By Leah Crane. Red and pleasant land? Science fiction has long dreamed of turning Mars into a second Earth, a place where humans could live without having to put on a space suit. The easiest way to do that would be to use carbon dioxide already on Mars to create a new atmosphere, but now researchers say that is impossible. Terraforming Mars to make its surface habitable for Earth life would involve raising both its temperature and pressure by adding an atmosphere made of heat-trapping greenhouse gases.
The only ones present on Mars in any significant amounts are carbon dioxide and water vapour, both of which are currently frozen.
The fundamental question is, is there enough stuff? But in terms of human life not all gravities are created equal. On Mars you weigh 0. Thus far, NASA and other organizations have studied effects of partial gravity to a limited extent on humans by producing Mars and lunar gravity for short periods under a minute during parabolic flight.
For long-term effects, which in weightlessness involve not only bone demineralization, but also muscle atrophy, immune system effects, and other complications throughout the body, there is no way to replicate partial gravity on Earth.
We can simulate it with various contraptions that have allowed researchers to study things like walking on Mars and whatnot. We can put people in bed for long periods with the beds angled so as to simulate the shifting of fluids on Mars or other worlds. So considering the air and gravity along with the distance from Earth, Mars actually may not be the best candidate for an off-world colony.
On the Venusian surface, the pull is approximately 91 percent what it is on the surface of Earth. On the other hand, Venus would have to be terraformed before anyone could live on the surface at all, since the high pressure and temperature would not allow for paraterraforming. Nevertheless, we might be able to terraform Venus just as easily as Mars.
Going in an opposite direction as Mars terraformation, a Venusian project would begin by having planetary engineers interfere with the runaway greenhouse effect that cooked the planet billions of years ago. Another gravitational fix could be found in free-space colonies. We already said that these could be built using lunar or asteroid materials, but another advantage is that we could build them in any shape. If built in the shape of a doughnut, such a colony could be rotated at the precise speed needed to produce the same gravitational pull as we feel on Earth — meaning that keeping our bones, heart, and other body systems healthy would be as easy as hopping on an Earth-style treadmill, kicking a few handstands, playing tennis, or whatever physical activity you enjoy.
I support an aggressive Mars exploration program. Very likely, the Red Planet will become the first place where we confirm the existence of extraterrestrial microbial life, providing us with a second datum for biology. Since all life on Earth that we know has basically the same chemistry, comparing it with a newly discovered system could stimulate quantum leap advances in biotechnology and medicine here on Earth.
But while Mars science must advance at full speed, it does not mean that the same world is the best first site to settle families with children.
Register or Log In. The Magazine Shop. Login Register Stay Curious Subscribe. The Sciences. Newsletter Sign up for our email newsletter for the latest science news. Sign Up. Artist's depiction of a pole colony on the moon. Credit: Asa Schultz.
Other comets might have high amounts of toxins. Choosing the right celestial bodies for diversion is very important. And we could divert one singe object as well as we could use millions of small comets.
Also, we must look at other icy objects found nearby. This can include Centaurs and icy moons. They are closer then Kuiper Belt objects and might be more easy to transport.
An advanced civilization will use a refinery. This way, some components will be left and others will be carried. First, volatile gasses like nitrogen and carbon dioxide can be covered with a layer of water ice, protecting them from immediate outgassing. Basically, we have to send a spaceship where the icy celestial body is located.
Further away, the speed is much slower. In case of icy moons that orbit around gas giants, we first must pull them away, into heliocentric orbit, then we will slow them. Overall, it will be more easy to divert a further object then to use a closer one, but also it will be faster to divert a closer object then a more distant one. With current technology, one good way for transport is the use of ion engines, which are slow but highly efficient.
We could also use water from the surface, split it into hydrogen and oxygen and use it in a chemical engine. In both cases, we will need nuclear power generators. And we will need to be patient.
This takes some time. The diverted object will travel together with the spaceship. Small trajectory adjustments need to be made from time to time. As the object gets closer to the planet, it starts outgassing and that can push it away from trajectory. Transport phase in the inner solar system must be fast, because outgassing will make us lose some of the volatiles and it might break the comet apart. When the diverted object comes close to the planet, there are two scenarios.
In the first one, it impacts the planet with full speed. The impact might be strong enough that debris will escape into space, both from the planet and the impactor. Also, this will alter the Geography by creating a huge crater and re-activating volcanoes.
It is possible to alter rotation axis, rotation speed and even orbit. The second scenario is for a more advanced civilization, which slows down the impactor until it becomes a satellite. Then, it is de-orbited slowly, for a much softer impact. A more advanced civilization would be able to extract gasses from a giant planet and transport them to the planet and moon they want to terraform. Some celestial bodies like Mars have water and gasses trapped in rocks and beneath surface.
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