In high school, my biology teacher showed us the science fiction movie "Star Trek III: The Search for Spock." The plot of the film intrigued me, particularly the depiction of the "Genesis Project" – a technology that turned a dead alien world into a living planet.

After the movie, the teacher asked us to write an essay on that technology. Is it realistic? Ethical? And, in line with Spock's logic: Does it make sense? That assignment deeply impressed me.

Today, as an engineer and professor, I develop technologies to expand human presence beyond Earth. I work on advanced propulsion systems that will allow spacecraft to travel beyond Earth's orbit. I am also involved in developing technologies for building on the Moon, supporting NASA's goal of long-term human presence on the Moon. I was part of a team that demonstrated how to 3D print habitats on Mars.

Maintaining life beyond Earth requires a lot of time, energy, and imagination. Nevertheless, engineers and scientists are already working on solving many challenges.

Basic requirements: food, water, shelter, air
After the Moon, the next logical destination for human settlement is Mars. But is it possible to terraform Mars – transform it to resemble Earth and support life? Or is it just science fiction?

For life on Mars, humans will need liquid water, food, shelter, and an atmosphere with enough oxygen to breathe, dense enough to retain heat and protect from the Sun's radiation. However, Mars's atmosphere is almost entirely composed of carbon dioxide, with almost no oxygen. It is also very thin – only about 1% of Earth's atmosphere's density.

The thinner the atmosphere, the less heat it can retain. Earth's atmosphere is dense enough to retain enough heat to sustain life, thanks to the greenhouse effect. But on Mars, the atmosphere is so thin that nighttime temperatures routinely drop to -101 degrees Celsius.

How to create an atmosphere on Mars?
Although Mars currently has no active volcanoes – at least as far as we know – scientists could trigger volcanic eruptions with nuclear explosions. Gases trapped deep in the volcano would be released and then spread into the atmosphere. But that plan is quite risky because the explosions would also introduce deadly radioactive material into the atmosphere.

A better idea is to redirect water-rich comets and asteroids to crash into Mars. This would also release gases from beneath Mars's surface into the atmosphere, while the water from the comets would further enrich Mars's surface. NASA has already proven that it is possible to redirect asteroids – but significant impact requires redirecting larger and more numerous asteroids.

Creating a hospitable Mars
There are many ways to warm the planet. For example, huge mirrors, built in space and placed in orbit around Mars, could reflect sunlight onto the surface and warm it.

A recent study suggested that Mars colonizers could spread aerogel, an ultra-light solid material, across the ground. Aerogel would act as insulation and retain heat. This could be applied across Mars, including the polar ice caps, where aerogel could melt existing ice and create liquid water.

For growing food, soil is needed. On Earth, soil consists of five components: minerals, organic matter, living organisms, gases, and water. However, Mars is covered with a layer of loose, powdery material called regolith. Think of it as Martian sand. Regolith contains few nutrients, not enough for healthy plant growth, and contains dangerous chemicals called perchlorates, which are used in fireworks and explosives on Earth.

Purifying regolith and turning it into something suitable for growing plants would not be simple. Martian soil needs some kind of fertilizer, perhaps produced by adding extremophiles – resilient microbes from Earth that can survive in the harshest conditions. Genetically modified organisms are also a possible option.

Through photosynthesis, these organisms would start converting carbon dioxide into oxygen. Over time, as Mars becomes more suitable for life forms similar to those on Earth, colonizers could introduce more complex plants and even animals.

Ensuring the right balance of oxygen, water, and food is extremely complex. On Earth, scientists have tried to simulate this in Biosphere 2, a closed ecosystem containing ocean, tropical, and desert habitats. Even though all environments in Biosphere 2 are controlled, scientists still struggle to achieve the right balance. Mother Nature really knows what she's doing.

A house on Mars
Buildings could be 3D printed; initially, they would need to be pressurized and protected until Mars reaches Earth's temperatures and atmosphere. NASA's Moon-to-Mars Planetary Autonomous Construction Technologies program is exploring how to achieve this.

There are many other challenges. For example, unlike Earth, Mars does not have a magnetosphere, which protects the planet from solar winds and cosmic radiation. Without a magnetic field, too much radiation penetrates the atmosphere for living beings to stay healthy. There are ways to create a magnetic field, but the science is still very speculative.

In fact, all the technologies I have described are far beyond current capabilities at the level needed to terraform Mars. Developing these technologies would require enormous amounts of research and money, probably much more than is possible in the near future. 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 many ethical questions to address before humans start transforming Mars into another Earth. Is it right to make such drastic, permanent changes to another planet?

If all this disappoints you, don't be. While scientists create innovations to terraform Mars, we will also use them to improve life on Earth. Remember the technology we are developing to 3D print habitats on Mars? I am currently part of a group of scientists and engineers using that same technology to print houses here on Earth – which will help address the global housing shortage.

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Original:
Sven Bilén
Professor of Engineering Design, Electrical Engineering, and Aerospace Engineering, Penn State