Death in space: The effect of reduced gravity on cell death

The future of human space exploration necessitates more research on the topic of death in space. Human curiosity drives us to want to explore space as a means for scientific advancement and long-term survival of humanity. It brings us further and further from Earth, to a harsh environment. With factors like microgravity, radiation, vacuum, temperature extremes and more causing all kinds of physiological effects. With growing space commercialization, space tourism and planned space missions to the Moon and Mars, more humans will venture to space in the coming decades than ever before. This increases the chances of someone dying in space. If this were to happen, protocols should be in place so the situation can be handled properly. These protocols should state how the death can be investigated and how the remains should be disposed of. In order to plan these protocols, there should be as much information as possible available on this topic. Some theoretical effects of the space environment on postmortem changes are discussed. Livor mortis will not happen in the absence of gravity. Algor mortis will not happen the same as on Earth because the only way of heat transfer in space is inefficient radiation. Rigor mortis will be more or less the same, dependent on how quickly putrefaction will set in. Bacteria play a big role in the decomposition process and a change or the absence of these bacteria will impact the process. One big question that is still unanswered is whether or not decomposition is affected by the space environment and if so, in what way Here, Normal Human Dermal Fibroblasts (NDHF) were cultured in normal media and in media with staurosporine added to it to induce cell death. These cells were then incubated at different levels of gravity for 24 hours using a Random Positioning Machine (RPM). Flow Cytometric analysis of the samples showed significantly less dead cells in the Moon and microgravity groups compared to the 1g group. Afterwards, a cytokine assay was performed on the cell media. IFN-gamma, TNF-alpha, IL-2 and IL-10 showed significant concentration differences between gravity levels with 1g always having the highest concentration. It can be concluded that lower levels of gravity, like on the Moon and microgravity, halted or slowed down the apoptosis induced by staurosporine. The research performed here has many implications surrounding biological functions concerning cell death in microgravity. The main goal was to start forming an understanding about the effect of the space environment on the decomposition process of human remains. The experiments seemed to show a delayed cell death process. It can be inferred that the decomposition is slowed down in microgravity. Given the limitations of this research, more extensive studies should be performed to validate these results and to make conclusions on death in space.