塩谷 圭吾

This work reviews the search for extraterrestrial life signatures with a special focus on the fluorescence microscope that we have been developing for the life-signature search on Mars and other sites. The surface and subterranean Mars, clouds of Venus, the Moon, asteroids, icy bodies, such as the moons of Jupiter and Saturn, and so on are important sites for life-signature exploration in the solar system. One possible exploration strategy is to target characteristics similar to those in terrestrial life, such as microorganisms with metabolic activity and similar uniform small structures microbes surrounded by a membrane that primarily comprise carbon-based molecules. These characteristics can be analyzed with fluorescence microscopy, which has a high spatial resolution and employs a combination of fluorescent pigments to distinguish microbial properties. Following an introduction, the life signature search and astrobiological analysis of the targeted characteristics are discussed. The extraterrestrial life exploration methods using a microscope are described. Also, other methods, including mass spectrometry, the sterilization-and-comparison method (detection of ability to die), proliferation, and analysis of shape, color, growth, or movement, are discussed. Lastly, we overview the life-signature detection fluorescence microscope that we have been developing, and present the Bread Board Model of it.

Many Earth-sized planets have been discovered and some of them are potentially in the habitable zone. In addition, several Earth-sized planets have been detected around low temperature stars near our solar system. However, it is difficult to characterize them as Earth-like or Venus-like, even though they are relatively very close to our solar system. We performed a conceptual design of an Ultraviolet Spectrograph for Exoplanet (UVSPEX) for World Space Observatory Ultraviolet (WSO-UV), which is 1.7-m UV space telescope being prepared by Russia. The spectral range is to exceed wavelengths from 115 nm to 135 nm to detect at least H Lyman alpha 121.6nm to O I 130 nm. The throughput is >4%. UVSPEX is planned to be a part of a Field Camera Unit (FCU). This additional instrument would enable us to observe similar to 20 Earth-like exoplanets and detect an oxygen exosphere if some of them have an Earth-like atmosphere.

We present a life detection fluorescence microscope (LDM) for near-future Solar System exploration. The search for extra-terrestrial life in the Solar System is considered a crucial issue in space science. Previously, the NASA Viking mission conducted some life science experiments on Mars in 1976. Other exploration missions have increased our knowledge of Mars. Nevertheless, the presence of life on Mars has not yet been conclusively demonstrated. The LDM uses fluorescence pigments and an excitation light source to identify biological cells, coupled to a microscope for imaging of fluorescent cells. An optical design for this compact microscope is presented herein. We discuss the application of this LDM both for Mars soils and regolith and other targets in the Solar System.