Thursday, December 17, 2015

Landers again

At risk of beating this topic to death...
This write-up is quite a bit different from my earlier Ceres proposal, but I think it would achieve the same objectives.

 NASA stands to gain significantly in the upcoming omnibus spending bill, as reported by SpaceNews. Space technology continues to get the shaft, while SLS and planetary science get boosts. Overall the agency is set to receive $756 million more than requested, for an overall award of ~$19.3 billion. Much of that is earmarked for specific projects. Most specifically, $175 million is earmarked for design of a Europa mission with a lander.

 Let's assume that this modified Europa mission will be roughly New Frontiers-class ($750 million to $1 billion). The design and development costs for the program will be finely-tuned to this one mission's requirements and eat more than two-thirds of the cash. The one-off flight hardware will be quite expensive. It will probably meet its primary and secondary objectives and return a lot of good science data.

 Instead of following this process, what would happen if we handle the design and development as a generic outer-bodies exploration vehicle program leveraging experience from the several successful deep space probes NASA has already fielded, most recently New Horizons?
 Consider the MCSB (modular common spacecraft bus) as a model program but scale it into the 20-40 ton fueled mass range, sized for an Ariane, Delta IV Heavy, Proton, Vulcan or Falcon Heavy main payload or as an add-on payload to an SLS launch.

Monday, December 14, 2015

Earthside - Rubble-eating block factory for disaster cleanup

These people have noble aims, but some unfortunate name choices.

The Mobile Factory is a project to build rubble processing and block forming equipment into shipping containers which can be deployed at disaster sites, primarily earthquakes. Local residents whose homes have been destroyed can operate the equipment, bringing in mixed rubble for sorting and processing and then casting construction blocks from the results. The blocks are meant to be used in the construction of earthquake-resistant housing, no mortar or rebar required. (Bamboo serves as vertical reinforcement.)

They have a nice user's guide that manages to express the workflow without words.

Unfortunately their site is very light on details like how exactly we get from fully-set concrete rubble to recast concrete blocks. I recommend the Reuters article about them from summer 2015. They describe their blocks as "shaped just like LEGO", which is a bit like taunting the lawyers at IBM. They also have named the blocks themselves Q-Brixx, a name that appears to describe ruggedized portable testing equipment from Gantner.

All of that aside, this is a project with functioning equipment and a demonstration plot, plus significant industry, NGO and government backing. Evidently their process works.

 I think this is a technology that might (and that's a big might) be applied to block formers intended for Mars or Luna. If done properly, a program under NASA (for example) could take this project's equipment as a starting point then automate and optimize. Equipment would be tested alongside the manual version at actual disaster sites, and the two projects could share information and design refinements.
 The aid project would benefit from additional resources and participation at disaster sites, and may see design improvements as a result. The space agency would be able to start from a working manual design and could make and test changes on Earth in a way that benefits people harmed by disasters. At some point the designs will probably diverge, but if the starting point is equipment that works in and is operated by an earthquake-ravaged community then rugged reliability and simplicity will be built in from the start.

 I only wish I knew more about their process. Perhaps it is as simple as using crushed and graded rubble as aggregate, then adding in new cement to form concrete blocks.

Friday, December 11, 2015

Public-private Ceres lander

My previous post on Ceres suggested landing a batch of payloads on the surface as a proof-of-concept mission for hardware intended to explore icy moons like Europa. Let's look at the numbers.

 I will assume launch service is a single Falcon Heavy to LEO, maximum payload 53 tons at a cost of $150 million (slightly above recent prices). According to Project Rho, the dV required is 4,739m/s to make orbit and 320m/s to land.

In short, my estimate of five Europa-sized payloads seems reasonable. Costs should be in the $1.1 to $1.4 billion range, with much of the development costs applicable to the actual Europa lander and follow-on icy moon landers. In fact, I think putting a lander on every major moon of the solar system except Io could be done for less money ($10-$14 billion) than a single manned Mars landing ($20-$200 billion). Even allowing for 50% cost growth that's still around $21 billion over perhaps 20 years, not a dealbreaking increase to NASA's budget.

Full details after the jump.


Ceres has ammonia-clay surface soils?

A (very) recent Nature paper suggests that Ceres has ammoniated phyllosilicates in the surface soil. (That is, nitrogen-bearing clay). The authors use infrared spectrum matching, a proven* technique.
(thanks to The Dragon's Tales for the link.)

 This is a big deal. It means Ceres has abundant quantities of carbon, nitrogen, oxygen and hydrogen, much of it already in the form of organic molecules. We already know* it has a liquid water layer under the icy crust. It appears to be very similar to a CI chondrite, so there should be sufficient amounts of the other minerals required for plant life.

 This makes Ceres a desirable destination for mining. With only 3% of Earth's gravity, moving huge amounts of material is fairly cheap. There is abundant water, carbon and nitrogen available and in easy to handle forms. It is the closest low-gravity body to Earth with proven water reserves and by far the closest such body with nitrogen reserves. (Most nitrogen we know of or predict is far enough from the sun to be nitrogen ice and far enough from Earth to take decades to retrieve.) Transit to and from Ceres is a long journey (2 years 7 months round-trip for short stay, 3 years 10 months for long stay), so this is likely to be an automated process. Still, this is going to be a much cheaper source of nitrogen (for breathing gas and fertilizer) than Mars or Earth if done properly.

 This also makes Ceres a desirable destination for scientific exploration. There have been rumblings lately about a mission to Europa to look for life. Ceres has 22% of Europa's gravity, enough sunlight for solar power, a shorter travel time and only normal radiation levels (vs. Jupiter's hellstorm of invisible death). With launch windows every 1 year 3.3 months and travel times (via Hohmann transfer) of 1 year 3.5 months, science returns will occur rapidly. (Jupiter's one-way trip is about 2 years 9 months and launch windows are every 1 year 1 month, so a Ceres mission is 16 to 18 months shorter.) The delta-V to Ceres is about 9.5km/s to orbit and 0.3km/s to land while Europa is about 25.2km/s to orbit and 1.4km/s to land. Equipment meant for exploring the outer icy moons could be tested at Ceres under less hazardous conditions and for less money. For the cost of one Europa mission we could send about five similar payloads to Ceres for competitive testing, not to mention the science return and the add-on opportunities to observe other bodies in the asteroid belt (perhaps including one or more permanent telescopes in orbit around Ceres).

 * The word "know" represents more of a sliding scale. Until we have actual samples of these compounds taken directly from Ceres we will not know for sure. Until we drill a shaft and see actual liquid water, again, we cannot be 100% certain. Still, given the evidence at hand these conclusions appear to be sound and sufficient reason for a Ceres lander to collect this evidence.

Wednesday, December 9, 2015

Menu planner update - now with peanuts

 I spent a few hours cleaning up my menu spreadsheet. The biggest change is the addition of peanuts, oats and barley. I also changed the default settings to eliminate beef, pork and dairy in exchange for peanuts. Oats, it turns out, are a terrible choice for food production: an embarrassing 1.5 grams per m² per day and 1.1 kcal/m² per day. Sweet potatoes and squash achieve more than 90 times that calorie yield.

 The upshot is I have a much healthier reference diet, but it takes about 12.6m² (50.4m³) per person rather than a bit over 9m². That's still only a third of the usual assumed area, so I'll take it. One important consideration: I use 4-meter heights for my hydroponic areas. A 3-meter height requires about 16.7m² (50.1m³), while a 2.5-meter height requires about 22.6m² (56.5m³). Shorter spaces lead to inefficient packing of shelves, so improvements over my crude method could be made. These numbers could be verified using vertical farming techniques and facilities on Earth today. (I should write a grant proposal...)

 Peanuts have an incredible impact on a planned diet. They are high in protein, fiber and good fat. They have low mass yields (18 grams/m² per day) and calorie yields ( 107 kcal/m²/day), but the protein:fat:carb balance is overwhelmingly pointing in the right direction for a grain- and vegetable-heavy diet.
 Evidence shows that a diet that includes nuts (any kind, even peanuts which are technically legumes) improves heart health, lifespan and to a lesser extent quality of life overall. Using even a small amount (less than one serving per day) allowed me to eliminate beef and pork as protein sources, dramatically reducing saturated fat and improving overall macronutrient balance.
 On the other hand, due to low yields even a small amount of peanuts requires a large amount of space; about a third of the growing area would be peanuts and another fourth would be barley and wheat. I would like to see if peanuts can be trained for continuous production since they are indeterminate plants; this could significantly increase yields.
 For every 2kg of shelled peanuts, 1kg of shells is produced. These are ideal for hydroponic media (after crushing) for root crops like peanuts, carrots and potatoes, as well as for seed-starting plugs.

 Perhaps surprisingly, eliminating animal protein from the diet actually increases the area required to feed a person. This is because the animals are fed harvest waste; they may process their calories inefficiently, but they are calories that would otherwise have gone to waste. As a result I increased servings of eggs, chicken and fish somewhat to use the available biomass effectively. The overall efficiency was about 1 kg of edible meat per 5kg of biomass, with 1kg of biomass produced per 2kg of edible plant mass.

 It doesn't look a whole lot like my present diet. People would be eating a whopping ten to fourteen 100-gram servings of vegetables and leafy greens pretty much every day. Animal protein makes up about three servings per day, two of them as eggs. Grains make up about another three servings, while sweet potatoes and related starches weigh in around two servings per day. Overall the diet ranges between 1.75kg/day (children) and 2.38kg/day (men), lots of volume, lots of fiber. One can also see how much additional water is required: about 2.2L for men, 1.2L for women and 0.9L for children per day. It might become common to eat four meals per day, or at least the traditional three with frequent raw vegetable snacks.

Monday, December 7, 2015

Long-term plan: large modular habitats

 I've made reference to plans for large-scale habitats before. It's time I write down the big picture as I continue the process of refining the details. The research I've been doing for this project has led to many of my posts here with information about radiation shielding, structural materials, agricultural yields and various life support systems. Perhaps that information will be more useful in context.

 There are several large habitats proposed, generally by people who are both smarter and better-educated than I am. Wherever possible I prefer to use solutions proposed or developed by others, but I disagree with some of the fundamental assumptions made for structures like the O'Neill cylinder. That will necessarily result in a different outcome, thanks to several design decisions that go in another direction. #1 on that list: There are no windows. None. Don't even think about it; windows in space are incredibly stupid.

 This will be a large post, so I'm continuing after the jump.

The headline results so far are as follows:
Design population: 5,000 people
Maximum population: 5,280 without major changes, up to twice that under emergency conditions
Mass: 142,750 tons shielding, 4,552 tons hull, 2,770 tons air, 350 tons occupants. As-yet unknown masses for furnishings, life support, hydroponics, other systems.
Volume: 2,262,000 m³ (79,882,000 ft³)
Area: 138,000 m² (13.8 hectares / 34 acres) under habitable gravity.

The structure would require the capture and exploitation of 160,000 to 200,000 tons of asteroidal material, or about 67,000 m³ of carbonaceous chondrites. Only about 600 tons (0.3%) needs to be carbon, but nearly 2,000 tons (1%) needs to be nitrogen. A single 50-meter diameter rock should just about do the trick, roughly the size of the Tunguska meteor. An alternative is sixteen 20-meter diameter rocks (Chelyabinsk sized) with the proper composition on average. There are anywhere from hundreds of thousands to tens of millions of near-Earth asteroids in this size range.


Thursday, December 3, 2015

SeaLaunch appears to be for sale

Hat tip to the Dragon's Tales for the link.

 Roscosmos and RKK Energia are reportedly looking for buyers or investors in the Sea Launch project, due to the high cost of ongoing maintenance. Said maintenance amounts to $30 million per year for the purpose-built command and integration vessel and self-propelled platform.

 Sea Launch is a joint venture between Norway, Ukraine, Russia and the United States with Boeing initially as managing entity. The project launches payloads to equatorial orbit using Zenit rockets on a specialized floating launch platform. After a bankruptcy in 2009-2010 controlling interest was acquired by a Russian company. Due to Russia's invasion of Ukraine the project ceased operation in 2014. In September of this year Boeing won a judgement in court related to costs of the 2009 bankruptcy filing, which makes possible a judgement of up to $356 million.


 Politics aside, the Sea Launch model has many advantages. Payloads go directly to equatorial orbit, increasing the mass to GEO by significant amounts. I see it as a 'toes in the pond' approach, a precursor to the 'dive-in' approach I describe here. I'm particularly pleased to see my maintenance estimate is twice the (rumored) actual maintenance cost for Sea Launch, which is exactly where I wanted it to be.

 Most of the players in commercial space development are well known and their die is cast, but who knows... maybe there's another billionaire out there willing to buy this hardware on the cheap and get creative with it.

Tuesday, December 1, 2015

Lunar circumferential railway

This is a followup to the last earthside post about arch-lock, looking at longer-term uses for the equipment on the moon. While I think it's more likely that we would build tramways using tensile towers and tether technology, this (relatively) low-tech approach could be started within a few years, without any radical advancements and with fewer leading 't's.

An example late-stage use case would be connecting a Lunar polar base to the equatorial L1 or L2 tether anchor sites. Read on for details.


Monday, November 30, 2015

Earthside - Simple arched structures using preformed blocks

This is an example of Earthside technology that could be applied to building structures on bodies with gravity, particularly the Moon or Mars.

Lock Block is a company that makes custom-engineered concrete blocks for building arched tunnels or structures. They do other things, but their zipper truck arch process is what interests me.
Here's a video of the process in action; there's no explanation in the audio track.
Here's a somewhat longer video with explanation.

In case you don't want to watch some random youtube videos I'll explain the concept after the jump:

Wednesday, November 18, 2015

Life Support - Menu planner

 As part of a larger effort, I have produced a spreadsheet that can be used to see the nutritional values of a menu on a weekly average basis. For a number of reasons detailed below it will be of limited usefulness to most people, but it can be adapted to track one's own diet with some effort.

I release the sheet as CC-SA, free to use but without any warranty express or implied. This does not constitute medical advice. No attribution is necessary, since anyone wanting to use it would have to put in some effort to make it presentable. Fine print after the jump.

Update 25 November 2015:
Broke the menu section into men, women and children (using 90th percentile height / weight).
Added a separate section detailing space and feed inputs for fish and livestock (fish still in progress).
Current version is nutritionally complete, though the fat balance is heavily weighted toward saturated fats as a consequence of using dairy.

Headline 1 from this is that it takes only 9.5m² per person using stacked grow racks. I expect this to increase slightly as I introduce less efficient grains and a wider variety of fruits and greens, but should easily stay within 12m².
Headline 2 is that the animal feed was within 15% of the agricultural waste already being produced, meaning the nutrients added from animal sources requires almost no additional hydroponic support. The difference can be made up with Spirulina from the waste processing system and excess milk.

The downside is that you cannot reasonably include pork or beef unless your population is at least 5,000 or so.
Also, fish turned out to be less space-efficient than chicken after considering pond space for breeders.
Further, far more milk is produced than is necessary; this could be powdered and used in animal feed or could be polymerized into PLA plastic.
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Wednesday, October 28, 2015

Earthside - Indoor farms

This is more of a movement than a single example. In many former industrial centers, abandoned warehouses and factories are being converted to grow food. The approaches vary but generally focus on water and energy efficiency and year-round productivity. Keywords are urban farms, vertical farms, etc. I'll list two examples and then discuss pros and cons, plus the (fairly obvious) synergies with space-based agriculture after the break.


Wednesday, October 21, 2015

Clothing

 One of the basic necessities not yet mentioned is clothing.

 Most clothing is made, not surprisingly, of cloth. That in turn is made of woven threads, which are made either of plastic, animal hair or plant fiber.

 I'm going to eliminate animal fibers simply on an efficiency basis. The varieties of animals that are raised for fur (sheep, rabbits, goats, yaks) can also produce meat and milk, but are much less efficient than purpose-bred varieties. Sheep are probably the best all-round performers (~5.4kg wool per animal per year eating about 2kg/day of feed), but we can still do much better than that. Of course any incidental fur, skin, etc. will be used for filling, lining, leather and such, but we cannot assume there will be enough of that material to clothe everyone.

Read on for the rest. This turned out to require a lot more growing space than I would have thought, 10.26m² per person.

Tuesday, October 13, 2015

Soap

Current hygiene in space leaves much to be desired. Ask an astronaut, or a recovery crewmember who pulls them out of their capsule. We've found a balance point that minimizes the use of consumables without causing significantly harmful effects, but it's a system most people wouldn't be able to stand for ten minutes, let alone years.

 Key to our clean civilization is soap, or more recently detergent. Humans have been making soap for at least 4,200 years, perhaps as much as 4,800 years. For the vast majority of that time the process was much the same: mix ashes, fat or oil and water, apply heat and hope the result doesn't dissolve your skin.

For the TL;DR:
Roughly 3.8kg of detergent per person per year. A mix of traditional soap and modern surfactants in the form of bar soap, liquid hand and dish soap, shampoo and laundry soap. Making these chemicals will cost fats, oils and sodium hydroxide. Making some of the modern compounds will require a bit more chemistry using the same raw material.

Friday, October 9, 2015

Edits and updates

Regular readers (all two of you) may notice that most of my past posts have been edited to include a page break.
I will make an effort to page-break all future posts so the main page isn't such a massive run-on article.

Additional note:
 I started this blog to store my thoughts because I was getting obsessive, compelled to work through scenarios in my head and build endless spreadsheets and projections. Putting things down in print has really helped me to stabilize, to be able to work on a problem for a little bit and put it down without worrying about losing my progress. I am finally out of draft posts, which means I will be backfilling some of my earlier posts with additional reference links. New posts may not be as frequent, and I will try to keep them fairly short.

 If anyone reading this has questions or comments about any posts, please ask. I like to be distracted by new or different problems from time to time.

 I am also putting some solid work into a meal planning spreadsheet that will help allocate space to various plants in a hydroponic system while cross-referencing those crops against USDA nutritional data. My goal there is to be able to demonstrate whether or not a given allocation of space meets nutrition guidelines on a weekly basis. This feeds back into my long-term goal of designing a self-sufficient habitat, so I feel good about that progress.

As an editorial note, I considered removing my budget post entirely since it is a political animal and is quite subjective. In the end, I've decided to leave it as is. Suffice to say, I'm voting Sanders. His budget is strongly backed by evidence and reflects the consensus opinion of most professional economists (the ones doing economics, not the ones appearing on TV to support their generous benefactors). Hopefully any who disagree will be able to objectively consider the rest of the blog's content.

Tuesday, September 29, 2015

Alternate funding method for NASA

What if we do something completely radical? Instead of bickering endlessly over NASA's budget every year, let's assign them a set of priorities (much like we already do) and then fund them for the next ten years. Set aside $225 billion (covering the current budget level plus a hefty increase for expanded programs, growing at 4% per year for the next 10 years) in an interest-bearing account. Now there is no budget uncertainty at all and NASA can do longer-term planning without risking a funding cut halfway through an expensive project. This will save money in the long run since less will be wasted on pivots or on research into projects that get canceled. If the agency saves money in a given year they will have more money available in a later year automatically.

10-year treasury bonds are going for about 1.5% right now, for an overall cost of $261.12 billion or total financing costs of $36.12 billion. We would have the option of paying or not paying into that debt over the next ten years, then the option of paying it off or rolling it into new bonds. We would also get to decide at that point whether to do another 10-year funding run or go back to traditional budgeting.

 Obviously accountability is a concern, so there would still be a need for an annual budget, annual review and a report to Congress on activities and progress so far. On the other hand, congresscritters and Presidents won't be able to pull course-changing publicity stunts or divert funding to their pet companies. As a check against too much individual power, the administrator could still be fired and replaced if they are running off the rails.


Budgets (controversial)

Warning: economic reality will be encountered below. If you are allergic to facts, go away.

Warning: contents will be considered by some to be political. I don't care. If what you read angers you then go away. If you have specific, rational objections I'd love to hear your opinion. You might change my mind, and I would prefer to catch and correct any mistakes.

Warning: I choose to rely on facts and on models and theories that have demonstrated their effectiveness in real-world conditions, not on rhetoric and cultish following.



I believe NASA could be doing much more to promote space exploration and utilization, but that requires money. So, let's take a brief look at the US budget for 2015. I will be proposing a list of changes I would have made; this may not exactly match the mutant monstrosity that will emerge from Congress and henceforth be known as the 2016 budget, but we're talking about sweeping generalizations anyway.

Let's look at NASA's budget for 2015 first.

Monday, September 28, 2015

Early days - tether systems (4/4)

Fourth of four. My thinking has varied over time and I'm currently favoring Spectra/Dyneema fiber vs. Zylon. Regardless, this is a broad outline for what would be a technically challenging program.

 This post is incomplete and does not contain financial estimates as do the other three, partly because actual tethers assembled in the context of a comprehensive campaign would have to consider the availability of mass from captured asteroids or sling-launched from the lunar surface. I put a couple of months into the problem and have not yet arrived at solid numbers.

Early days - space nuclear reactor program costs (3/4)

third of four.

Space Nuclear Power Program


This program aims to develop high-power, safe, reliable nuclear energy sources for manned and deep-space missions. Nuclear electric propulsion will open a new frontier of exploration in the outer solar system and allow manned missions to Mars and other places with difficult solar power problems.

Early days - asteroid redirect (2/4)

This is a follow-on to the previous post describing carrier spacecraft. I know asteroid retrieval has its haters and certainly compared to the goals of the Constellation program it sounded like a major letdown, but if you dig into the data it starts making sense. Here's my take on an aggressive capture program:

Asteroid Redirect Program


This is essentially the NASA ARM program described by the 2012 Keck Institute report, with some modifications. First, deployable microsatellites will be used to bag targets (including loose concretions or binaries). Second, a tether-based solution will be used to despin targets (saving about 500kg fuel). These two factors together allow a much broader range of targets to be captured. Third, the program will be considered an ongoing project to accumulate mass in Lunar orbit rather than a one-shot mission to grab a single target. The program will benefit from the carrier program by gaining high-power in-space radar observation of targets, reliable on-orbit assembly of mass-efficient solar arrays and multiple onboard microsatellites for redundancy and safety.

Early days - carrier spacecraft (1/4)

There are a lot of people with a lot of ideas they would love to try out in space. Most of them will never get the opportunity under the current model; launch costs are too high, opportunities are too rare and profitability hasn't yet entered the equation unless you're a parts supplier.

 The recent trend of packing a set of small satellites (CubeSats, NanoSats, etc.) as secondary payload on other launches is helping. Colleges and private companies are getting their payloads into LEO and doing science. Most of that is aimed towards degrees and attracting research funding (or demonstrating experience and attracting investment capital); in other words, a short-term view with near-term goals. I don't think there is anything inherently wrong with the projects that have been selected so far, nor do I have any preferred pet projects that lost out. I just think the whole ecosystem needs to crank things up to 11.

Earthside - Smart Floating Farms

source
article

 Here is a proposal to build floating aquaculture barges. Solar PV for power on the top level, hydroponic crops on the middle level and fish farm tanks on the bottom level.

 It's a great idea, there's just not enough detail on their website to decide if I should take them seriously. Some of my wilder ideas are better-defended with links and data, to be honest.

 The article mentions a depressing value for productivity; 2.04km² of growing area and only 7.3 tons of vegetables + 1.5 tons of fish per year. That's less than 3.6 grams per m² per year of produce and 0.74 grams per m² per year of fish. I'd be disappointed if those were the hourly production numbers, so hopefully someone mistook their per-barge yield with their barges-per-year productive area or something.

Monday, September 21, 2015

Earthside - Agbotic

 This one's just a news report, but it provides a data point for automated greenhouse operations.
That point is 1.2 pounds of vegetables per square foot per month, or 5.86 kg/m² per month (195g/m²*day). That's only 10 m² to feed a person just under 2kg of food per day.

 This is a prototype. Improvements to the design are certain to occur, as are improvements to yield. The article mentions species-specific programming, so the environment and care of each crop is tailored to its specific needs. Even without these improvements their demonstrated yields are more than twice as high as my estimates for growing area. Imagine what could be done in a vertically dense, LED-lit soilless system.

Friday, September 18, 2015

In-situ zone refining

 This is a proposed design for a solar-thermal zone refining cell. The first few would probably be delivered but the rest should be assembled using local resources.

 The body of the cell is made of magnesium oxide (magnesia). This is a fairly strong material with a tensile strength between 83 and 166 MPa, compressive strength of 830 to 1660 MPa and a melting point of 3125 K (2852 °C). It has the odd property of being transparent to infrared A and B bands (0.7 to 3 micrometers), so a substantial portion of solar energy passes right through it. One reference lists about 55% of solar energy at earth's surface is infrared; in space that ratio is likely to be higher due to the lack of water absorption. The A and B bands are a small portion of the infrared spectrum and I don't have a value for the energy fraction in this range, but the specific amounts are not important at this stage.

Mars: CO2 microburst excavation

 Excavation on Earth sometimes uses explosives to break up rock or densely-compacted soil. This can be less expensive than using a drill bit or other grinding or impact tools if the explosive is cheaper than the cost of wear on the drill.

 On Mars, drilling and grinding tools shipped from Earth are enormously expensive. They could be made from local materials, but not easily and not as an automated process without significant advances. Explosives are in the same boat; anything shipped from Earth is super expensive. Nitrogen is about 1% of the Martian atmosphere, but in a form that requires substantial chemical processing. (Nearly all industrial explosives use chemicals with nitrogen bonds as the source of their explosive power).

Dealing with alloys (AlSi LOX tank example)

 An enormous centuries-long effort has been devoted to the art and science of separating metals. One thing becomes clear: very pure metals are very difficult to make. Most of the successful methods involve a combination of chemical reactions and crystallization plus filtration.

 For space-based industry, any process that requires a chemical reagent is expensive; there are always leaks and no recovery method is perfect, so each kg of final product requires consuming some amount of another chemical. In most cases that other chemical is not available locally and has to be shipped from Earth. For some processes this is still mass-effective; if 1kg of reagent can help produce 10t of product then it is probably worth the cost. Still, this is an additional level of complication and expense. Also, filtration may seem like a simple thing to do but try it in space using automated equipment and a recoverable filter while removing sub-millimeter crystals from a vat of molten metal. Possible but not easy.

Thursday, September 17, 2015

Better lunar mining with nuclear power

As mentioned in an edit to my early lunar mining post, the possibility exists of a 30kWe-class nuclear reactor rated for surface operations on Mars. This would be using a design very similar to the Prometheus project reactor for the canceled JIMO mission. This was developed to a high level including non-nuclear test articles of all major components and irradiance testing of critical components. In other words, this project yielded engineering test data from physical objects; it's not someone's simulation paper slapped together for a hoped-for mission, but the product of a significant amount of time, money and ingenuity. Solid performance data is available. Taking a reactor designed for use on Mars and operating it on the Moon would give NASA a chance to field test the device before committing it to a manned mission; applying it to a mining and ISRU mission would let them test related technologies in a way that yields tangible benefits (lots of useful mass generated on the moon and delivered to LEO) in addition to good engineering data.

Tuesday, September 15, 2015

Early asteroid mining

This is a followup to the early lunar mining post.
I assume a suitable asteroid has been delivered to EML1 or lunar orbit for processing. I also assume that a painstakingly detailed dissection with full science yield is not necessary; relevant samples and readings are assumed to have been taken and the rock is available to be destroyed. The mission is in no particular hurry to complete the task, but several groups are to be given a chance at testing process technology.

results:
containment bag, 200kg
grinder arm, 2000kg
solar oven, 600kg
ore sorting, 1000kg
ore processing, 1700kg
cryogenic processing, 1000kg
power, 400kg
radiators, 800kg
storage bags, 800kg
water tanks, 1000kg
LOX tanks, 10,000kg (could be subbed by a visiting ULA ACES-121 tanker)
Total mass: 9.6t with tanker, 19.6t standalone

Labor - Community services

There are three broad types of work:

Community labor is the work necessary to maintain the wellbeing of the crew. Medical, hydroponics and a vast array of services.
Environmental labor is the work necessary to keep the colony's systems functioning. Structure, maintenance, air processing, waste treatment and power.
Productive labor is the work necessary to expand the colony either physically or financially. ISRU, mining, manufacturing, exportable research, etc.

Since people are the heart of a colony and the reason for its existence, let's start with community.
The short version:
1000 people need 49 in healthcare, 37 in hydroponics, 168 in food preparation, 29 in cleaning and 10 in other services. That's 293 people or 29.3%.
5000 people need 229 in healthcare, 180 in hydroponics, 846 in food preparation, 142 in cleaning and 50 in other services. That's 1,447 people or 28.9%.

Early lunar mining

 Returning to the theme of bootstrapping for a bit, let's examine what kind of material processing could be done with a modest payload. I'll cover two scenarios, lunar surface and captured asteroid; the first post will discuss the moon.

 As with all unproven technology, mass estimates for mining equipment are wild guesses. I'll be using the wild guesses of people smarter and/or better informed than myself. Most of the concepts presented are well-known; I've simply combined them a different way and extrapolated the results.

For those not interested in reading the wall of text to follow, here are my results:

3x haulers based on NASA chariot / lunar electric rover (1.2 ton each)
3x prospecting package: gamma spectrometer, neutron spectrometer, UV/VIS/IR spectrometer, magnetometer, robotic scoop (included in hauler mass)
2x excavator equipment package: bucket and cable rig, sized to fit hauler chassis (up to 3 tons each)
60kW power center (1 ton)
6x 90m² solar reflecting ovens with electrodes (0.5 tons each)
ore separation / benefication (0.5t)
cryogenic oxygen plant (4t)
tank press (0.5t)
radiators (2t)
electrical cables, 6ga/10.5mm, 4-conductor, 108v 3phase, 6kW, 8km (4t)
4000x cryogenic tank valves (0.2kg each)

total: 25.9t
(1 SLS or 2-3 Falcon heavy)

Tuesday, August 18, 2015

Life support - Trees

This will be a background post, with deeper data by species coming later.

 Fruit and nut trees are not often considered for hydroponics, and for good reasons. They take years to mature and several meters of vertical space. Less commonly known is that many trees control flowering by the gravitational flow of hormones, so zero-G orchards may not behave in predictable ways. Also, behavior of many species is seasonal and dependent on both temperature and daylight hour changes. Trees are often less efficient at converting light and CO2 than other plants, and significant amounts of their production is in the form of wood instead of food. As a result, the edible yield of trees is not competitive with vegetables. Experience with hydroponic orchard production is very limited. Almost all trees require pollinators or hand pollination and many require different varieties for fertility.

 These are not insurmountable problems for a permanent colony, particularly one on a body with gravity. Let's look at the benefits so we can make some comparisons. Nut trees produce nutritious food that can be stored for months at ambient conditions. Fruit trees produce a variety of fruits, good for improving the diversity of the diet; fruits also often have higher sugar content than hydroponic produce. The physical appearance of trees can have psychological benefits for colonists, as can the dietary contributions. Pollen from tree flowers can likewise improve the variety of diet for pollinators. Trees themselves are quite adaptable and almost certainly have enormous untapped potential for the development of space-adapted varieties. Trees produce wood, a useful material for handles, furniture, etc. Wood waste fibers can be made into paper. The cellulose in wood fibers can be extracted and used as a film, converted to polymers or converted with nitric acid into nitrocellulose as blasting charges. A variety of spices and medicinals are only available as trees or inconveniently large shrubs. Allspice, clove, cinnamon, nutmeg, bay, mace, ginko and witch hazel are all examples. Most of these are used in trace quantities, so low productivity is not a problem. More common species like willow can be used for aspirin (for example), though it might be more efficient to synthesize it; on the other hand willow is a good source of material for making activated carbon filters. Trees can soak up the area lighting in public spaces, turning energy that would otherwise have become heat into food and air. They can help reduce CO2 concentrations when a lot of people are in one spot and provide some fallback capacity if the air system is temporarily offline.

 My early data for fruit trees is based on semi-intensive orchard growing on Earth using semidwarf trees. Apples seem to be the best producers at around 5 kg/m², followed by pears and plums at 3 kg/m² and cherries and peaches at 2 kg/m². Noncommercial species like pawpaw or quince yield around 1.2 kg/m². In daily terms that's only 5.5 to 13.7 grams per square meter per day. It does mean that apples can be more productive than barley (for example, at about 12g/m²*day) on an energy basis, but not even close on a volume basis. Nuts, unfortunately, are much less productive than fruits; almonds weigh in around 0.2 kg/m² or about half a gram a day per square meter. Almond milk is not likely to find itself on the menu.

 For fruits, the difference in yield by species has little to do with inherent productivity. Apples have been the focus of commercial orchard breeding programs for longer periods and larger budgets than the other species. It's true that peaches and cherries are also undergoing heavy investment and there seems to be no reason why their yields could not exceed that of today's apples. Pears and plums have not been so intensively developed, though they started with a bit better output and have still seen improvement by many dedicated researchers and breeders. Crossing over into intensive hydroponic production has generally meant incredible productivity gains for most crops. Average yields can be expected to double at the very least simply by eliminating disease, pests and competition and providing optimal levels of light, water, nutrients, temperature and air composition. A more accurate projection might be to use Earth record yields instead of average yields. Space-specific pruning and training plus a good breeding program and the potential for shortened production cycles should at least double that number again. If everbearing varieties could be developed then yields could be pushed even higher. I think given enough time and resources that apple yields could be brought as high as 120 g/m²*day, comparable to many vegetable species. We won't know until it is attempted, and given the time it takes for each generation to mature this is a process that will take 2-3 decades of sustained effort.

 The drawbacks are pretty significant and need to be addressed. Not all species have suitable dwarfing rootstocks for grafting. (Most fruit trees are a franken-tree made from one variety or species {the rootstock} that resists pests and has good growth plus another variety {the graft} that has good flavor and yield.) At this point we must assume any orchard crop will require gravity, so they are restricted to some unknown threshold probably above 0.5 g. Even mini-dwarf apples require 2 meters of aboveground clearance while the smaller semidwarf trees need nearly 4 meters if they are pruned according to normal methods. The solution I think is to emphasize the psychological aspect and place trees in public spaces. They do not need the high light output, long light hours and high CO2 concentrations of super-productive vegetables, so their growing conditions are compatible with habitation areas. Trees can be trained to grow into space-saving shapes, a practice called espalier which can produce fencelike barriers; this produces a visually pleasing structure that can screen out noise and unwanted sights while producing edible fruits. These trees will provide a sense of steady change combined with a sense of permanence and will contribute to making public areas feel more organic and living. If you think that sounds like a bunch of hippie BS, consider that just having a couple of bean plants on the ISS made a significant measurable improvement in astronaut mood and outlook. Depressed people do not get along well; mental health is critical in an environment where carelessness can kill.

 I think a large enough colony will benefit from the investment of trees. I also think a successful program of adaptation will take much longer than similar programs for vegetables and other single-year crops, and much of the work will require access to reduced-gravity growing areas. In other words, this kind of research will be enabled by spin-gravity colonies or research stations; early stations will not be able to bank on specific productivity numbers if they include trees in their design.


Earthside - Nemo's Garden

Supporting ourselves in space means developing and demonstrating technologies on Earth.

 This is one excellent example: Nemo's Garden, a project to build underwater hydroponics bays. A structure is anchored to the seafloor a few meters underwater; compressed air is used to inflate it. Plants grow as they do in any other hydro environment. The system collects fresh water from evaporation and condensation, so no external water source is required. The temperature and humidity are very stable and pests are eliminated. Gas exchange with the seawater (presumably) allows for O2/CO2 transport. Nutrient solutions would still be required, as well as some electrical power for monitoring, pumps, etc.

 This is something that can be deployed without large real-estate expenses, without straining fresh water supplies and without the risk of weather-induced losses. Under the right conditions these systems could produce clean fresh water as a byproduct. Island nations with minimal arable land could meet their food needs without imports even as rising sea levels threaten their growing areas.

 Something interesting: plants in the test systems grow faster than they should. One theory is that the increased pressure at depth may allow for more efficient respiration. If true, that means the hydro bays of future colonies could be operated at greater than 1 atmosphere for increased efficiency. It's at least something to consider during engineering trades. It's possible this is simply that the partial pressure of CO2 is closer to ideal at normal concentration and increased total pressure, in which case a reduced-pressure atmosphere with high CO2 concentration might achieve the same result. We won't know until someone does the research.

 In the long run, the technologies required for permanence in space will enable human habitation of the worst Earth has to offer: deserts, tundra, mountaintops, deep caves and under water. Those same technologies could make life easier and safer for people who live on the margins today.

Monday, August 17, 2015

Life support - Goats

Another entry in the series of animal yields and requirements.

Let's consider a herd of 100 producing goats, just as we did for dairy cattle. The required protein in feed is 16% (with short periods at 20%); as ruminants these animals require plenty of bulk fiber. (It is possible to raise goats without roughage, basically forcing them not to develop their rumen; this is protein-intensive and cannot be used for herd replacement.)

Mixing feed inputs

To hit the right crude protein for animal feed given two ingredients:
Low protein ingredient A
High protein ingredient B
Target protein content C
Proportion of first ingredient X

X = (C-B) / (A-B)

For example: A is 10% protein, B is 45% protein and C is 16% protein
X = (.16 - .45) / (.1 - .45)
X = .8286
Mix about 83% of ingredient A with 17% of ingredient B.

Friday, August 14, 2015

Life support - Pigs and Cattle

This is a follow-on to the previous post about raising animals for food. I won't go into detail about background issues like I did last time, I'll just dive right into the numbers and then compare.

To review, on a per kg ag waste basis we can produce one of:
490 g edible insects
290 g chicken eggs
140 g chicken
140 g catfish or tilapia
100 g rabbit

As a cheat sheet, here are my results for this post:
 90 g pork
 16 g beef + 1.094 kg cow's milk

Thursday, August 13, 2015

A mass-produced booster concept (updated costs and SPS notes)

This is an idea I had kicking around for a while before SpaceX started getting serious about reusable rockets. It seems wasteful somehow, but if we had an urgent need to start lifting a lot of mass in a short time I think it could still be useful.

 Consider a booster family constructed entirely of modular tanks and one or two types of engine. All components are sized to fit inside standard shipping containers. The fuel is liquefied natural gas and the oxidizer is liquid oxygen. One or more launch platforms can be built out of converted floating drydocks or oil-rig tugs; add a solar-powered cryogenic oxygen plant and docking facilities for both commercial LNG tankers and commercial containerized cargo ships.

 A container ship delivers the components for several launches. The booster is assembled on the deck of the platform using cranes and quick-lock connectors. A LNG tanker delivers the fuel and the on-platform plant delivers the oxygen. Customer payload is delivered by air if it is light enough, otherwise by sea. Any nearby vessels clear the area, then the booster is launched. Wash, rinse, repeat. If there is enough onboard storage, the fuel and components for several missions can be taken onboard and then launched as fast as they can be assembled while the next shipment is in transit.

Tanks

I have a spreadsheet I use for estimating the mass of fuel tanks. It has been useful for indulging my obsessions, so I'm posting it here in case someone else finds it useful. Or wrong. I'd love to hear about either.

It has two tabs, one for spherical tanks and one for cylinders with spherical endcaps. I'll consider doing a 2:1 endcaps tab if someone actually wants such a thing. The spherical tank tab assumes you only want one fluid in the tank, while the cylindrical tab assumes you want two fluids separated by a flat circular bulkhead.

Tuesday, August 11, 2015

Plastic

I've mentioned several times that plastic can be produced from agricultural waste and/or CO2.

 The plastic of interest is polyethylene, or rather ultra high molecular weight polyethylene (UHMWPE, UHDPE, polyethene or trade names Spectra or Dyneema). It is formed of very long single chains of carbon, so the unit formula is CH2. This material is a thermoplastic, melting around 130 °C (or less if it contains solvents and/or crystalline defects). In normal use it should be kept between -150 °C and about 80 °C, so in-space applications will typically require a protective coating such as thin-film aluminum.

Life Support - Animals for food

It is often assumed that animal protein is not reasonable in a space habitat. Certainly if we try to feed high-quality grains and soy to an animal and then eat it we will have wasted significant amounts of calories, protein, electricity and other resources. Meat requires finding ways to use biomass that would otherwise be wasted.


Monday, August 10, 2015

Life support - growing plants for fun and profit

In the first life support post I discussed removal of CO2 and water vapor from residential air. Now we look at what happens to them downstream.

 Plants require water, carbon dioxide, light, a set of 14 essential minerals and reasonable temperatures. Many plants can handle microgravity and low pressures without difficulty. Some have useful properties like extracting pollutants from water, growing edible food or producing medically useful compounds. Their two main uses in space are to convert CO2 to oxygen for breathing and to produce food.

Early Days

 Unless some cataclysmic event occurs, we are not going to be building huge thousand-person colonies in space any time soon. It's just too expensive, with uncertain payoffs, unknown risks and very long time scales.

 The only way to get around that is to solve problems cheaply and use the available materials. For example, we have multiple rovers on the surface of Mars. These have operated for long periods of time and have taken photos and rock samples across an impressive track of travel in a very hostile environment. What could we do with a rover the size of the Mars Science Lab (Curiosity) on the Moon, with equipment for gathering resources?

Friday, August 7, 2015

Life support - CO2, humidity, air conditioning

First up is carbon dioxide. People exhale around 0.998 kg of CO2 per day and consume 0.835 kg O2 per day. The OSHA limit for normal exposure is 1000 ppm, while NASA's 1000-day limit is 5000 ppm. (Granted, NASA is specifying a 70-kg man in peak condition; the population will be mixed gender and age including children, but a little excess capacity doesn't hurt.)

 Zeolites (a type of molecular sieve that can be used for CO2 capture) work by adsorbing a specific gas until the structure is full, then releasing the gas under heat and/or vacuum. This release is called the regeneration phase and normally takes less time than the adsorption phase. For continuous operation the system requires twice the amount of zeolite needed for the adsorption phase; adding a third measure provides a good safety factor and could also provide emergency capacity if needed. The behavior of zeolites depends strongly on their molecular structure and they can trap more than one kind of molecule, so a detailed design will consider water vapor and other gases.

 NASA currently uses a four-bed system with silica/13X beads to adsorb water and 4A beads to adsorb CO2; the beds are exposed to vacuum and strongly heated to reject the CO2 into space. This takes a lot of power and wastes the CO2. The silica beds also have to be heated over 100 °C to force the water out.

Monday, August 3, 2015

Where to?

To get into deeper detail requires settling on one or more locations.

 I think we can rule out any free-space colonies just on the basis of radiation shielding. The required mass is just so enormous that there does not seem to be any cost-effective way to collect it. A habitat for 10,000 people could take up to a few hundred thousand tons of shielding. NASA's asteroid retrieval mission was set to retrieve about one thousand tons for one to two billion dollars. Granted if one wanted to capture a hundred asteroids the economies of scale would drive down the cost, but we would still be talking about tens of billions of dollars.

Resources

A colony in space will need a wide variety of resources to survive. Let's look at some of them and where to find them.

Air
 Earth's atmosphere is roughly 78% nitrogen, 21% oxygen and 1% argon. Nitrogen and argon are inert; as air we need them only for bulk. The pressure in a colony affects how much of each gas is needed; you can have a half-pressure atmosphere with 42% oxygen, 30% nitrogen and 28% argon and breathe just fine. You could also breathe a pure oxygen atmosphere at one fifth pressure, but this is extremely dangerous; the slightest spark can start a very rapid fire even in materials that aren't normally flammable.

Radiation

Radiation. Scary word. Makes us think of fallout and glowing waste.
The truth is, most radiation is harmless. That warm feeling of sunlight on skin? Radiation. Microwave ovens? Strong radiation sources. Same for wi-fi, cellphones, broadcast TV, radio, infrared heat lamps, blacklights and remote controls.

Radiation takes two forms: electromagnetic and particle.
 Electromagnetic radiation is packets of energy carried by photons (or one could say waves of energy). This is defined by the electromagnetic spectrum. Most of this radiation is harmless or even useful as long as it is at the visible level or below.

The Basics

Some say space is hard. Things break, people die.

It's still true.

We are in our infancy, struggling to find our feet and set out on the path to a sustainable and permanent presence in space. We have learned an enormous amount from the first pioneers. We have a framework, we do tests, we simulate. Still, things go wrong. It's unavoidable.

Set aside for a moment our current state. Look to the future. How would a permanent human colony look?

greetings

This is a digital workspace for me to collect my thoughts about humanity becoming self-sufficient in space. I promise only that there will be errors in my work.

Comments welcome. I will turn on moderation if necessary.

In case future humans ever actually read this...
I'm a college dropout (physics major) with a talent for technology. I work in the broadcast industry as a technician. The contents of this blog are not generated by an expert, merely an obsessed amateur.