Mars. The planet we’re pretty sure is Elon Musk’s home, and the place he’s been trying to get back to this whole time. In the past few years, there has been a lot of talk circulating about Mars, and the recent successful launch of SpaceX’s Falcon Heavy rocket reinvigorated much of the conversation. A lot of this discussion revolves around one big question – can humans colonize and inhabit the Red Planet?
It’s easy to understand why this discussion exists – of all the planets in our Solar System, Mars’ surface conditions are most similar to Earth’s. Mars likely has underground reserves of water. The planet is tilted on a similar axis to Earth, giving it Earth-like seasons, and its days are just 40 minutes longer than Earth’s. Of course, Mars has a host of issues that are impediments to human colonization. In this article, we’ll highlight several of these problems, ranging from smaller-scale factors like extremely low surface temperatures and pressures, to the more large-scale, long-term roadblocks to colonization, like the planet’s lack of a magnetosphere and the subsequent erosion of the planet’s atmosphere over time.
Temperature & Atmospheric Conditions
It’s no secret that Mars isn’t exactly a tropical paradise. Although daytime highs at the equator have clocked in at a toasty 20°C (68°F), the planet’s average temperature sits at a cool -60°C (-76°F), with lows falling below -150°C (-240°F) at the poles. Although this sounds bad, it’s worth noting that the thin Martian atmosphere translates to a weak convection system compared to Earth. This basically means the thinner Martian air is worse at leaching heat than Earth’s thicker atmosphere. As a result, -100°C (-148°F) on Mars can feel like roughly 0°C (32°F) on Earth. Really, Mars’ temperatures aren’t the problem. The main obstacle is that thin atmosphere we just mentioned.
It’s probably common knowledge that the Martian atmosphere has very little oxygen in it (just 0.15% O2). However, the real problem is that Mars’ atmosphere has very little of anything in it – the air pressure at the surface of Mars measures a total of 600 Pascals. For comparison, the air pressure at sea level on Earth clocks in at 101,300 Pascals. Mars’ atmosphere is just 0.6% the density of Earth’s – low enough for liquid water on the Martian surface to instantly boil away. This doesn’t bode well for growing crops on Mars, as low-pressure environments cause plants to dry out and die, even with ample water sources. Exceedingly high construction costs and engineering constraints mean we are not currently capable of attaining Earth-pressures in a Martian greenhouse. As a result, theoretical Martian greenhouses have to operate using a fraction of Earth’s atmospheric pressure, meaning we have to find a way to grow plants in low pressure environments. There is promising research in genetically modifying plants to withstand low pressures (as well as other factors like cold temperatures and foreign soil), but the work is still in its preliminary stages.
Roadblocks to Terraforming
Although low temperatures and surface pressures are problematic, there are at least tangible ways for small human colonies to combat them. Elon Musk famously suggested dropping thermonuclear bombs on the Martian poles to release carbon dioxide into the atmosphere. The idea behind this proposition – vaporizing frozen CO2 to thicken the atmosphere and spark a greenhouse effect – makes sense. But, most scientists think nuking Mars may not be the best way to terraform the planet. Regardless, the most common proposals for terraforming Mars involve the same idea – freeing CO2 in the crust to thicken the atmosphere, increasing surface pressures and temperatures.
Some issues, however, are far more challenging to tackle. Chief among them is Mars’ lack of a strong magnetosphere, or area around the planet dominated by its magnetic field. On Earth, a swirling, liquid iron-nickel outer core produces electric currents, which generates a powerful magnetic field that extends far above the atmosphere. Figure 1 below details this phenomenon.
This magnetic field is crucial to Earth’s habitability – the field acts as a shield against charged particles from solar wind. Without the magnetosphere, solar wind would strip the Earth of its protective upper atmosphere, exposing life on the surface to harmful ultraviolet and cosmic radiation.
Unlike Earth, Mars’ liquid metal interior has long since cooled, and as a result, the planet does not have a strong magnetosphere to protect its atmosphere from solar winds. It is believed that at some point billions of years ago, Mars had a thick atmosphere comparable to Earth’s, allowing for liquid water oceans to form on the surface. However, the lack of a magnetic field allowed the Martian atmosphere to gradually be blown away by solar winds. This, combined with Mars’ light gravity, is why the planet’s atmosphere is so thin, and consequently why surface pressures are so low. The atmospheric erosion is still happening today, although at a slower rate than in the past. This is an important phenomenon that cannot be overlooked – we can nuke the Martian icecaps and release all the surface CO2 we want, but without a protective magnetosphere, much of that newly released gas will eventually be lost. Scientists at NASA are currently researching the possibilities of placing an artificial magnetic shield between the Sun and Mars to deflect incoming solar winds, but this technology is still theoretical.
Although this article makes it seem we are against colonizing Mars, the reality is that we see Martian colonization as an important milestone both for scientific advancement and for the long-term survival of human civilization. However, we believe the general attitude that Mars is an easy “back-up” world in the event of the Earth becoming uninhabitable due to climate change, resource exhaustion, overpopulation, or other such similar catastrophes is misguided. For the foreseeable future, Mars is a world hostile to human life, with a myriad of hazards that would challenge future colonization missions. These hazards not only include the thin atmosphere, low surface pressures, and lack of a magnetic field discussed above, but also issues like the degenerative effects Mars’ low gravity would have on the human body.
It will likely be generations before Mars’ climate is suitable for anything more than a small research colony. Let’s face it – life as we know it evolved here, on Earth. An astounding number of factors had to fall into place here on Earth for life to even get its start. After billions of years of evolution, complex life is highly attuned to conditions on Earth – the planet’s gravitational pull, the tidal effects of the moon, the protective radiation shielding from the upper atmosphere and magnetosphere, the nutrient cycling from active geology, the density of the atmosphere, and much more. Astronomer Carl Sagan once said “The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment Earth is where we make our stand.”
The colonization of other worlds, including Mars, is a critical endeavor for scientific advancement, but we cannot use Mars as an excuse to shirk our responsibilities to Earth and its inhabitants – both present and future. Humanity is currently faced with a number of seemingly insurmountable challenges like climate change, overpopulation, and habitat destruction – issues that can be resolved if we as a collective gather the willpower to do so. Before we look to other worlds to settle, we must first strive to restore and protect our pale blue dot, so when the first human explorers set foot on Mars, it will curiosity that drives them, not necessity.