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


 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.

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)