Bioprinted bone sample in spaceflight research. 3D printed human bone sample held in a researcher's gloved hands. Bioprinting human tissue could help keep astronauts healthy on long journeys, such as those planned to Mars. A European Space Agency (ESA) research project produced these initial bioprinted skin and bone samples. This bone sample was printed with human stem cells using human blood plasma as a nutrient-rich 'bio-ink' with the addition of a calcium phosphate bone cement as a support material. The viscosity of this bio-ink was increased to make it suitable for use in low-gravity conditions. Image published in 2019.