Suspended Animation, Gateway to a Second Life and Interstellar Travel

Abstract
Suspended animation (SA) is the temporary (short- or long-term) slowing or stopping of biological processes. Here, we will briefly review two major applications of SA. There are two main fields where long-term SA constitutes an irreplaceable technology, namely manned deep space travel and cryonics, the cryopreservation of humans after clinical death with the aim to reanimate them in the future. We will present a brief overview reviewing the evidence on which is based the expectation that in the future it will be possible to revive cryopreserved animals and humans. For many years cells have been cryopreserved in liquid nitrogen (LN) and then thawed and cultured indefinitely. It has also become routine to cryopreserve human and animal embryos in LN, which are then rewarmed and implanted into the uterus of females that become pregnant and give birth to healthy individuals. There has also been much progress in cryopreservation of adult tissue, such as the ovarian cortical tissue of young women suffering from cancer, in order to preserve viable oocytes for post treatment. The final section provides an overview of a group of emerging technologies that seem to propose to us a Faustian pact, achieving immortality in exchange for abandoning our biological nature. The vertiginous advances that science has shown in recent decades create well-founded hopes that, in a not too distant future, technology will be able to free the human species from the tragic final destiny that nature imposes on each individual, death.