SELENE data suggests no perpetual sunlight on lunar poles

Research by a National Astronomical Observatory of Japan (NAOJ) team has shown that no areas of the moon’s surface receive perpetual sunlight.

The surface of the moon around the poles was thought to have areas of constant sunlight, making it a good spot to establish a lunar base powered by solar energy. While this research refutes the existence of areas in constant sunlight, the polar regions remain strong candidates for long-term settlements due to the higher possibility of finding ice there.

The sunlit conditions of the lunar polar regions were estimated by using a digital elevation model made by the laser altimeter data onboard the Japanese lunar orbiter KAGUYA (SELENE). The result shows that i) there are no peaks of eternal light in either north or south polar regions, ii) most continuously lit surfaces are 89% for north and 86% for south, iii) there are permanently shadowed regions. This information will be useful for long-duration landing experiments on the Moon and possibly for human activity on the Moon in the near future.

To measure the incidence of sunlight in these areas, the research team collected daily SELENE data from Jan. 1, 2000, on areas of the moon’s surface at both poles (between 85 and 90 degrees latitude).

The area with the highest incidence of sunlight was 89% at the north pole, followed by 86% at the south pole, equating to 324 and 314 days of sunlight a year, respectively. There were also many areas around crater rims where the yearly percentage of sunlight was at least 80%. The existence of polar areas believed to be in permanent shadow was confirmed by the survey.

Hirotomo Noda, researcher of planetary science at NAOJ, said: “This should help the design for a power generation and research base.”

The team’s findings were published in the U.S. journal of geophysics:
Noda, H., H. Araki, S. Goossens, Y. Ishihara, K. Matsumoto, S. Tazawa, N. Kawano, and S. Sasaki (2008), Illumination conditions at the lunar polar regions by KAGUYA(SELENE) laser altimeter, Geophys. Res. Lett., 35, L24203, doi:10.1029/2008GL035692.

posted by: Soderman/NLSI Staff
source: Mainichi Daily News

http://mdn.mainichi.jp/mdnnews/news/20090203p2a00m0na010000c.html