Balloon-based Exposed Payload Designed for Astrobiological Research in Earth’s Near Space

Earth’s near space is a region between 20 and 100 km above sea level, which is characterized by low temperature, low atmospheric pressure, harsh radiation, and extreme dryness. These conditions are analogous to the surface of Mars and the atmosphere of Venus, and thus make it a unique natural lab for astrobiologists. To address the important astrobiological questions of the effects of the near space environmental conditions on biology and of the survival strategies of representative organisms in this planetary analog, teams from the Chinese Academy of Sciences have developed a scientific balloon platform named the Chinese Academy of Sciences Balloon-Borne Astrobiology Platform (CAS-BAP) and carried out a series of experiments in lower near space since 2019. Here, we describe the Biological Samples Exposure Payload (BIOSEP) loaded on CAS-BAP with respect to its structure and function. The primary role of BIOSEP is to expose biological/chemical samples to the planetary analog environments of Earth’s lower near space. Exposed samples will be returned to laboratories for morphological, physiological, chemical, and genetic analyses. The development of BIOSEP and associated biological exposure experiments will improve our understanding of the livelihood of potential Mars lives and the potential habitability of the atmosphere regions of other planets in the Solar System and beyond.