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date: 18 February 2020

Public Impact of Planetary Science

Summary and Keywords

The public impact of planetary science, or, alternatively, the public value of planetary science, is poorly understood, as little research has been published on the subject. Public impact may be linked to scientific impact, but it is not the same as public impact. Nor is it the same as public benefit or public understanding. No clear, agreed-upon definition of “public impact” exists, and certainly no definition of “the public impact of planetary science” exists. It is a matter of judgment as to whether global spending on planetary science has yielded positive public impacts, let alone impacts that are worth the investment.

More research on the public impact of planetary science is needed. However, the study of public impact is a social scientific enterprise, and space agencies, space research institutes, and aerospace companies historically have invested very little in social scientific research. Without further study of the subject, the public impact of planetary science will remain poorly understood.

Keywords: science communication, public understanding of science, public engagement, public outreach, public opinion, social studies of science


The public impact of planetary science, or, alternatively, the public value of planetary science, is poorly understood, as little research has been published on the subject.1 Assessing public impact, or public value, is a social scientific enterprise, and most space agencies, organizations, and companies do not have the proper expertise to conduct such research. Historian Steven J. Dick (2014) has noted that assessing the public impact of space science and exploration is a complex endeavor. “One can ask, for example, what does impact mean? Who is being impacted? What is the evidence that anyone is being impacted? And if there is an impact, individuals are undoubtedly affected in different ways depending on their worldviews or individual interests and predispositions” (p. 74). Most planetary scientists likely would say that planetary science has had a considerable public impact. However, research has not documented the nature, breadth, or depth of that impact.

In the United States, the National Science Board conducts a biennial study of public attitudes toward and understanding of science and technology (National Science Board, 2018, Chapter 7, pp. 1–99). The European Commission occasionally conducts similar studies (European Commission, 2014). Studies have been conducted on public interest in space exploration (Aviation Week Market Briefing, 2014; Funk & Strauss, 2018);2 the history of public opinion about NASA (Billings, 2010, pp. 171–177); the history of public opinion about U.S. human space flight (Launius, 2003); the impact of space exploration on public opinion, attitudes, and beliefs (Bainbridge, 2015); public attitudes about the U.S. space program (Miller, 1987, 2004); public understanding of science;3 the public value of science (Wilsdon, Wynne, & Stilgoe, 2005); public engagement with science (Entradas, 2011; Leshner, 2003) and with space exploration (Space Studies Board, National Research Council of the National Academies, 2011); and public support for space science and exploration (European Space Agency, 2005). However, little research has focused specifically on public interest in, understanding of, engagement with, and support for planetary science in particular.

Attention has been paid to the scientific impact of planetary science—for example, in the U.S. National Academy of Sciences’ so-called decadal surveys of planetary exploration missions. Though it sometimes may appear to be difficult to distinguish between the two, scientific impact and public impact are not one and the same. Historian Roger Launius (2013) has observed that since its beginnings in the 1960s, planetary exploration has “redefined the planets, characterized their nature, and developed new, fundamentally significant perspectives on the nature of our place in the cosmos” (p. 10). This description of the impact of planetary science certainly characterizes scientific impact. One might assume that these advances have public value, but it has yet to be demonstrated with any certainty that they do.

A further consideration in attempting to assess public impact is that there is no such thing as a monolithic “public.” As political scientist Henry Lambright (2013) has noted, U.S. planetary science has many “publics” to attend to, including NASA, the broader scientific community, the President, the White House Office of Management and Budget, Congress, the aerospace industry, the media, and a wide variety of other “public” audiences. The same argument applies to any other nation.

Perhaps the greatest public impact of planetary science comes from comparative planetology. By studying other planets, scientists came to understand that planets, including Earth, are evolving, not static, worlds. Planetary science has contributed to a deeper understanding of geological evolution, climate change, and the role of impacts in the history of planets. Comparative planetology has generated numerous observations that Einstein and Infeld (1938) would have found useful.

Other public impacts of planetary science include a deeper understanding of the nature and boundaries of life and habitability, the development of a few technologies with commercial applications (especially digital image production and processing), and an appreciation of the beauty of the natural environment extending beyond Earth. Constructions of “environment” and “nature” in what sociologist Steven Yearley (2008) has called “advanced modernity” have been, and are being, extended from Earth into space. The public impact of this change in perspective has not been studied in any depth but is worth considering.

Understanding How Planets Evolve

Spacecraft have flown by, orbited around, or landed on Mercury, Venus, Mars, Jupiter and several of its moons, Saturn and several of its moons, the dwarf planet Pluto and its moons, and the dwarf planet Ceres. Comparative planetology is a thriving field. Studies of geological features on other planets such as faults, landslides, and mountain chains have led scientists to better understand such features on Earth. Planetary science has revealed how and why planetary environments change, how and why climate change occurs, and how and why a planetary greenhouse effect can occur. By comparing Earth with other planets, scientists have also come to understand how life and its environments co-evolve. By studying other planets, scientists have come to the realization that other planets were not like Earth and explored how these planets had evolved over time.

Given global concerns about climate change on Earth,4 it is reasonable to state that this widespread understanding that Earth is a planet and unlike any other planet in our solar system, that planets evolve over time, and that life and planets co-evolve have had, and are having, a widespread public impact, on citizens as well as decision makers. As astrobiologist David Grinspoon (2016) has recently observed, “looking homeward from the vantages we’ve gained through our interplanetary journeys gives us valuable perspective for navigating the planetary-scale changes we are now facing— and causing” (p. xiv). In his book Pale Blue Dot, Carl Sagan (1994) expressed a similar view. He observed that while the human ability to see Earth from space has changed the way we think about our home planet, “the connection between exploring other worlds and protecting this one is most evident in the study of Earth’s climate and the burgeoning threat to that climate that our technology now poses. Other worlds provide vital insights about what dumb things not to do on Earth” (p. 221)—for example, atmospheric ozone depletion, greenhouse warming, and the generation of a nuclear-winter phenomenon.

In the 1960s, planetary science focused on Mars and Venus. It was not only science-fiction fans but also planetary scientists who, until missions to explore it took off, thought Mars could be a living planet, with plant life waxing and waning with the seasons. Early missions to Mars revealed that the planet was cold, dry, and seemingly lifeless—certainly without surface plant life. These missions also revealed geological features that appeared to have been caused by water and volcanism, leading scientists to later determine that Mars had had large volumes of surface liquid water billions of years ago and then to speculate that Mars might even have extant subsurface water, and perhaps even life. Venus has been called Earth’s “twin sister” because its size, mass, density, and gravity are similar to Earth’s. Until missions to Venus revealed otherwise, scientists believed that Venus was a hot and wet planet, and possibly habitable. Spacecraft observations showed that it was very hot (surface temperature over 400 °C), completely arid, with a 97% carbon-dioxide atmosphere, and not habitable.

In 1969, planetary scientist Andrew Ingersoll published a paper, “The Runaway Greenhouse: A History of Water on Venus” (Ingersoll, 1969), in which he explained how Venus evolved from hot and wet to hot and dry. This understanding of how the climate of Venus changed over time contributed to an understanding that the greenhouse effect that has kept Earth habitable was accelerating at a dangerous pace on Earth, spurred by human activity. While the scientific consensus is that Earth is experiencing an accelerating greenhouse effect, there is no consensus that Earth is experiencing, or is headed toward, a runaway greenhouse effect (Runaway greenhouse effect, n.d.). However, climate scientist James Hansen (2009) has argued that if humans keep burning nonrenewable fossil fuels at current rates, a runaway greenhouse effect is possible.

As historian Erik Conway (2013) has noted, “NASA’s explorations of Venus and Mars during the 1960s in search of extraterrestrials helped focus scientific attention on the intersection of chemistry and climate” (p. 184). “There are several threads to the ‘big story’ of global warming,” Conway has observed. “There is a paleoclimatology thread, a radiative transfer thread, a modeling thread, and . . . a planetary science thread . . . By the mid-1970s, they all converged in a general understanding that the Earth was a far different place than thought 20 years before” (p. 197).

Conway (2010) has shown how what came to be known in the 1980s as Earth systems science—“a new discipline focused on the dynamics of planetary-scale processes” (p. 579)—was an outgrowth of planetary science. The enterprise of Earth remote sensing was built upon the remote-sensing science and technology of planetary exploration, in particular missions to Mars and Venus in the 1960s and 1970s. For example, NASA’s Mariner 9 mission to Mars in 1971 “enabled scientists to watch a planetary-scale climate change occur before their very eyes.” A planet-wide dust storm “reflected sunlight back into space, causing the surface to cool very rapidly” (p. 574). The Soviet Union’s series of Venera missions to Venus in the 1960s, 1970s, and 1980s—carried out by atmospheric probes and landers (the first and only spacecraft to land on Venus thus far)—contributed greatly to understanding of the Venusian environment.

From Impact Cratering to Planetary Defense

Planetary science has revealed that bodies throughout the solar system—including Earth’s Moon—are riddled with impact craters. Over time, planetary scientists came to understand that impact cratering played a role in the history of Earth as well. By the 1980s and 1990s, planetary scientists were pointing out that asteroid impacts continue to occur throughout the solar system and that planning for planetary defense against a possible future asteroid impact with Earth was needed.

Barringer Crater, also known as Meteor Crater, a 1.2-kilometer-diameter crater in northern Arizona, was originally identified in the late 1800s as a product of volcanism. In 1903, mining engineer John Barringer proposed that the crater was made by the impact of a meteorite.5 For decades, the scientific community dismissed the impact hypothesis. In the 1960s, planetary geologists collected evidence to confirm that Meteor Crater was, indeed, caused by an asteroid impact. This finding led to the identification of impact craters, most obscured by weathering, all over the world.6

One major step forward in understanding the risk of possible future asteroid impacts with Earth was the discovery of a large, buried impact crater in Mexico, the Chicxulub crater, and the finding, published by Luis and Walter Alvarez and colleagues in 1980, the father-and-son team of the Alvarezes are most known for this discovery, so may we refer to this paper in this way? that this crater was caused by the impact of a 10–15-kilometer (6–9-mile)-sized asteroid with Earth. They theorized—and their theory has since been validated—that this impact event caused global environmental changes that led to the extinction of the dinosaurs.

In 1994, the breakup and impact of Comet Shoemaker-Levy with Jupiter, long predicted and widely observed from the ground and from space, most notably by the Hubble Space Telescope, provided real-time evidence that impact events continue to occur in the solar system. Efforts to find and track asteroids that might come near Earth and pose a risk of impact stepped up considerably after the Shoemaker-Levy impact event, with NASA establishing a near-Earth object (NEO) observations program in 1998, responding to a directive from the U.S. Congress to conduct a program to discover at least 90% of 1-kilometer-sized or larger NEOs within 10 years. NASA met this goal in 2010. In 2005 the U.S. Congress directed NASA to provide an analysis of alternatives to detect, track, catalog, and characterize potentially hazardous NEOs and develop a program to survey 90% of the potentially hazardous objects measuring at least 140 meters in size by the end of 2020. In addition, Congress directed NASA to submit an analysis of alternatives that NASA could employ to divert an object on a likely collision course with Earth. NASA is in the process of complying with these directives.

Due to global efforts to find, track, and characterize NEOs and predict close approaches (within 5 million miles of Earth’s orbit) and possible future impacts with Earth, a worldwide network of organizations and individuals interested in planning for planetary defense against future asteroid impacts is in place. The European Space Agency has a Space Situational Awareness Program that includes a NEO Segment. NASA’s Planetary Defense Coordination Office and the European Space Agency’s (ESA’s) NEO Segment are members of the International Asteroid Warning Network (IAWN) and the Space Missions Planning Advisory Group (SMPAG), multinational endeavors recommended by the United Nations for an international response to the NEO impact hazard and established and operated by the space-capable nations. Other members of IAWN and SMPAG include research institutions and observatories in Eastern and Western Europe, Asia, and South and North America.

The Minor Planet Center (MPC), sanctioned by the International Astronomical Union, is the global repository for positional measurements of asteroids and comets. The MPC is responsible for identification, designation, and orbit computation for all of these objects. Worldwide, space agencies are working with disaster-planning and emergency-response organizations to prepare for planetary defense. In 2016, the United Nations General Assembly designated June 30 International Asteroid Day, in order to “observe each year at the international level the anniversary of the Tunguska impact over Siberia, Russian Federation, on 30 June 1908, and to raise public awareness about the asteroid impact hazard” (United Nations, 2016).

Extraterrestrial Resource Exploitation

It is safe to say that for the foreseeable future, extraterrestrial resource exploitation will have no public impact, mainly because mining and processing extraterrestrial resources is technologically and financially infeasible. A few companies and organizations have made claims over the years that trillions to quadrillions of dollars/euros of extractable resources are to be found in asteroids. These claims are not supported by data, as very few asteroids have been characterized to the extent that the value of their extractable resources can be calculated (Billings, 2019b).

Two asteroid mining companies launched in 2012—Planetary Resources and Deep Space Industries—have since been acquired by other companies. Preceding its acquisition by Bradford Space, Deep Space Industries backed out of the business of asteroid mining and went into the business of developing propulsion technologies. Planetary Resources was acquired by ConsenSys, Inc., a blockchain venture production studio (Billings, 2019a).

On December 1, 2014, The Hague Institute for Global Justice convened a roundtable on the governance of space resources. Following that meeting, the International Institute of Air and Space Law at the Leiden Law School, Leiden University, spearheaded the establishment of The Hague International Space Resources Governance Working Group (United Nations Committee on the Peaceful Uses of Outer Space, 2018). On January 23, 2019, the Grand Duchy of Luxembourg and the Kingdom of Belgium signed an agreement to develop an international framework for the exploration and utilization of space resources.

Mining engineer John Holloway (2018) has noted, “Only one sample has ever been taken from an asteroid successfully: in 2005, the Japanese Hayabusa spacecraft landed on the small asteroid Itokawa and returned to Earth with a few grams of dust from its surface. The minerals in it were plagioclases and olivine and pyroxene, almost valueless metal silicate compounds found pretty well everywhere on Earth.” The Japanese Hayabus-2 mission is scheduled to return a sample from the asteroid Ryugu in 2020. While geologist Jeff Kargel (1994) has argued that the economic potential of asteroid mining is significant, he has also noted that “first-order technological, scientific, and economic uncertainties remain before the feasibility of exploitation of asteroids for precious metals can be ascertained.”

Understanding the Boundaries of Life and Habitability

The search for evidence of extraterrestrial life in our solar system has been a driver of planetary exploration since the beginning of the Space Age. Astrobiology—classified by most funding agencies as planetary science—is the study of the origin, evolution, and distribution of life in the universe and the science at the heart of the search for extraterrestrial life.7

The search for evidence of extraterrestrial life in our solar system began with NASA’s twin Viking orbiter-lander missions to Mars in the 1970s. Life-detection experiments on those missions did not collect any definitive evidence of life. From the 1970s to the 1990s, astrobiology research focused on better understanding the origin, evolution, and distribution of life on Earth, revealing that Earth life—that is, carbon-based cellular life—can survive in virtually all known terrestrial environmental extremes—nuclear radiation, permafrost, Earth’s deep subsurface, deep-sea hydrothermal vents, hypersaline environments, and so on. Wherever humans or their technological counterparts have gone on Earth, they have found life. Most of these so-called extremophilic life forms are microbes. Microbial life accounts for a significant portion of the biomass on Earth, and astrobiology research has shown that a vast and diverse community of microbes resides deep beneath the surface of Earth.

Given what they now know about the diversity of life and environments on Earth, astrobiologists and other planetary scientists are considering the possibility of a diversity of surface and subsurface biospheres beyond Earth, from the ice-covered global ocean of Europa to extrasolar planets (exoplanets) that might be potentially habitable. Ocean worlds in our solar system—in particular, Jupiter’s moon Europa and Saturn’s moons Enceladus and Titan—are among top targets for astrobiological investigations of prebiotic chemistry, habitability, and possible life. NASA’s Galileo mission to the Jupiter system revealed evidence of a subsurface liquid water ocean on Europa, raising the prospect that Europa might be habitable. In 2003, when the Galileo orbiter was out of propellant and about to fall out of orbit around the planet, NASA intentionally crashed the spacecraft into Jupiter to avoid the possibility that it might accidentally crash on Europa, thereby possibly contaminating the moon. Many astrobiologists are exploring the possibility of extant life in the deep subsurface of Mars. While some planetary scientists have argued that Venus could have been habitable in the distant past, and some have explored the idea that the atmosphere of Venus could be hospitable to some form of life, the consensus is that Venus is not habitable.

At the same time that research into the origin, evolution, and distribution of life as we know it is revealing that life is highly diverse, adaptable, and resilient, these same lines of research are helping to reveal how life and its environment are deeply interdependent. Over the past 60 years, astrobiology research has contributed to a widespread understanding that life and environments co-evolve. Planetary scientists now know that on Earth, life and environment have co-evolved, and thus they assume that if life has evolved in other planetary environments, such co-evolution would have occurred there as well. Some key lines of research in this area—such as understanding the timing and mechanics of the rise of oxygen in the atmosphere of early Earth; the role of the environment in the production of organic molecules; and the co-evolution of climates, atmospheres, interiors, and biospheres—are improving understanding of the evolution, and future, of habitability and life on Earth and prospects for the evolution of habitability and life elsewhere, contributing to our understanding of global climate history and evolution.

This modern scientific understanding of the highly interdependent nature of life and its environment—their co-evolution—is changing the way that both experts and nonexperts think about the terrestrial biosphere and the place of humanity in it. Though little hard evidence is available to prove the point, popular discourse indicates that the search for extraterrestrial life has affected the way that people conceive of the biosphere, and the way they think about their home planet and their place on it. The search for extraterrestrial life can help humans to feel at home in the universe, fostering a sense of belonging.


From the 1950s to the present, a small community of researchers has pursued what they call the search for extraterrestrial intelligence (SETI), a matter of using radio telescopes to listen for signals that could be verified as the products of extraterrestrial technology. SETI efforts have not been fruitful to date. Meanwhile, planetary science more broadly and astrobiology research more specifically have contributed to an understanding that in order to attempt to answer the ages-old question, “Are we alone?,” the best strategy to pursue is to search for evidence of habitability and past or present microbial life in our solar system and to look for signs of habitability on exoplanets. The search for evidence of extraterrestrial intelligent beings is thus put into proper perspective as a more speculative exercise. Recently SETI researchers have been talking about searching for “technosignatures”—not just radio signals but other signs of an extraterrestrial culture that has developed technology that is like human technology and would yield detectable signs (signatures). However, astrobiologists are focused primarily on looking for biosignatures—detectable signs of biological activity on another planet.

Social and Conceptual Issues in Astrobiology

Some researchers in the natural sciences, the social sciences, and the humanities have considered the possible public impact of the discovery of extraterrestrial life. The discovery of extraterrestrial life, one scholar has argued, “has the potential to reconfigure our assumptions about the fundamental nature of reality. And while science may tell us what exists, how it came into being, and what physical processes are necessary for life, science alone cannot address the issues of what these discoveries mean. Science alone cannot assess the implications for society if we find evidence of life (microbial or complex), and how to grapple with ontological questions in a universe where life may not be the exception but rather the rule. These questions, prompted by science, must be addressed by philosophy, the humanities and the social sciences” (Steinhauer, 2014).

Science roadmaps and strategies published by the NASA astrobiology community in 1998, 2003, 2008, and 2015 acknowledged the need to address the broader implications of discovering life beyond Earth. However, historically, projects addressing “societal implications of astrobiology” have been sparse, sporadic, and disconnected. For the past few decades, questions relating to how the discovery of extraterrestrial life might affect “society” have been addressed by a small community of researchers largely involved with the search for evidence of extraterrestrial intelligence (SETI) and thus have focused primarily on possible public responses to the discovery of extraterrestrial intelligent life. The field of astrobiology is focused on the search for evidence of past or present microbial life in the solar system, and thus discussion of ethical, philosophical, theological, and legal issues relating to astrobiology needs to broaden, and focus, accordingly. In addition to a SETI-centric focus, past efforts to address “societal implications” have also been largely Western-centric and thus limited in scope.

One of the earliest gatherings of a multidisciplinary group of scholars to address “the social, philosophic, and humanistic impact” of the discovery of extraterrestrial life was a NASA-sponsored symposium held at Boston University on November 20, 1972, “Life Beyond Earth and the Mind of Man” (Berendzen, 1973). The symposium was convened to address the question: “How might human beings react to the discovery of life beyond Earth?” Discussion focused on the possible discovery of evidence of extraterrestrial intelligent life. Symposium participants were anthropologist Ashley Montagu; physicist and SETI advocate Philip Morrison; planetary scientist and SETI advocate Carl Sagan; theologian Krister Stendahl, then Dean of the Harvard School of Divinity; and biologist George Wald.

In the late 1990s, the NASA astrobiology program, in the face of growing scientific, political, and public interest in the possibility of extraterrestrial life following published claims of possible evidence of past microbial life on Mars (McKay et al., 1996), focused some attention on social, ethical, and philosophical questions relating to the discovery of extraterrestrial microbial life, and funded efforts to introduce astrobiology to the broader scientific community and to public audiences as well. First, the program cosponsored a series of workshops organized by the American Association for the Advancement of Science’s Dialogue on Science, Ethics, and Religion (DOSER) on the philosophical, ethical, and theological implications of astrobiology, held in 2003–2004 (American Association for the Advancement of Science, 2007). A workshop on the societal implications of astrobiology organized by and held at NASA Ames Research Center in California in 1999 (NASA, 1999) addressed implications of astrobiology for human psychology, society, and culture, and the contributions that the social sciences could make to the field of astrobiology.

In 2015, the NASA astrobiology program initiated a round of activities intended to broaden and diversify the community of scholars participating in the ongoing dialogue about astrobiology in culture and to refocus this dialogue on the possible cultural impacts of the discovery of extraterrestrial microbial life—which most members of the astrobiology community believe is more likely, and more imminent, than contact with extraterrestrial intelligent life. One of the aims of these NASA-sponsored initiatives was to broaden the discourse about how social, cultural, ethical, and theological considerations relating to astrobiology may manifest themselves in different cultures and according to different worldviews.

One initiative supported by the NASA astrobiology program was a year-long (2015–2016) scholarly “inquiry on the societal implications of astrobiology” conducted by the Center of Theological Inquiry in Princeton, New Jersey. Questions guiding this inquiry were:

  • If there are many different forms of life, known and unknown to us, what does it mean to be “alive”?

  • How would art and literature depict life as we know it against this background of other possibilities?

  • To what extent do our moral relations depend on the biology we share with other persons and other life?

  • With all these unanswered questions about life in the universe, how do we organize ourselves to investigate the possibilities? (Billings, 2016)

European scholars have also focused some attention on the societal impacts of astrobiology. A report (Capova, Persson, Milligan, & Duner, 2018) from a European Union (EU) study group notes:

Astrobiology is . . . bound up with questions concerning who we are and where we come from, worldview questions of a more existential and philosophical sort . . . The social significance of astrobiology stands out in its impact on forms of social life such as religious beliefs, spiritual commitments and the worldviews of contemporary Europeans. The question “where do we come from?” [is] a central component of human self-understanding and a cultural frame of reference in worldview formation. (p. 19)

The EU study group recommended the creation of a European Astrobiology Institute (EAI) that would devote some time and resources to addressing social and conceptual issues in astrobiology. The EAI’s first annual congress took place in the Czech Republic in May 2019.

A global network of scholars in the social sciences and humanities have formed an organization called the Society for Social and Conceptual Issues in Astrobiology (SoCIA). This organization held its first meeting in Greenville, South Carolina, in 2016, and its second in Reno, Nevada, in 2018. Its third meeting will be in Oxford, Mississippi, in 2020.

Aesthetic, Philosophical, and Spiritual Appreciation of the Planets

According to natural historian Stephen Jay Gould (Office of Space Science, 1994), “The thrill, the wonder, the aesthetic value” (p. 5) of seeing Earth and other planets from space has made solar system exploration well worth the effort. “Knowledge . . . has its own aesthetic frisson . . . Think, for example, of the back side of the moon. Many of us grew up not knowing what it looked like.” But now, thanks to spacecraft, “that most invisible yet nearest bit of cosmic wonder is put before us so that the increment of knowledge also has its aesthetic side” (p. 6). Gould said planetary exploration thrilled him by revealing “planets as persons” and Mars as a possible home to life. “Knowledge and wonder are the dyad of our worthy lives as intellectual beings,” he said. The Voyager missions to the outer planets of our solar system “did wonders for our knowledge but performed just as mightily in the service of wonder . . .” (p. 6).

Astrobiologist Ian Crawford (2018) has argued that the field of astrobiology “cannot help but engender a worldview infused by cosmic and evolutionary perspectives. Both these attributes of the study of astrobiology are, and will increasingly prove to be, beneficial to society regardless of whether extraterrestrial life is discovered or not” (p. 57).

Educational Impact

Planetary science has been incorporated into primary, secondary, and higher education curricula around the world. The impact of this incorporation has not been measured.

NASA,8 ESA,9 the Japan Space Exploration Agency (JAXA),10 and other space agencies and organizations around the world devote time and resources to educating students, teachers, and citizens about planetary science. But little has been done to evaluate the public impact of planetary-science education and public outreach efforts in particular. One study conducted by U.S. researchers (Slater, Slater, & Olson, 2009), a survey of 800 teachers to determine whether and how the teachers were using widely available planetary science data, found that “teachers’ primary use of the Internet for data is to download images to share with students.”

The American Astronomical Society’s Division of Planetary Sciences (DPS) says it “is committed to enriching educational experiences for students, teachers, and the general public in the multiple disciplines of planetary science and supporting disciplines of math and technology.”11 DPS offers resources to planetary scientists who are interested in participating in educational and public outreach activities. The international Committee on Space Research (COSPAR) has a panel on education.12 The Europlanet Society offers science communication training, information on best practices in public outreach, funding for public engagement activities, and an annual prize for public engagement.13 The United States–based Planetary Science Institute offers educational resources for students, teachers, and citizens.14 Also based in the United States, the Planetary Society is an organization focused on advocating for government funding of space and planetary science and inspiring and educating people around the world about those fields. The Planetary Society says it has over 50,000 members in 100 countries.15

Public Interest, Public Engagement, and Popularization

When members of the space community talk about the need to improve public understanding and interest and engagement in space science and exploration, they are usually talking about their desire to expand public support. Public understanding and interest are no guarantee of public support, nor are they good indicators of public impact.

From the beginning of the Space Age to the present, polling firms have been commissioned by aerospace industries and associations, government agencies, and the mass media to gage public opinion about space programs—though not specifically planetary science—and considerable attention has been paid to the resulting quantitative indicators of public knowledge or interest. These polls and surveys have not been designed to gage public impact. Many members of the space community interpret high levels of public interest as indicators of public support, a correlation which poll results themselves have shown to be spurious. Weaknesses of public opinion polling and public opinion research include a lack of reporting on survey nonresponse rates and insufficient research on the sources and effects of nonresponse.

In attempts to contribute to the public impact of planetary science—whether improving public understanding, engaging public audiences, or building public support—many planetary scientists, writers, and filmmakers have worked on popularizing planetary science (e.g., Bond, 2007; Gallentine, 2016; Stern, 2002). It would be a gargantuan task to conduct a thorough study of the public impact of popular books and programs about planetary science. Thus, it has not been done.

American astronomer and planetary scientist Carl Sagan (1934–1996) is perhaps the best-known contributor to this endeavor. He worked on several NASA planetary science missions and published widely in the scientific and popular literature about planetary science. His public television series Cosmos, which he cowrote and narrated, was viewed by 500 million people in 60 different countries ( “Carl Sagan,” n.d.).

Historian Peter Westwick (2013) has noted that NASA’s planetary program “pursued visual images not only for science but also for public relations . . . Visual images provided a prime source of public interest in the space program” (p. 158).


NASA and other space agencies often tout technological spinoffs as a public benefit of space exploration. Few NASA technologies adopted for commercial markets appear to be spinoffs from planetary science. Three commercial products that could be attributed to planetary science are improved radial tires, scratch-resistant lenses, and digital image sensors.

Goodyear Tire and Rubber Company developed a material five times stronger than steel to make parachutes that would soft-land NASA’s Viking landers on Mars. Goodyear refined this material to produce a new radial tire with a longer tread life ( “NASA Spinoff Technologies,” n.d.).

According to historian Michael Meltzer (2010), some technologies developed for the NASA-ESA Cassini–Huygens mission to the Saturn system have proved to have commercial and military value: a computerized resource trading system, advanced integrated circuits, a solid-state power switch and solid-state data recorder, inertial reference unit “hemispherical resonator gyros. . . [and] better knowledge of how to build spacecraft with augmented defense capabilities” (p. 468), such as autonomous operations and radiation hardening.

Perhaps the planetary science spinoff that has had the greatest public impact is the overall development of digital image processing. Historian Peter Westwick (2013) has documented how planetary science led to the development of digital image production and processing systems, now widely used globally for a variety of purposes. “Image processing capitalized on and helped drive the development of computers,” Westwick notes. “Several review articles on image processing acknowledged the inspiration provided by [planetary science missions] . . . Proliferating textbooks and special journal issues in the 1970s . . . helped spread” planetary imaging techniques (p. 153). The invention of digital image sensors, now widely used in mobile phones and cameras, was a product of efforts to miniaturize cameras for interplanetary missions (“NASA Spinoff Technologies,” n.d.).


It is a matter of judgment as to whether global spending on planetary science has yielded positive public impacts, let alone impacts that are worth the investment. Even in the global scientific community, writ large, there may not be consensus that planetary science yields a public impact, or value, commensurate with its cost. In the global space community, there appears to be widespread agreement that planetary science has public impact and value. But, again, there is little to no evidence to support claims of public impact and public value.

Nonetheless, the number of nations engaging in planetary exploration is growing. China, India, Japan, Russia, the United States, the European Space Agency (ESA) and some ESA member states have launched planetary science missions into space. These nations appear to be more concerned with the public impact of planetary science missions from a political/economic perspective—that is, with how their missions contribute to their scientific and technological competitiveness and political/economic position, power, and influence in the global sphere.

The United States and Russia are well known for their decades of competition to be “the” world leader in space exploration. For comparison, consider India. The Indian Space Research Organization has conducted successful missions to the Moon (Chandrayaan-1, 2008) and Mars (Mars Orbiter Mission (MOM), 2014). More Indian planetary missions are in the works. Upon the launch of India’s first mission to Mars, MOM, Prime Minister Narendra Modi said, “The success of our space program is a shining symbol of what we are capable of as a nation” (Wall Street Journal, 2014). International reaction ranged from surprise to praise to commentary on the political implications of the mission. BBC News (Bagla, 2014) reported, for example, that the Mars mission “makes a big global geo-political statement ahead of Mr. Modi’s imminent visit to the U.S.” to address the United Nations.

Another example of this kind of positioning by means of planetary science is the United Arab Emirates (UAE), which is developing a robotic mission to Mars, to be launched in 2020. The UAE Space Agency says the mission is intended to be “a symbol of capability and hope”:

As the first-ever Arab Islamic mission to another planet, the project demonstrates the capability of the Arab people as contributors to humanity and civilisation. It proves that optimism, confidence and ambition can deliver the greatest achievements no matter the place. It is a symbol of hope for a new era of peaceful human development. It will inspire a young generation to think positively and see a future filled with possibility.

(UAE Space Agency, n.d.)16

As a growing number of nations engage in planetary science by building and launching their own planetary exploration missions, opportunities for collaboration among these nations might yield a desirable public impact: more and stronger partnerships bridging geopolitical divides, sharing knowledge and expertise, and working toward common goals.

Further Reading

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(1.) A search of Google Scholar on October 16, 2018, for publications about the “public value of planetary science” or the “public value of planetary exploration” yielded no results. A search of Google Scholar for publications about the public value of science yielded 473 results. A search of the U.S. Library of Congress catalog on October 17, 2018, for books about “planetary science” yielded 129 results. Titles indicate that these books are either about the science or its history.

(2.) The General Social Survey, conducted annually by the National Opinion Research Center in the United States, has included a question since 1973 asking respondents whether the United States is spending too little, too much, or just the right amount on the space program.

(3.) A peer-reviewed journal called Public Understanding of Science has been publishing research on the subject since 1992.

(4.) See, for example, Intergovernmental Panel on Climate Change, “Global Warming of 1.5°C, an IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty,” October 2018.

(5.) A meteorite is an asteroid or asteroid fragment that reaches the surface of Earth.

(6.) One of those geologists was Eugene Shoemaker of the U.S. Geological Survey (USGS). Shoemaker established an astrogeology branch of the USGS in 1963.

(7.) In 1960, NASA established an exobiology program. In the 1990s, it started an astrobiology program, encompassing the existing exobiology research program. Both terms are still in use, and they are more or less interchangeable. This entry will use the term “astrobiology” to refer to the study of the origin, evolution, and distribution of life in the universe.

(8.) See “For Educators”, and “For Students”.

(10.) See “What’s new”.

(11.) See “Education

(12.) See “Panel on Education

(15.) “About us”.