One of the main directives of space agencies all around the world, when explore the solar system, contamination from Earth spread to other celestial bodies. There are policies and laws in place to prevent the contamination of other planets with an entire section of space law called planetary protection. The planetary protection system is designed to protect planets, moons, comets, and asteroids from being contaminated. For five decades, governmental organizations around the world have accepted the rules and laws.
However, a major challenge for the future is that an ever-increasing number of commercial space missions are taking off, and there is fear that some private companies may not follow the rules completely. Planetary protection comes in two versions, known as forward and backward. Forward protection concerns not contaminating other planets with material taken from Earth.
Part of the reason is to protect any life that may be on other planets already and prevent the accidental detection of earth life on another planet. Backward contamination is to prevent Earth from being contaminated by life from other planets that might hitch a ride back.
To prevent contamination, spacecraft are typically made inside clean rooms, which are some of the cleanest places on earth. These rooms are routinely tested for biological contamination. While every effort is made to keep them clean, in 2013, a new type of bacteria was discovered in two different clean rooms 2500 miles apart. The bacteria was found nowhere else on Earth. These rules and laws are in full effect as three missions are set to arrive at Mars this month, with two of them eventually touching down on the surface of the Red Planet.