Areology

Summary

Areology is the interdisciplinary study of Mars. Most of the earth science disciplines can be applied to areology. As an interdisciplinary endeavor, areology also includes the study of the technologies for Mars exploration. This is both by robotic and manned craft, and the history of human speculation concerning life on Mars. These include scientific principles, expectations, and designs for human colonization and the engineering of the Martian planetary surface to support human life.

Definition and Basic Principles

Areology is sometimes narrowly defined as the study of the geology of Mars. It more properly involves not only most of the other earth sciences (including meteorology, hydrology, and mineralogy) but also space physics, cosmochemistry, and astrobiology. Given that it deals with largely speculative prospects for life on Mars—both indigenous and imported, in the past, present, or future—areology must also take into account both the history of science and the literature of science fiction.

The term “areology”—derived from the words areo- (Ares, the Greek god of war, whose Roman name was Mars) and -logia (theory)—was popularized by science fiction author Kim Stanley Robinson. This was done in his Mars trilogy Red Mars (1992), Green Mars (1993), and Blue Mars (1996). The debate in the scientific community has largely swung between the poles of “wet Mars,” which holds that Mars once had water. An opposing viewpoint is termed “white Mars” and believes the planet never contained water sources. American astronomer Percival Lowell, who claimed to see through his telescope visions of supposedly water-filled canals on Mars, established one pole of the debate. This was that Mars was a dynamic planet warm and wet enough to support life at the present time.

From its zenith in Lowell’s work of the 1890s, this vision of Mars declined to its nadir after the Mariner 4 flyby in 1965. Mariner 4 showed a cratered, dusty ball clad in only the most diaphanous of atmospheres. This was one whose white polar regions were declared to be most likely covered in dry ice (carbon dioxide) rather than water ice. As the data from the Viking landers of the 1970s proved inconclusive and controversial, the vision of dry, white Mars dominated discussion of the planet for decades.

The successes of orbiters, landers, and rovers began to suggest in the 1990s and 2000s that Mars was not as dry and white as many in the planetology community had long contended. The notion that water ice was an important component on the Martian surface made a comeback, along with physical and chemical evidence of a potentially watery past.

These unmanned spacecraft set the parameters for the continuing discussion of the efficacy, expense, and likelihood of manned missions to Mars. This included concepts for an eventual human colonization of the planet.

Background and History

Scientific interest in Mars dates back to the seventeenth century and the work of Galileo Galilei, Johannes Kepler, and Giovanni Domenico Cassini. In 1666, Cassini observed the Martian polar caps and calculated the length of the Martian day. The apparent Earth-like nature of Mars led French author Bernard le Bovier de Fontenelle in 1688 and British astronomer William Herschel in 1784 to speculate on the nature of life on Mars.

Despite this, in the scientific community before the end of the nineteenth century, Mars was generally not seen as the best candidate for a second life-supporting world in the solar system. Venus, at first, seemed the more likely choice as it was significantly more similar to the Earth in terms of size, mass, gravity, and distance from the sun. This perception held until probes carrying radar and radio telecopy penetrated the thick Venusian atmosphere and confirmed the planet’s merciless heat.

Literature provided a similar picture. Lucian of Samosata wrote about a trip to the moon in his True History which was written in the second century Common Era. In the eighteenth century, both Jonathan Swift (in Gulliver’s Travels, 1726) and Voltaire (in Micromégas, 1752) hypothesized the existence of two as-yet-undiscovered Martian moons. It was not until 1877, after Italian astronomer Giovanni Schiaparelli claimed to see on Mars a network of straight lines he called canali (canals), that writers began to examine Mars as the solar system’s other main abode of life. This shift began with Across the Zodiac (1880) by Percy Greg and continued most prominently with The War of the Worlds (1898) by H. G. Wells.

Since Wells, the scientific understanding of Mars has been shaped by the writings of a number of science-fiction authors, including Aleksandr Bogdanov, Edgar Rice Burroughs, J. H. Rosny, Stanley G. Weinbaum, Ray Bradbury, Leigh Brackett, Robert Heinlein, Isaac Asimov, Philip K. Dick, Frederik Pohl, and Kim Stanley Robinson. Nowhere is the relationship between scientific speculation and speculative fiction clearer than in the future Mars projects and programs put forward by space scientists from Wernher von Braun to Robert Zubrin.

How It Works

Telescopy. Although areology is a relatively new term, the roots of a general discipline of Mars studies stretch back nearly four centuries. For most of this time, however, these studies were exclusively telescopic. Mars was an object viewed through an eyepiece from Earth. The power of telescopes and the levels of resolution they offered grew steadily over time, and telescopic studies remain very important in areological research. Nonetheless, recognition of the inherent limitations of such studies led the push to move scientific instrumentation closer to Mars. Eventually, this led to the landing of scientific payloads on the planet’s surface, then making those payloads capable of self-propulsion across that surface.

Flyby. Mars 1, also known as Sputnik 23, was launched on November 1, 1962, and was intended to fly past Mars at a distance of about eleven thousand kilometers, or seven thousand miles. It was the first Soviet Mars probe and carried a package of scientific instrumentation that included television photographic equipment, a magnetometer probe, a spectral reflectometer, a spectrograph, a micrometeoroid impact instrument, and radiation sensors. Data from this instrumentation package were to be broadcast back to Earth via radio and television transmitters. Although Mars 1 lost contact with Earth before accomplishing its mission, the configuration of its scientific instrumentation package (for collecting data) and transmission capabilities (for returning that collected data to Earth) became the standard for all Mars flyby missions.

The American craft Mariner 4, launched on November 28, 1964, completed the first successful flyby of Mars. Mariner 4’s television pictures of the Martian surface were the first images of another planet sent back from deep space and changed the way the scientific community viewed the possibility of life on Mars. Mariner 6 and Mariner 7, in 1969, were similarly successful flyby missions, making closer approaches and adding more photographic and other data to that already compiled by Mariner 4.

Orbiter. In 1971, Mariner 9 was launched and, once inserted into orbit around Mars, became the first spacecraft to orbit another planet. It was followed soon after by two successful Russian orbiters, Mars 2 and Mars 3.

While orbiting the planet, Mariner 9 photographed 100 percent of the Martian surface and was able to wait out a prolonged dust storm that obscured much of the planet’s surface—something a flyby mission could not have done. Mariner 9’s successful data collection laid the groundwork not only for the later Viking orbiter/lander missions but also for successful later-generation orbiters with more advanced instrument packages. During the first decade of the twenty-first century, other orbiter missions included the Mars Global Surveyor in 1996. and Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter.

Lander. The Soviet Mars 3, whose orbiter was successful, also had a partially successful lander component. Its descent module, which contained both a lander and a rover, was able to utilize aerodynamic braking, parachutes, and retro-rockets to make a soft landing. Unfortunately, twenty seconds after touching down, the lander stopped transmitting and was unable to deploy its rover component.

Considerably more successful were the American Viking 1 and Viking 2 craft, whose orbiters achieved orbit and whose landers, again through a combination of aerodynamic braking, parachutes, and retro-rockets, landed softly and stayed in operation for years. They completed scientific objectives such as photographic imaging at the planet’s surface, soil analysis, and biological-assay experiments for evidence of organic compounds and, potentially, the presence of life.

Later successful US landers included the 1997 Mars Pathfinder lander/rover mission. This system utilized airbags rather than retro-rockets during the last phase of its landing. Later in 2008, the National Aeronautics and Space Administration;s (NASA's) Phoenix lander studied the geologic history of water on Mars. It added to the base of knowledge on Martian climate change, and the planet’s past or future habitability.

In 2018, the InSight mission (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) landed on Mars. InSight was a geophysical lander used to study Mars's deep interior. NASA scientists studied Insight data to build a better understanding of how Mars, Earth, Mercury, and Venus were shaped billions of years ago. InSight was deactivated in December 2022.

Rover. Although the Russian Mars 2 and Mars 3 descent modules brought rovers with them as early as 1971, no rover was successfully deployed on Mars until the Mars Pathfinder mission of 1997 deployed its Sojourner rover. Able to travel about a half kilometer, or one-third of a mile, from the lander, the Sojourner rover returned 550 photographs to Earth and the data from chemical analyses of sixteen locations on the Martian surface.

The Mars Exploration Rovers (MERs) Spirit and Opportunity landed on opposite sides of Mars in 2004. Both vehicles were intended to engage in geologic, hydrologic, and biologic assessment activities: to examine rocks and soils for evidence of past water activity, as well as assess whether the environments that prevailed when water was present were conducive to life.

The Spirit and Opportunity rovers were tremendously successful, as their missions lasted well beyond their planned duration. The two rovers covered far more terrain and provided far more data than any previous mission. Spirit continued in operation until 2010, while Opportunity endured until 2018.

NASA's Mars rover Curiosity landed on Mars in 2012. Curiosity’s mission is to determine if Mars ever had an environment capable of supporting microbes. In May 2013, NASA reported that the rover had found evidence in Gale Crater that Mars’s ancient environmental conditions were favorable to sustaining microbes. In 2018, Curiosity helped scientists make two significant discoveries. It found organic molecules in 3-billion-year-old sedimentary rocks near the surface of the planet. Although organic molecules can be created by non-biological processes, the discovery motivated scientists to keep looking for evidence of life on Mars. The rover also allowed the detection of seasonal variations in methane gas levels within the Gale Crater. Curiosity has remained in operation through the mid-2020s.

NASA's Mars 2020 Mission successfully transported the Perseverance rover to the Martian surface on February 18, 2021. The rover is searching for signs of past microbial life and collecting and caching samples of surface minerals for future missions to collect and bring back to Earth. In 2022, Perseverance broke a record for the longest distance traveled by a rover during a single Martin day. The rover traveled more than 800 feet.

Surface Helicopter. The Mars 2020 Mission also delivered Perseverance's companion, Ingenuity, the first helicopter designed to fly in the thin Martian atmosphere. On April 19, 2021, Ingenuity made the first of 72 flights, making it the first powered aircraft to fly on another planet. In January 2024, following damage to a rotor, NASA was compelled to retire the Martian helicopter.

Applications and Products

NASA lists more than two thousand applications and products on its spin-off database. These spin-offs from space research contribute to national security, the economy, productivity, and lifestyle, not only in the United States but throughout the world. These spin-offs are so numerous and ubiquitous that people are scarcely aware of them and too often take them for granted. Below is a sampling of those specifically related to Mars research, many of which were developed in response to areological studies of Martian surface conditions.

Sensors. NASA research into detecting biological traces on Mars has resulted in biosensor technology monitoring water quality. Sensors incorporating carbon nanotubes tipped with single strands of nucleic acid from waterborne pathogens can detect minute amounts of disease-causing bacteria, viruses, and parasites and be used to alert organizations to potential biological hazards in water used for agriculture, food and beverages, showers, and at beaches and lakes.

NASA’s Jet Propulsion Laboratory (JPL) developed a bacterial-spore-detection system for Mars-bound spacecraft that can also recognize anthrax and other harmful, spore-forming bacteria on Earth and alert people of the impending danger. The JPL also developed a laser-diode-based gas analyzer as part of the 1999 Mars Polar Lander mission to explore the possibility of life-giving elements on Mars. This analyzer has since been used on aircraft and on balloons to study weather and climate, global warming, emissions from aircraft, and numerous other areas where chemical-gas analysis is needed.

Computing and Imaging. NASA Advanced Supercomputing (NAS) division, which includes the Columbia supercomputer, is responsible for a wide range of products, from the development of computational fluid dynamics (CFD) computer codes to novel immersive visualization technologies used to pilot the Spirit and Opportunity rovers. Wide-screen panoramic photography technologies developed for the Mars rovers’ Pancam robotic platform gave rise to the GigaPan System platform for automating the creation of highly detailed digital panoramas in consumer cameras.

Materials. Multilayer textiles developed for the airbags used in the Mars Pathfinder and the MERs are being used in Warwick Mills’ puncture- and impact-resistant TurtleSkin product line of metal flex armor (MFA) vests. These are comparable to rigid steel plates but far more comfortable. The thin, shiny insulation material used extensively in the Mars rover missions is found in applications ranging from reflective thermal blankets to party balloons. This material is a strong and lightweight plastic and vacuum-metallized film. It minimizes weight impact on vehicle payload while also protecting spacecraft, equipment, and personnel from the extreme temperature fluctuations of space.

Careers and Course Work

Courses in astronomy, biology, chemistry, computer science, engineering, geology, and mathematics are foundational for students wishing to pursue careers in areology. Masters and doctoral degrees are often the necessary minimum qualifications for more advanced academic, government, or industrial careers in Mars-exploration-related sciences. More specialized courses may include astrobiology, biochemistry, geophysics, climatology, hydrology, geodesy, and robotics, as well as a number of specializations within engineering, particularly mechanical, electrical, human factors, or systems.

Although areology is geological at its root, it is also the general study of a world other than that known to humans. A background in a diversity of fields, including the history of science and the study of literature concerning Mars, can also prove very helpful.

Social Context and Future Prospects

For areology, the twentieth century was shaped by two important movements. One was the transition from an understanding of Mars based on only telemetry to one based on more diversified data. This was made possible by fly-bys, orbiting, landing, and discharging mobile quasi-autonomous vehicles onto the surface. Here, these probes “followed the water” and looked for evidence of life. The second movement was the movement from an understanding of Mars based primarily on fictional speculation to one increasingly based on science.

The question of past or present life on Mars, however, remains in the realm of speculation. The great debates in this century for areology will begin with whether remotely controlled or increasingly autonomous robotic vehicles can conclusively decide the question of past or present life or whether that question can be conclusively decided only through expensive, potentially dangerous (and perhaps infeasible) manned missions to Mars. That in itself, however, presents a problem: If there is no life on Mars, should the planet be preserved in its pristine state? Conversely, if there is life on Mars, should people risk causing the extinction of that life through contamination from Earth?

These sound more and more like the speculations of science fiction, and matters become only more speculative as people contemplate the efficacy and feasibility of expensive, dangerous, and longer-term effects of colonization and terraforming of Mars by humans.

In trying to find Mars analogues on Earth, scientists are learning more about the limits to life on the world. By setting up microbial observatories in environments that may be in at least one way or another like certain environments on Mars, people have broadened their understanding of the diversity of life on Earth, ultimately serving to make Mars and Earth look more like each other at their extremes than previously assumed.

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