SELENE

From Vero - Wikipedia
Jump to navigation Jump to search

Template:Short description Template:About Template:Use mdy dates Template:Expand Japanese Template:Infobox spaceflight SELENE (Template:IPAc-en; Selenological and Engineering Explorer), better known in Japan by its nickname Template:Nihongo, was the second Japanese lunar orbiter spacecraft following the Hiten probe.<ref name=redorbit>Template:Cite news</ref> 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.<ref name="lunarimpact">Template:Cite web</ref>

Nickname

File:Japanese Fairy Book - Ozaki - P118.png
"The Receding Princess" from The Japanese Fairy Book, 1908

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.<ref name="jaxa_nickname">Template:Cite web</ref> After their successful release, its sub-satellites, Rstar and Vstar, were named Okina and Ouna, also derived from characters in the tale.<ref name="jaxa20071012">Template:Cite press release</ref>

Mission objectives

The main scientific objectives of the mission were to:

Launch

File:H-IIA F13 launching KAGUYA.jpg
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 Template:Convert (perigee) / Template:Convert (apogee) geocentric parking orbit.<ref>Template:Cite web</ref><ref name="jaxa20070919">Template:Cite web</ref> The total launch mass was Template:Convert.<ref name="jaxa20070613">Template:Cite web</ref><ref name="SELENE"></ref>

The SELENE mission was originally scheduled to launch in 2003, but rocket failures on another mission and technical difficulties delayed the launch until 2007.<ref>Template:Cite web</ref> Launch was planned for August 16, 2007, but was postponed when some electronic components were found to be installed incorrectly.<ref>Template:Cite web</ref>

Lunar operations

On October 3, it entered an initial Template:Convert polar lunar orbit.<ref>Template:Cite press release</ref> On October 9, the relay satellite was released into a Template:Convert orbit, while on October 12 the VLBI satellite was released into a Template:Convert one.<ref name="jaxa20071012" /> Finally, by October 19, the orbiter was in a circular Template:Convert orbit.<ref name="jaxa20071001">Template:Cite web</ref> 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 Template:Convert orbit, and finally to an elliptical Template:Convert one, with a controlled impact occurring by August 2009.<ref>Template:Cite web</ref> Because of a degraded reaction wheel, the plan was changed so that on February 1, 2009, the orbit was lowered to Template:Convert ± Template:Convert,<ref name="JAXA20090218">Template:Cite web</ref> and impact with lunar surface occurred at 18:25 UTC on June 10, 2009.<ref name="lunarimpact" />

Design

The mission featured three separate spacecraft:

Main orbiter

Source:<ref name="jaxa20070613" />

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.<ref name="JAXA20090218" />

  • Function: two-way radio science relay, orbiter-earth
  • Mass: Template:Convert<ref name="jaxa20070613" />
  • 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: Template:Convert
  • 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: Template:Convert
  • 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: Template:Convert
  • Inclination: 90 degrees

Instruments

File:Earth at 11000 km.jpg
First optical still captured by the onboard HDTV camera. Earth is seen at a distance of 11,000 km.<ref>Template:Cite web</ref>

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":<ref name="index">Template:Cite web</ref>

  • Terrain camera (TC) (resolution 10 meters [33 ft] per pixel)<ref name="lism">Template:Cite web</ref>
  • 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 outreach.<ref>Template:Cite web</ref> The HDTV system, developed by NHK (Japan Broadcasting Corporation), produced over 1.3 TB of video and stills over 19 months.<ref>Template:Cite journal</ref>

JAXA collected names and messages that were carried on SELENE through their "Wish Upon the Moon" campaign.<ref>Template:Cite press release</ref> 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.<ref>Template:Cite web</ref>

Results

Major results include:

Other lunar probes

SELENE was part of a renewed global interest in lunar exploration; it was "the largest lunar mission since the Apollo program".<ref>Template:Cite web</ref> It followed Japan's first lunar probe, Hagoromo, launched in 1990.<ref name=redorbit /><ref>Template:Cite web</ref> 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.<ref>Template:Cite web</ref>

Template:-

See also

Template:Portal

References

Template:Reflist

Template:Wikinews

Template:Moon spacecraft Template:Japanese space program Template:Solar System probes Template:Orbital launches in 2007

Retrieved from "https://wiki.sarg.dev/index.php?title=SELENE&oldid=510555"