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There's an opportunity for human exploration of Mars to help with Earth's troubles [1]

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Date: 2023-01-11

4th Rock from the Sun, or is it 5th (do we count Earth's moon)?

NASA is currently attempting to send a crewed mission to Mars, optimistically scheduled for the early 2030s. How useful that mission will be in regards to combating climate change and social inequality will depend heavily upon how NASA decides to get there. There are a range of possible mission designs and it’s important that we push for a mission that maximizes our returns for Earth.

But before we get into designs, it would help to know a little bit more regarding the challenges of a Mars mission. From a rocket standpoint, we’ve long been able to reach Mars with an unmanned rocket. The delta-v to get there is not that much more than getting to the moon. Delta-v is the common metric in space travel to determine the amount of rocket thrust needed to reach a destination in the solar system. It stands for “change in velocity” and because it is mass independent, or more precisely the delta-v for each rocket can be calculated based on it’s own mass, it serves as a useful measurement. A LEO (Low Earth Orbit) to low moon orbit mission takes 13,196 m/s of delta-v, whereas a LEO to low Mars orbit takes 14,958 m/s. So a rocket with 15,000 m/s of delta-v could go to either the moon or Mars (one way). So what’s the problem with Mars? The time it takes to reach the destination is considerably different.

Hohmann Transfer

The most common (and lowest cost in delta-v) way to get from one part of the solar system to another is called a Hohmann transfer. There are other useful transfers, but we’ll ignore those for now. In a Hohmann transfer, you can start from a circular orbit, say near the Earth in what we call LEO (Low Earth Orbit) which is number 1 in the figure. Without a transfer burn (of the engine), you just circle around forever*. The first burn marked by the delta-v symbol sends the spacecraft into a highly elliptical orbit marked as 2 in the diagram. The dotted line of 2 indicates the path of the ship if there is no second burn to “circularize the orbit”. As you can see orbit 2 takes you around to where you begin without a second burn. By conducting a second burn at the farthest point of the elliptical orbit, you can circularize the orbit. In the case of the moon, the burn would be slightly different as the first burn is timed so that the spacecraft reaches the moon when it’s at the furthest most point of the elliptical orbit (number 2). Then instead of circularizing the orbit, the burn instead slows down the spacecraft so that it is captured by the Moon’s gravity and is then in orbit around the moon. Mars would work similarly.

These burns are a tiny fraction of the time the ship is in space. The spacecraft performs the burn, then the engine is turned off and the ship coasts until the second burn is needed. This is important to realize as ships don’t just point at an object and thrust towards it all the way. That would be great if we had efficient enough engines, but we don’t. If we did, we’d save a lot of trouble. A 1 G constant acceleration engine (so that the spacecraft would feel like it has normal gravity for the trip) would get us to Mars in 2 or so days. But it would require a vastly more efficient engine than we currently have. Instead, we burn and coast using the Hohmann transfer and instead of 2 days, we get to Mars in 9 months.

In addition to taking our merry old time to get to Mars, these Hohmann transfers need the planets to be in a particular alignment. These alignments are called “windows” as there is a spread of days where the distances involved are good enough. The Earth-Mars Hohmann transfer window happens every 26 months. If we are talking about a crewed mission, the return window is about 3 months after arrival. This means most Mars missions will be 21 month missions. This is why Mars is hard. Even though the rocket size is pretty close, the time taken isn’t.

The long Mars mission time makes for two main problems. The first big problem is exposure to high energy rays in space. The Apollo missions were short enough to not seriously risk the crew, though if they had been unlucky they could have been seriously hurt. Over the course of a 21 month mission, the crew will need to be protected. On Earth we are protected by Earth’s magnetic field which goes out far enough to protect the international space station as well. Once past it, the space ship will need to protect the astronauts, even on Mars as Mars does not have a significant magnetic field.

The other problem is that astronauts will need to bring a LOT more food, air and other essentials. The round trip to the moon is roughly 8 days. It wasn’t too hard to pack enough space ice creams to get Apollo astronauts there and back. It was short enough some astronauts purposefully constipated themselves so as to not have to defecate while in space. I don’t think you want to try that going to Mars. But this problem of living in space for an extended time is also our opportunity for Earth.

There are two basic ways to solve the problem of needing more food and oxygen for the round trip to Mars. The first is to make a larger space ship to hold everything the astronauts need. It would basically be one big storage vessel. For comparison sake, a nuclear submarine mission can be around 6 months, but in that case oxygen is provided from sea water. So it’s theoretically possible to brute force our way to Mars and back.

The second way is to recycle as much of the standard wastes as the astronauts can. This would mean growing food in space. Given light, the plants scrub CO2 out of the air turning it into food and oxygen. Human waste would need to be composted and could then be provided to the plants to keep them growing. Plants can even be part of the water filtration process. But as space aboard a space ship is extremely precious, much research needs to be done on space efficient agriculture. Some of this research can be applied on Earth. Our current agriculture system on Earth uses space inefficient monocultures that destroy soil and make harvesting fossil fuel intensive (to run the machines). People have already started to experiment with polyculture farming such as Permaculture. The benefit of adapting these techniques to space travel is that space travel demands everything works. On earth, if you didn’t plant enough tomatoes, you can go to the store to get some more. On a Mars mission, if you are short, you are short. Better hope the shortage is not mission critical, as the mission goes 21 months no matter what. There are no easy ways to return early.

Space efficient polyculture farming may not seem like a big deal, nor be strictly related to climate change, but it really is a massive deal. American conventional farming is heavily fossil fuel intensive for fertilizer, plowing, harvesting and transport. Making our agriculture more space efficient, with less energy needs, and capable of being inside a building will be critical in both reducing our CO2 footprint and also growing food in harsher, warmer climates. Being space efficient means more food can be grown closer to where people are, reducing transportation costs.

But astronauts need more than just food and oxygen. Machinery breaks down from usage. Similar to food, the mars mission can choose to bring all the spare parts with them, or devise ways to make what they need there. Bringing spare parts is fine, until you run out of parts. If a particular component runs through spare parts at a higher rate than anticipated, the crew better get its MacGyver on and fast. Go watch Apollo 13 to get a sense of what that means. Apollo 13 was 8 days, imagine having to MacGyver for 21 months. The alternative is to be capable of producing parts on site. NASA is already experimenting with space based 3D printing. But that’s only part of the problem. What happens if the 3D printer breaks? How do you get more material to put into the printer if it runs out? What about things that can’t be easily 3D printed?

Part of the solution comes from Mars itself. We can get some things from Mars such as water, silicon, and other elements. In space terms this is called ISRU (in-situ resource utilization). On Earth it’s called mining, water collection, air purification, and so on. For 3 months on the surface of Mars, and in perpetuity if we decide to colonize, the Mars mission demands that the astronauts become their own little closed loop economy. Waiting for a resupply mission from Earth takes 9 months at minimum, up to 26 months if you are unlucky. Any mission to Mars demands that the astronauts be able to make or recycle as much as they possibly can. Which is something we need to be doing on Earth as well.

Our current globe spanning economy based on fossil fuel usage gives immense power to those who control those resources which come from limited places. Russia and Saudi Arabia wield immense power due to their ability to control significant amounts of fossil fuels. But we are also learning from Russia what happens when you are able to provide needed items for yourself. We can take power away from oil thugs by not needing as much, or preferably any oil.

Globalization has taken us away from relatively small closed loop economies. A closed loop economy is one in which all goods, raw materials, and energy is produced inside the economy. In science fiction, the Star Trek world is one where an individual with a replicator and energy source can produce everything they may need for themselves. It’s the ultimate closed loop of one. It doesn’t mean they can’t get things from elsewhere, but they can provide for themselves. Being able to provide for yourself means you are not dependent upon opportunistic individuals who attempt to take advantage of other’s needs.

Imagine building a small town on Earth today designed on a closed loop economy. Initially, it wouldn’t be so small. But as our research into closed loop economic tools progresses, the size of the town would start to shrink. Eventually we could get to a point where whole groups of people are fully self-sufficient. As each group becomes self-sufficient, they in turn help other groups. If my group is properly run and supports everyone in it, we become far less dependent upon predatory individuals. If predatory individuals do manage to take over a group, being able to establish new ones easily means people can simply leave the predatory groups. If we all have solar panels on our houses, then power companies have less impact. If we can build our own solar panels, we become less dependent upon companies like Tesla. If we have compact units that can synthesize a variety of medications, we become less dependent upon Big Pharma. And so on.

We don’t need a perfect closed loop from the get go. We implement what we can where we can. If we can increase recycling and decrease needless transport of goods, we decrease out carbon footprint while improving equality. A mission to Mars can put considerable resources into solving all these problems and making small scale production of items easier and more efficient. Learning to live in space forces us to understand what is critical. It forces us to come up with new solutions that businesses don’t want us to have. A business wants to sell you a gadget, not have you learn how to make the gadget for yourself. A mission to Mars puts funding into easier ways to make critical gadgets, and to make the machines that help make the machines.

This won’t all be perfect. It won’t all happen at once. But just like Apollo led to weather satellites (and other related satellites) which have been instrumental in detecting and measuring climate change, the Mars mission can help teach us how to be more independent, efficient, and environmental on Earth.

So long as we design the mission right.

* Not really forever as the orbit may decay due to other objects such as the moon slowly adjusting the orbit until the orbit starts to get into enough of Earth’s atmosphere where drag starts to become an issue.

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[1] Url: https://dailykos.com/stories/2023/1/11/2145456/-There-s-an-opportunity-for-human-Mars-exploration-to-help-with-Earth-s-troubles

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