Solar Sailer

by Stephan Besik

  Chaz smiled. “Okay. I’ll get started.

  Our first issue of concern is the magnetic field of the moon. Or rather, the lack of one. It turns out that the moon doesn’t have a magnetic field.

  This is a significant issue because of Item Two on our list, what scientists call the solar wind. In addition to light, the Sun generates a high velocity flow of ions, a plasma, consisting almost entirely of single protons and electrons, the constituents of hydrogen atoms. There are traces of other stripped elements in the wind, but the wind is almost entirely ionized hydrogen.

  The velocity of the solar wind relative to the Earth or the Moon is on the order of hundreds of kilometers per second. The density of the solar wind is pretty low, however, so over short periods of time it’s generally not dangerous. The short-term hazards tend to be Coronal Mass Ejections (CMEs), during which the solar wind can increase by a couple of orders of magnitude. While those are an issue, the real problem is long-term exposure. Over months and years continuous exposure to the solar wind can do a lot of damage.

  On Earth we are protected by our planet’s magnetic field, which diverts the solar wind around the Earth, rather than bombarding the Earth’s surface. We get a few leftovers, but typically very little of the solar wind ever reaches the Earth.”

  Aman interrupted. “We knew about these problems early on in the project. Do we have any solutions that look feasible?”

  “I’m getting there. I wanted to cover issues and ramifications of some of the problems first. A lot of these things are linked together, and solutions might well have to address multiple issues at one time.”

  Aman nodded. “Got it. We’ll follow where you lead.”

  Chaz went back to the problems.

  “Since the Moon lacks a magnetic field the surface is bombarded by the high-speed ions of the solar wind wherever and whenever the surface is exposed to the Sun. The ion bombardment causes the rocks of the Moon’s surface to break down in a process called sputtering, producing a layer of superfine dust over much of the Moon.

  While the overall solar wind is electrically neutral, the electrons and protons distribute across the Moon in a way that causes different parts of the Moon’s surface to have different charges. If a drone or a person moves around on the surface, a charge can be built up in one place that discharges in another place because of the difference in charge in that area. Sort of like miniature lightning. This can mess with any kind of equipment that is electrically sensitive, so the things we send up to the Moon have to be shielded or grounded to be protected from the charge levels on the Moon’s surface. If a person or a vehicle is moving around, the protection has to be good enough to prevent discharges that might do damage.

  While the charge buildups are a problem, the superfine dust created by the long-term bombardment of surface rocks by the solar wind is a problem in and of itself. It’s so fine it acts as a high quality abrasive. It also gets into anything with a seam in it. And the dust itself is charged, so it is drawn to and clings to anything that isn’t magnetically shielded in some way.

  It seems like it’s never been talked about in a really public way, but it’s also no secret. Apparently the first astronauts ran in to problems with the dust getting in to the very fine seams on their spacesuits and with dust eroding things like the soles of their moon shoes. I don’t think anyone’s ever come out and said it but I think there’s a chance that no one’s been to the moon since the first landings because some pretty extensive precautions have to be taken against the dust. The dust gets into everything and quickly destroys most anything we might want to send up there.”

  Aman raised his hand again.

  “The dust problem sounds awkward. Do you think no one has tried a long stay on the Moon because of a bunch of dust?”

  Chaz shrugged. “Possible. This is just the first of some pretty big problems, however. The variation of charge on the Moon’s surface is also a substantial issue. Apparently variations of several hundred volts can arise across relatively small areas of the Moon’s geography, so it’s necessary to make sure there’s a way to stay grounded. It doesn’t seem to be a problem if a machine or a man stays in a really limited area, but over a distance, say between the top and bottom of a hill, the voltage drop can be pretty large. A discharge of a few hundred volts would give us our miniature lightning strike, and most electronics don’t take kindly to that sort of variation in their environment.

  There are also things like the two-week long days that cause overheating in the day and sub-zero freezes at night, but compared to a locally charged surface and clingy, superfine dust the heating and cooling problem might be a relatively minor issue. Temperature variations just add increments to the really big problems.”

  “So, do we have an approach or are we stuck?”

  “We have suggestions. Suggestions that we think can be implemented. Whether our solutions will work…” He shrugged again. “We can find out quite a bit here on Earth, as well as in space. But we won’t know for sure if our solutions work until we land some probes designed to test solutions.

  For example, we have ways of sheltering our Lunar station, or stations, from the solar wind. The easiest seems to be locating as much as we can in caves. That’s probably the easiest thing we can do.

  The problem with that solution is that it isn’t complete. There are going to be things at our Lunar stations that have to be on the surface, exposed to the solar wind. Right offhand, two examples come to mind- research facilities like observatories, and energy producing facilities like solar panel farms. For these we need a surface solution, and the best one seems to be a man-made version of Earth’s protection. That’s some form of a magnetic shield. Such a shield will be the first of its kind, and it’s nearly certain that any lunar station, even an automated one, will be some kind of hybrid that mixes facilities in caves or other forms of shelter with magnetically shielded resources on the Lunar surface.”

  Chaz took a breath to start another topic. He wasn’t used to long presentations, and this one was going to be pretty long.

  “Caves and a magnetic shield reduce the likelihood of solar wind damage in the foreseeable future. But what about the damage that has already been done? In particular, what about the moon dust?

  This might actually be the problem with the easiest solution. Our idea is to use plasmas or lasers to melt the dust. Once melted, the dust will reform as rock again. Carefully done, it’s possible that melting the dust will result in fairly even, possibly even smooth, platforms on which to build. Or under which to build. Remember that we have to find a way to protect our resources from the solar wind.

  It’s likely that we will use some kind of high-energy laser to do the melting, but at this point plasmas can’t be excluded. There are some scenarios in which a plasma sprayer of some sort may be the best solution. We have to do some R & D to make our decision.”

  Chaz continued. “So we have what appear to be feasible solutions to the problems represented by items One, Two, and Three. Now we have to deal with item Four, or more generally the availability of elements critical to the survival of humanity on the Moon.

  The most amazing thing about the Moon is that there is a great deal of oxygen locked up in rocks on the Moon’s surface. Or amazing to us, at least. It turns out that oxygen is extremely common in the universe, and actually composes almost forty percent of the elements on the lunar surface. The oxygen is bound into various compounds, of course, but it is there for the taking.

  With the solar wind bombarding the surface with what are essentially disassociated hydrogen atoms, we have not only oxygen but the other constituent of water in quantity. In answer to your question about air and water, Aman, we can crack oxygen out of Moon rock. As for water, there are not only deposits of water ice in areas not exposed to the Sun, but we may be able to use the solar wind to help create water.

  There’s not a lot of water on the surface of the Moon because water is volatile and simply evaporates off of most parts of the
Moon as soon as it is created in the heat of the Lunar day, probably within seconds of the hydrogen and oxygen atoms getting together. The trick will be to capture any water we generate so it can be used. We have a limited answer to the problem of water because there are places on the Moon where water ice appears to have accumulated, and there is probably enough water ice to make a small population self-sufficient. With some ingenuity, though, we may be able to produce water from the free hydrogen bombarding the surface and the substantial quantities of oxygen locked in rocks. The first trick will be to catch and hold free oxygen and hydrogen. The next trick is to combine them and hold on to the water once it forms.

  Creating our own water may not be necessary, though. We may be doing ice mining, since some estimates of the availability of water on the Moon suggest the supply is enough to last many decades, if not centuries.

  There are also substantial quantities of things like silicon and iron, even titanium, stuff to make things with. This is one of the major positives of an effort to inhabit the Moon. Concerns about oxygen and water may not be all that significant and there are other quite useful elements on or near the Moon’s surface.

  There are some things that are missing, however. Things that are quite important to life on Earth, and which will probably be critical to survival on the Moon. The two most important elements that appear to be in short supply are nitrogen and carbon. We tend to think of Earth’s atmosphere as composed primarily of oxygen, but as you know nearly eighty percent of the atmosphere is nitrogen. It’s all over the place down here and it’s in a lot of things that humans need to survive.

  Carbon is needed as well. It is a fundamental component of every organic compound and also has some important uses beyond that. No carbon, and humans won’t be around very long. The problem on the Moon is that there isn’t much carbon in the ground and no atmosphere full of nitrogen, and both carbon and nitrogen are trace elements on the Moon’s surface.”

  Aman spoke up again. “I’m not sure why you’ve got the lack of nitrogen and carbon as long-term problems. Seems to me that could be a concern pretty quickly.”

  Chaz nodded. “It could be, but the need is so critical that we simply can’t go to the Moon if we don’t carry nitrogen and carbon with us. They are in us, they are in our food and the wastes we produce, and nitrogen pretty much has to be available in the atmosphere we create. In effect we are importing carbon and nitrogen from the first minute we step on the Moon.

  This is a bit like our problem of holding on to oxygen and water. What we have to do is hold on to the carbon and nitrogen that the inhabitants bring with them. We have to make the environment for our people as efficient as possible with recycling, so that we don’t waste the elements we bring with us. Over the long term, we hope to minimize losses so that we only need to bring additional nitrogen and carbon to the Moon to replace those small losses. For example, if we want to grow food on the Moon we can use waste products from people, the way primitive peoples have done for centuries, to provide most of the nitrogen and carbon needed. But no process is ever one hundred percent efficient so there will have to be injections of new material from Earth or somewhere else to make up for any losses in our processes.

  One of the Moon’s paradoxes is the lack of surface carbon. Carbon happens to be the fourth most common element in the universe, and yet it is available only in trace amounts on the Moon’s surface. Is it possible that there is carbon below the surface somewhere, carbon that could be mined? If so, we have a long term solution to our issue. And if not, why not? Where did it go? If we don’t have naturally occurring carbon on the Moon, can we bring it in cheaply?”

  Chaz took a breath. “So those are the major issues. Some of the problems require nearly immediate solutions, like a shield from the solar wind and a solution for the dust. Some are probably intermediate, like generating oxygen and water or mining water ice to reduce the need for imports from Earth. Some are long-term, like finding a way to preserve nitrogen and carbon in the new settlements and finding inexpensive ways to replace rare elements that will inevitably be lost over time.”

  Chaz highlighted Item Five on his laptop.

  “Once we have items One through Four resolved, we arrive at Item Five- deciding on locations and building human habitations and other facilities. On Earth, Item Five is where colonization starts. That is, we have to decide where to put settlements, and build shelters that make human habitation safe. Compared to our first four issues, Item Five is pretty straightforward. Not easy, we still have to come up with structures that are airtight or vacuum tolerant and can either accommodate the temperature swings on the Moon or be protected from them in some way. If we solve the big problems, though, locating and building settlements will be practical. If we don’t take care of the first four, putting settlements on the Moon for even moderate periods of time, on the order of months, may not be practical.

  The drones we are going to send down from the first cargo run of the sailer will be focused almost entirely on the gathering of data for selection of research and human habitat locations. We have a fair amount of data from prior lunar probe missions, but our purpose is to get very practical about our options and opportunities.

  We have had at least one good idea arise from some of our consideration of Item Five. That is, we should plan on using solar panel installations not only to generate power, but to provide a first level of shelter for surface structures that do not require visual or radio access to the surface. The idea will help with temperature control, reduce the area that requires magnetic protection, and provide first-line shelter from radiation and physical penetrations of more expensive facilities. Perhaps not genius, but definitely food for thought as we plan construction of surface lunar facilities.

  Our second-to-last bullet is Gravity. I chose to put this one near the bottom because at present we have an approach to low gravity survival and our best estimates don’t look too bad, based on what we know of human life in zero gravity. Gravity is a low priority issue for us because we have experience in zero gravity at the International Space Station and on earth via a number of experiments that have been conducted over decades. According to current estimates, visitors to the surface of the Moon can stay for up to two years without experiencing irrecoverable physical issues. We don’t want to take chances, though, so I believe that we will set a limit of a year for a stay on the Moon for any given person. That should be enough time for most researchers to get things done. It should also be adequate to allow construction workers and other service personnel to acclimate and be productive for an extended period.

  This doesn’t mean that we can simply let visitors go to the Moon without making them aware of the issue and providing an approach to living on the Moon that maximizes their chances of recovery from a low gravity environment. That approach is to provide people with rigorous exercise regimes and set limits on the amount of time that any human stays on the Moon to avoid irreversible damage. Based on what we know of zero gravity living, visitors will have to be monitored, and our time limit should be rigorously enforced.

  One thing we don’t do much of in zero gravity at present is use machines to do work, rather than people. People are still more versatile than machines in space, but there are things about the lunar environment that might make automation much more cost effective.

  Bottom line is that we have a successful approach to the problem of low gravity. Even though it’s untested in low gravity as such, it has been tested in a more severe environment- that of zero gravity. Unless we are missing something pretty big, our experiences with zero gravity should provide a decent guide for survival of humans on the Moon.”

  Chaz highlighted the last item on his list. This one blinked off and on, and drew some laughter from the audience. Aman smiled, but he didn’t laugh.

  “Last but not least, we have Item Seven- Funding. Putting humans back on the Moon is going to cost money, especially if the decision is to keep a number of habitations operating on a permanent basis.
Clearly this is a problem that is in a class by itself. Our principle backer is shelling out quite a bit of his personal wealth to get our solar sailers up and running. If we want our ships to have places to go, however, we have to start thinking technologically about how we build successful human habitats someplace other than Earth. To do that, we need to find backers, whether they be private concerns or governments, to help pay our way. In the short run we may be able to make it by supplementing Treble funds with research grants. In the long run, however, we have to find financial or other important reasons to have people live on the Moon. Some form of return on investment will be needed. Perhaps not in the first couple of years. By year five, however, I think colonization of the Moon will be in trouble if we can’t find something in the way of ROI that at least gives people hope that permanent human habitats on the Moon can be made to pay for themselves.”

  **

  The following day, Aman and Chaz were having lunch at Aman’s office. When coffee came out, they settled back to talk about destination issues on the Moon.

  “It sounds like I have to write the solar ships off or we develop a marketing plan to get backers for colonization of the Moon. I guess it would help if our marketing plan actually had a potentially profitable product to sell.”

  Chaz stared at his coffee cup and toyed with it. “I think we can find you a product, but this thing still isn’t going to be cheap. I’m not sure I would have brought you this project if I had recognized some of the colonization issues beforehand. You were looking for something to do, though, and the ships looked like a good project.”

  He looked at Aman. “I think your first step has to be deciding what you want to do with your life. The ships will be done fairly soon, but colonization will take years. Probably decades. Do you really want to spend your time finding money for a proposition that is as risky as this one?”

  Aman chuckled. “When I was a young guy I couldn’t have imagined what I’m about to say.” He took a sip of coffee and turned serious. “I want to leave something behind when I go, something more than a pile of cash that someone else is going to waste. I don’t have any kids and there is no way I want to leave my money in some trust for lawyers to get fat on. I’m thinking that the Moon colony, for better or for worse, is something I can leave behind. Even if it’s not a success, at least we will have left the information about what made the failure. Even if we fail, our attempt may help someone else to get it done.”