JAXA - KAGUYA(SELENE)

[Notebook]

February 13, 2009 (JST)
Japan Aerospace Exploration Agency (JAXA)

The Japanese lunar explorer KAGUYA (SELENE) has been operating since
nominal operations started in December 2007 to elucidate the origin
and evolution of the Moon. Four KAGUYA research reports using
observation data from the Terrain Camera onboard the KAGUYA and a
perspective titled "Seeing the Missing Half" were published as part of
a KAGUYA special edition in Science Magazine dated February 13, 2009.
This special edition, which is featured on the cover page, is epoch-
making and succeeds the special issues of planetoid explorer "HAYABUSA"
in June 2006 and the solar observation satellite "HINODE" in December
2007.

The titles of the research reports in Science magazine that aim to
provide new knowledge to stimulate the study of the origin and
evolution of the Moon are as follows:
1) Lunar Radar Sounder Observations of Subsurface Layers under the
Nearside Maria* of the Moon
2) Farside Gravity Field of the Moon from the Four-way Doppler
Measurements of the SELENE (Kaguya)
3) The Lunar Global Shape and Polar Topography Derived from Kaguya-
LALT Laser Altimetry
4) The Long-lived Volcanism on the Lunar Farside Revealed by the
SELENE Terrain Camera

* The relay satellite "OKINA (RSTAR)" made an impact on the lunar
surface on February 12, 2009 (JST), and the four-way Doppler
measurement mission was successfully completed.
* Mare (Plural maria): Any of the large and low-lying dark areas on
the Moon. The lunar maria is believed to consist of volcanic basalts.

Reference
Science : http://www.sciencemag.org/magazine.dtl
JAXA SELENE project: http://www.kaguya.jaxa.jp/index_e.htm
NAOJ : http://www.nao.ac.jp/E/index.html/
Tohoku University: http://www.tohoku.ac.jp/english/
Nagoya University: http://www.nagoya-u.ac.jp/en/
Kyoto University: http://www.kyoto-u.ac.jp/en/
Kyusyu University: http://www.kyushu-u.ac.jp/english/index.php


Appendix: Research Reports Titles with Outlines

1) Lunar Radar Sounder Observations of Subsurface Layers under the
Nearside Maria of the Moon
Takayuki Ono*1, Atsushi Kumamoto*1, Hiromu Nakagawa*1, Yasushi
Yamaguchi*2, Shoko Oshigami*2, Atsushi Yamaji*3, Takao Kobayashi*4,
Yoshiya Kasahara*5, Hiroshi Oya*6
*1 Tohoku University, *2 Nagoya University, *3 Kyoto University,
*4 Korea Institute of Geoscience & Mineral Resources, * Kanazawa
Univeristy, *6 Fukui University of Technology

- Radar sounding from the Kaguya spacecraft reveals subsurface layers
at an apparent depth of several hundred meters in nearside maria.
- Comparison with the surface geology in the Serenitatis basin implies
that the prominent echoes are probably from buried regolith layers
accumulated during the depositional hiatus of mare basalts. The
basalts that accumulated during this quiet period have a total
thickness of only a few hundred meters. These observations suggest
that mascon loading did not produce the tectonics in Serenitatis
after 3.55 Ga. Global cooling probably dominated the tectonics after
2.84 Ga.

2) Farside Gravity Field of the Moon from Four-way Doppler Measurements
of SELENE (Kaguya)
Noriyuki Namiki*1, Takahiro Iwata*2, Koji Matsumoto*3, Hideo Hanada*3,
Hirotomo Noda*3, Sander Goossens*3, Mina Ogawa*2, Nobuyuki Kawano*3,
Kazuyoshi Asari*3, Sei-itsu Tsuruta*3, Yoshiaki Ishihara*3, Qinghui
Liu*3, Fuyuhiko Kikuchi*3, Toshiaki Ishikawa*3, Sho Sasaki*3, Chiaki
Aoshima*4, Kosuke Kurosawa*5, Seiji Sugita*5, and Tadashi Takano*6
*1 Kyushu University, *2 JAXA, *3 NAOJ, *4 Fujitsu, *5 Tokyo
University, *6 Nihon University

- The farside gravity field model of the Moon has been improved from
the tracking data of the SELENE via a relay subsatellite "Okina
(Rstar)." The new gravity field model reveals that the farside
impact basins have concentric rings of positive-negative-positive
anomalies unlike plateau-shaped positive anomalies of the nearside
basins, suggesting rigid lithosphere on the farside and compensation
at the crust-mantle boundary on the nearside. Farside basins are
classified into two types depending on the magnitude of the central
gravity high, indicating mantle uplift at a time of impact and
association of mare volcanism with post-impact deformation. The
basin structure possibly reflects the thermal state of the
lithosphere, and gives an important clue to understand the thermal
evolution of the Moon.

3) Lunar Global Shape and Polar Topography Derived from Kaguya-LALT
Laser Altimetry
H. Araki1*, S. Tazawa*1, H. Noda*1, Y. Ishihara*1, S. Goossens*1, S.
Sasaki*1, N. Kawano*1, I. Kamiya*2, H. Otake*3, J. Oberst*4, C. Shum*5
*1 National Astronomical Observatory *2 Geographical Survey Institute,
*3 JAXA, *4 German Aerospace Center, *5 Ohio State University

- A global lunar topographic map with a spatial resolution of finer
than 0.5degree has been derived using data from the laser altimeter
(LALT) onboard the Japanese lunar explorer KAGUYA (SELENE). In a
comparison with the previous Unified Lunar Control Network
(ULCN 2005) model, the new map reveals unbiased lunar topography for
scales finer than a few hundred kilometers. The newly derived lunar
topographic spectrum indicates the lunar crust is rigid enough to
support the surface topography that is rougher than that of the
Earth, which may indicate the drier lithosphere of the Moon than the
Earth.
- The highest point on the Moon is on the southern rim of the
Dirichlet-Jackson basin and the lowest one is in the Antoniadi
crater in the SPAT. The topographic range is about 19.81 km, which
is greater than the ULCN 2005 result that is 17.53 km for the next
highest and lowest points whose positions are generally identical to
our highest and lowest points with differences less than a few
degrees.

4) Long-lived Volcanism on the Lunar Farside Revealed by SELENE
Terrain Camera
Junichi Haruyama 1*, Makiko Ohtake*1, Tsuneo Matsunaga*2, Tomokatsu
Morota*1, Chikatoshi Honda *1, Yasuhiro Yokota*1, Masanao Abe*1,
Yoshiko Ogawa*2, Hideaki Miyamoto*3, Akira Iwasaki*3, Carle M.
Pieters*4, Noriaki Asada*5, Hirohide Demura*5, Naru Hirata*5, Junya
Terazono*5, Sho Sasaki*6, Kazuto Saiki*7, Atsushi Yamaji*8, Masaya
Torii*9, Jean-Luc Josset*10
*1 JAXA, *2 NIES, *3 University of Tokyo, *4 Brown University,
*5 University of Aizu, *6 NAOJ, *7 Osaka University, *8 Kyoto
University, *10 Fujitsu, *11 Space Exploration Institute

- The formation ages of geological units in mare can be determined by
crater counting based on the idea as "a newly created surface will
accumulate craters with time." The Terrain Camera aboard the SELENE
(KAGUYA) provides high resolution (10 m / pixel) images to
sufficiently detect small craters. As a result of crater counting by
TC observation data, several units at various locations including a
part of the Mare* Moscoviense on the lunar farside show their
younger ages, clustering at -2.5 Ga, which were much younger than
previously known on some farside mare units (-3.0 Ga). This result
means "volcanic activity on the lunar farside lasted longer than
previously considered and may have occurred episodically." "The long-
lived farside volcanism" will be an important key factor for
consideration on the lunar thermal evolution.


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* The relay satellite "OKINA (RSTAR)" made an impact on the lunar
surface on February 12, 2009 (JST), and the four-way Doppler
measurement mission was successfully completed.

Didn't know about that, wonder where it hit?

.