I look at rocks on Mars for a living—a lot of rocks. Because of this, I’ve gotten pretty good at knowing what to expect and what not to expect when analyzing the chemical make-up of a Martian rock. You expect to find lots of basalt, the building block of all planets.
What I didn’t expect were large amounts of manganese. So when my colleagues and I found exactly that on a Martian rock called “Caribou” back in 2013, we thought, “This has to be a mistake.”
Trace amounts of the element manganese typically exist in basalt. To get a rock with as much manganese as Caribou has, the manganese needs to be concentrated somehow. The rock has to be dissolved in liquid water that also has oxygen dissolved in it.
If conditions are right, the manganese liberated from the rock can then precipitate as manganese oxide minerals. On Earth, dissolved oxygen in groundwater comes from our atmosphere. We’ve known for some time now that Mars once had vast oceans, lakes and streams. If we could peer onto Mars millions of years ago, we’d see a very wet world. Yet we didn’t think Mars ever had enough oxygen to concentrate manganese—and that’s why we thought the data from Caribou must have been an error.
So what do you do when you find a Martian rock with a chemistry you didn’t expect? You go look for more.
When NASA’s Curiosity rover arrived at the Kimberly region of Gale crater, we went to work, looking at the mineral-filled cracks in sandstones on the floor of what was once a deep lake. We used the ChemCam instrument, which sits atop Curiosity and was developed here at Los Alamos National Laboratory, to “zap” rocks on Mars and analyze their chemical make-up. (In less than four years since landing on Mars, ChemCam has analyzed roughly 1,500 rock and soil samples.)
When ChemCam fires its laser pulse, it vaporizes an area the size of a very small pinhead. The system’s telescope on the rover peers at the flash of glowing plasma created by the vaporized material and records the colors of light contained within it. This light allows us here on Earth to determine the elemental composition of the vaporized material.
And what did ChemCam discover? More rocks filled with manganese oxides. So Caribou was not a mistake — far from it.
We never expected to find manganese oxides on Martian rocks because we didn’t think Mars ever had the right environmental conditions to create them. We can look to Earth’s geological record for an explanation. More than 3 billion years ago, Earth had lots of water but no widespread deposits of manganese oxides until after photosynthesizing microbes raised the oxygen levels in our atmosphere.
Although there was already plenty of other microbial life on Earth at this time, these new photosynthetic microbes used sunlight energy in a new way and created a new type of waste product in the process: oxygen.
By adding oxygen to the atmosphere, these tiny microbes transformed Earth’s environment. Suddenly, minerals never before formed on Earth started being deposited, including manganese oxides. This monumental environmental shift is recorded in the chemistry of rocks of that age all over the world. Earth has never been the same since. (Some hypothesize that more complex life forms, such as humans, might never have developed without this atmospheric change.)
So to summarize: In the Earth’s geological record, the appearance of high concentrations of manganese marks a major shift in our atmosphere’s composition, from relatively low oxygen abundances to the oxygen-rich atmosphere we see today. The presence of the same types of materials on Mars suggests that something similar happened there. If that’s the case, what formed that oxygen-rich environment?
One way oxygen could have gotten into the Martian atmosphere is from the breakdown of water when Mars was losing its magnetic field.
Without a protective magnetic field to shield the surface from ionizing radiation, that radiation split water molecules into hydrogen and oxygen. Mars’ relatively low gravity couldn’t hold onto the very light hydrogen atoms, but the heavier oxygen atoms remained behind. Rocks absorbed much of this oxygen, leading to the rusty red dust that covers the surface today. While Mars’ famous red iron oxides require only a mildly oxidizing environment to form, manganese oxides require a strongly oxidizing environment. Finding manganese oxides suggests that past conditions were far more oxidizing than previously thought.
NASA’s Opportunity rover, which has been exploring Mars since 2004, also recently discovered high-manganese deposits in its landing site thousands of miles from Curiosity, which supports the idea that the conditions needed to form these materials were present well beyond Gale crater.
Of course, it’s hard to confirm whether the ionizing-radiation scenario I’ve presented here for creating Martian atmospheric oxygen actually occurred. But it’s important to note that this idea represents a departure in our understanding of how planetary atmospheres might become oxygenated. So far, abundant atmospheric oxygen has been treated as a so-called biosignature, or a sign of existing life.
The next step in this work is for scientists to better understand the relationship between manganese minerals and life. On Earth, they are highly related—but they certainly don’t need to be.
So how can we tell whether the manganese on Mars might actually be made by microbes? The answer is lots and lots of laboratory experiments. If it’s possible to distinguish between manganese oxides produced by life and those produced in a non-biological setting, we can apply that knowledge directly to Martian manganese observations to better understand their origin.
In the meantime, we’ll keep our eyes trained on the Martian surface and see what other secrets it has to reveal.
Nina Lanza is a staff scientist at Los Alamos National Laboratory, which has built and operated more than 500 spacecraft instruments for national defense. That background gives the Laboratory the expertise to develop discovery-driven instruments like ChemCam and its souped-up successor, SuperCam, also developed by the Laboratory and scheduled for the Mars 2020 rover mission.
It’s a major component of solid rocket propellants. It allows water to exist as liquid on Mars, despite atmospheric pressure at the Martian surface being roughly 0.6 percent that on Earth. It also can be broken down to release oxygen that astronauts and future colonists in a Mars settlement could breathe.
It’s called perchlorate and it’s abundant on Mars –10,000 times more abundant in Martian dirt than in soils and sands of Earth. That may sound like a good thing, considering the useful properties of perchlorate, but there’s also a flip side.
Being a negative ion, perchlorate (ClO4–) forms various salts, but it has detrimental health effects. Potassium perchlorate is used as a drug to treat certain forms of hyperthyroidism (overactive thyroid). But exposure to environmental perchlorate causes the opposite of hyperthyroidism, namely hypothyroidism — an underactive thyroid.
It would be devastating for Martian colonists.
An Ubiquitous Chemical Solves Two Mysteries
Perchlorate is all over the Martian surface. In 2009, NASA’s Phoenix lander identified perchlorate in the Martian dirt pretty much everywhere it looked. Then, last September, NASA’s Mars Reconnaissance Orbiter demonstrated very high concentrations of perchlorate salts within recurring slope lineae (RSL), features on the planet’s surface that were formed from relatively recent water flows. The finding solved a mystery of how Martian water could be liquid long enough to change the landscape.
Because of the thin atmosphere, pure water on the Red Planet can persist only as ice or vapor, depending on the temperature. But dissolved salts change the physical chemistry, enough that subsurface liquid water can emerge from time to time and stick around as lakes and streams.
Following the perchlorate could lead us to underground water, which in turn could lead to native microorganisms, a long-sought milestone in space biology. But it would also factor into the choice for landing sites for human missions and colonies, plus it would facilitate terraformation – changing the planet to be more like Earth.
A Source of Energy and Oxygen
The oxygen and energy contained in perchlorate make it a potential energy source on Mars, both for generating electricity and for rocket propulsion. Ammonium perchlorate was the main propellant in solid rocket boosters of the space shuttles that NASA flew from 1981-2011. Mars colonization, and even early human landings, will depend on utilization of Mars resources to fuel craft that will ferry people between the surface and orbit, where they will link with larger ships that make the interplanetary voyage.
Having four oxygen atoms per molecule also makes perchlorate useful to life-support systems. Colonists could employ certain microorganisms from Earth that break up the molecule to release O2. The extracted O2 could be pumped through life support systems of enclosed underground habitats.
Later, the process could be scaled up to enrich air that’s pumped into sealed caverns and craters to help achieve paraterraforming — creating Earth-like environments within limited enclosed areas rather than encompassing the entire planet.
Not a Solution for Liquid Water
Although high concentrations of perchlorate will maintain water in a liquid state, it would be toxic to drink and wouldn’t support microbial life. On Earth, salt-loving microorganisms thrive in the Dead Sea. However, Dead Sea salts are not perchlorate salts, and Mars’ surface water is far more briny than the Dead Sea — even more briny than Antarctica’s Don Juan Pond, where salinity is 44 percent.
Along with hypothyroid conditions, perchlorate has also been implicated in aplastic anemia and agranulocytosis, conditions characterized by a life-threatening deficiency of blood cells. Perchlorate is particularly dangerous for infants dependent on lactating mothers; that’s enough of a concern on Earth, but especially alarming on a new world that interplanetary colonists might populate.
This means that we’ll have to take extreme precaution to remove perchlorate from Mars water and dirt, or from any crops that we grow in it. Dust will have to be kept from contaminating air circulating through life support systems. Future explores and colonists will have to do all of this, not only as they capture the perchlorate in order to reap its benefits, but also as they confront space radiation, physical deconditioning from low gravity, and other potential Martian threats to human health.
Whether it’s extreme climate change, an impending asteroid impact, scientific curiosity or even space tourism, there are compelling reasons to think about calling Mars our second home. But before expanding humanity’s cosmic real estate holdings, scientists will need to make the Red Planet feel a little more like our blue marble.
That, in a nutshell, is the goal of researchers thinking about ways to terraform another planet.
Elon Musk, of Tesla and SpaceX fame, has suggested we nuke the polar ice caps on Mars to unlock liquid water and release clouds of CO2 that would thicken the atmosphere and warm the planet. This notion got some press last year when Major League Baseball player and amateur astrophysicist Jose Canseco tweeted: “By my calculations if we nuked the polar ice caps on Mars we would make an ocean of 36 feet deep across the whole planet,” thereby enshrining the idea in our popular imagination. Giant mirrors concentrating sunlight on the poles and smashing an entire moon into Mars also top the list of grandiose proposals to Earth-ify the Red Planet. Read More
The Mars-like deserts of the American Southwest are some of Earth’s most iconic stargazing grounds. Far from pestering city lights and free from regular cloud cover, they provide a starry-skied sanctuary for lovers of the night.
So, it would stand to reason that the deserts of Mars itself would be even more idyllic. After all, there’s no light pollution and cloud cover is hard to come by.
And to some degree, that’s true. It doesn’t get much darker than nighttime on the Red Planet. And Mars’ atmosphere is so weak — just one percent of Earth’s — that the stars don’t twinkle. Read More
NASA’s chief scientist recently announced that “…we’re going to have strong indications of life beyond Earth within a decade, and I think we’re going to have definitive evidence within 20 to 30 years.” Such a discovery would clearly rank as one of the most important in human history and immediately open up a series of complex social and moral questions. One of the most profound concerns is about the moral status of extraterrestrial life forms. Since humanities scholars are only just now beginning to think critically about these kinds of post-contact questions, naïve positions are common.
Take Martian life: we don’t know if there is life on Mars, but if it exists, it’s almost certainly microbial and clinging to a precarious existence in subsurface aquifers. It may or may not represent an independent origin – life could have emerged first on Mars and been exported to Earth. But whatever its exact status, the prospect of life on Mars has tempted some scientists to venture out onto moral limbs. Of particular interest is a position I label “Mariomania.”
Mariomania can be traced back to Carl Sagan, who famously proclaimed
If there is life on Mars, I believe we should do nothing with Mars. Mars then belongs to the Martians, even if the Martians are only microbes.
Chris McKay, one of NASA’s foremost Mars experts, goes even further to argue that we have an obligation to actively assist Martian life, so that it does not only survives, but flourishes:
…Martian life has rights. It has the right to continue its existence even if its extinction would benefit the biota of Earth. Furthermore, its rights confer upon us the obligation to assist it in obtaining global diversity and stability.
To many people, this position seems noble because it calls for human sacrifice in the service of a moral ideal. But in reality, the Mariomaniac position is far too sweeping to be defensible on either practical or moral grounds.
Suppose in the future we find that:
Mariomaniacs would no doubt rally in opposition to any such intervention under their “Mars for the Martians” banners. From a purely practical point of view, this probably means that we should not explore Mars at all, since it is not possible to do so without a real risk of contamination.
Beyond practicality, a theoretical argument can be made that opposition to intervention might itself be immoral:
Obviously, there are a great many subtleties I don’t consider here. For example, many ethicists question whether human beings always have higher moral value than other life forms. Animal rights activists argue that we should accord real moral value to other animals because, like human beings, they possess morally relevant characteristics (for instance, the ability to feel pleasure and pain). But very few thoughtful commentators would conclude that, if we are forced to choose between saving an animal and saving a human, we should flip a coin.
Simplistic claims of moral equality are another example of overgeneralizing a moral principle for rhetorical effect. Whatever one thinks about animal rights, the idea that the moral status of humans should trump that of microbes is about as close to a slam dunk as it gets in moral theory.
On the other hand, we need to be careful since my argument merely establishes that there can be excellent moral reasons for overriding the “interests” of Martian microbes in some circumstances. There will always be those who want to use this kind of reasoning to justify all manner of human-serving but immoral actions. The argument I outline does not establish that anyone should be allowed to do anything they want to Mars for any reason. At the very least, Martian microbes would be of immense value to human beings: for example, as an object of scientific study. Thus, we should enforce a strong precautionary principle in our initial dealings with Mars (as a recent debate over planetary protection policies illustrates).
Mariomania seems to be the latest example of the idea, common among undergraduates in their first ethics class, that morality is all about establishing highly general rules that admit no exception. But such naïve versions of moral ideals don’t long survive contact with the real world.
By way of example, take the “Prime Directive” from TV’s “Star Trek”:
…no Star Fleet personnel may interfere with the normal and healthy development of alien life and culture…Star Fleet personnel may not violate this Prime Directive, even to save their lives and/or their ship…This directive takes precedence over any and all other considerations, and carries with it the highest moral obligation.
As every good trekkie knows, Federation crew members talk about the importance of obeying the prime directive almost as often as they violate it. Here, art reflects reality, since it’s simply not possible to make a one-size-fits-all rule that identifies the right course of action in every morally complex situation. As a result, Federation crews are constantly forced to choose between unpalatable options. On the one hand, they can obey the directive even when it leads to clearly immoral consequences, as when the Enterprise refuses to cure a plague devastating a planet. On the other hand, they can generate ad hoc reasons to ignore the rule, as when Captain Kirk decides that destroying a supercomputer running an alien society doesn’t violate the spirit of the directive.
Of course, we shouldn’t take Hollywood as a perfect guide to policy. The Prime Directive is merely a familiar example of the universal tension between highly general moral ideals and real-world applications. We will increasingly see the kinds of problems such tension creates in real life as technology opens up vistas beyond Earth for exploration and exploitation. If we insist on declaring unrealistic moral ideals in our guiding documents, we should not be surprised when decision makers are forced to find ways around them. For example, the U.S. Congress’ recent move to allow asteroid mining can be seen as flying in the face of the “collective good of mankind” ideals expressed in the Outer Space Treaty signed by all space-faring nations.
The solution is to do the hard work of formulating the right principles, at the right level of generality, before circumstances render moral debate irrelevant. This requires grappling with the complex trade-offs and hard choices in an intellectually honest fashion, while refusing the temptation to put forward soothing but impractical moral platitudes. We must therefore foster thoughtful exchanges among people with very different conceptions of the moral good in order to find common ground. It’s time for that conversation to begin in earnest.
Don’t panic, future astronauts, but GMOs will probably accompany you on your adventures to deep space.
Scientists hope to genetically engineer organisms to survive off-Earth and to do some of the dirty work on spaceships and other planets. The field of study is called “space synthetic biology.” And this new frontier in genetic research could be key to opening up the final frontier.
Synthetic biology refers, generally speaking, to the work of giving some organism altered or even novel characteristics by changing its genes. Space synthetic biologists genetically alter organisms to make them more space-worthy — resistant to radiation or heat, for instance — and to make them useful to space missions — like turning Martian dirt into concrete. It sounds “out-there,” but microbes already make our planet habitable and pleasant.
“We’re breathing oxygen that was biologically produced,” says Lynn Rothschild, the head of the synthetic biology program at NASA’s Ames Research Center. “I’m wearing cotton that was biologically produced.”
We’re not going to take sheep on space missions, she clarifies, but we could take the capabilities of oxygen- and cotton-making plants and put them into the DNA of more portable life, like yeast. “Start looking at biology as technology,” she says, a “genetic hardware story” that could infuse all aspects of space missions.
Rothschild advises the Stanford-Brown team in the International Genetically Engineered Machine competition, where her groups have, among other things, made wires using DNA as a template; created a biodegradable drone; and taken genes from extreme bacteria and inserted them into E. coli to create hybrid organisms that resist extreme pH, temperature, and dryness. They called it the Hell Cell.
Such bio-based technology, according to a November report from a team led by Amor Menezes California Institute for Quantitative Biosciences in Berkeley, requires 26-85 percent less mass than “abiotic” (non-living) systems. For instance, a spaceship could carry a habitat to Mars, like the Apollo missions did to the moon, but no one wants to live in a tin can, and also that tin can is heavy.
“Think in analogy with early long-term travel on Earth,” says Rothschild, like pilgrims to North America. “They didn’t bring houses. They learned to live off the land.”
Future astronauts will have to live off of inhospitable land and also spaceships, which have no land. Menezes’s report sets forth a plan for those astronauts, suggesting directions the research could go. The microbes we use for terrestrial composting and waste treatment, for instance, produce nitrous oxide, which is spaceship go-juice. We could genetically engineer those microbes to do their duties in space, with different oxygen requirements and faster reaction capabilities but the same basic chemistry. Just by pooping and making trash, then, astronauts could create the raw material for fuel.
Once those refuse-creating colonists arrive on Mars, they could use carried-on microbes to mine the materials for building their new homes. Microbes that make acid could dissolve the Martian rock that surrounds metals, leaving just “the resource.” Or we could engineer microbes to dissolve the resource itself, so that it flows out and can then be reconstituted into a colonial outpost.
Construction companies on Mars could take the “regolith,” or surface material, and bind it together using natural glue, like mussel foot protein (engineered for optimal performance on Mars). Scientists could also make microbes that chew on the regolith and spit out calcium or iron to make “biocement.”
Poop processing, manufacturing, and construction all leave behind useful byproducts, like methane, which could help keep the colony’s lights on. The outpost, while electrified, wouldn’t have many frills. But scientists do have to ensure astronauts’ basics: air, water, and food, indefinitely.
Menezes recommends that we develop space-friendly microbes that can turn byproducts of wastewater treatment into food (yum!). While the food doesn’t have to be Michelin-star-quality, it does have to qualify as “nutrient-dense biomass that supplements astronaut dry-food while being versatile in flavor and texture.”
If the walls of a ship or colony were alive (it’s not creepy), the microbes could up-cycle carbon dioxide into oxygen and would — bonus! — shield astronauts from radiation. Not only does radiation zap our DNA with cancerous mutations, it also makes medicines expire faster.
People will still get sick in space, so synthetic biologists are also working on bio-based medical care. Microorganisms and plants could be engineered to make medicines and to shift the microbiome — the community that lives in symbiosis with each of us — back into order.
“If astronauts could grow their medicine in algae I think that would be super cool,” says Josiah Zayner, a space synthetic biologist at NASA’s Ames Research Center, who was not an author on the paper, “but I think it would take a lot of money and resources to make this happen.”
But what if the ship or colony were even more alive, Menezes wonders, full of biosensors and biological control systems? If it sounds a little too Battlestar Galactica-Cylon for comfort, don’t worry yet, says Zayner. “Honestly, I think this is just their ‘out there’ idea,” he says. “Systems that they are describing have not really been invented yet. They lost me at ‘hybrid robot version of tumor killing bacteria.’”
But it’s not that out there, contends Menezes.
“The space cybernetics grand challenge essentially calls for implementing control systems ideas into biological systems,” he says — the same control systems that put people on the moon and let Curiosity rove on Mars. But with biology. Integrating the two with technology will “take some time,” he continues, but “complete and tested space synthetic biology systems should be ready within a couple of decades, and if not in time for the first U.S. human Mars expedition, certainly by the second or third one.”
But even a cybernetic ship or colony with living walls, algae gardens, and nutrient-dense biomass isn’t quite enough for a self-sustaining, long-lived Martian habitat. To create that, we either need to make Mars a planet like Earth — or we need to make a miniature Earth on Mars.
To “terraform” a planet is to Earthify it. But “paraterraforming” is the more realistic step down: turning a smaller, contained space into a self-sustaining, human-friendly place. In the case of Mars, this would be a habitable spot surrounded by god-awful instant-death desert. Scientists would have to engineer an entire ecosystem that creates what astronauts need to eat, drink, breathe, and stay healthy, sane, and productive. All while recycling their waste products and keeping their environment cut off from the aforementioned god-awful instant-death desert — using microbes.
“This, I think should be the number-one research goal before missions to Mars,” says Zayner.
And the missions to Mars are what Menezes’ report looks toward.
“All of this is coming from the viewpoint of making it to Mars in the next 20 years and not from the viewpoint of what synthetic biology will be doing in 20 years,” says Zayner, “because that is extremely hard to plan for.” And it depends on the available of both cash and people to do the job.
Zayner also cautions that any life-based space systems will need to be tested and built years before they appear on a crewed capsule or a colony on the Red Planet. As a result, the bleeding-edge technology that exists when a Mars mission launches probably won’t be part of that Mars trip — well-characterized, older technology likely will be. That’s true in any space mission, which engineers blueprint and begin building many years before launch.
But Menezes says the gap between prototype and practical use is shrinking, largely because the space industry is no longer run entirely by a government.
“Just yesterday, I learned that there was a recent project that went from concept idea to actual space deployment within six months,” he says. “Although this timeline is atypical at the moment, with the advent of commercial space ventures, it is now possible to partner to quickly test and characterize fruitful ideas in space.”
But after the ship launches with its promising technology, problems could arise on Mars, too. The regolith that we might use for construction contains perchlorates, salts that can be toxic to humans. Toxic bricks do not an ideal colony build.
“Perchlorates are certainly a problem at the moment,” says Menezes. But we could figure out how to deal with those, and, in our initial attempts at exploiting Mars’s resources, use Mars’s air instead of its land. “For instance, 95 percent of the Mars atmosphere is carbon dioxide. This carbon dioxide will be the primary carbon source for the microbes.”
While making our own special-snowflake space biology sounds sci-fi, non-fictional scientists are working to make the concepts nonfictional, too. To engineer organisms that will be useful on other planets, they first look to our own world and its biology. And in altering and organizing those biological beasts into useful space systems, scientists will also learn how to make life better back on Earth.
“The possibilities of space synthetic biology are truly endless, yet each of them has immense importance back on Earth,” says Menezes.
Synthetic biological solutions to space problems in medicine, food, and carbon dioxide can address similar issues on Earth: personalized medicine, agriculture for growing populations, and fixing our carbon-dioxide-laden atmosphere. And while paraterraformed spaces give astronauts a safe place to sleep, the technologies can also help us learn to live sustainably on Earth. A Martian colony would be the ultimate zero-waste green space, whose ethos every earthling should get behind.
“I find the notion of doing ‘far-out space stuff’ that is simultaneously a priority on Earth really captivating and compelling,” says Menezes.
Louis Friedman has always balanced his optimistic vision for the future of human space exploration with a dose of reality, and his tempered outlook courses through his new book, Human Spaceflight From Mars to the Stars, in which he charts the distant future of human space travel.
Friedman is optimistic that human space exploration will continue well into the future. However, here’s that dose of reality from Friedman: humans will never venture beyond Mars, at least not in any historically significant way. Once humans tame Mars, how will humanity continue to explore cosmic frontiers, and to what end? Space travel, according to Friedman, will be an act more focused on transporting our minds — with the help of new technologies — rather than our bodies. Read More
I have always been in awe of the night sky, trying to comprehend the vastness of space and the countless wonders it contains. But I have always felt a certain dissatisfaction with only being able to see it at a distance.
One day I imagine that humanity will be able to visit other planets in the solar system, and venture even further to other stars, but this has always seemed very far away. That’s the reason why I applied for the Mars One mission, aimed at starting a human colony on Mars – it seemed like a real opportunity to get closer to the rest of the night sky, to give me a chance to be a part of taking humanity into the stars.
Mars is, in a way, the perfect stepping stone into the rest of the universe. Despite its inhospitable conditions, it has a day-night cycle only 39 minutes longer than on Earth. Unlike the moon, it is resource-rich, and has a soil and atmosphere rich in water and nitrogen respectively. Mars does not suffer from the sweltering heat and toxic atmosphere found on Venus, closer to the sun from Earth, but still receives enough light from the sun to enable the generation of solar power.
But that hasn’t stopped the Curiosity rover from running around saying “This spot would have been habitable” and “That spot definitely has water.” And it hasn’t stopped astronomer Nathalie Cabrol from searching for the ever-elusive “biosignatures”: evidence, like geological graffiti, that proclaims “LIFE WUZ HERE.”
But it isn’t as easy as finding a spray-painted tag. First of all, the life almost certainly isn’t alive anymore. And second of all, it probably hasn’t been alive for a long time. Around 3.5 billion years ago, Mars changed from being a relatively nice place into the frozen radiation-zapped desert it is today. It was never San Juan, but it does seem to have had a milder climate, water oceans, and a thick, protective atmosphere. If this young sub-Caribbean Mars was home to life, that life may have left its mark. The problem is that we aren’t totally sure what that mark might look like.
The collective space vision of all the world’s countries at the moment seems to be Mars, Mars, Mars. The U.S. has two operational rovers on the planet; a NASA probe called MAVEN and an Indian Mars orbiter will both arrive in Mars orbit later this month; and European, Chinese and additional NASA missions are in the works. Meanwhile Mars One is in the process of selecting candidates for the first-ever Martian colony, and NASA’s heavy launch vehicle is being developed specifically to launch human missions into deep space, with Mars as one of the prime potential destinations.
But is the Red Planet really the best target for a human colony, or should we look somewhere else? Should we pick a world closer to Earth, namely the moon? Or a world with a surface gravity close to Earth’s, namely Venus?
To explore this issue, let’s be clear about why we’d want an off-world colony in the first place. It’s not because it would be cool to have people on multiple worlds (although it would). It’s not because Earth is becoming overpopulated with humans (although it is). It’s because off-world colonies would improve the chances of human civilization surviving in the event of a planetary disaster on Earth. Examining things from this perspective, let’s consider what an off-world colony would need, and see how those requirements mesh with different locations.