At The Space Review Eric R. Hedman is making a case for a manned mission to Mars in his essay The best reason to go to Mars. He presents two argument to implement a Mars program: Continue reading The case for Mars?
This post was originally published on blogspot.com on February 3, 2012
In this post I will discuss the pros and cons of the colonization of Mars.
The colonization of Mars is considered by some as the holy grail of human space exploration. Since the end of the second World War many plan for manned missions to Mars are proposed and also the possibility to establish permanent human settlements on the Red Planet is regularly discussed by Space enthusiasts.
Until the 1970s the Moon and Mars were the logical locations for the first human colonies in our Solar System. Because both celestial bodies are relatively easy to reach (a manned mission to other solar systems would take several thousands years with current technology). But at the end of the 1960s scientists like Gerard O’Neill started to explore the possibilities of free space habitats and their designs gave way to a new approach to Space colonization.
The main problem with the colonization of both the Moon as Mars, is the small gravitation of these bodies. Especially in case of the Moon, this would give serious problems for human health, however it is currently unknown of Mars’ gravity would be sufficient for humans. In space habitats the problem of low gravity is solved by centrifugation.
O’Neill e.a. proposed to use lunar and asteroidal resources to build space habitats. The advantage of this is that both the Moon as asteroids have a low escape velocity compared to Earth, while Mars’ escape velocity is roughly half Earth’s. This is one, among many others, reason why we of Republic of Lagrangia are in favor building space habitats in the Lagrange points of the Sun-Earth system.
Although manned Mars missions are a recurrent theme, no such mission has been undertaken. Main reason for this is (shortsighted) politics, not science and technology. Actually it is estimated that the US government has wasted a few times more money in Iraq and Afghanistan, than the price of a manned mission to our Red Neighbor.
But we have to ask ourselves if despite the abundant, and therefore cheap, recourses of the Near Earth Asteroids, there is potential for colonizing Mars. First I would say that regardless of any advantage of space habitats over Mars, there will be people who want to settle on the Red planet, simply because of planetary chauvinism. But there is a good reason for colonizing Mars, I will discuss them later in this post.
From a technical point of view colonization of Mars, is not that difficult (the biggest problem with any manned mission is the trip itself). Actually, one can argue that Mars is easier to settle than the Moon. As Zubrin argues in this article Mars possesses all the elements necessary for human civilization. Therefore Martian colonists will not dependent on importation from Earth as much as Lunar colonists.
Main problem with populating the Red planet, is establishing habitats in which people can function in a normal way. Well one can make domed cities by using Martian made glass or plastic. Another solution is building subsurface structures. In both cases the habitats will be filled with breathable air.
If we have livable habitats on Mars, than the next big problem is power supply. For the colonization of Mars there are essentially two sources of energy: nuclear and solar power. Since Mars is farther away from the sun, it reserves only 42 percent of the amount of solar as Earth.
Deposits with relatively high concentration of thorium and uranium should exist on Mars. These elements can be used for Martian fission reactors, further Zubrin states that the percentage of deuterium is five times higher than on Earth (mainly because deuterium is heavier than normal hydrogen, and therefore possesses a higher boiling point). This can be used as fuel for nuclear fusion reactors. Both fission and fusion power not only produce electricity, but also provide colonists with heath for their habitats.
Although Mars only receives half as much solar power than Earth, solar power is the most promising candidate for powering Martian colonies. Since our planet receives every hour more energy, than the annual global energy consumption, we can safely assume that solar power is able to provide enough energy for Mars.
By solar power most people will think of large parts of Mars covered with solar arrays, however it will be more efficient to build solar power satellites in orbit around Mars. In orbit SPSs will receive sun light nearly continuously and the can be made arbitrarily large. Further, by beaming the harvested energy through high intensity microwaves, less Martian surface is needed for power generation.
Since the escape velocity of Mars is roughly half Earth’s, it doesn’t make sense to build SPSs from Martian resources. In the 1970s it was proposed to construct SPSs for use in near earth space from lunar material, in order to circumvent high launching costs from Earth. Happily there several small bodies in near Mars space: first have the two moons of Mars, which are believed to be captured asteroids. And there are also Mars trojans, a family of asteroids orbiting the L4 and L5 points of Sun-Mars system.
The moons and trojans can not only provide resources for SPSs, but can also deliver huge amounts of volatiles for Martian and other Space colonists.
Despite the technical feasibility of the colonization of Mars, he have to ask why we should do it. In this article, Eric Drexler provide several arguments against the colonization of Mars. In essence the main contra argument is that Mars has a too high escape velocity to be competitive with asteroidal mining schemes. And since mining would be the prime motive for Martian settlement, this seems to be the end the Martian Dream. Due the relatively large travel time between Earth and Mars, tourism is unlikely to become a big drive settling the red planet. For the space tourist industry Lunar colonies are more attractive, since the Moon can be reached in just a few days.
However there is one reason for colonizing Mars worth to be considered, Zubrin argues that Mars could produce food for colonies in the Asteroid belt. Crops can easily be grown on the red planet. We have only the build greenhouses and launch sites. Question is whether this should be necessary. Assuming that the first settlers in the Asteroid belt are mainly involved in mining, they have to import their food. In order to launch food from Earth to the asteroid belt we need to overcome Earth’s gravity (escape velocity) and we need energy to change from the orbit of the Earth around the Sun to the Belt (delta V). For Mars both the escape velocity as the delta V are lower, so transporting food from Mars to the Belt consumes less energy and is therefore cheaper. However if we assume that before the Belt man will first colonize Near Earth asteroids, we have to consider the possibility of transporting food from them to the Belt. Well, free space habitats have zero escape velocity, while delta V is roughly the same as for transport from Earth.
Despite its technical feasibility, we of Republic of Lagrangia believe that colonizing our Red Neighbor should only happen, if ever, after the colonization of the Lagrange points of the Earth-Sun system.