https://blogs.scientificamerican.com/observations/microbes-might-be-the-key-to-a-mars-mission/

Picture a group of adventurous companions setting out into the great frontier to explore a barren, wild land. They must bring only the most important things they’ll need to survive on their own. Every ounce of weight they decide to take with them means another ounce they must transport. It sounds like an extreme backpacking trip, but I’m actually talking about a future mission to the surface of Mars.

We take for granted all the things we have on Earth that support human life—air for breathing, water for drinking and nutrients in the soil that allow us to grow food. On Mars, however, astronauts will need to bring their own life support systems, which can be prohibitively costly to transport. Without a lightweight flexible technology that can manufacture a variety of products using limited resources, the first Mars explorers won’t survive their journey.