Radon alpha-ray detector on-board lunar mission SELENE

J. Nishimura, T. Kashiwagi, T. Takashima, S. Okuno, K. Yoshida, K. Mori, M. Itoh, K. Saeki, K. Furuichi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Alpha-ray detector (ARD) will be on-board SELENE, a Japanese lunar orbiter to be launched around 2006. Primary target is the alpha particles emitted by 222Rn and 210Po. 222Rn is produced by the decay of 238U and emanates from the lunar surface. It is trapped by the lunar gravity and decays with the half-life of 3.8 days emitting 5.490 MeV alpha particle. In the decay sequence of 222Rn, 210Po emits alpha particle with the energy of 5.305 MeV. Time scale of the activity is dominated by the 21-year half-life of 210Pb. Thus, alpha particle intensity from 210Po is an indicator of the change of radon emanation rate and change of crust condition due to seismic activity or impact events for the time scale of ∼50 years, while that of 222Rn reflects the current emanation rate. Results from Apollo 15, 16, and recent Lunar Prospector mission indicate that the average amount of radon on the lunar surface is much smaller than expected, and the radon-alpha distribution suggests that radon comes out through gas emanation from fissures of the lunar surface. We developed a large-area detector of 326 cm2 for the ARD, which is 15-20 times larger than the detectors of Apollo and Lunar Prospector. Reduction of the background was achieved with the anti-coincidence by rejecting cosmic-ray tracks. It will enable: (1) precise global mapping of the radioactive material on the lunar surface; (2) identification of gas emanation location; (3) study of the radon gas emanation mechanism on the lunar surface and the origin of the lunar atmosphere; (4) obtaining information on the crustal movement during the last ∼50 years.

Original languageEnglish
Pages (from-to)34-37
Number of pages4
JournalAdvances in Space Research
Volume37
Issue number1
DOIs
Publication statusPublished - 2006
Externally publishedYes

Fingerprint

Lunar missions
lunar surface
Alpha particles
Radon
radon
rays
alpha particles
Detectors
Lunar Prospector
detectors
half life
lunar atmosphere
decay
Lunar Orbiter
particle intensity
gases
gas
timescale
radioactive materials
Gases

Keywords

  • Lunar orbiter
  • Lunar science
  • Radon emanation
  • Selene mission

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Nishimura, J., Kashiwagi, T., Takashima, T., Okuno, S., Yoshida, K., Mori, K., ... Furuichi, K. (2006). Radon alpha-ray detector on-board lunar mission SELENE. Advances in Space Research, 37(1), 34-37. https://doi.org/10.1016/j.asr.2005.04.036

Radon alpha-ray detector on-board lunar mission SELENE. / Nishimura, J.; Kashiwagi, T.; Takashima, T.; Okuno, S.; Yoshida, K.; Mori, K.; Itoh, M.; Saeki, K.; Furuichi, K.

In: Advances in Space Research, Vol. 37, No. 1, 2006, p. 34-37.

Research output: Contribution to journalArticle

Nishimura, J, Kashiwagi, T, Takashima, T, Okuno, S, Yoshida, K, Mori, K, Itoh, M, Saeki, K & Furuichi, K 2006, 'Radon alpha-ray detector on-board lunar mission SELENE', Advances in Space Research, vol. 37, no. 1, pp. 34-37. https://doi.org/10.1016/j.asr.2005.04.036
Nishimura, J. ; Kashiwagi, T. ; Takashima, T. ; Okuno, S. ; Yoshida, K. ; Mori, K. ; Itoh, M. ; Saeki, K. ; Furuichi, K. / Radon alpha-ray detector on-board lunar mission SELENE. In: Advances in Space Research. 2006 ; Vol. 37, No. 1. pp. 34-37.
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AU - Yoshida, K.

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