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