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| Mars lander over Valles Marineris by William Black |
The Technology
In May 2018, I wrote a piece about what was then called the BFR (now renamed Starship) entitled Full speed ahead--Mars by 2024. Musk had announced his "Mars Colonial Transporter" the previous September, and he described this goal as "aspirational". Spoiler alert: we won't get to Mars by the end of this year. But it looks as if he will prolly be just 2 years off. Given that 7 years ago when Musk announced this project, most people thought that it would never happen, that's a signal achievement.
Why two years? Mars and Earth are in "opposition" (i.e. Earth is between Mars and the Sun) roughly every 2 years and two months, which is when they are closest in each current orbital period. And that is when we would launch an expedition to Mars, because that is when the journey would have the shortest duration.
The next opposition will be on January 15th, 2025--we're not going to make that one. The opposition after that will be on February 19th 2027. I think that will be the date, more or less, that ships from Earth will land on Mars. Assuming a six months flight to Mars, the expedition taking advantage of the February 2027 opposition would have to leave in September 2026. A return journey will not happen until the next opposition, on March 25th 2029. Once again, any ship that returns to Earth will leave 6 months or more before the opposition.
Why am I convinced that SpaceX will be able to do it on this timeline?
Let's start with the success of flight 4 (IFT 4) of the Starship/Super Heavy booster combo. Both the booster and the ship managed soft landings, despite some problems with re-entry and the rocket engines. Each flight has gone further and achieved more than the previous one. This is how SpaceX works, by iteration. It tests, learns, redesigns, and tests again. The gaps between each test flight have grown shorter.
Musk has said that there will have to be "hundreds" of flights before humans climb aboard. NASA's Artemis program to land astronauts on the Moon will be using Starship, and that is (coincidentally) also scheduled for September 2026. So by then there would have had to be hundreds of successful Starship flights. How will that be possible? Well, the whole point about Starship is that it is meant to be re-usable. So each Starship will be able to fly often, perhaps once a day, to test its ability to launch and re-enter safely. And SpaceX plans to ramp up its production line to a Starship a day.
But ... re-usability depends on the heat tiles working and not needing to be completely replaced after every flight. The Space Shuttle was supposed to be re-usable, but the time and expense needed to refurbish its heat shield after every flight made it very expensive. Musk has said that the heat shield tiles, made from a kind of ceramic, are like china plates attached to the outside of the ship. They are vulnerable to vibration, cracking, chipping and breaking up. They have a different thermal expansion coefficient to the stainless steel of the ship's body.
It is a formidable problem, if you want full re-usability. Videos from IFT4's re-entry showed that most of the tiles visible to the on-board cameras were OK, but debris from the re-entry showed that some tiles were disintegrating. IFT5 (end July?) will test new shielding, including a layer of fibrous heat shield under the solid heat shield tiles. If the heat shield has to be replaced after every flight, this will mean the Starship is not fully reusable, which in turn means that my putative Mars timeline won't happen.
SpaceX has already faced up and solved many technological issues with Starship. But this is the most formidable yet. Will they solve it?
Consider how far SpaceX has come since Musk's announcement of the BFR is September 2017. A carbon-fibre ship was the first proposal. Then SpaceX pivoted to a stainless steel ship and booster, because of its superior ability to withstand the heat of re-entry as well as its far lower cost. In effect, they started from scratch at that point (2019). Observers mistook the first test vehicle at Boca Chica for a steel water tank. It's been just 5 and a half years since SpaceX started with the current Starship design. So progress has been remarkable.
Therefore, I do in fact expect to see boots on Mars in 2027.
The Economics
So we will have a scientific outpost, as we do in Antarctica. But will it ever be more than that? Will there be colonisation? Will there be a city of a million inhabitants? The issue now shifts from the technical challenges of getting to Mars (difficult but doable) to the economics of settling there in enough numbers to reach a self-sustaining million people (much more doubtful).
Before I answer these questions, read about all the problems of living on Mars in this piece I wrote. To summarise that piece: Mars is very, very cold; has practically no atmosphere, and what it does have is poisonous; there is no soil, and the rock and dust on the surface (regolith) is contaminated with poisonous perchlorates; the planet's surface is bathed with lethal radiation; its gravity is just 40% of the Earth's.
Terraforming Mars will take at least a century, prolly many more. So everyone will have to live in domes or in caves. To preserve the researchers' sanity, spouses and partners will be permitted to stay too; there will be parks under the domes or in the caves to provide some Earth greenery; there'll be guest suites, and tourists. Tourists? Surely, yes. Just a few in the early years, but numbers rising rapidly as costs decline.
The research stations will require fresh food, water purification, air purification, genetically modified plants, dome construction technology, and above all, energy. There will be powerful technological forcing functions in all these areas, and in the spaceship technology to get us there, resulting in huge cost reductions over time.
There were 350 settlers at the Jamestown colony in Virginia in 1610. By 1630, there were 4.6 thousand settlers (and descendants of settlers), a compound growth rate of 14%. By 1650, 50 thousand, a growth rate of 13% per annum for those two decades. There are many more people on Earth now than there were in 1610, so there could in theory be more settlers. But on the other hand, back in the 17th century, once the settlers had arrived, they could hack themselves a field out of the forest, build a log cabin, and start a new life. On Mars, they'd have to live in a dome, pay for the dome's maintenance and upkeep, and find themselves a job. No homesteading, no going off into the wilds to make your fortune. Not only will you have to find the fare, but also enough money to live on in a high-tech environment where everything has to be paid for, including air and water.
Musk talks about a million people on Mars by 2050. It could happen, maybe, if technological advances are enough to cut costs rapidly. But I hae me doots.
The first passage to Mars will cost $6 million per person (assuming 10 people per ship, with the rest of the payload being stuff needed to keep them alive). But they'll be scientists, with their fares paid by Earth's space agencies. The second expedition will perhaps cut that to $300K per person, and the one after that to, say, $200K.
But that's still far more than most people can afford.
Only a millionaire could afford these fares. There are 59 million millionaires in the world. I suppose it's possible that 0.1% of them will give up their lives of comfort and luxury on Earth for a hardscrabble living on Mars. That's roughly 60,000 people. 60,000 in total who can both afford it and also want to do it.
There's no way there are going to be a million people on Mars by 2050 --- unless there are big subsidies from Earth to achieve this. It would cost, say, $100 billion a year to send 200,000 people every opposition (2,000 Starships!), at a million dollars per colonist (fare plus living costs), until the Mars colonies are self-sustaining, and all you'd have to fund is the fare. Whatever you think about the desirability of colonising Mars, no government is going to provide that much money. Unless .... geopolitics intervenes, and the US funds settlement to secure a hold on Mars. Will that happen? I can't tell. But it has to be a possibility. Without that, maybe 10,000 colonists every two years, at $1 million a pop? $5 billion a year? Yes, possibly. 110,000 residents by 2050, assuming deaths are balanced by births (can mammals even have offspring in lower gravity? No one knows.) A long way from a million.
So, will there ever be a viable colony on Mars? I used to think there would be. But I don't know, any more. What do you think?
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