Still think about terraforming Mars

Whether it is building a planetary space station or a full planetary replica, it is unlikely that we will experience this feat at least in our lives. However, terraforming an existing planet is a more viable option.

In science fiction, we often see people inhabiting planet-sized objects. From the legendary Star Wars Death Star to the structure of the planetary structure in the Hitchhiker's Guide to the Galaxy to the giant ring world, the prototype of the Dyson sphere. The question is, can we do it? If so, how can we do that?

basic requirements

If we want to populate an artificially created planet, we must first find a suitable place for it in space. The most important thing is that it is in the habitat. This means that the orbit of this man-made planet, or the distance from it to the nearest star, must be suitable for the temperature to be acceptable.

If this planet is too close to a star, we will simply fry from the stellar radiation, while too much distance means we will freeze in cold temperatures. We also need plenty of liquid water, because without water there can be no life.

In addition to the correct temperature and the correct distance to the star, we also need an atmosphere with breathable air, stable earth gravity, correct day and night cycles and so on. If we can meet these requirements, then only can we think of building a habitable planet from scratch.

What could be viewed as an "artificial but habitable planet" could have two interpretations.

The literal interpretation is to create an exact replica of the planet in which a massive boulder turns into a giant sphere, indistinguishable from other planets in our solar system.

Another way to do this is to build a massive satellite in space, possibly a spherical space station like the Death Star from Star Wars. This second option won't literally be a planet other than a spherical shape. It will also not revolve in a fixed orbit around the sun, but can simply hover over the earth like our other satellites.

Either approach would be a daunting task for engineers and scientists, but the second approach is comparatively more practical. So let's start with that.

Planetary space station

As mentioned earlier, building a spherical space station that looks like a planet is easier than building a giant planet like Earth.

The Death Star featured in Star Wars IV: A New Hope was about 160 km in diameter, which is a lot! For comparison: the largest space station we have ever built is less than 120 meters long. However, if you compare such a station to the Earth's diameter of 12,742 km, it still looks like a dwarf.

If we were to build this new planet-like space station and build it mostly out of steel, it would take about a quadrillion (105) tons of steel. Extracting this amount of steel with our current technological advances will take over 800,000 years to mine just steel! We can currently only produce around 1.8 billion tons of steel per year worldwide.

The only way to get the raw materials to build a planet-like space station is to get them from space itself, rather than relying on Earth's resources. To do this, we will likely need to develop asteroids and possibly even the moon. In fact, many companies are working on this idea, and several studies on the subject are ongoing.

If we now assume that we can somehow overcome this logistical problem with the extraction of raw materials, we need advanced robots (able to work in microgravity) that are able to construct a spherical body in which we can live .

We have to build a space station like a planet so that it has gravity like the earth because our body suffers from the lack of gravity. Astronauts on long missions to the International Space Station (ISS) are often faced with bone loss, low blood pressure, and other weightlessness-related health problems.

While creating a planetary spherical space station resembling a Death Star sounds like a very tempting idea, it probably suffers from an inherent flaw: lack of stability.

The death star

It will take a lot of active maintenance to keep it stable. To do this, we have to be a Type 1 civilization on the Kardashev scale, and according to some scholars, we are a few centuries away from attaining that status.

So ... how about creating a full planet?

Planet copy

Mark Hempsell, aerospace engineer at Reactions Engines, a privately owned UK aerospace company, has carried out a comprehensive study of the feasibility of a planetary replica. His work was published in the Journal of the British Interplanetary Society (JBIS).

Hempsell believes that it is not necessary to copy the earth to its exact size in order to make a copy.

We can handle a smaller replica just fine. He believed that engineers could try to "pack" one-tenth the mass of the earth into a sphere almost the size of the moon to achieve the equivalent of earth's gravity on an artificial planet.

For reference, the mass of the earth is 5842 trillion tons (5.9 × 1024 kg) and the diameter of the moon is 3474 km. That's not all, but Hempsell suggests how engineers can mimic the natural way the planet was created.

Rocky planets like Earth were formed from the remains of material released by the sun during its birth. These remaining grains fused one by one for millions of years until the actual planet was formed. Hempsell believes we can try to mimic the process of nature creating the planet, but at an accelerated pace.

To speed up the process, we need to build an advanced thermonuclear facility near the sun that will be able to mine the heavier materials needed to create a new Earth-like planet.

Denser elements like osmium, iridium, and platinum would be good choices to create a replica of the planet, Hempsell said. Layers of these heavier elements could be stacked and then allowed to cool.

Hempsell admits that the only known way to obtain these elements is through thermonuclear supernova explosions. Perhaps we have to move to a Type 2 civilization on the Kardashev scale to master nuclear fusion with such great power.

Even if we could speed up the process of building a planet using this process, it would still take thousands of years to create a planet using this method.

Terraforming: the best alternative

As an alternative to these two exciting ideas, there is a more realistic option - colonizing planets or their satellites through terraforming.

Terraforming doesn't require you to build a planet from scratch. All we have to do is manipulate the existing planet to make it habitable for life.

For example, we could conduct nuclear explosions on Mars and heat the planet's atmosphere at will, and then look for ways to give that planet an Earth-like atmosphere. Many researchers believe that this will be possible in a few decades.

To sum up, the idea of ​​building a planet from scratch is a good science fiction plot, but in fact, we're not even close to getting it anywhere anytime soon. However, in a few decades we may terraform Mars or the Moon, which will still be an incredible feat for humanity and a new step into our cosmic future!