Mars is a barren, inhospitable planet, and a long, long way from home (if you live on Earth), but that hasn’t deterred Elon Musk.
The entrepreneur who established Tesla Motors and SpaceX, and built a giant battery for South Australia so its lights wouldn’t go out again, now wants to launch the first manned mission to Mars by 2024.
He’s investing a lot in this dream and has even outlined a plan for a spaceship that could send 100 people into space, powered by 42 state-of-the-art rocket boosters.
During the next five years, he wants to establish infrastructure on Earth and Mars that will allow humans to travel to the red planet for long, potentially permanent, residence.
While the possibility of humans living on Mars any time soon is remote, even fanciful, he says he wants to make Mars “a nice place to be” before we get there.
That’s definitely going to be a challenge considering Mars’ environment. It's an extremely cold, dusty planet, and you can’t breathe on its surface.
For Dr Jasmina Lazendic-Galloway and Professor Tina Overton, the speed at which technology is advancing, and the possibilities it's opening up for final-frontier space travel and colonisation, presented an educational opportunity.
Last year, the Monash University academics created a massive free online course, “How to survive on Mars: the science behind the human exploration of Mars”, and were flooded with applications.
It's a one-month course that explores the science of what's needed to survive on Mars, and also provides an opportunity to reflect on “how precious our natural resources are on Earth, and that we should take greater care of them”, Dr Lazendic-Galloway says.
“We want to inspire people, especially young people, to pursue science in high school and beyond, because we will need some innovative problem-solving approaches to make lives on Mars sustainable.”
So just what are some of the basic things that humans are going to need in order to get to Mars, and survive?
Mars’ atmosphere is roughly one-10th the atmospheric pressure of Earth’s and is 95 per cent carbon dioxide, making it completely unsuitable for supporting human life. Humans will have to live inside enclosed structures, providing a controlled environment suitable for housing us separated from the harsh red deserts outside. The most important resource is oxygen, which we have the ability to create already. Technology used on the International Space Station (ISS) is providing a steady supply of oxygen to astronauts.
By passing a current of electricity through water, you create hydrogen and oxygen gases. The process is called electrolysis, and the chemical equation for the reaction looks like this:
2 H2O (water) → 2 H2 (hydrogen gas) + O2 (oxygen gas)
Using water to create oxygen might seem a little sketchy for long-term stays away from Earth, as water is also a vital resource that humans need. So how would we get water on the red planet?
There is running water on Mars; however, it’s not suitable to drink for humans, as it’s saltier than any water than can be naturally found on Earth. Much of that salt is in the form of perchlorates, which humans on Earth use for propellants and not for salting our food, because perchlorates can do serious damage to our thyroid gland, skin, breasts and gastrointestinal tract.
Currently on the ISS, drinking water is maintained partially through recycling old water. Wash from sinks and showers, urine, and even water vapour from breathing is collected, filtered, and repurposed to be used again. There's also another process that uses the hydrogen gas that is a byproduct of oxygen production from water, as well as the carbon dioxide that humans breathe out naturally. Hydrogen gas can react with carbon dioxide to produce water and methane. The methane gas is ejected into space. (On Mars, it can be used for making rocket fuel).
4 H2 (hydrogen gas) + CO2 (carbon dioxide) → 2 H2O (water) + CH4 (methane gas)
“Reduce, Reuse, Recycle” is the strategy of long-term outer space resource management. You want to dump as little matter as possible into outer space, because any valuable atoms you toss into the vacuum are wasted resources.
There’s no short supply of carbon dioxide on Mars, but where would we find hydrogen? It turns out there's water on Mars that we can collect, but it comes in the form of ice at the poles and is buried in underground glaciers. That ice is less concentrated in perchlorates, but still contains 0.5 to 1 per cent of the stuff. Luckily, it’s thought that current desalination technologies that we already use on Earth to remove salt from seawater would be sufficient enough to make it drinkable.
So we’d probably use a combination of water recycling and desalination to keep a Martian water supply steady. But this is all going to take a lot of power.
The surface temperature on Mars can be around a comfortable 20 degrees Celsius during the day, but can drop to -153 degrees Celsius at night due to the lack of an insulating atmosphere. Minus 153 degrees Celsius is colder than it sometimes gets during Antarctic winter nights, so a human colony needs to be very well insulated and generate a lot of heat. Considering this and all of the other technologies that humans will need on Mars, there has to be some way to generate the electricity to power it all. Coal would likely be unavailable on Mars, as most of the coal on Earth was deposited there by plants in swampy environments that were buried underground for about 300 million years, and it’s unlikely that Mars ever had that kind of ecosystem. Uranium is an option, but it would take a while to set up the infrastructure to collect and process it. We need a way to start generating power as soon as we get there.
Solar panels on Earth are inefficient compared to their counterparts outside the Earth’s atmosphere, which can collect much more solar energy because the sun’s rays aren’t being partially reflected by the Earth’s atmosphere. Mars’ thinner atmosphere would provide solar exposure much closer to that of empty space than to Earth’s surface. The higher collection rate of solar energy on Mars is somewhat reduced by the further distance from the sun compared to Earth, but it still makes solar power a very good candidate for a Martian colony’s electrical supply. We already have solar panels on Mars that power our probes that we’ve sent there and are already aware of some of the difficulties with the technology. Solar panels on Mars are known to fall victim to dust storms, lowering their solar energy collection rates significantly. This has proven a killer to unlucky probes; however, assuming that some self-cleaning mechanism weren’t possible or otherwise broken, astronauts could feasibly just clean them manually if they were there.
Elon Musk’s SpaceX announced recently that it has succeeded in launching and landing a reusable rocket. This is a significant development in reducing the cost of space travel so that regular trips from Earth become financially viable. SpaceX boasted of 15 launches this year, with a further 30 planned in 2018. Sending shuttles into space is a highly expensive endeavour that eats up plenty of money in non-reusable parts. Up to a quarter of the cost in launching a rocket into space can go into the fuel tank for the boosters that gets discarded mid-launch to help the shuttle shed extra weight.
Reducing the material and technological waste in rocket launches will enable many more launches more frequently and give more opportunities for more people to escape Earth’s gravity. The hope for Musk is that he’ll be launching larger reusable rockets by the end of 2018. But even then, it will be a long time before space travel becomes a commercially viable service to the majority of people. Is it possible to make space travel affordable to the average person?
Reducing cost of travel
Even with the advent of reusable rockets, a ticket to Mars would nonetheless cost an exorbitant amount of money. It is possible now to buy a trip to Earth’s higher orbit and experience the wonders of outer space; however, it costs US$20 million at a minimum. It would be disappointing if the opportunity to settle Mars was siphoned off to only the highest of high-income earners, so we need to find a way to bring the costs down.
A solution that Musk proposes is an increase in demand. He estimates that if one million people can be flown to Mars, that volume would bring the cost of a Mars ticket down to about US$500,000. Still a mighty sum, but far more affordable for a large number of people. This is the same model that Musk has used for battery-powered Tesla cars.