The Ethics of Space Exploration

Liz Miller shares her ethics & society case study, which she completed as part of our Young Scientist Program.

Space exploration is an exciting and constantly progressing field. Fulfilling natural human curiosity about worlds other than our own, exploration of our solar system and beyond is generally met with support by people from all walks of life. While the bulk of our effort is put into allowing both objects and humans to survive safely on other planets and moons, there is also a need to protect other environments from us. The potential contamination and destruction of other worlds and other life is both a practical and an ethical problem.

Contamination is generally categorized as forward or backward (Rummel, 2001). Backward contamination is contamination of Earth by substances that have been to other bodies in the solar system, and is generally of little concern. Few objects that we send to other planets or moons ever return to Earth, and thus far no other life or transferrable hazards have been found. Forward contamination, on the other hand, has been a concern since the first voyages to Mars by the Viking spacecraft in 1976 (Rummel, 2001). Forward contamination is the contamination of other worlds, and any potential indigenous life, by Earth. We can’t know what effect Earth-based life might have on alien life, but the legacy of invasive species and pathogens wreaking havoc on native species on Earth suggests great harm could come of contamination.

Various organizations exist to develop guidelines and rules for preventing forward contamination, including NASA’s Office of Planetary Protection and COSPAR, the International Counsel of Science’s Committee on Space Research. Since the 1960s these organizations have set various rules about the sterilization of spacecraft and tools sent to other planets, with particular focus on Mars and Europa, two of the most promising and accessible locations for potential alien life. Unfortunately, their guidelines are often based on outdated, arbitrary, or theoretical values of the probability of contamination and damage to alien environments and life (Greenberg & Tufts, 2001). Additionally, it is impossible to completely sterilize spacecraft leaving Earth. When humans travel in those spacecraft, contamination is almost certain (McKay, 2009). Beyond contamination, ethical questions must also be considered about human intervention and research of potential alien life.

The theoretical ethics of planetary protection might play out in different ways, depending on the situation. For comparison, two potential scenarios of contamination and human intervention will be explored here. In the first scenario, small amounts of microbial life are found on Mars. These microbes could actually originate from Earth, as meteorite exchange between the two planets has been fairly common during the history of the solar system (McKay, 2009). In this case, the Martian life may be feeble and have a very high possibility of extinction. Mars is a hostile environment, cold and unprotected from lethal UV radiation (McKay, 2009). Would humans have an obligation to protect Earth-originated life, possibly to the extent of changing Mars into a more nurturing environment? As humans we tend to value life and work to protect it, but in this case that might mean forever altering the abiotic Martian environment. Interfering in the course of Martian evolution might sound amoral to some, but others would argue that standing by and letting a unique form of life become extinct would be worse. This is, of course, assuming that well-intentioned interference would not result in lethal contamination, which is practically impossible to prevent. Additionally, what is the difference between Earth-originating life that was introduced by meteorite or life that was introduced by spacecraft? At what point does that life become truly Martian?

In a very different scenario, a voyage to Europa, a Jovian moon with a high potential for liquid oceans that could support life, results in the discovery of a complex and highly developed ecosystem of living organisms. Many scientists believe Europa has the highest possibility of non-terrestrial life in our solar system (Greenberg & Tufts, 2001). In this case, the ethical question would not be whether or not to protect this life, but whether or not to study it. Exploring the universe and learning more about it is generally considered unproblematic and even necessary for the advancement of humans. However, studying alien life creates a paradox. It is impossible to know how to prevent harm without knowing anything about what is being studied– and scientists can only know about something by studying it. In attempting to learn how Europan life might be vulnerable to Earth pathogens, researchers would risk destroying an entire ecosystem with non-sterile tools. Consider how diseases innocuous to Europeans decimated entire indigenous populations in the Americas. The basis of this ethical problem is not knowing how our actions, no matter how noble in intent, might affect life so fundamentally different from ourselves.

Clearly, the problem of planetary protection goes far beyond simply preventing contamination. As space exploration allows us to travel farther from Earth and explore more worlds, we will need policies and protocols to guide us and allow us to learn more about the universe in an ethical way. One possible way to protect other environments is to only send robots, not humans. This may be disappointing to those who dream of walking on an alien world, but the effectiveness of sterilization is so much greater for robots that this may be the only ethical way to continue exploration. Additionally, learning from our own history and mistakes on Earth may help guide us towards thoughtful and preventative policies. As the two examples explained above demonstrate, it is difficult to design policies that encompass the wide range of possible scenarios in which other worlds need protection from humans. Despite the difficulty of this task, it is essential that we have these discussions, and that people from all walks of life and around the world have a voice in designing guidelines for space exploration. Somewhere between the extremes of exploring without care for contamination or other harm, and stopping space exploration altogether, there might be a set of protocols which minimize destruction and allow us to continue to satisfy our curiosity and drive for discovery.

Works Cited
Greenberg, R., & B. R. Tufts. 2001. Macroscope: Infecting Other Worlds. American Scientist 89(4): 296-299.
McKay, C. P. 2009. Biologically Reversible Exploration. American Association for the Advancement of Science 323(5915): 718.
Rummel, J. D. 2001. Planetary Exploration in the Time of Astrobiology: Protecting against Biological Contamination. Proceedings of the Natural Academy of Sciences 98(5): 2128-2131.