The challenges of human space exploration produce some of humanity’s greatest technological and scientific advances, not excluding innovations in medicine. The microgravity environment causes a whole host of physiological changes, and exposure to dust on the Moon caused considerable pulmonary distress to astronauts during the Apollo missions. As NASA and other space organizations prepare for long duration exploration missions to Mars, the hazards and consequences of the Martian surface need to be accounted for. This review investigates how substances analogous to the hazardous components of Martian dust have caused disease in people on Earth. Because of the small grain size of Martian dust, dust on Mars is more likely to cause lung irritation, absorb into the bloodstream, and lead to diseases in astronauts. Toxic components of Martian dust to astronaut health include perchlorates, silica, nanophase iron oxides, and gypsum in addition to trace amounts of toxic metals whose abundances are debated: chromium, beryllium, arsenic, and cadmium. Predicted effects of dust exposure ranges from asymptomatic to life threatening, with many substances being carcinogenic and most damage impacting the pulmonary system. The longer transit time for astronauts to return home makes the operations of performing emergency medical treatment more difficult and increases both the likelihood and consequences of developing chronic disease. Exposure mitigation needs to be prioritized; however, supplements may be taken to prevent disease from breakthrough exposures and treatment regimens could lessen morbidity and mortality. Treatments and equipment need to be carefully thought out and transported with the astronauts to be prepared for all possible scenarios.

Nickel stable isotopes (δ60Ni) provide insight to Ni biogeochemistry in the modern and past oceans. Here, we present the first Pacific Ocean high-resolution dissolved Ni concentration and δ60Ni data, from the US GEOTRACES GP15 cruise. As in other ocean basins, increases in δ60Ni towards the surface ocean are observed across the entire transect, reflecting preferential biological uptake of light Ni isotopes, however the observed magnitude of fractionation is larger in the tropical Pacific than the North Pacific Subtropical Gyre. Such surface ocean fractionation by phytoplankton should accumulate isotopically lighter Ni in the deep Pacific, yet we find that North Pacific deep ocean δ60Ni is similar to previously reported values from the deep Atlantic. Finally, we find that seawater dissolved δ60Ni in regions with hydrothermal input can be either higher or lower than background deep ocean δ60Ni, depending on vent geochemistry and proximity.