I think it is a mixture of - the background of movies and science fiction stories - and also the way that Mars looks quite "Earth like" from space.
It's actually far colder than it looks. If it had enough water the entire surface would be white. And though a white Mars like that would be far more habitable for humans - it wouldn't look so habitable.
Would the Mars colonists want to go to Mars if it was covered in a kilometers thick layer of ice like Antarctica? Yet Antarctica is far far more habitable than the most hospitable areas for life on Mars.
It just looks more habitable than it is because it is so very dry, that it doesn't have enough water to be covered in ice.
Also I think many don't realize how thin the atmosphere is. That it is only 1% of the Earth's. For all practical purposes it is a vacuum. Your saliva would still boil and you'd die pretty quickly within seconds if exposed to it, even if supplied with oxygen. You need a full spacesuit, just as for the Moon, not just an air breather.
Similarly when building greenhouses and habitats, you need massive constructions to hold in tons per square meter (ten tons per square meter for a habitat, and one ton per square meter outwards pressure for a lower pressure greenhouse). The 1% of Earth's atmospheric pressure only provides 100 Kg per square meter of pressure in the other direction from outside.
And the CO2 in its atmosphere is hardly of much value, except for creating fuel, after all it is normally a waste gas you try to remove from habitats.
And the atmosphere makes a landing on Mars far more dangerous than a landing on the Moon. It is just enough atmosphere so that you are committed as soon as you hit it, and can't abort like Apollo (they were able to abort and fly back to orbit even when they were a few tens of meters above the surface). But not enough atmosphere to parachute to the surface like Earth - that's why the landing systems for Mars are so complex, always involving multi-stage systems (at least to date). Where everything has to work in sequence and just one glitch would be fatal.
But for me the main reason we shouldn't land humans on Mars is for planetary protection reasons as you'll see from my other answers here.
So - I think that's another reason, that most people are not aware that there are planetary protection issues with landing humans on Mars at all. For some reason, the writers of articles and tv presenters and such-like almost never raise the question of planetary protection at all when human missions are discussed. Yet often do when unmanned missions are covered, all though they are far less risky for planetary protection. I think this is a kind of a collective blindspot.
But - Mars is one of the most interesting places for the search for life. And also new discoveries suggest that it may well have liquid water in thin films, and be habitable for present day life. This would be an amazing discovery - either to find life on Mars - or indeed - if it doesn't have life - to find out what chemistry and what "almost life" processes happen on a planet like that with organics, but without life.
The very last thing you want to do, if you want to study Mars and see if there is life there already - is to land a spaceship with humans. Because, sadly, we can't be sterilized .We have something like a hundred trillion microbes in about ten thousand species co-existing on and in our bodies. Many of them unknown to science. And extremophiles, able to live on Mars, could occur anywhere as there are many extremophiles that are quite comfortable also living on us, in our clothes, in the soil and in the air.
I think that if this was more widely understood then many people, at least, would not want to land on Mars any more.
We can do exciting missions however to orbit, and explore it via telerobotics. I think that is the future, at least the near future for the next few decades. Because it is also a huge planet, and it will surely take some decades before we understand it at all well. Especially since life, at the low concentrations we expect on Mars, wouldn't be visible from orbit. And also is likely to be a few cms below the surface of the soil in many of the proposed habitats. Easily contaminated by Earth life, but not visible from orbit.
As for those who worry about us becoming a multi-planet species - well - there are no imminent disasters likely at all that have a chance to make humans extinct. The dinosaurs didn't have submarines, and deep mines and spacesuits and so forth. At least a few humans would survive even the biggest asteroid strikes in recorded geological history.
Earth is indeed predicted to become uninhabitable for humans eventually, perhaps 500 million years from now. But I think most don't realize quite how long a timescale that is. So far into the future that a microbe just beginning to make its first steps towards multi-cellularity could evolve to a human by then. 500 million years ago is the time of the Cambrian explosion - the first occurrences of widespread multi-celullar life on Earth.
So, I think no urgency to colonize Mars right away in the next decade, or century, or millenium or even million years. And it's not at all clear that Mars is the best place anyway. I'd favour free space colonies like the Stanford Torus myself. Because - they can be built in a few decades or less and are already habitable, as habitable as the tropics on Earth, and can be adjusted to ideal conditions for humans. And if something goes wrong, worst thing happens is you have to sterilize the air and soil and start again. You can never do that with a planet if things go wrong there. And it takes a thousand years or more, just to get Mars to the point where you can go out of doors safely with an air breather, and can grow trees, but not any animals or birds yet - and that is a timeline that seems hugely optimistic to some. And also not many realize - but the plans to terraform Mars are also temporary - not thought that it would remain terraformed for billions of years like the Earth. On some timescale, we don't know how long, it would lose its atmosphere again and end up in a worse state than it is now.
It's actually far colder than it looks. If it had enough water the entire surface would be white. And though a white Mars like that would be far more habitable for humans - it wouldn't look so habitable.
Would the Mars colonists want to go to Mars if it was covered in a kilometers thick layer of ice like Antarctica? Yet Antarctica is far far more habitable than the most hospitable areas for life on Mars.
It just looks more habitable than it is because it is so very dry, that it doesn't have enough water to be covered in ice.
Also I think many don't realize how thin the atmosphere is. That it is only 1% of the Earth's. For all practical purposes it is a vacuum. Your saliva would still boil and you'd die pretty quickly within seconds if exposed to it, even if supplied with oxygen. You need a full spacesuit, just as for the Moon, not just an air breather.
Similarly when building greenhouses and habitats, you need massive constructions to hold in tons per square meter (ten tons per square meter for a habitat, and one ton per square meter outwards pressure for a lower pressure greenhouse). The 1% of Earth's atmospheric pressure only provides 100 Kg per square meter of pressure in the other direction from outside.
And the CO2 in its atmosphere is hardly of much value, except for creating fuel, after all it is normally a waste gas you try to remove from habitats.
And the atmosphere makes a landing on Mars far more dangerous than a landing on the Moon. It is just enough atmosphere so that you are committed as soon as you hit it, and can't abort like Apollo (they were able to abort and fly back to orbit even when they were a few tens of meters above the surface). But not enough atmosphere to parachute to the surface like Earth - that's why the landing systems for Mars are so complex, always involving multi-stage systems (at least to date). Where everything has to work in sequence and just one glitch would be fatal.
But for me the main reason we shouldn't land humans on Mars is for planetary protection reasons as you'll see from my other answers here.
So - I think that's another reason, that most people are not aware that there are planetary protection issues with landing humans on Mars at all. For some reason, the writers of articles and tv presenters and such-like almost never raise the question of planetary protection at all when human missions are discussed. Yet often do when unmanned missions are covered, all though they are far less risky for planetary protection. I think this is a kind of a collective blindspot.
But - Mars is one of the most interesting places for the search for life. And also new discoveries suggest that it may well have liquid water in thin films, and be habitable for present day life. This would be an amazing discovery - either to find life on Mars - or indeed - if it doesn't have life - to find out what chemistry and what "almost life" processes happen on a planet like that with organics, but without life.
The very last thing you want to do, if you want to study Mars and see if there is life there already - is to land a spaceship with humans. Because, sadly, we can't be sterilized .We have something like a hundred trillion microbes in about ten thousand species co-existing on and in our bodies. Many of them unknown to science. And extremophiles, able to live on Mars, could occur anywhere as there are many extremophiles that are quite comfortable also living on us, in our clothes, in the soil and in the air.
I think that if this was more widely understood then many people, at least, would not want to land on Mars any more.
We can do exciting missions however to orbit, and explore it via telerobotics. I think that is the future, at least the near future for the next few decades. Because it is also a huge planet, and it will surely take some decades before we understand it at all well. Especially since life, at the low concentrations we expect on Mars, wouldn't be visible from orbit. And also is likely to be a few cms below the surface of the soil in many of the proposed habitats. Easily contaminated by Earth life, but not visible from orbit.
As for those who worry about us becoming a multi-planet species - well - there are no imminent disasters likely at all that have a chance to make humans extinct. The dinosaurs didn't have submarines, and deep mines and spacesuits and so forth. At least a few humans would survive even the biggest asteroid strikes in recorded geological history.
Earth is indeed predicted to become uninhabitable for humans eventually, perhaps 500 million years from now. But I think most don't realize quite how long a timescale that is. So far into the future that a microbe just beginning to make its first steps towards multi-cellularity could evolve to a human by then. 500 million years ago is the time of the Cambrian explosion - the first occurrences of widespread multi-celullar life on Earth.
So, I think no urgency to colonize Mars right away in the next decade, or century, or millenium or even million years. And it's not at all clear that Mars is the best place anyway. I'd favour free space colonies like the Stanford Torus myself. Because - they can be built in a few decades or less and are already habitable, as habitable as the tropics on Earth, and can be adjusted to ideal conditions for humans. And if something goes wrong, worst thing happens is you have to sterilize the air and soil and start again. You can never do that with a planet if things go wrong there. And it takes a thousand years or more, just to get Mars to the point where you can go out of doors safely with an air breather, and can grow trees, but not any animals or birds yet - and that is a timeline that seems hugely optimistic to some. And also not many realize - but the plans to terraform Mars are also temporary - not thought that it would remain terraformed for billions of years like the Earth. On some timescale, we don't know how long, it would lose its atmosphere again and end up in a worse state than it is now.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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