The idea of making Mars habitable for humans has captured the public’s imagination, so we decided to take a look at science exploring possibilities in the not-so-distant future.
Earth and Mars have their share of differences, but human activity on each could have significant implications for their respective planetary environments. Image Credit: NASA
The ability to transform a planet from a barren, lifeless state into a thriving ecological wonder seems unimaginable, but science fiction has begun to merge with science future as a some scientists begin to research the concept of terraforming nearby planets with potential small-scale experiments in the near-future.
Most people are already familiar with the concept of terraforming, even if they don’t realize it. Altering global environments to support specific Earth-like biology, or terraforming, has been highlighted in several popular fictional movies such as “Independence Day” and “Man of Steel.”
Planetary scientists and astrobiologists have made incredible strides developing the building blocks to enable an oxygen-sustained ecosystem in previously uninhabitable environments in laboratories here on Earth (i.e, under Earth gravity, atmospheric pressure, etc.). But, as this seemingly crazy notion of terraforming comes incrementally closer to fruition, people are wondering whether we also should bring this tantalizing possibility closer to home. This notion of a human-made transformation of Earth environments is known in scientific circles as geoengineering.
It is no mystery that the Earth of today is different than it was before humans emerged. Any climate scientist can explain the ways global environments have altered due at least in part to urbanization, the consumption of fossil fuels, and other forms of human activity including deforestation. The result of these human activities has been a gradual warming of the planet by a few degrees Celsius per century, which has led to rising sea levels, accelerated species extinction and the shrinking of specific fragile ecosystems, among other changes.
Environmentally friendly programs intended to halt or impede these changes have been implemented, but only with limited success to date. When repeated frequently and on a large scale, many actions (such as those that have contributed to current climate change) can alter a planetary environment and its habitability, especially on regional scales. This makes at least partial terraforming relatively easy to achieve accidentally and over decades, but the complexities of a planet’s global array of ecosystems make it difficult to achieve with a specific result in mind. Some futuristic thinkers are looking at the idea of terraforming Mars with eyes for how to apply similar potentially world-changing techniques on Earth.
The NASA Curiosity rover has been one of several tools instrumental in uncovering what we currently know about Mars’ local environmental conditions, including space radiation levels, atmospheric constituents and former habitable conditions involving the role of liquid water. Image Credit: NASA (NASA/JPL/MSSS)
Scientists remain uncertain as to whether Mars was ever “green”—the environment might have only been barely habitable for bacteria—but the possibility of a thriving biological ecosystem on the planet in the future is not out of the question. Of course, without an internal magnetic field, Mars is unprotected from the ravages of space radiation from galactic cosmic radiation and solar protons, for example, none of which is experienced on the Earth – thanks to our planet’s magnetic field. The scientific community is still discussing the implications of this information as well as different sources of existing evidence that support and discredit the notion of previously inhabited (by microbes) Martian environments.
Data collected by NASA’s Mars Curiosity Rover has led scientists to believe it is likely that Mars had persistent surface running water at some point in the planet’s ancient history, and information from the MAVEN orbiter has similarly suggested the presence of a thicker atmosphere long ago (as have models based upon data from the Mars Reconnaissance Orbiter). This could be unique among the planets in our solar system, so Boland’s team is focused on using these building blocks as a starting point for making terrestrial life viable. They have found inspiration on Earth from extremophiles, hardy microbes that live in harsh environments such as volcanic sea floor vents and dark, dry caves, as well as in sub-zero conditions in the Antarctic. If these microorganisms could become established on Mars, fixing nitrogen in the regolith and slowly (over potentially millions of years) developing a thicker, more chemically protective atmosphere, the planet could be ready for terrestrial plants and other photosynthesizers to move in; however, the effects of non-terrestrial space radiation and lack of accessible liquid water may be major impediments.
Since extremophiles often take decades to double in number under the harshest of environmental conditions, it could take tens of thousands of years for even a small local area to become inhabited. Boland says ecopoiesis isn’t exactly the sexy part of terraforming, but it is a crucial first step to establishing life.
This tiny and alien-looking extremophile is known as the tardigrade or water bear and has been known to survive extreme temperatures, pressures, food and water droughts and radiation, which makes it an ideal candidate for ecopoiesis experiments. Image Credit: Science Source
“The problem is there are people already living here,” said Chris McKay, senior scientist at NASA’s planetary systems branch at the Ames Research Center in Mountain View, California. As a researcher focused on the evolution of the solar system, McKay has traveled to hot desert and arctic environments in an effort to understand more about what Mars’ current climate means for hardy terrestrial organisms. He explains the conundrum of terraforming Earth with a simple metaphor: “(Geoengineering Earth) is like rearranging furniture while people are still in the room. If you ship out the furniture first and then people come in the room, then they just sit down where the furniture is. Whereas, if you’ve got people sitting in the room already and you start throwing couches and chairs there, it may not be so pleasant.”
The Earth is a complex and intertwined set of ecosystems and local environments and habitats. It is nearly impossible to adjust one aspect or environment without affecting many others, often negatively. This is the real danger of geoengineering, McKay explains. Good-natured attempts to change the Earth’s planetary climate back to what it was thousands of years ago could raise a whole new set of problems no one could have anticipated. Even the best models and predictions can only make an educated guess at the future, so any attempts to terraform the only known habitable planet must be made very carefully, if at all.
Most ideas for geoengineering our planet’s temperature revolve around the concept of increasing the Earth’s albedo, the portion of solar energy that is reflected by the planet. These ideas would make it easier for the planet to reflect more of the sun’s warming rays. The most seriously considered of these concepts comes from Paul Crutzen, a Dutch atmospheric chemist and winner of the Nobel Prize in chemistry. His 2006 editorial essay in “Climatic Change” suggested that filling the atmosphere with reflective aerosols would cool the planet. Crutzen wrote that while it certainly is not an ideal solution, the strategy of “artificially enhancing Earth’s albedo and thereby cooling climate by adding sunlight reflecting aerosol” warrants further investigation. In particular, he suggested releasing sulfide (S2) or hydrogen sulfide (H2S) into the stratosphere, where it will form sulfur dioxide (SO2) that will reflect the sun’s rays for one to two years before dissipating. But given current understanding of the atmospheric chemistry of planet Earth and the role of sulfur-species, the unintended consequences of this activity cannot be fully modelled. For example, Venus is believed to have a complex sulfur cycle in its atmosphere and crust, but today it is hellishly uninhabitable, despite its hypothesized oceanic past.
Before Crutzen’s paper, geoengineering was not seriously considered as a realistic or necessary strategy for addressing negative effects of climate change. The Nobel laureate’s credibility encouraged others to develop their own geoengineering schemes, and soon the scientific community was flooded with geoengineering designs ranging from the extraordinarily technical to the extremely far-fetched. Some of the ideas to deflect the sun’s warming rays include manufacturing clouds, painting urbanized areas and deserts a reflective white and sending giant mirrors into space. Another widely regarded approach to cooling our planet involves depositing iron into the ocean to stimulate the growth of certain types of phytoplankton that will take in more of the carbon dioxide in the atmosphere. All of these suggestions, including Crutzen’s atmospheric aerosols proposal, will require extensive research before scientists will be able to determine the effectiveness and practicality of each.
But even if geoengineering proposals receive a go-ahead from the scientific and engineering community, achieving the approval of governments and associated funding is another matter. Now that we’ve seen the damage our species can do to our home planet, many people are wary of intentionally trying to change it, even in an attempt to correct our unintended past mistakes. McKay uses another everyday metaphor to illustrate this unusual scenario: “It’s like a patient that’s sick but is afraid of the medicine. We know we’ve got climate change. We’re not about to stop doing it, but we’re afraid of the corrective action of the medicine, so we don’t do it either.”
There is considerable public backlash about geoengineering. Clive Hamilton, professor of public ethics at Charles Sturt University, and Vandana Shiva, Indian environmentalist and global justice activist, are joined by organizations such as the ETC Group in their criticisms of geoengineering’s promised quick fixes to centuries of unsustainable human activity.
Shiva sums up the concerns of fellow geoengineering opponents: “Geoengineering is trying to solve the problems (of climate change) with the same old mindset of controlling nature.”
She and others in the opposition to geoengineering argue that human ignorance has already done enough to mess up Earth’s natural systems and that using geoengineering as a way of cheating the climate into what we want would result in potentially disastrous and unforeseeable consequences.
Scientists who support geoengineering say they recognize the dangers. In fact, their ignorance of how terraforming or geoengineering will affect global environments is the reason many continue to study proposed ideas before suggesting any widespread action.
As Boland noted, “Let’s understand what we’re doing before we look back and understand why we did it wrong.”
For terraforming on Earth and Mars, scientists have a lot more research to do before terraforming can safely make the jump from science fiction to reality.
While good science must come first so that any concepts for terraforming anywhere are conducted safely and with adequate information, the enormity of what we have yet to learn is precisely what makes the terraforming research important, according to Boland.
“There’s something to be learned about what happens to a planet after it goes through an extinction,” he said, referring to the desolate Martian landscape of today that he believes may have slowly replaced a once healthy and habitable (at least microbial) environment. The implications of his statement are clear: What we learn about Mars’ history may help us to avoid our own annihilation.
Jonathan Udlock is an undergraduate mechanical engineering student at the University of Denver. He is an enormous fan of NASA, science and technology, science fiction, and “Calvin and Hobbes.”