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Mars is a harsh, cold world. The temperature on Mars is much colder than on Earth; but then, the planet is also farther from the sun. The small, barren planet also has a thin atmosphere that is 95 percent carbon dioxide.

Extreme differences

Mars's atmosphere is about 100 times thinner than Earth's. Without a "thermal blanket," Mars can't retain any heat energy. On average, the temperature on Mars is about minus 80 degrees F ahrenheit (minus 60 degrees Celsius). In winter, near the poles temperatures can get down to minus 195 degrees F (minus 125 degrees C). A summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 C).

NASA's Mars Curiosity rover measured air temperatures as high as 43 degrees F (6 degrees C) in the afternoon, with temperatures climbing above freezing for a significant number of days.

"That we are seeing temperatures this warm already during the day is a surprise and very interesting," Felipe Gómez, of the Centro de Astrobiologia in Madrid, said in a statement.

Frost forms on the rocks at night, but as dawn approaches and the air gets warmer, the frost turns to vapor, and there is 100 percent humidity until it evaporates. The high humidity could help make Mars more habitable, if the water condenses to form short-term puddles in the early morning hours.

"The conditions on Mars, where the relative humidity is high and the available water vapor is approximately 100 precipitable microns, is the equivalent of the drier parts of the Atacama Desert in Chile," John Rummel, of East Carolina University, told Space.com by email.

According to Rummel, the humidity of Mars is tied to temperature fluctuations. At night, relative humidity levels can rise to 80 to 100 percent, with the air sometimes reaching atmospheric saturation. The daytime air is far drier, due to warmer temperatures.

On Earth, some forms of life are able to survive in parched regions by poaching water from the humid air. Among these, lichens dominate, surviving in arid climates without succumbing to the dry spells that frequently occur. Some lichens in super-dry areas have been found to photosynthesize at relative humidity levels as low as 70 percent. Other research has demonstrated that a form of Antarctic lichen can adapt to life under simulated Martian conditions.

"Such short-term wet periods might be long enough and warm enough to allow for Earth organisms to metabolize and even reproduce," Rummel said.

(Image credit: NASA, Christine Daniloff/MIT News)

Seasons on Mars

Like Earth, Mars has four seasons because the planet tilts on its axis. The seasons vary in length because of Mars' eccentric orbit around the sun. In the northern hemisphere, spring is the longest season at seven months. Summer and fall are both about six months long. Winter is only four months long.

During a Martian summer, the polar ice cap, composed mainly of carbon dioxide ice, shrinks and may disappear altogether. When winter comes, the ice cap grows back. There may be some liquid water trapped beneath the carbon dioxide ice sheets, scientists say.

An evolving world

In the past, Mars may have been warmer and wetter, with an average global temperature of 50 degrees F (10 degrees C).

"We've learned that Mars is a dynamic planet," Michael Meyer, lead scientist for NASA's Mars exploration program, told reporters in 2011. "We've learned that it has a history where it was warm and wet at the same time that life started here on Earth."

Other research suggests that the Red Planet may have once been white, an icy wasteland with an average temperature of minus 54 degrees F (minus 48 degrees C). According to Robin Wordsworth, a researcher at Harvard, a colder scenario is more straightforward to model because Mars only gets 43 percent of the solar energy of Earth, and early Mars was lit by a younger Sun believed to have been 25 percent dimmer than it is today.

"That makes it very likely early Mars was cold and icy," he said in a statement.

And the planet continues to change today. Recent research found that the planet is emerging from an ice age involving shrinking polar caps and growing glaciers at midlatitudes.

"All around the ice cap, there is evidence for a climate change from ice age to interglacial period," planetary scientist Isaac Smith told Space.com. Smith studied the shrinking ice caps while at the Southwest Research Institute in Colorado.
Additional reporting by Nola Taylor Redd, Space.com contributor

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Mars is a harsh, cold world. The temperature on Mars is much colder than on Earth; but then, the planet is also farther from the sun. The small, barren planet also has a thin atmosphere that is 95 percent carbon dioxide. Mars's atmosphere is about 100 times thinner than Earth's.

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Mars is a harsh, cold world. The temperature on Mars is much colder than on Earth; but then, the planet is also farther from the sun. The small, barren planet also has a thin atmosphere that is 95 percent carbon dioxide.

Extreme differences

Mars's atmosphere is about 100 times thinner than Earth's. Without a "thermal blanket," Mars can't retain any heat energy. On average, the temperature on Mars is about minus 80 degrees F ahrenheit (minus 60 degrees Celsius). In winter, near the poles temperatures can get down to minus 195 degrees F (minus 125 degrees C). A summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 C).

NASA's Mars Curiosity rover measured air temperatures as high as 43 degrees F (6 degrees C) in the afternoon, with temperatures climbing above freezing for a significant number of days.

"That we are seeing temperatures this warm already during the day is a surprise and very interesting," Felipe Gómez, of the Centro de Astrobiologia in Madrid, said in a statement.

Frost forms on the rocks at night, but as dawn approaches and the air gets warmer, the frost turns to vapor, and there is 100 percent humidity until it evaporates. The high humidity could help make Mars more habitable, if the water condenses to form short-term puddles in the early morning hours.

"The conditions on Mars, where the relative humidity is high and the available water vapor is approximately 100 precipitable microns, is the equivalent of the drier parts of the Atacama Desert in Chile," John Rummel, of East Carolina University, told Space.com by email.

According to Rummel, the humidity of Mars is tied to temperature fluctuations. At night, relative humidity levels can rise to 80 to 100 percent, with the air sometimes reaching atmospheric saturation. The daytime air is far drier, due to warmer temperatures.

On Earth, some forms of life are able to survive in parched regions by poaching water from the humid air. Among these, lichens dominate, surviving in arid climates without succumbing to the dry spells that frequently occur. Some lichens in super-dry areas have been found to photosynthesize at relative humidity levels as low as 70 percent. Other research has demonstrated that a form of Antarctic lichen can adapt to life under simulated Martian conditions.

"Such short-term wet periods might be long enough and warm enough to allow for Earth organisms to metabolize and even reproduce," Rummel said.

(Image credit: NASA, Christine Daniloff/MIT News)

Seasons on Mars

Like Earth, Mars has four seasons because the planet tilts on its axis. The seasons vary in length because of Mars' eccentric orbit around the sun. In the northern hemisphere, spring is the longest season at seven months. Summer and fall are both about six months long. Winter is only four months long.

During a Martian summer, the polar ice cap, composed mainly of carbon dioxide ice, shrinks and may disappear altogether. When winter comes, the ice cap grows back. There may be some liquid water trapped beneath the carbon dioxide ice sheets, scientists say.

An evolving world

In the past, Mars may have been warmer and wetter, with an average global temperature of 50 degrees F (10 degrees C).

"We've learned that Mars is a dynamic planet," Michael Meyer, lead scientist for NASA's Mars exploration program, told reporters in 2011. "We've learned that it has a history where it was warm and wet at the same time that life started here on Earth."

Other research suggests that the Red Planet may have once been white, an icy wasteland with an average temperature of minus 54 degrees F (minus 48 degrees C). According to Robin Wordsworth, a researcher at Harvard, a colder scenario is more straightforward to model because Mars only gets 43 percent of the solar energy of Earth, and early Mars was lit by a younger Sun believed to have been 25 percent dimmer than it is today.

"That makes it very likely early Mars was cold and icy," he said in a statement.

And the planet continues to change today. Recent research found that the planet is emerging from an ice age involving shrinking polar caps and growing glaciers at midlatitudes.

"All around the ice cap, there is evidence for a climate change from ice age to interglacial period," planetary scientist Isaac Smith told Space.com. Smith studied the shrinking ice caps while at the Southwest Research Institute in Colorado.
Additional reporting by Nola Taylor Redd, Space.com contributor

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Mars is a harsh, cold world. The temperature on Mars is much colder than on Earth; but then, the planet is also farther from the sun. The small, barren planet also has a thin atmosphere that is 95 percent carbon dioxide. Mars's atmosphere is about 100 times thinner than Earth's.

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https://www.space.com/16907-what-is-the-temperature-of-mars.html

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Reviewed different sources

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What materials will we need to make plant life on Mars

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I made the sparkvideo and discussed the questions with my group

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Again I asked the why question and made sure we had the right info

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11/26/18 I made sure that the rescources were are using are reliable
11/27/18 Checked over the new rescources as well as search more reliable sites to use

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Establishing a permanent colony of humans on Mars is not an option. It's a necessity.

At least, that's what some of the most innovative, intelligent minds of our age - Buzz Aldrin, Stephen Hawking, Elon Musk, Bill Nye, and Neil deGrasse Tyson - are saying.

Of course, it's extremely difficult to foresee how manned missions to Mars that would cost hundreds of billions of dollars each, could benefit mankind. It's easier to imagine how that kind of money could immediately help in the fight against cancer or world hunger. That's because humans tend to be short-sighted. We're focused on what's happening tomorrow instead of 100 years from now.

"If the human race is to continue for another million years, we will have to boldly go where no one has gone before," Hawking said in 2008 at a lecture series for NASA's 50th anniversary.

That brings us to the first reason humans must colonize Mars:

1. Ensuring the survival of our species

The only home humans have ever known is Earth. But history shows that surviving as a species on this tiny blue dot in the vacuum of space is tough and by no means guaranteed.

The dinosaurs are a classic example: They roamed the planet for 165 million years, but the only trace of them today are their fossilized remains. A colossal asteroid wiped them out.

Putting humans on more than one planet would better ensure our existence thousands if not millions of years from now.

"Humans need to be a multiplanet species," Musk recently told astronomer and Slate science blogger Phil Plait.

Humans need to be a multiplanet species. - Elon Musk

Musk founded the space transport company SpaceX to help make this happen.

Mars is an ideal target because it has a day about the same length as Earth's and water ice on its surface. Moreover, it's the best available option: Venus and Mercury are too hot, and the Moon has no atmosphere to protect residents from destructive meteor impacts.

2. Discovering life on Mars

Nye, the CEO of The Planetary Society, said during an episode of StarTalk Radio in March that humanity should focus on sending humans instead of robots to Mars because humans could make discoveries 10,000 times as fast as the best spacecraft explorers we have today. Though he was hesitant to say humans should live on Mars, he agreed there were many more discoveries to be made there.

One monumental discovery scientists could make is determining whether life currently exists on Mars. If we're going to do that, we'll most likely have to dig much deeper than NASA's rovers can. The theory there is that life was spawned not from the swamps on adolescent Earth, but from watery chasms on Mars.

The Mars life theory suggests that rocks rich with microorganisms could have been ejected off the planet's surface from a powerful impact, eventually making their way through space to Earth. It's not a stretch to imagine, because Martian rocks can be found on Earth. None of those, however, have shown signs of life.

"You cannot rule out the fact that a Mars rock with life in it landing on the Earth kicked off terrestrial life, and you can only really test that by finding life on Mars," Christopher Impey, a British astronomer and author of over a dozen books in astronomy and popular science, told Business Insider.

3. Improving the quality of life on Earth

"Only by pushing mankind to its limits, to the bottoms of the ocean and into space, will we make discoveries in science and technology that can be adapted to improve life on Earth."

British doctor Alexander Kumar wrote that in a 2012 article for BBC News where he explored the pros and cons of sending humans to Mars.

At the time, Kumar was living in the most Mars-like place on Earth, Antarctica, to test how he adapted to the extreme conditions both physiologically and psychologically. To better understand his poignant remark, let's look at an example:

During its first three years in space, NASA's prized Hubble Space Telescope snapped blurry pictures because of a flaw in its engineering. The problem was fixed in 1993, but to try to make use of the blurry images during those initial years, astronomers developed a computer algorithm to better extract information from the images.

It turns out the algorithm was eventually shared with a medical doctor who applied it to the X-ray images he was taking to detect breast cancer. The algorithm did a better job at detecting early stages of breast cancer than the conventional method, which at the time was the naked eye.

"You can't script that. That happens all the time - this cross pollination of fields, innovation in one, stimulating revolutionary changes in another," Tyson, the StarTalk radio host, explained during an interview with Fareed Zakaria in 2012.

It's impossible to predict how cutting-edge technologies used to develop manned missions to Mars and habitats on Mars will benefit other fields like medicine or agriculture. But we'll figure that out only by "pushing humankind to its limits" and boldy going where we've never been before.

4. Growing as a species

Another reason we should go to Mars, according to Tyson, is to inspire the next generation of space explorers. When asked in 2013 whether we should go to Mars, he answered:

"Yes, if it galvanizes an entire generation of students in the educational pipeline to want to become scientists, engineers, technologists, and mathematicians," he said. "The next generation of astronauts to land on Mars are in middle school now."

Humanity's aspirations to explore space are what drive us toward more advanced technological innovations that will undoubtedly benefit mankind in one way or another.

"Space is like a proxy for a lot of what else goes on in society, including your urge to innovate," Tyson said during his interview with Zakaria. He added: "There's nothing that drives ambitions the way NASA does."

5. Demonstrating political and economic leadership

At a February 24 hearing, Aldrin told the US Senate's Subcommittee on Space, Science and Competitiveness that getting to Mars was a necessity not only for science, but also for policy.

"In my opinion, there is no more convincing way to demonstrate American leadership for the remainder of this century than to commit to a permanent presence on Mars," he said.

If Americans do not go to Mars, someone else will. And that spells political and economic benefit for whoever succeeds.

"If you lose your space edge," Tyson said during his interview with Zakaria, "my deep concern is that you lose everything else about society that enables you to compete economically."

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5 undeniable reasons humans need to colonize Mars - even though it's going to cost billions

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Aside from ensuring the survival of the human species.

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Over population

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Global warming and the start of losing important rescources

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100% probablity that earth will be hit by another meteor and other attributes that life threatening

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Get NASA to fund the project and why it’s important

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I constantly asked the why question and made sure that we have what we need for our presentation and that it was valuable information

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Research suggests Martian soil has some of the nutrients plants need to grow and survive (see "Plants' Nutrients," right). But because of Mars's extremely cold conditions, plants such as Watney's potatoes would need to grow inside a controlled environment, such as his Hab. Also, just like on Earth, nutrients in Martian soil may vary from place to place. So, people stranded on Mars should be prepared to turn to ingenious ways for making the soil more suitable for plant growth-even if the only option is using their own feces, as Watney did.

When soils are rich in nutrients-such as nitrogen, phosphorus, and potassium-crops grow well. But when the soils are not as rich-with even just one of the needed nutrients in low supply-plants would not grow as well. Fertilizers help farmers to double or triple their crop yields and contain 5% or more of primary plant nutrients. These fertilizers also supply nutrients to the crops that some soils do not have.

Here on Earth, experts encourage using organic waste, or manure, to fertilize soil, although U.S. environmental agencies regulate the use of manure to avoid transmission of viruses and bacteria that could contaminate harvests. Other sources of nutrients, such as organic food waste, are also useful. That is why, for example, some people mix banana peels or coffee grounds into soil in their gardens.

On Mars, Watney did not have any man-made fertilizers available to him. He was not planning to stay there for a long time, let alone having to farm there, so his feces acted as organic waste that contained nutrients. In fact, in earlier times, when technology was less advanced, farmers used their own sewage to provide important nutrients, such as nitrogen and phosphorous, to their land.

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Growing Green on the Red Planet - American Chemical Society

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Research suggests Martian soil has some of the nutrients plants need to grow and survive (see "Plants' Nutrients," right). But because of Mars's extremely cold conditions, plants such as Watney's potatoes would need to grow inside a controlled environment, such as his Hab.

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Mike Malaska * May 15, 2012

The surface of Mars is a tough place to survive, but researchers at the German Aerospace Center (DLR) found some lichens and cyanobacteria tough enough to handle those conditions.

How tough is it on Mars? Pretty tough. First, the Martian surface pressure of 6 millibars is pretty much a vacuum compared to Earth's surface pressure of 1000. 6 millibars of pressure corresponds to a point waaay up in Earth's middle stratosphere about 35 kilometers above the surface. This is an altitude almost 5 times taller than Mount Everest and right about where altitude records for air-breathing jet airplanes are set. Next, you've got the harsh radiation from the Sun. On gentle Earth, much of the dangerous photon radiation from the sun is filtered out by Earth's thick atmosphere. But on atmospherically-challenged Mars, energetic ultraviolet rays blast the surface. These rays could plow through an unprotected biological cell and wreak havoc on the critical information-carrying genetic material in the cell. If that weren't bad enough, the rays can also smack constituents of the martian rocks and dirt and make some really nasty reactive chemical species that could chew up any cellular biological membranes not tough enough to resist. Finally, Mars is very dry and cold, dryer than the driest deserts on Earth. Any water might come in a brief morning dew that quickly evaporates as the temperature rapidly fluctuates. Life would have to struggle getting water quickly during these transient events then survive being freeze-dried for long periods of time.

To see if they could find terrestrial life tough enough for Mars, the researchers collected specimens of organisms that were found in some of the most extreme and inhospitable places on Earth. They collected organisms from inside rocks, on mountain tops, and in the polar regions. These are places that might come closest to the environment on Mars. The researchers then created an environmental chamber that simulated conditions on Mars: ultraviolet radiation, infrared radiation, martian soil, low pressure, atmospheric mix, temperature ranging from -50 C to 23 C, the whole bit. They threw the collected specimens in the chamber to see if any could survive.

After a little over a month had passed, the researchers found that some lichen and cyanobacteria were still alive. Most surprisingly, the lichen and cyanobacteria didn't just sit dormant, huddled down waiting for someone to open up the chamber and let them out; they were active. They sat in the martian chamber and took in simulated martian sunlight and made molecules and did all the things a living, functioning, active organism should do - they were happy!

So what are these things anyway and why does this matter?

Cyanobacteria are very important to the story of life on Earth. Cyanobacteria used to be called blue-green algae, but they are bacteria, not algae. While algae have a nucleus that has the information-carrying genetic material, cyanobacteria do not. Cyanobacteria have the genetic material distributed all over the inside of the cell, rather than specialized compartments. Cyanobacteria use molecules like chlorophyll, phycoerythrin, and phycocyanin to harvest light energy. It is the phycocyanin that gives the cyanobacteria the characteristic blue-green color. The light-harvesting compartments in algae and plant cells, called chloroplasts, may have originally started out as cyanobacteria that got incorporated inside the algae or plant cells. Cyanobacteria are special in that they can live in high-oxygen or low-oxygen environments. Importantly for us oxygen-breathing types, cyanobacteria may have been responsible for generating much of the oxygen in Earth's early atmosphere. Fossil structures of cyanobacteria have been found that are over 2.8 billion years old. Cyanobacteria are primordial, and they changed our planet.

Lichens are incredibly tough. If you look around you will find them everywhere, on tree bark, rocks, walls, and on statues. Lichens exist as a form of a partnership of a fungal cell buddied up with a cyanobacteria or algae cell. The fungus forms the basic framework that incorporates the cyanobacteria or algal cell. The fungal cell provides protection, walls, structure, water storage, and mineral-gathering capability to the partnership. The cyanobacteria or algae cell, in turn, provides light-harvesting ability. This combination is famous for being able to survive harsh, dessicating conditions.

On Earth, lichens are one of the first things to colonize a bare rock surface. Lichens break down rocks and minerals so that other organisms can gain a foothold. Lichens are thought to have been one of the earliest things to colonize Earth's barren surface over 400 million years ago. Lichens have also been found at high altitudes and in polar regions. These are just the kind of terrestrial environments that might be the closest match to surface environments of Mars. Both cyanobacteria and lichen are tough little pioneers. If you had to pick some organisms that might be able to survive on Mars, these might be the ones you'd champion.

So now we have examples of both cyanobacteria and lichens that could survive on Mars for at least a month. Does that mean that those types of organisms are there now? We don't know. But it does mean that if life arose (or got transferred) to Mars, and managed to evolve into something as tough as cyanobacteria or lichen, then that life could still be there today and be perfectly happy. That's encouraging, because it means that the habitability zone for life just got extended outward. This result applies to the martian environment but also extends to possible exoplanet environments as well.

As they say, life is tough; but it just got tougher!

Emily Lakdawalla

Brittney Cooper

Emily Lakdawalla

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Earth's toughest life could survive on Mars

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Mike Malaska * May 15, 2012 The surface of Mars is a tough place to survive, but researchers at the German Aerospace Center (DLR) found some lichens and cyanobacteria tough enough to handle those conditions. How tough is it on Mars? Pretty tough.

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NASA and private entrepreneurs are pushing to land people on Mars within the next generation. To survive on Mars, colonists will need a lot of gear, not least of which is food. Since lugging food adds a lot of weight to spacecraft - and packaged food only retains its nutrients for so long, anyway - any would-be Martians will need to grow food on site in order to survive.

But conditions on the Red Planet are different than on Earth. The surface receives less than half the amount of sunlight that Earth does, and dust in the atmosphere can attenuate it even more. Due to the absence of an ozone layer, more ultraviolet radiation reaches the ground. As to the Martian surface itself, the dirt (technically "regolith") is more iron-rich, particularly in iron oxides.

To see how terrestrial plants might fare in Martian soil, students at Villanova University last semester conducted the Red Thumbs Mars Garden Project. They obtained simulated Martian soil, made from volcanic basalts similar to those on Mars, and mixed it with other compounds to make it about 90% similar to Martian regolith.

The students focused on nutritious plants, including lettuce, kale, garlic, and potatoes, as well as hops (the business students were looking for inventive ways to make Martian greenhouse products marketable, professor Edward Guinan quipped during his talk January 12th at the American Astronomical Society meeting in Washington, D.C.). They then planted the seedlings in different concentrations of Martian soil in a campus greenhouse rigged for light levels on the Red Planet and let things unfold.

Despite hiccups in the pilot study (lack of greenhouse temperature control, students forgetting to water plants), several of the experimental foodstuffs grew fine in the Martian simulated dirt. Mixed greens such as lettuce and kale did well, but potatoes - the mainstay of protagonist Mark Watney in The Martian - did not. The clay-like Martian simulant was so thick that it crushed the growing taters, giving them no room to expand.

Overall, plants did much better when the students added filler such as coffee grounds to the Martian simulant, Guinan says. The filler fluffed the dirt up enough that water could percolate through and reach the roots.

One major difference between the Villanova project and real Martian soil is perchlorate (CClO ₄). Perchlorates abound in the uppermost layer of Martian regolith, potentially lowering the freezing temperature of water enough to explain some fleeting signs of liquid water activity on Mars.

But perchlorate is toxic to humans, causing thyroid problems and even death. Humans on the Red Planet might breathe it in from dust that infiltrated habitats, and growing food with it would be dangerous. "Matt Damon would have died," Guinan said, referring to the Hollywood version of the novel. "It was never mentioned in the movie, you know - you don't want to talk about things like that."

Farmers on Mars will need to remove any perchlorate from the Martian soil before using it. One way is to rinse the soil, since perchlorate dissolves in water. Another, more enticing way is to use perchlorate-eating bacteria, which produce oxygen as a metabolic byproduct. That might protect the colonists from serious health problems while also bolstering their breathable air supply.

For those interested in doing similar projects with their students, Guinan recommends lettuce. "It grows fast, and you can eat it," he says. "I ate the lettuce. I'm still here."

You can watch a video about the project: "The Red Thumbs: Mars Garden Project". The class obtained their dirt from The Martian Garden.

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Some Plants Grow Well in Martian Soil - Sky & Telescope

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NASA and private entrepreneurs are pushing to land people on Mars within the next generation. To survive on Mars, colonists will need a lot of gear, not least of which is food.

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None of us would be alive today without plants, and if humans want to survive beyond Earth long-term, we'll need to bring our leafy greens with us. Eventually, astronauts are going to have to become space farmers.

There's an obvious argument for growing plants in space: unless we want to pack enough shrink-wrapped protein bars to last until the end of time, we'll need a self-replenishing food supply. But there's even bigger reason to bring plant life with us into the cosmic void, and it has to do with turning our spaceships into ecosystems. We need plants to conserve and recycle resources, helping maintain a breathable atmosphere and a drinkable water supply.

Much easier said than done. In order to build a space greenhouse that doesn't eventually kill us, we first need to understand how plants make a living and how they've shaped our planet. We then need to deal with some of the strange challenges of life in a sealed environment.

How Plant Life Made the Earth Livable

There's a lot on planet Earth we take for granted. Oxygen to breathe. Water to drink. Invisible chemicals in our atmosphere that keep Earth warm, others that prevent the sun from frying us. Earth is our cozy blue marble, but life on this planet hasn't always been such a picnic. In fact, for much of its history, the world we call home was a miserable wasteland covered in a thin, asphyxiating atmosphere and awash in sterilizing UV radiation.
Today, forests like the Amazon exchange massive amounts of CO2 and oxygen with the atmosphere.

It was the ancestors of plants-cyanobacteria using the same photosynthesis machinery-that first started transforming the Earth into something habitable for animals like us. Beginning some 2.3 to 2.7 billion years ago and lasting for nearly a billion more, the cyanos filled our atmosphere with oxygen, a waste product of photosynthesis, as they soaked up carbon dioxide and sunlight to make sugar. When more complex plants came on the scene roughly half a billion years ago, they took up the photosynthesis torch and began shaping our atmosphere more dramatically, drawing down larger amounts of carbon and spewing out even more oxygen.

Eventually, the atmosphere became became oxygen-rich enough for large, complex animals with high metabolic rates (like us) to evolve and spread across the planet.

That's all ancient history, and you might wonder what it has to do with space gardens. The answer is, everything. Photosynthesis keeps our atmosphere in balance. It's the reason we live on a world that doesn't run out of oxygen and where the CO2 we exhale doesn't accumulate to the point that everybody asphyxiates. (The o ceans help draw down CO2 as well, and over much longer timescales, so does Earth's crust). These may seem like big, abstract concerns, but rest assured, if we stuck you in a sealed metal can, they wouldn't be.

Of course, that's to say nothing of the fact that photosynthesis forms the base of nearly every food web on our planet. If you've never thanked a plant for keeping you from choking and starving, you can go do so now.

Clearly then, plants offer some serious advantages-without them, our space habitats would need an artificial means of replenishing their atmosphere, which would cost precious energy and resources. But plants are a double edged sword. They keep Earth's biosphere in balance, but in a more confined space, the gases they exchange can get out of whack quickly.

Which is to say, we can't simply stick a bunch of tomato plants and grow lamps in the cargo bay and expect our spaceship's environment to run smoothly. Closed environments need to be approached very scientifically, as two cautionary tales help illustrate.

Biosphere 2 and Mars One

Perhaps the most ambitious (certainly the largest) closed ecosystem humans have ever conceived is Biosphere 2, a 3.14-acre Earth system research complex located in the desert outside of Tuscon, Arizona. Built in the early '90s by the now-defunct company Space Biosphere Ventures, this massive glass and metal greenhouse complex, filled with representative "biomes" from across the planet, was intended to serve as a simulation for future space habitats. It was constructed as a materially closed system, meaning there was no exchange of atmosphere or water with the outside world, only sunlight.
The Biosphere 2 complex.
A Biosphere 2 living experiment began in 1991, when eight men and women sealed themselves inside the complex with nothing but simple tools. The plan was to grow all of their own food and survive off the land for as long as possible. It was an unmitigated train wreck.

Throughout the two years that the living experiment lasted, CO2 levels within the habitat fluctuated by as much as 600 parts per million every day, thanks to the drawdown of carbon during sunlight hours by photosynthesis, and its subsequent release at night through plant metabolism. (The concentration of CO2 in Earth's atmosphere today is just north of 400 ppm). CO2 also varied seasonally with light availability, reaching peak concentrations of 4,500 ppm in the winter and 1,000 ppm in the summer. Most of the complex's vertebrate life and pollinating insects died, while populations of greenhouse ants and cockroaches exploded. Morning glories threatened to choke out all other plants. Filtrations systems clogged, and unexpected condensation made the desert soggy.

Worst, oxygen concentrations in the facility fell steadily, from a healthy 20% at the outset to 14.5% at 16 months in-roughly equivalent to oxygen levels at an altitude of 13,400 feet. When the half-starved Biospherians began suffering from sleep apnea and chronic fatigue, the management group decided to intervene and artificially boost the O2.

The reason for the oxygen shortage was unclear at the time, but later studies would demonstrate that the culprit was probably decomposer microorganisms in the soil. When the Biospherians built the system, they included the most organic-rich soils possible to give the plants their best chance at survival. But the fertile soils also harbored large populations of oxygen-consuming microbes. This issue-and many of the experiment's other problems-might have been prevented had the system been designed with greater scientific oversight.
Inside Biosphere 2's ocean environment.
And yet, the efforts of the intrepid humans who sealed themselves inside Biosphere 2 weren't a total waste, because we learned an awful lot. Biosphere 2's failure became an important cautionary tale, underscoring how easily closed ecosystems can spiral out of control if the initial conditions of the system are not carefully measured and aligned. (After more than a decade of inactivity, the facility was acquired by the University of Arizona in 2007, and has since been repurposed as a state-of-the-art Earth science laboratory).

But Biosphere 2 is also massive, and far more complex than anything we might hope to build on the first or second generation of space habitats. In space, we'll probably grow plants without dirt, so we won't have to worry about invisible soil critters mucking things up. We certainly (knock on wood!) won't have to deal with cockroaches. Surely a little plot of potatoes and soybeans won't crash and burn like this gigantic Earth-in-a-bottle did?

Well...let's not be too sure. Take Mars One, for instance. One of the world's most hyped (and haphazard) space colonization initiatives, Mars One became a household name in 2012, when the company announced to the world that it'd be shipping humans off to the Red Planet in the mid-2020s to live out the rest of their lives in small, inflatable bubbles. Even more ambitious than Mars One's timeline, however, is the company's plan to have its colonists grow 100% of their food on site. Unfortunately, this plan has all the makings of a catastrophe that Biosphere 2 did, and for surprisingly similar reasons.
The proposed Mars One colony, a series of inflatable habitats.

Mars One-perhaps concerned that other groups will steal its great ideas-has refused to tell us much of anything about the technical details of its proposed mission. This prompted a group of MIT PhD students to publish their own feasibility analysis last fall. Using all of the information available on the company's website, the researchers calculated the resources needed to sustain the colonists and ran models to evaluate the stability of the habitats over time.

It wasn't pretty. First off, the study found that the cropping space inside the habitat Mars One was proposing wasn't nearly large enough to meet the caloric and nutritional demands of the crew. As the mission was designed, everyone would probably starve. If they didn't starve, model simulations showed that the crops would, over time, produce unsafe levels of oxygen, which could cause the atmosphere to spontaneously combust (also bad). Counteracting the extra oxygen, the atmosphere would be rather swampy, because plant transpiration would increase the relative humidity to 100%. (Still wanna sign up? Just send 'em a check!)

But the MIT researchers took things one step further. Rather than simply showing us the many ways Mars One was doomed, they redesigned the mission in order to keep the astronauts alive.

We've talked a lot about what can go wrong. What does a successful space farming colony look like?

How a Closed Ecosystem Could Work

We've gotten a taste of how space habitats can spiral out of control when we start trying to introduce ecology. To make a closed ecosystem work, we have embrace and take advantage of that closed part. That means putting things in separate compartments, and controlling and measuring the fluxes between them.

For Martian colonists to grow their food locally, the MIT researchers proposed placing the crops in a separate enclosed chamber, effectively decoupling their use of resources from that of the crew. An oxygen removal system would siphon O2 from the plant chamber into a dedicated tank for later use. The CO2 exhaled by the crew would likewise be collected and sent into the crop unit to feed the plants. Ideally, robotic food processors would be deployed so that the crew never had to interact with the garden at all.
Environmentally controlled gardens, such as MIT's CityFarm, offer a template for how we should be structuring our space gardens.

Making such a design work will mean getting a number of different technologies up to speed. Oxygen removal systems have been used extensively on Earth, but space-rated versions don't yet exist, and hardware can fail in strange ways after liftoff. (In 2011, NASA published a report on hypothetical technologies to help recycle the ISS's oxygen supply, but as of 2015, astronauts are still dependent on regular shipments of O2 in cryogenic tanks). CO2 removal systems, which use a synthetic rock called zeolite to scrub carbon from the air, are already in use on board the ISS. While these scrubber systems currently vent CO2 to space, they could be repurposed to shuttle the gas into a growth chamber.

Water is another big issue. Plants and humans both require lots of it, and, like everything else, blasting water out of Earth's gravity well is wildly expensive. Astronauts are currently using a variety of methods to recover and recycle water on the ISS: condensing it out of the air, recollecting urine, heating and filtering the stuff to make it potable again. A process called the Sabatier reaction, wherein hydrogen gas and CO2 are combined to form water, is also being explored by NASA.

Biology can help us do even better. Biofiltration systems that use plants, fungi and microorganisms to remove excess nutrients, heavy metals, bacteria and viruses from water are cropping up everywhere. Such technologies are not yet well developed for space life. But in a draft technology roadmap published this past May, NASA identified "bioregenerative food systems" as an R&D priority. Hopefully, that's a sign that research on how to integrate gardens into our space habitats to maximize their resource recycling potential is coming.

Of course, even if we do our damndest to recycle everything, we're still going to have to accept small amounts of resource loss. Even the best sealed compartment will leak a little bit of atmosphere, and more will vent every time we open the airlocks. Ship parts will get old and need to be replaced. Trace metal shortages could cause nutrient deficiencies among the crew. Replenishing resources in the depths of space will probably mean mining metal and water-rich asteroids, or, on a planet, extracting resources in situ. NASA, Planetary Resources and Deep Space Industries are currently developing these technologies, but space-based resource extraction tech still has a long way to go.

Making space gardens, and more broadly, space ecosystems work, starts with the right conceptual approach. Measure everything. Waste nothing. Recycle as much as possible. If done properly, our gardens could be oxygen farms, CO2 recycling centers, nutrient and metal recovery plants, and water purification systems. But if we fail to pay careful attention to habitat design, plant life could be our undoing out there.

The Biospherians were lucky to be inches away from a plentiful source of fresh air. Millions of miles from Earth, we better get our space ecology right.

Follow Maddie on Twitter or contact her at maddie.stone@gizmodo.com
Top Image: Space gardens in the movie Sunshine.

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The Most Important Thing We Will Need to Survive In Space

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None of us would be alive today without plants, and if humans want to survive beyond Earth long-term, we'll need to bring our leafy greens with us. Eventually, astronauts are going to have to become space farmers.

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In "The Martian," Mark Watney uses the Martian soil to grow potatoes in the controlled environment of the "Hab." In reality, the soil on Mars has the nutrients plants would need to survive on Mars.

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How does the soil on Mars affect plant growth?

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And power might be a bit trickier, says Paul van Susante, senior lecturer in engineering at Michigan Tech University. "I am not sure what power sources we could scale up easily on Mars without bringing nuclear power from Earth," he says. "Small scale power is one thing, but on a larger scale local power generation may be needed in the form of solar farms."

All of these techniques, while viable, remain largely theoretical. The first tests will have to be conducted on Mars, to match the true conditions, so the results are still years away at best.

Finding resources
"We face two possible scenarios for the future of humanity," says Jason Dunn, co-founder and CTO of Made In Space, Inc. "One is where the human species never exploits resources off of planet Earth and instead uses only Earth-found resources."

The other option, he says, is one in which we move beyond Earth to harness the resources in the inner solar system. "The second scenario in my mind is the only one worthy of pursuit because it is in the only option that ensures the survival, growth, and prosperity of humanity and really the rest of Earth's biome."

Made In Space's premise is that one day, everything will be able to be created in space.

So, could we ever live completely independently from Earth? "It's a complicated question, " says Dunn, "but the answer has to be an unequivocal yes."

"I think we could produce most of our things on Mars except perhaps the most sophisticated electronics and such," says van Susante. "From a biological standpoint the picture is less clear since there may be trace elements and vitamins, that we would need to import."

One of the biggest challenges in this line of research is funding, according to Dunn. For example, because it is cheaper, research is going into simulated lunar soil, or asteroid regolith, instead of obtaining the real thing. "Our first mining machines to the Moon or asteroids may be designed without ever being tested on a real asteroid or lunar soil and this can pose a real problem in design development," he says.

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And power might be a bit trickier, says Paul van Susante, senior lecturer in engineering at Michigan Tech University. "I am not sure what power sources we could scale up easily on Mars without bringing nuclear power from Earth," he says.

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We always assume that oak trees and pink lilies grow only on Earth, but can they sprout in outer space? A recent NASA experiment conducted on the International Space Station suggests that they can.

The researchers observed a small, white flower called Arabidopsis thaliana as it germinated and grew in a weightless environment. The team demonstrated that patterns previously associated with plant growth on Earth can occur in outer space as well. For example, the root tips still exhibited "skewing," or growing at an angle, and "waving," or regularly changing growth direction - just as they do in soil on Earth but without gravity to guide them.

Zero gravity conditions pose separate challenges for plant care, but NASA researchers have developed solutions for many of these issues. For example, since the lack of gravity prevents the use of watering cans, researchers developed special tubes that run through the plant's roots that can deliver water without flooding the plant. NASA researchers now believe that plants can flourish in weightless environments. In fact, space agriculturalists are investigating the possibility of growing plants on Mars and on the moon.

NASA's findings are especially consequential to those who wonder if humans will eventually move to another planet. Anna-Lisa Paul, a plant geneticist and the lead author of the study, remains optimistic about growing food crops in microgravity. "When we saw the first pictures come back from orbit [...] we were quite surprised," Paul said in an interview with National Geographic. "Bottom line is that although plants 'know' that they are in a novel environment, they ultimately do just fine."

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NASA researchers have adopted a variety of innovative techniques to care for plants in space. Courtesy of NASA. We always assume that oak trees and pink lilies grow only on Earth, but can they sprout in outer space? A recent NASA experiment conducted on the International Space Station suggests that they...

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How can we make up for the lack of water on other planets?

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How does the climate efffect the growth of plant life?

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How does the climate efffect the growth of plant life?

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Life on Venus - environment - Windows to the Universe

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Windows to the Universe, at http://windows2universe.org/ from the National Earth Science Teachers Association (NESTA). The Website was developed in part with the support of UCAR and NCAR, where it resided from 2000 - 2010. © 2012 National Earth Science Teachers Association. Windows to the Universe® is a registered trademark of NESTA.

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1. Can we grow plants on other planets (Mars)?

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Skeptic: Lucy
Class connector: Cece
Source finder: Anna

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What we need to know