The recent spike in planetary missions has caused astrobiologists to worry about the potential for ‘interplanetary contamination’ on Mars. This concept encompasses any biological contamination of a planetary body by spacecraft, whether intentional or accidental. As commercial space travel progresses and ambitious missions increase, this concern becomes more prevalent.
Context: The Aim of Recent Space Missions
A number of missions have been launched towards Mars recently. China’s Tianwen-1 aims to land on the Martian surface, whilst the UAE’s Al Amal (Hope) is set to study the Martian atmosphere from orbit without landing. The United States is also set to launch its Perseverance mission soon, marking NASA’s 10th successful Mars landing since 1975. The Perseverance mission aims to search for signs of ancient life and collect rock and soil samples from Mars.
In the past, space missions have made physical contact with comets, asteroids, and even landed astronauts on the moon. However, these celestial bodies are known to be hostile to life, making their potential contamination less of a concern.
Types of Contamination: Forward and Backward
The potential for interplanetary contamination can occur in two forms: forward contamination and backward contamination. Forward contamination refers to the transportation of Earth-based microbes to other celestial bodies. Since liquid water has been found on Mars, this raises the possibility of Martian life. This imparts an ethical obligation on humanity to prevent Earth-based organisms from disturbing a potential Martian biosphere, allowing it to progress naturally.
Backward contamination refers to the transfer of extraterrestrial organisms back into Earth’s biosphere. Scientists believe that Mars-based life forms may not pose a risk as their biochemistry would differ significantly from that on Earth.
Planetary Protection Measures
The United Nations Outer Space Treaty of 1967 serves as a safeguard against the militarisation of space, and also mandates countries to consider contamination risks. It is supported by 110 state parties, including Russia, the United States, China, and India.
The Committee on Space Research (COSPAR) enforces a ‘planetary protection policy’ to limit the microbes sent to other planets and to prevent alien life from causing issues on Earth. Implementing this responsibility translates to far-reaching implications on spacecraft design, operational procedures, and mission structure. NASA and the European Space Agency have even assigned Planetary Protection Officers to oversee these concerns.
Solutions: Sterilisation and Containment
To prevent forward contamination, spacecraft are often sterilised. This was practiced in all previous Mars missions, such as NASA’s Viking landers of the 1970s, and continues with the upcoming Perseverance mission.
Backward contamination poses a different problem as sterilisation could harm extraterrestrial samples. In this case, containment becomes the only option to break the contact chain between potential alien microbes and life on Earth.
The Way Forward
As nations vie for a strategic edge in space, ethical aspects of space technology can sometimes be overlooked. The conception of space as a military domain must be avoided to preserve its peaceful usage. Violations of Outer Space must not be tolerated. At the same time, preserving the natural biosphere of Earth and other planetary bodies will require international cooperation.
