The End of the Ice Age and the Start of the Space Age: The Freeze-Drying of Gametes

In the future, human migration to other planets is inevitable. Thus, diversity must be preserved to sustain species on another planet to prevent inbreeding and endure environmental changes. Numerous individuals of each species would have to be transported by spacecraft, which would be a costly and challenging endeavor. Therefore, the most likely means of preserving animal diversity on other planets would be transporting human germ cells rather than individuals. However, the current method for preserving germ cells requires liquid nitrogen, which spacecraft and the International Space Station (ISS) cannot accommodate. Moreover, if an accident interrupts the supply of liquid nitrogen, all germ cells will melt and become useless. Additionally, spermatozoa and oocytes of space tourists and animals are exposed to deep-space radiation for longer durations during trips to the moon, Mars, or other planets. Because of the DNA damage caused by radiation to the cells, including spermatozoa and oocytes, we must determine whether healthy offspring will be born after interplanetary migration. Therefore, we have developed a method for freeze-drying spermatozoa (FD sperm) that allows them to be stored at room temperature and increases their radiation tolerance. We have already conducted experiments on the ISS involving the long-term preservation of FD sperm. This section discusses the advantages of FD sperm for safe preservation at room temperature and in space.