These earplugs would be very useful on a mars mission because rocketships are extremely loud. Your eardrums are very sensitive to loud sounds. One of the loudest sounds is a rocket launching. Astronauts also may have trouble sleeping. It is important in their form of work to not strain themselves and to get enough rest. Due to the very loud noises and the straining work, it is hard for them to fall asleep, so with earplugs, it will block out most of the noise. Loud noises are very damaging to ear drums and could cause potential deafness. These earplugs are made from memory foam, or polyurethane. This blue memory foam provides comfort in the ears and blocks out sound. These earbuds are sized to fit average adult ears. These can help on a three year mission because, even if you bring earbuds on the rocket you could potentially lose them or forget them. These are also good because you have a large supply of them, so you could change them daily which will make sure you have good hygiene.