Sven Bilén: When I was in high school, my biology teacher showed our class the science fiction movie “Star Trek III: The Search for Spock.”
The plot drew me in, with its depiction of the ‘Genesis Project’ – a new technology that transformed a dead alien world into one teeming with life.
After watching the movie, my teacher asked us to write an essay about such technology. Was it realistic? Was it ethical? And to channel our inner Spock: did it make sense? This assignment has had a huge impact on me.
Fast forward to today, and I am an engineer and professor developing technologies to expand human presence beyond Earth.
For example: I work on advanced propulsion systems to move spacecraft beyond Earth’s orbit. I help develop lunar construction technologies to support NASA’s goal of long-term human presence on the moon. And I was on a team that showed how to 3D print habitats on Mars.
Supporting people beyond Earth will take a lot of time, energy and imagination. But engineers and scientists have begun to tackle the many challenges.
A partial checklist: food, water, shelter, air
After the moon, Mars is the next logical place for humans to live outside of Earth.
But is it possible to terraform Mars, that is, transform it to resemble Earth and support life? Or are those just the musings of science fiction?
To live on Mars, humans need liquid water, food, shelter and an atmosphere with enough oxygen to breathe and thick enough to retain heat and protect against radiation from the sun.
But Mars’ atmosphere is almost entirely carbon dioxide, with virtually no oxygen. And it is very thin – only about 1% as dense as Earth’s.
The less dense an atmosphere is, the less heat it can retain. Earth’s atmosphere is thick enough to retain enough heat to sustain life. This is called the so-called greenhouse effect.
But on Mars, the atmosphere is so weak that nighttime temperatures routinely drop to 150 degrees below zero Fahrenheit (-101 degrees Celsius).
So what’s the best way to give Mars an atmosphere?
Although Mars has no active volcanoes now – at least as far as we know – scientists could trigger volcanic eruptions via nuclear explosions. The gases trapped deep within a volcano are released and then float into the atmosphere. But that plan is a bit foolhardy, because the explosions would also release deadly radioactive material into the air.
A better idea: divert water-rich comets and asteroids so they crash on Mars. This would also release gases from beneath the planet’s surface into the atmosphere, while also releasing water from the comets. NASA has already shown that it is possible to redirect asteroids – but relatively large ones, and lots of them, are needed to make a difference.
Making Mars fun
There are countless ways to warm the planet. For example, giant mirrors built in space and placed in orbit around Mars can reflect sunlight to the surface and heat it up.
A recent study suggested that Mars colonists could spread airgel, an ultralight solid material, on the ground. The airgel would serve as insulation and retain heat. This could be done anywhere on Mars, including the polar ice caps, where the airgel could melt existing ice to create liquid water.
You need land to grow food. On Earth, soil consists of five ingredients: minerals, organic matter, living organisms, gases and water.
But Mars is covered in a blanket of loose, dust-like material called regolith. Think of it as Martian sand. The regolith is low in nutrients, not enough for healthy plant growth, and contains some nasty chemicals called perchlorates, which are used on Earth in fireworks and explosives.
Cleaning up the regolith and turning it into something viable wouldn’t be easy. What the alien soil needs is some Martian fertilizer, perhaps made by adding extremophiles: hardy microbes imported from Earth that can survive even the harshest conditions. Genetically engineered organisms are also a possibility.
Through photosynthesis, these organisms would convert carbon dioxide into oxygen. Eventually, as Mars became more life-friendly for Earth-like organisms, colonists were able to introduce more complex plants and even animals.
Providing oxygen, water and food in the correct proportions is extremely complex. On Earth, scientists have tried to simulate this in Biosphere 2, a closed ecosystem with ocean, tropical and desert habitats. Although all of Biosphere 2’s environments have been controlled, even there scientists are struggling to find the right balance. Mother Nature really knows what she is doing.
A house on Mars
Buildings can be 3D printed; initially they would have to be pressurized and protected until Mars acquired Earth-like temperatures and air. NASA’s Moon-to-Mars Planetary Autonomous Construction Technologies program is investigating how exactly this can be done.
There are many more challenges. For example, unlike Earth, Mars does not have a magnetosphere, which protects a planet from solar wind and cosmic rays. Without a magnetic field, too much radiation gets through for living things to remain healthy. There are ways to create a magnetic field, but so far the science is highly speculative.
In fact, all of the technologies I’ve described far exceed current capabilities on the scale needed to terraform Mars. Its development would require enormous amounts of research and money, probably much more than is possible in the short term. While the Genesis device from “Star Trek III” could terraform a planet in minutes, terraforming Mars would take centuries or even millennia.
And there are still many ethical questions that need to be resolved before humans start turning Mars into another Earth. Is it right to make such drastic permanent changes on another planet?
If all this makes you disappointed, don’t. As scientists create innovations to terraform Mars, we will also use them to improve life on Earth. Remember the technology we’re developing to 3D print habitats on Mars? Right now, I’m part of a group of scientists and engineers using the exact same technology to print houses here on Earth – which will help address the world’s housing shortage.
Sven Bilén, professor of engineering design, electrical and aerospace engineering, Penn State
This article is republished from The conversation under a Creative Commons license. Read the original article.
