Reasons for space exploration

Space exploration is driven by an interest in scientific and technological progress, but it is also motivated by an innate desire to explore the unknown, as well as geopolitical and strategic considerations. In fact, the first man set foot on the Moon in 1969 specifically for the latter reason, as President Kennedy had made clear a few years previously: “The exploration of space will go ahead, whether we join in it or not, and it is one of the great adventures of all time, and no nation which expects to be the leader of other nations can expect to stay behind in the race for space.”[1]

Today, after 40 years of relative cooling-off, space projects are being revived, at a time when China is trying to supplant the United States (U.S.) as the dominant power on Earth and has shown rapid advances in space, while the U.S. seeks to maintain its leadership position.

This revival of the space race is also inspired by other factors, such as the emergence of private initiatives in the sector, with a focus on tourism, and space resource mining.

The current goal is to set foot on Mars, a major challenge that would show who the world leader is, through a fundamentally emotional achievement. Buzz Aldrin, one of the three astronauts who first went to the Moon, stated clearly in The Guardian in 2009: “Mars for America’s future. I am not suggesting a few visits to plant flags and do photo ops but a journey to make the first homestead in space: an American colony on a new world.”[2]

Ethical considerations

Development of these projects is already underway and the most speculative of them (albeit widely accepted), relating to the colonization of the universe, have opened the logical debate on the ethical issues and moral permissibility of the different technological strategies to tackle the rigors of space travel and colonization.

There are numerous and very diverse ethical aspects of space activities that warrant attention, ranging from the management of space waste and protection of the environment (both of the Earth and other planets), the legal status of space, its militarization, resource management and many others. Without a doubt, however, actions that directly affect human beings bring the most significant ethical repercussions to the fore.

Analysis of these ethical implications leads us to differentiate between the immediate projects to be carried out (a first manned scientific mission to Mars) and the commonly held notion of making a permanent settlement with thousands or hundreds of thousands of settlers on the Red Planet.

Manned mission to Mars

NASA’s current Artemis program[3] has planned different flights to the Moon this decade, with the establishment of a permanent base on its surface, all with a view to developing the technology for a manned flight to Mars. This is what NASA administrator Jim Bridenstine said when he presented this program: “We’re going back to the Moon for scientific discovery, economic benefits, and inspiration for a new generation of explorers,” adding that “As we build up a sustainable presence, we’re also building momentum toward those first human steps on the Red Planet.”[4]

NASA’s 2022 white paper Mars Transportation[5] suggests the year 2039 as a reference for man’s arrival on Mars. There is no detailed plan for its execution, but the development of all the devices needed for round-trip transportation must be based on known technologies, so its progress can be predictable and programmed. However, the behavior of the human body in the adverse conditions that govern space is unknown, and providing adequate protection may be more difficult to plan.

The frailty of man

The Earth has a protective shield around it due to its magnetic field, the magnetosphere, which largely filters out cosmic radiation. Additionally, the human body has evolved to live on Earth, with its atmosphere and specific gravity. The first step to going into outer space must be to understand and be able to mitigate the health challenges that await us out there.

The International Space Station, which is a research laboratory in microgravity and in which many astrobiology experiments have been conducted, has been in orbit around the Earth for a little over 20 years. As astronomer and popularizer Bob Berman explains, “Results from astronauts who’ve spent a long time on the International Space Station (ISS) show good reason for concern about space travel’s medical consequences.”[6] This is despite the fact that our experience is very limited, since the majority of astronaut visits there have been for less than 6 months and have been free from the real effects of galactic cosmic radiation, as the ISS orbits within the magnetosphere.

The journey to Mars presents us with a much longer stay in space. Even when the planets are as close as possible, the round trip distance between the Earth and Mars is about 950 times the round trip distance to the Moon. Furthermore, once on Mars, travelers have to wait until the distance to Earth is optimal; thus, if Armstrong, Aldrin, and Collins’ trip to the Moon lasted 8 days, the trip to Mars would last more than 1000 days.

Outer space is an inhospitable place. Astronauts are bombarded with carcinogenic radiation, subjected to lack of gravity, confined to small spaces, and must live on a restricted diet. NASA’s Human Research Program aims to develop and provide the knowledge base, technologies, and countermeasure strategies for safe and successful manned space travel. At present, different high-priority risks have been identified, such as: the effects of radiation, which induces DNA breaks in cells; reduced gravity, which causes the fluids of the human body to circulate towards the head and thus put pressure on the brain and eyes, affecting vision; and mental stress resulting from isolation in a small space. Adequate countermeasures are not available at this time, as stated in the 2022 NASA white paper: “we don’t yet understand all of the mechanisms involved, or the extent that multifactorial contributors to human system risks may limit which countermeasures would be effective […].”[7]

Nevertheless, the situation would be worse, according to an article authored by researchers from different universities and agencies in different countries, who consider that “there are good reasons to assume that even the most substantial and invasive ways of biomedical enhancement may be far from enough to provide safe and effective interstellar travels for humans.”[8]

There is pressure to speed up the process

In recent years, private investment in the space sector has increased greatly, creating a growing interest in its rapid development and attempting to expedite the different projects. Three well-known billionaire visionaries, Elon Musk, Jeff Bezos and Richard Branson, are no strangers to this pressure. However, it seems more achievable to accelerate the development of flight and landing systems than the knowledge and prevention of abnormalities in the human body in outer space. This can lead to pushing the dangers that astronauts must assume. Elon Musk has repeatedly spoken out about taking risks to accelerate this process: “It’s dangerous, it’s uncomfortable, it’s a long journey. You might not come back alive. But it’s a glorious adventure, and it’ll be an amazing experience.”[9] He has even alluded to the advertisement that Ernest Shackleton supposedly placed in a newspaper in the nineteenth century when he sought to assemble a crew for the first trip to Antarctica and that would have received more than 5,000 responses: “Men wanted for hazardous journey, small wages, bitter cold, long months of complete darkness, constant danger, safe return doubtful, honor and recognition in case of success.” Musk is aware that he will not lack volunteers: “A bunch of people will probably die.”[10]

Risks have already been taken in the past, on the occasion of the first moon landing. President Nixon, aware of the dangers to which the first visitors to the Moon were subjected, had prepared his speech in the event of a fatal outcome: “Fate has ordained that the men who went to the Moon to explore in peace will stay on the Moon to rest in peace. (…) For every human being who looks at the Moon in the nights to come will know that there is some corner of another world that is forever mankind.”[11]

We know that zero risk does not exist — so far 19 astronauts have died in space missions and another 11 perished during testing and training on Earth — but we must consider the ethical issue of sending human beings to such a dangerous environment without the guarantee of having effective, sufficiently proven countermeasures.

A common belief: we must colonize Mars

In the 1970s, biologists Edward Wilson and Eugene and Howard Odum published their thoughts on the possibility of creating extraterrestrial colonies, an objective that started gaining supporters among the public, and also in scientific circles. It was adopted in 1986 by the U.S. National Space Commission, which concluded that the long-term ambition of the U.S. civilian program should be “to support human settlements beyond Earth orbit, from the highlands of the Moon to the plains of Mars.”[12]

Different reasons are given to justify this colonization, such as science, economic opportunities and resources, inspiration and adventure. Much emphasis is placed on the long-term survival of humanity. Elon Musk strongly insists that this project is for the good of humanity, believing that becoming a “multi-planetary species” will increase our chances of survival. This is both a utopian and morally reprehensible idea, as the actions required to carry out this project, according to current technology, are ethically unacceptable.

Mikko M. Puumala and other researchers from Turku University[13] enter into the debate and recognize the value of this concept: “Protecting humanity is indeed a noble cause and avoiding premature annihilation is largely considered extremely desirable. Therefore, if settling Mars helps us to safeguard humanity, it vastly increases its moral desirability.” Nevertheless, they consider that it is not a realistic goal or the best way to avoid the extinction of humanity. Some of the arguments they make are: we are not in a position to create a self-sustaining and sustainable settlement; some extinction risks considered, such as a pandemic or a war, could affect both populations at the same time; and the cost of this project would be much more expensive than that of mitigating extinction risks on Earth, which in any case would still be home to the vast majority of the population.

Terraforming Mars

Mars has long lost its atmosphere and life on its surface is not possible for humans. To overcome this, two alternatives have been proposed: so-called “terraforming” Mars, i.e., generating an atmosphere that allows human life in it; or genetically modifying humans to make them resistant to galactic radiation and other conditions on the Martian surface. In reality, both would be necessary, and both are ethically reprehensible.

The term “terraforming” was introduced by Jack Williamson in 1942 in a science fiction novel. Carl Sagan, in 1961, was the “first scientist to speculate about terraforming in the pages of a technical journal.”[14] Since then, very different ideas on how to achieve this goal have been published, but observations made by spacecraft in the last 20 years have eliminated this possibility. Dr. Bruce Jakosky, principal investigator of NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) mission, believes that “terraforming Mars is not possible with today’s technology.”[15]

In any case, this goal of some people remains and, given that we increasingly feel the need for an ethical relationship with our planet, we must ask ourselves if we should not think similarly about the extraterrestrial environment.

Genetically modifying humans

Since the human species is not well adapted to live and work in space for long periods of time, proposals have been made to artificially improve human adaptation to space by biomedical means.

However, this is only possible through treatments that affect our DNA, which would have to be specifically adapted to enable a long and healthy life on Mars, including genetic modifications for good muscle, bone and brain health. These traits should be heritable, so that Martian settlers could pass them on to their offspring.

There is a school of thought that seeks to justify germline genetic engineering due to the need to adapt human beings to the conditions of space. An example of this is an article authored by 14 researchers from different universities and organizations from five different countries, led by Konrad Szocik from the Interdisciplinary Center for Bioethics at Yale University.[16] It states that: “Some ethical considerations are relevant for issues discussed on Earth, but differ markedly when applied to the context of space missions.” The argument for accepting the use of genetic engineering would be the consideration of “preventive medicine” rather than “enhancement of the species” for those humans who must survive on Mars. This gives rise to accepting that, over time, new species of astronauts and their descendants would be generated that could become a species different from Homo sapiens.

This line of thinking is contrary to the consensus that has prevailed so far. The ethical debate on human gene editing has been going on for more than 50 years, wherein scientists, philosophers, theologians and other people participating in it have used the somatic and germline distinction as a moral limit. “Somatic” means changing the genes of some of an existing person’s cells in a way that does not affect their reproductive cells, while “germline” means changing the genes of someone’s offspring and, ultimately and to a small extent, of the human species. This was stated in 1997 by the Council of Europe in the Convention for the Protection of Human Rights with regard to the Application of Biology and Medicine: “An intervention seeking to modify the human genome may only be undertaken for preventive, diagnostic or therapeutic purposes and only if its aim is not to introduce any modification in the genome of any descendants.”[17]

It has also been reaffirmed in a Statement by the Organizing Committee of the Third International Summit on Human Genome Editing held in London last year: “Hereditable human genome editing remains unacceptable at this time.”[18] At the summit, Tina Rulli, associate professor at the University of California, Davis, specialized in normative and applied ethics and bioethics, declared the following: “There are a bevy of serious objections to reproductive genome modification,” such as “concerns about the safety of the modification … the risk of dangerous modifications let loose in the human gene pool, a slippery slope to using the technology to make designer babies, unethical eugenic uses of the technology that harm disability communities, and unequal unfair access to the technology that only advantages the wealthy.”[19]

There are many philosophers and scientists on whose thinking this limitation is based. Jürgen Habermas believes that any genetic interference that could change human nature should be morally prohibited, as it alters the very essence of human nature. Redesigning humans means reducing them to objects, by fundamentally evaluating the conformity of the object (or means) to an end, reasoning that is directly applicable to missions to space or Mars.[20] Philosopher Francis Fukuyama, author of Our Posthuman Future. Consequences of the Biotechnology Revolution, considers that genetic enhancement is never a morally acceptable solution, as it would lose (perhaps irreversibly) those essential characteristics that support the “sense of who we are and where we are going, despite all of the evident changes that have taken place in the human condition through the course of history”. This leads him to conclude, with respect to the idea of Mars as a refuge, that while we could think about genetically enhancing and then transferring an entire population to another planet, this would not save the human species from the risk of extinction, since the people who would leave the Earth would no longer belong to our species.[21]

A future without astronauts

The idea that we will soon establish colonies on Mars inhabited by hundreds or thousands of people is sheer nonsense and an unmitigated denial of the tremendous challenges posed by that prospect. “It’s a dangerous illusion to think [as some do] that we can escape Earth’s problems by going to Mars,” says Martin Rees,[22] a British astronomer and authority in different fields of science. Lucianne Walkowicz, an astronomer at the Adler Planetarium in Chicago and a researcher of the ethics of Mars exploration, puts it more radically: “I think this idea of Mars as a backup planet would be almost comical if it wasn’t so sinister.”[23]

Faced with so many unrealizable projects and utopian goals, it is possible to put forward more realistic ideas that allow us to advance in the knowledge and exploration of the solar system. Man’s ability to act in space does not necessarily require his physical presence in outer space. Space technology, which uses probes, satellites and automatic devices, can, in most cases, be just as effective, and is often less expensive than a manned mission. Robots are already good space probes, and they will be increasingly intelligent in the near future.

Credit: NASA/JPL-Caltech

Robot development is set to become more economical and effective than humans in the endeavor of investigating outer space. In addition, visiting Venus or Mercury with manned spacecraft is unfeasible due to their high temperatures, and similarly, it is impossible to travel to Jupiter or the asteroid belt due to their extremely low temperatures.

“The fact is that robots are getting better and cheaper all the time,” says Rees, “so I don’t see a case for that huge public expenditure of sending people into space.”[24]

Perseverance, NASA’s latest rover, has been on the surface of Mars since February 18, 2021. Its mission is fundamentally to detect whether there are signs of life. For this it works tirelessly, and has already sent many thousands of data. Led by six principal investigators, one of whom is Spanish, hundreds of scientists work daily analyzing the information received. In reality, the real “exploration” takes place on Earth, in laboratories spread across all continents.

The robotic space program is a much more cost-effective means of advancing our scientific knowledge of the universe. The manned exploration of space best satisfies the spirit of epic and curiosity of our species, but we must abstract ourselves from the epic that science fiction has breathed into our minds, telling us the kind of space adventures that people want to see and for which reality has been changed: imagining a space small enough to be able to move easily; crowded and noisy enough to be exciting; a place where the physics of flight works just as we see it on Earth; where space adventure is like a maritime adventure, with planets for islands, and the opportunity to tell stories of piracy, exploration and colonialism… And surrender to the evidence: the human being is fragile against the conditions of outer space.

What man must be satisfied with is his intelligence, which allows him to advance his understanding of the keys to the universe using his ingenuity. Every time a robotic ship discovers new enigmas of the universe, we should be proud, because that is the fruit of our intellect.

Manuel Ribes

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia


[1] Sebastian Gerhard Lyhne Hanssen, Aiming for the Moon The Arctic University of Norway Master’s thesis in Political Science, STV – 3900, May 2023

[2] Buzz Aldrin, Time to boldly go once more The Guardian Thu 16 Jul 2009

[3] M. Ribes A New Space Race Bioethics Observatory UCV October 2022

[4] Neel V. Patel How the Artemis moon mission could help get us to Mars  MIT Technology Review   September 23, 2020

[5] White Paper MARS TRANSPORTATION NASA’s 2022 strategic analysis

[6] Bob Berman Will It be Safe for Humans to Go to Mars? Maybe Not. Almanac November 13, 2023

[7] White Paper MARS TRANSPORTATION NASA’s 2022 strategic analysis

[8] Konrad Szocik et al. Future space missions and human enhancement: Medical and ethical challenges – ScienceDirect Elsevier Ltd. July 31 2021

[9] Chelsea Gohd Elon Musk reminds us all that ‘a bunch of people will probably die’ going to Mars April 28, 2021

[10] Jackie Wattles Elon Musk on Mars: ‘You might not come back alive’  CNN Business April 27, 2021

[11] James Mann The speech Richard Nixon would have given ‘in event of moon disaster’ The Washington Post  July 12, 2019

[12] PIONEERING THE SPACE FRONTIER The Report of the National Commission on Space  NASA 1986

[13] Mikko M. Puumala et al. Moving to Mars: The Feasibility and Desirability of Mars Settlements  Elsevier Ltd.  2023

[14] Martyn J. Fogg  The ethical dimensions of space settlement  Elsevier Science Ltd.  1999

[15] Bill Steigerwald, Nancy Jones Mars Terraforming Not Possible Using Present-Day Technology. Mars Exploration Programm News July 30, 2018

[16] Konrad Szocik et al. Future space missions and human enhancement: Medical and ethical challenges – ScienceDirect Elsevier Ltd. July 31, 2021

[17] Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine Official State Gazette (BOE) 251 of 20/10/1999 Sec 1 Pag 36825 to 36830

[18] Rob Stein Ethical concerns temper optimism about gene-editing for human diseases    Shots – Health News : NPR   MARCH 8, 2023

[19] Ibid.

[20] Balistreri, M., Umbrello, S. Modifying the Environment or Human Nature? What is the Right Choice for Space Travel and Mars Colonisation?. Nanoethics 17, 5 (2023).

[21] Ibid.

[22] Josh Sims What’s Lost When Robots Replace Astronauts  InsideHook newsletter November 27, 2023

[23] Bob McDonald Is it ethical to go to the red planet?  Quirks & Quarks CBC Radio Jun 12, 2020

[24] Josh Sims  What’s Lost When Robots Replace Astronauts  InsideHook newsletter   November 27, 2023


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