Space has been one of the most interesting and eye-catching research and science fields during the past 60 years, since the first artificial satellite was launched into Earth’s orbit. The technological advance that has been occurring in the past decades in all fields of science is reflecting upon space technologies and is driving this field towards miniaturization with the clear scope of acquiring knowledge, discover new worlds and explore the Solar System and beyond. The ultimate goal of space research is to understand our past and respond to crucial questions such as “where did we come from?” so that we can project and, more important, plan our future as humans and respond to the next question “where are we going towards?”. In order to find responses to these questions throughout research and exploration, humanity sometimes had to step on ethics, or on the side of it, in order to reach the desired goal. A number of questions raise ethical doubts, such as “Is it fair to disturb the ecosystem of one space-object?” or “what gives us the right to establish which level of intelligence we consider life?”. Even more concerning in such a beautiful field like space exploration is the involvement of politics, global strategy and eventually war: “should politics be involved in space exploration?”. It is well known that the human exploration of the Moon was a political competition between the Americans and Russians which concluded with a historical moment that indeed rose in us the desire to know more about space and research the surrounding objects to our planets, but are the motivations behind the triggering of this desire to know more about space, ethical? As a species we have been constantly evolving throughout our existence and this is mainly due to the human desire of acquiring knowledge and respond to questions that have no immediate or obvious response. Due to the advancements in all sciences such as in medicine, underwater exploration and space exploration, we are becoming our own gods, but does this give us the right to disregard and invade any planet in the solar system and beyond? Are we “qualified“ to do so when we are driving our own planet towards the end? Last but not least, is academic integrity in the aerospace field respecting the moral code and ethical policies when it comes to exciting ideas and discoveries?
This paper aims at raising and trying to respond to several crucial questions that we, as scientists and engineers working in the space field, are continuously facing every day.
What is ethics and how does it relate to the space field?
Ethics in general concerns the difference between right and wrong behaviour, between how the world is and how the world should be. We as humans are interested in these ethical questions because the consequences of our actions can maximize our well-being. This largely incomplete definition of ethics sounds slightly egoistic, which partially describes in a very superficial way the human race throughout history since homo sapiens until present. We, as humans, always fought hard towards acquiring comfort and happiness for ourselves with little care of the surrounding environment. Humans have never been good at changing themselves at the pace imposed by the planet that hosts us and respecting the environment, instead we have been rather impatient and changed the environment in order to suit us better. This clearly shows the strict relationship between ethics and the natural desire of mankind to extend the frontiers of our exploration and knowledge beyond Earth: or in other words, the relationship between ethics and space research and science.
A large amount of literature has been dedicated in the past to ethics in the (aero)space field and all related ethical questions. Only part of this literature will be cited here, with no expectation to be complete or exhaustive.
In her papers, Billings [1,2] describes the changes in the space exploration scenario of the last decades, where new international actors have appeared (China, India, Europe, Japan) and the initial US-centric perspective has been by a more multifaceted environment in which cultural and political differences between the involved countries bring new challenges on the table. In the beginning, human exploration of space would be compared to the experience of the pilgrims who initially emigrated from Europe to settle in the newly formed United States of America, or the pioneers leaving from the East coast of the US to conquer the West: in the same way as these former pilgrims, space explorers would expect to “claim their land” without political or governmental interference. This situation is not possible anymore in the current scenario, where it starts to be extremely relevant to pose questions like “should there be competition or cooperation”, “who should claim property on the space frontier, and how”, “should we talk about conquering space, or exploring space”, “are there ethical issues in introducing terrestrial organisms into planetary environments, and how should these issues be regulated in a strongly international space exploration scenario”.
The importance of ethics for aerospace engineering is often highlighted in literature by discussing specific catastrophic events, such as the Challenger or the Columbia disasters [3,4]. A significant amount of debate is also present in literature on the role of aerospace leaders, and how ethical leadership can contribute to form the mind-set of the aerospace industry, research and governmental institutions. Generally speaking, when analysing leadership in engineering (thus, not only in the aerospace field), a study from Groves and LaRocca  showed that leaders following deontological values (altruism, universal rights, etc.) are strongly associated with transformational leadership, while leaders giving more importance to teleological values (such as utilitarianism) are more associated to transactional leadership. It is therefore important not only to identify the values that should be associated to ethical leadership, but also to define which ones among these values have to be taken into account based on the type of ethical leadership that is considered; several methods have been proposed to this purpose (and, in general, to provide a measure of ethical leadership), such as the Authentic Leadership Questionnaire (Walumbwa et al.) , the Servant Leadership Questionnaire (Barbuto and Wheeler), the Ethical Leadership Questionnaire (Yukl et al.) .
When referring more specifically to leadership in the aerospace field, several papers have discussed the extensive perception, also reflected in the common practice, that management competency is considered more important for project management than pure technical competence . Experience and cross-competence in military disciplines are still seen as an important element for successful leadership (especially in the US aerospace scenario), with clear consequences in terms of ethical leadership [10, 11]. Other authors focus on the importance of correct mentorship and supervision in aerospace education [12, 13], as well as the strategic relevance of including ethics in the curriculum of typical aerospace engineering studies . Whistleblowing is another side of the coin for ethical leadership in aerospace engineering . Several papers discuss the different activities that might result in whistleblowing, from falsifying engineering records to discriminating people to financial misconduct. The relevant aspects of ethical leadership in aerospace Academia will be discussed more in detail in section 7 of this paper.
Ethically relevant aspects in Space Exploration
Space exploration brings the enjoyment and fulfilment of human curiosity with respect to unknown aspects of worlds outside our immediate reach. While we, as humans, put a lot of effort in investigating and eventually colonizing other planets, there is a critical need to protect their (eco)systems from ourselves and minimize potential contamination of extra-terrestrial worlds that can reach to potentially destroying, or irreversibly changing, the visited object.
Contamination is defined (Rummel, 2001)  as being of two types: backward and forward. Backward contamination refers to the actual contamination of Earth with substances or samples coming from other bodies in the solar system. Backward type of contamination is currently of little concern: it is well known that many samples have been brought to Earth either by meteoroid impacts or by actual sample return missions such as the Apollo program which returned approximately 400 kg of lunar rocks and regolith (lunar soil). The most known is the “Genesis Rock” returned by Apollo 15 lunar mission in 1971 (Figure 1). In general, only a limited number of objects that we send to space ever come back to Earth, but in the past 20 years, the space field has also focused its research on how to use autonomous vehicles (e.g. spacecraft and landers) for sample return from other bodies orbiting Earth. Hayabusa (from the Japanese Exploration Space Agency, JAXA) represents a well-known success among asteroid missions through its attempt to bring a sample return from asteroid 25143 Itokawa .
The mission also had as an objective the detailed study of spin state, shape, topography, density, composition and history of the asteroid. Its successor, Hayabusa 2 , is a currently ongoing mission launched in 2014 which has recently performed a rendezvous with the Ryugu asteroid and will perform another sample return tentative like its predecessor mission. Another relevant ongoing mission is OSIRIS-REx from NASA , launched in 2016, which has as its main goal the return of a sample from the asteroid 101955 Bennu. All these missions fall under the description provided by Rummel  in terms of backward contamination. The discoveries made through the data sent by these 2 missions so far are breath-taking. Such missions help in understanding that the measurements that we perform from ground based observations in order to characterize the compositions of asteroids are not accurate, and more in-depth in situ exploration of such bodies is necessary to better understand them. Rosetta , another historical space mission which explored a comet, assumed a type of surface and designed its lander spacecraft in accordance with that expected type of surface, but it turned out that the assumptions made in the design phase on the comet surface were wrong, and the landing was unsuccessful. This proves why sample return missions are crucial and how they can help at better understanding why ground based observations are incorrect.
The next challenge is understanding NEO composing materials in terms of strength, thermo-mechanical properties and response to impacts. This task is currently performed based on the interpretation of telescopic observations in terms of meteoritic materials and models allowing us to extrapolate from the microscale (meteorites) to the macroscale (asteroids). But missions like Hayabusa 2 and OSIRIS-REx found that although size and composition of their target asteroids were predicted very accurately, the surface topology of both Ryugu and Bennu was not the expected one: they are covered with boulders with sizes ranging from several tens of meters down to a few decimetres, and they are not smooth and covered by cm-scale regolith particles as it was predicted from pre-encounter modelling of telescopic observations, in spite of the fact that these models have been cross-validated for years. So far, the conclusions of these missions are that we are not really aware of the materials that exist on asteroids (specifically small ones) and these have been recently discovered thanks to in-situ observations performed by actual space missions. This brings us to what Rummel  describes as forward contamination: the contamination of other worlds by us, humans from Earth. Contamination in general refers to the transfer of life and other forms from Earth to other celestial bodies; when a spacecraft is sent to a different celestial body, measures to minimize human contaminations are taken very seriously.
Contamination with multicellular life is unlikely to occur for robotic missions, but it has to be taken very seriously in crewed missions to celestial bodies. We cannot know so far what effects our forward contamination has made on the visited bodies, however we can safely say that we have contaminated with human artefacts many objects such as asteroids, the Moon, Mars, etc. A list of landings or crashes which certify a certain level of forward contamination on other celestial bodies can be found in . It is important to notice that we have contaminated so far: a) Planets such as Mercury (Messenger – intentionally crashed at end of mission), Venus (Venera 3-6 crushed, Venera 7 – soft landing transmitted for 23 minutes, Venera 8 – soft landing transmitted for 50 minutes, Venera 9 – soft landing first picture transmitted for 53 minutes, Venera 10- soft landing transmitted for 65 minutes, Pioneer Venus Multiprobe transmitted for 67 minutes, Venera 12-14 soft landing and transmitted from 57-127 minutes, Vega 1 lander soft landing, Vega 2 soft landing transmitting for 57 minutes), Mars (Mars 2 lander – crashed, Mars 3 lander – soft landing worked for 20 seconds, Mars 6 lander contact lost at landing, Viking 1&2 soft landing, Mars Pathfinder and Sojourner rover first airbag landing and first rover, Mars Polar Lander and Deep Space 2 penetrators, contact lost prior to landing, Beagal 2 lost, MER-A Spirit, MER-B Opportunity, Phoenix, Curiosity, Schiaparelli contact lost after entry, InSight), Jupiter (Galileo atmospheric probe intentional impact, Galileo intentional impact), Saturn (Cassini orbiter intentional impact); b) Planetary moons, such as Earth’s Moon (more than 35 confirmed devices), Moons of Saturn (Titan – soft landing, transmitted data for 90 minutes), c) asteroids and comets, such as Comet 9P/Tempel 1 mission Deep impact, Comet 67P/Churyumov-Gerasimenko Rosetta mission – lander and satellite, Osiris-Rex sample-return on 101955 Bennu, Hayabusa sample-return missions on Ryugu and Itokawa asteroids. Figure 1 The Genesis Rock returned by Apollo 15
The COSPAR (Committee on Space Research) develops recommendations with respect to sterilization of components (specifically Mars and Europa which are the most promising and accessible locations for life) in order to avoid interplanetary contamination and it is split into five groups : Category I – no planetary protection requirements for celestial bodies that do not represent an interest for origin of life or evolution; Category II – documentation with intended or potential impact, planetary protection plan submission, post-encounter and End-of-Mission Report for celestial bodies such as Moon, Venus and comets; Category III – flyby and orbiter missions to celestial bodies of interest for origin of life or evolution such as Mars, Europa, Enceladus, apart from those documents stipulated in category II, requirements may include clean room assembly, inventory of organics, trajectory biasing; Category IV – lander, probe or sample return missions to the same celestial bodies as stipulated in category III whereas the measures to be applied depend on the body to be visited (e.g. Mars and specific regions) and more information can be found in ; Category V – divided into unrestricted (judged to have no indigenous lifeforms and therefore there are no special requirements – Mars, Europa, Enceladus) and restricted sample returns (scientific opinion is unsure – Venus, Moon) in which requirements include containment of all returned hardware, containment of any unsterilized sample returned to Earth.
Nowadays one of the main focuses in space exploration is related to research on asteroids, as already described above. This can eventually evolve into planetary protection missions (through asteroid deflection) and lastly asteroid mining. An example of short-term mission with a focus on asteroid exploration and preparation for planetary protection is Hera, part of the international Asteroid Impact and Deflection Assessment (AIDA) mission . Hera is the first planetary defence mission intended to validate an asteroid deflection procedure by means of a “kinetic impactor”.
The mission (Figure 2) aims at characterising the binary near-Earth Asteroid Didymos using a mothership equipped with various instruments including two small CubeSat spacecraft. An impact spacecraft, DART (Double Asteroid Redirection Test), developed by NASA, will impact the secondary asteroid of the Didymos binary system. The ESA spacecraft is expected to contribute to the evaluation of changes in geophysical and dynamical properties after the impact. Hera is designed based on the previous lessons learned from its ESA predecessor, Asteroid Impact Mission (AIM) and targets the re-use of several pre-designed technologies. One of Hera’s high level objectives consists of validating the kinetic impactor technique through DART in order to enable its applicability to other future targets. Are the words “planetary protection” a strong enough motivation to justify this strong form of forward contamination?
Delft University of Technology recently expressed the intention to embark in a project that aims at releasing a net in such a way that would warp the complete surface of a small targeted Near-Earth-Object with a design adapted to low-gravity bodies and their peculiar requirements in terms of ejection velocity and precision (Figure 3). The purpose of the research, and future in-situ validation technology, is to take measurements of the key properties of such asteroid in terms of temperature in various locations, magnetic field, topography, density of the celestial body, etc. The overall goal is to contribute to the characterization of such objects that, as previously mentioned, are not accurately characterized through telescopic observations. Of course in this case, the net will remain on the surface of the body forever and would contribute to the forward contamination which means that this will be added to the list provided in . Until what extent can we justify the endanger of celestials bodies (eco)systems?
“Ecosystem” is defined as a “community of living organisms”. It is well known that meteoroid exchange between Earth and Mars has been occurring in the past, therefore, how can we know if potentially found microbiological life on Mars is not in fact from Earth? Is that potential life Martian or not? Do humans have the right to change or alternate the environment of Mars in order to make it more friendly for humans? Are we able to perform slight alterations and avoid fatal contamination?