Potential survival of the lichen Caloplaca flavovirescens under high helium-beam doses

K. Miki, S. Kawashima, Y. Takahashi, S. Yonemura

Research output: Contribution to journalArticlepeer-review


Testing the limits of survivability in space is the primary focus in astrobiological research. Although a number of previous studies have examined terrestrial life survival in an extraterrestrial environment, only a few have investigated how life systems respond to high doses of alpha cosmic ray, the main component of cosmic rays. We used respiration and photosynthetic rates as indicators of the vital signs of the lichen Caloplaca flavovirescens, which is a symbiotic life form including fungi and algae. Our experiment demonstrated that the photosynthetic rate decreased with increased helium-beam doses, whereas the respiration rate was relatively unaffected. Specifically, under a helium-beam dose greater than 10 Gy, the respiration rate remained nearly constant regardless of further increases in the radiation rate. Our results indicate that the different metabolic systems of terrestrial life forms might exhibit different survival characteristics when they are in space.

Original languageEnglish
Pages (from-to)449-454
Number of pages6
JournalRadiation and Environmental Biophysics
Issue number3
Publication statusPublished - 2019 Aug 1
Externally publishedYes


  • Caloplaca flavovirescens
  • Helium-beam
  • Lichen
  • Photosynthetic rate
  • Respiration rate

ASJC Scopus subject areas

  • Biophysics
  • Radiation
  • General Environmental Science


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