This is a response to the question Will the human race ever populate another planet? posted on Toshiba’s Love to Lead site. Toshiba set a question and then bloggers answer it, with links back to the Toshiba site in the hope of winning a laptop. You can also add a button like the one on the right like I have, because I’m not proud. It looks like an interesting competition, but more importantly it’s an interesting question. It’s also an excuse to talk about Robert Zubrin’s thought provoking book The Case for Mars.
Populating another planet really depends on two factors. There has to be the ability and the will to settle another planet. If we lack either then it will not happen. in particular, the crunch point is the ability. Is it physically possible? If it’s not then no amount of wishing is going to make it happen. What are the challenges we need to overcome getting to, and settling on, Mars? Shortly after reading Oliver Morton’s excellent Mapping Mars, I read Robert Zubrin’s The Case for Mars, as it was mentioned so often by Morton. If you want an overview of the problems in interplanetary colonisation this is an excellent introduction. Even if you don’t agree with the conclusions, the explanation of the problems he tackles is usually eye-opening. For instance, first of all you’ve got to get there.
Getting to Mars
There are a few problems in getting to Mars. The method that uses the least energy is a Hohmann orbit. This is an ellipse where the lowest point in the orbit meets Earth, and the highest point is at Martian orbit on the other side of the Sun. If you fly this orbit then you’re committed to around nine months of travel. This means nine months of supplies and power. It also means nine months of weightlessness and nine months of being exposed to cosmic radiation. These are both serious problems because it could mean that when you arrive in orbit around Mars, you’re not going to be in a fit state to land. The solution to weightlessness that Zubrin proposes is elegant.
If you’ve seen 2001 then you’ll have seen Kubrick’s rotating space station. This, he thought, would be a necessity. The station generated gravity by centrifugal force. If you sit in a rotating space station you’ll feel as if you’re pushed out from the centre. Zubrin proposes that any spaceship sent to Mars should rotate around a counter-weight to simulate gravity. This gives your muscles something to push against, and so they don’t waste away during the flight. The radiation is harder to avoid.
Radiation is one of the reasons why some people think the Moon landings were a hoax. The Earth is surrounded by the Van Allen belts, regions of strong radiation. The radiation is particles spewed out by the Sun and concentrated by the Earth’s magnetic field. If the Apollo astronauts had dawdled in the Van Allen belts then they would have all died of cancer. The radiation between Earth and Mars isn’t so intense, but the length of the trip will mean that there might be a fatal exposure. Zubrin spends six pages tackling this problem. It is real and he calculates the dose will be around 50 rem on a two and a half year mission to Mars. In realistic terms this means that the chance of you getting developing cancer during the thirty years after you get back to Earth from a short Mars mission will be 1%. Travelling to or living on Mars will be a risk, but sitting in a rocket fuelled with liquid hydrogen is risk. Some people would be willing to take it.
Using chemical rockets to get to and from Mars is almost feasible with current technology. It’s well within reach of a properly funded programme. But settlement is different. Once you’re there what will you live off?
Energy is going to a major problem for any settlement. Oil and gas require biological deposits, and they haven’t been found on Mars yet. Solar panels have proven amazingly efficient for the Mars rovers Spirit and Opportunity. Nasa were expecting a large reduction in the power available to their rovers due to dust acculmulating on them. Instead what they’ve found is that particles in the Martian wind might be scouring the solar panels clean. Despite this Zubrin thinks he’s spotted a better source of energy, geothermal energy.
Mars is home to the Solar System’s largest volcano, Olympus Mons. This is huge. Staggeringly huge. It’s so massive that if you were standing on Olympus Mons then you wouldn’t be able to see it, because it’s so large. That probably doesn’t make sense. Surely the bigger something is, the easier it is to see? Imagine standing in Kansas City and trying to see the whole of North America. This is the problem you would have. Olympus Mons is a bulge on the surface of Mars, and must have been raised by a terrific amount of geological activity. The best current guess is that this stopped millions of years ago, but geologically speaking this is a short period of time. There are likely to be hotspots where a colonist could drill down to access still warm rock buried deep beneath the surface. Pump water down one hole and it can emerge as steam to drive turbines from another, or else to heat the settlement. Hydrothermal power is a major energy source for Iceland, which is sat on a crack between North American and Eurasian tectonic plates. The first settlers, Zubrin notes, have the luxury of choosing exactly where to set up base, and this means that they can situate themselves directly over a suitable hotspot.
What Zubrin didn’t know about when he was writing his book is that there may well be liquid water close to the Martian surface. This was recently reported by Nasa. With a source of energy and liquid water it’s possible to produce oxygen for breathing. Other problems are then soluble if people are willing to make the effort. It won’t be a trivial effort though. Why on Earth would you want to go to Mars?
Zubrin puts forward two reasons. His worst is that America needs a frontier spirit. The Case for Mars is littered with celebrations of how the West was won. Space exploration isn’t so much for all mankind, but for the USA. This is a feature which may grate if you’re from a country where football is a game played with the feet. A better reason he puts forward is the chemical wealth of Mars. One thing Mars has which Earth doesn’t so much is Deuterium.
Deuterium is a form of Hydrogen. Usually Hydrogen is an atom with just one proton and one electron. Deuterium has one proton, one electron and also one neutron, making it twice as heavy per atom. It’s usable in nuclear reactors today, and will be essential if for fusion reactors, if there is a will for clean nuclear energy and a reduction in greenhouse gas emissions. On Earth around 160 parts per million of Hydrogen are Deuterium. On Mars Zubrin says it’s over eight hundred parts per million. The value of deuterium per kilogramme is currently less than gold, but not that much less. There may also be sources of rare-earth elements. The lack of water on the surface of Mars means that wherever these ores were found, they’d be accessible. Personally I suspect there may be something more valuable to be found on Mars that has yet to be found, due to the presence of heat and water.
Life on Mars?
In 1996 Nasa issued a press release of a controversial discovery. It started:
A NASA research team of scientists at the Johnson Space Center (JSC), Houston, TX, and at Stanford University, Palo Alto, CA, has found evidence that strongly suggests primitive life may have existed on Mars more than 3.6 billion years ago.
The evidence was what appeared to be microfossils of bacteria-like organisms. This was rejected by many as the bacteria were too small. However, nanobacteria may have now been found on Earth. Certainly there are thirty-four meteorites known to have come from Mars on Earth. It is likely that exploration of Mars will find meteorites from Earth on its surface. The two planets have been exchanging small samples of material for millions of years. Could bacteria have hitched a lift on a meteorite to travel from one planet to another?
The Apollo 12 mission brought back samples from the Surveyor 3 probe. On the surface of the probe were still viable organisms of Streptococcus mitis. As Nasa says: “50-100 organisms survived launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees above absolute zero, and no nutrient, water or energy source.” Modelling suggests bacteria could survive the trip through space and landing on Mars. Could they live there?
A hot research topic at the moment is into extremophiles. There’s no set definition, but effectively it’s any organism which survives where you really, really wouldn’t expect it. They can be found in buried lakes underneath the Antarctic ice, in temperatures in excess of 100°C and even in nuclear reactors. The exciting ones for Mars are Lithoautotrophs. These are microbes that need water, heat and rock. They’ve already been found on Earth. They’re happy in what we would consider impossible conditions, like 3km into the Earth’s crust. And there could be a lot of them, the mass of the deep biosphere might exceed the mass of the biosphere in the surface of the Earth. at the moment it’s too early to say for sure. If any of these were carried to Mars could they survive? With the presence of geothermal heat, and the possibility of liquid water beneath the surface it’s entirely possible. It is possible that there’s a whole sophisticated ecosystem beneath the surface of Mars.
It’s here I move from being slightly out of my depth to very out of my depth. If there is life on Mars and it’s different to terrestrial life then biologists will be ecstatic because it effectively gives them access to entirely new material to test their idea on. However, if Earth and Mars have been sharing biological material, so that the life shares a common ancestor then they will still be ecstatic.
Since the seventeeth century Physics has undergone a huge revolution in discovery because Isaac Newton provided a framework that has proven useful for building new ideas on. It’s only since the early twentieth century that the work of Darwin and Mendel has been put together to achieve something similar for Biology. Someone in the early eighteenth century could not be expected to predict what would be achieved by the twenty-first century. Similarly it’s hard to say what the state of Biology will be by the early twenty-third century.
Zubrin frequently uses historical analogies with the colonisation of North America in his book. The social sciences are the weakest element of the book for me. A section on the Martian calendar being based on the zodiac is entirely speculative and almost certainly not going to happen. He argues that the promise of riches drew people out to the New World. He’s right to an extent, but as well as the pull of the New World, there was also a push. People were often not leaving to get a better life, but leaving to escape a worse one. Despite that I think he is right that if the economic incentives are there then colonisation of space will happen. To an extent it already has. Many of the satellites in orbit of the Earth are privately owned. There reason no people are up there for corporations is that there’s no profitable reason why they should be. If there is a profitable reason people will follow.
If you’re interested in space exploration then I highly recommend Oliver Morton’s Mapping Mars and Robert Zubrin’s The Case for Mars. They’re both excellent and intelligent books.
You can read more about the colonisation of Mars at the Mars Society website set up by Robert Zubrin.