The cislunar econosphere (part 2)
by Ken Murphy
|Staging from EML1 offers a multitude of advantages that more than overcome the difficulties of getting set up there.|
There is a slight penalty for the Earth’s chubbiness around the middle, in terms of inclination (particularly polar orbits—curse you, J2!), but with aerobraking the job could be done for under 1 km/s of delta-V, a number that is eye-opening, but requires the use of a heatshield that has been carried out to EML1 (from somewhere). Using a direct transfer to the orbit, the cost is around 4 km/sec delta-V, but with much less of a heat-shield requirement. For debris retrieval purposes these would likely be altitudes of 800 to 1,000 kilometers, where a lot of the Earth-observation traffic is located. The strategy I would adopt would be to retrieve as many satellites (non-functioning and thus potential debris, obviously) near a particular inclination, perhaps with “sticky harpoons”, from newest to oldest (as the older ones have demonstrated stability over time), and then take them back to EML1 for forensic analysis and repurposing of the parts.
The hurdle is the trip up the gravity well. A delta-V of 4 km/sec to EML1 from LEO is not insignificant, so the trip has to be worth it through the creation of value. For LEO debris retrieval, one possible solution would be to launch a fuel payload from Earth directly to the target inclination to be retrieved by the vessel from EML1 as it collects objects of interest in LEO.
What else does staging from EML1 enable?
A) The delta-V from EML1 to GEO and back is less than the delta-V just from LEO to GEO. If you’re going to be making trips to GEO, EML1 is the long-term transport solution. What would Sirius XM Radio‘s [NASDAQ: SIRI] financial condition be if, instead of having to build out a new satellite well ahead of schedule, and at significant cost in the capital markets, they could have spent much less to send out a technician to fix the problem? If you’re retrieving salvage from GEO, you can do forensic analysis on that debris to better understand space weathering effects. You can then repurpose that debris for something else (except for the antennas and other strategic components, which DARPA is interested in), like the creation of a…
B) Solar system-wide network of data-gathering probes that provide ongoing data over decades, rather than expensive one-off missions as we do now that provide a spurt of data that is then pored over for years until the next data set arrives. EML1 can serve as an on-ramp to the Inter-Planetary Superhighways (IPS), whereby “Hubble-ized” (i.e. upgradeable) probes, likely using instruments sent from Earth and bolted on a salvaged bus and power supply from GEO, are sent out to particular stations of interest around the solar system. These would provide relays to communicate around the Sun, as in the case of probes sent to the Venus equilaterals (Sun-Venus L-4 and L-5), or keep an eye on the asteroid belt at the Sun-Mars L-2 or Sun-Jove L-1. Out-of-plane objects coming in from the Oort Cloud could be watched from a variety of locations. The point is not the utility of observations of any one kind or specific locations, but rather that with a change in our thinking we can change the way we study our Solar system. We can collect ongoing data, giving us better situational awareness, and we can service and upgrade our instruments a la Hubble by bringing them back to EML1 on the IPS. We don’t have to keep throwing very capital-intensive (human and fiscal) tools into the void for intermittent datasets.
C) Remember the materials science research being conducted at facilities down in LEO? By the time you’re putting facilities at EML1, there should have been some promising results, some of which may be ready to move into the production phase. Freeflyer platforms can be launched from EML1 into a trajectory constrained by the sphere of influence of the Moon whereby, after a certain period of time, it will return to the vicinity of an EML1 facility where it can be retrieved for processing. The completed production run can be harvested, and the next round of production set up before it’s sent back out on its course. The finished product would then be shipped back down to LEO, to whichever particular facility had arranged for its production.
D) Eye in the Sky: in addition to trying to keep track of orbital assets and debris from Earth’s surface, facilities at EML1 will offer the opportunity to see the “big picture” all the way out to GEO from a vantage point roughly 85 percent of the way to the Moon. In this way it could end up as a node in an orbital traffic control network.
E) Clutter-free work environment: EML1 doesn’t require much station keeping—on the order of hundreds of meters per second per year or less—but it is required. Undirected objects won’t hang around very long, getting perturbed into one of the two gravity wells on either side.
|There will come a day where the people who are itching to go beyond LEO will do so.|
F) “Specializationator”: having service facilities at EML1 provides the opportunity to modularize the traffic in cislunar space. It doesn’t make much sense to carry Lunar landing legs from the Earth to LEO, LEO to the Moon, and then from low Lunar orbit (LLO) to the surface, the only time they’re really actually needed. Instead, consider bolting them on at EML1. Complicated waldos and cargo racks for retrieving satellites and other debris aren’t really needed anywhere other than for work in GEO and perhaps LEO. Don’t carry them around when they aren’t needed. Instead, get your supplies when they’re needed for where they’re needed… at EML1.
G) Asteroid Watch: a less popular suggestion is to have equipment at EML1 facilities dedicated to identifying and characterizing the Near-Earth Asteroids (NEAs). This would help lay the groundwork for later missions to asteroids staged from EML1.
H) EML1 also provides an ideal staging place for missions to the Moon. It offers 708/12½ (that’s 708 hours per Lunar “day”, 12½ “days” per year) access to the entirety of the Moon’s surface. Poles, equator, mid-latitude, front side, back side, it’s all about 2.5 km/sec delta-V each way, down and up. Rather than be tied to a single location on the Moon, facilities at EML1 could provide support logistics to a base at the south pole, while also providing a staging ground for sorties to areas of interest, like the skylights in Marius Hills.
Remember, all LEO inclinations of interest can get to EML1 for about the same delta-V, a little under 4 km/sec change in velocity. This helps in things like standardizing the propulsion systems and fuel depot loads for trans-LEO trips. This means that the guy who is selling orbital depots to NASA for use at their Kennedy inclination facility can also sell them to the folks with facilities at 41° inclinations, and even to the EML1 folks, as it’s the same change in velocity to park back down in LEO propulsively.
There will come a day where the people who are itching to go beyond LEO will do so. Part of it will be the record-setting aspects of things, as with the Space Adventures folks, whose trip around the Moon, while expensive, might allow them to become the farthest travelers beyond Earth, ever—until the next folks to do so. Others will want to get in early on setting up facilities out at EML1 and on the Moon. While their companies may crater, they’ll nevertheless be the ones with the experience, and those who come after will have to learn from them.
Once at EML1, things like zombiesats in GEO and debris in LEO can start being addressed, and this will drive demand for propellant. In the early years this will, by necessity, be shipped from Earth, but pressure arises early to source at least the oxygen component (about seven-eighths of the mass needed) from somewhere else. The logical source of this propellant will be the Moon; it’s a one-day-away (from EML1) source of enormous amounts of oxygen that can be extracted by a variety of methods. At first, the main demand will come from EML1 in support of the crews dropping down to GEO, HEO, MEO, and LEO for some satellite husbandry, but eventually it will become possible to ship it all the way down to LEO for use in the fuel depots there. This would allow for much more significant shipments to orbit of hydrogen from Earth. Some of which will be shipped on to EML1.
A word on orbital fuel depots. The space community seems to like to bifurcate, and in the case of fuel depots that seems to be along the lines of LOX/LH for everything vs. storable propellants like RP-1 or UDMH, each of which have their pluses and minuses. My view is that the orbital depot solution will evolve along the lines of using long-term storables for tugboat duties, such as fetching freeflyer platforms or satellites post-launch. The kind of stuff that is done on an ongoing basis and will need ready access to propellant.
When the LOX/LH is needed, it’s likely to show up at about the same time it’s needed, or shortly before if it’s shipped as water and needs to be cracked (which not every facility may be able to provide due to power needs). It will be more of a just-in-time process to reflect the inherent volatility, especially of hydrogen, which just loves to get through tiny gaps. A variety of methods have been proposed to allow for longer-term storage of cryogenic propellants. It’s not a question of either/or, it’s a question of how the people doing the work of meeting market demand actually solve the problem.
The complement of EML1 on the near side of the Moon is EML2 on the far side of the Moon. It is sometimes offered as an alternative to EML1, but in the near-term doesn’t offer any particular advantages to make it a priority over EML1 as a development destination.
Oxygen, which comprises some 40–45 percent of the Moon’s composition, although locked up in rocks, was quickly identified as a key commercial product for cislunar and trans-lunar space activities. Production of oxygen from Lunar sources leads to the production of slag as a byproduct. This slag is not useless, and can serve at least two functions. One is radiation cladding for vehicles operating in cislunar space. The slag can be shaped into pieces that can be bolted on facilities at EML1 and vehicles operating from there to other destinations. These would clearly be of interest to folks who are staging missions from EML1 out to nearby asteroids. The other use is as heat shields. These could be used by vehicles traveling from EML1 to LEO and want to use aerobraking to save fuel, or could be shipped down to LEO to be used as a bolt-on heat shield for vehicles returning from LEO to Earth (which would save weight on the launch phase of the taxi).
|One of the key difficulties that people have about resource utilization on the Moon is that it is going to have to be a process of aggregation of the materials desired. The challenge then becomes how to make lemonade from that lemon.|
Mining oxygen on the Moon can support economic activity in cislunar space, like salvaging the zombiesats in GEO, and allow for greater shipments of hydrogen from Earth. Other materials wrested from the soil, like rare earth elements and metals, could support microgravity production facilities in cislunar space whose products, like foamed metals and unique alloys, would likely find a market on Earth.
One of the key difficulties that people have about resource utilization on the Moon is that it is going to have to be a process of aggregation of the materials desired. Mother Nature and water haven’t acted on the Moon to help pool resources together. Impact violence and destruction has thoroughly distributed the constituents, and no matter what you’re trying to collect, you’re going to have to process large volumes of material to get any amount of usable stuff that you’re interested in. The challenge then becomes how to make lemonade from that lemon.
One example is the Solar-Wind Implanted Elements (SWIEs). The Lunar Sourcebook by Heiken et al. notes that if one cubic meter of regolith is heated up to approximately 800°C, it will generate approximately ten atmospheres of pressure of volatile gases. These can be drawn off and treated separately, perhaps by creative use of cold traps at the polar regions to progressively liquefy and draw off successive elements from the product. This sets the stage for helium-3 (He-3) processing of the helium portion of the gases generated. This won’t be generating large amounts of He-3, but if the opportunity is there as part of this process it should be taken advantage of. One consideration is that samples from each batch of regolith processed needs to be forwarded to scientists for processing in their “ice core” studies.
The regolith of the Moon contains the history of the Sun’s output over billions of years (the SWIEs), as well as its journey around the galactic core (GCRs, Galactic Cosmic Rays), embedded in its grains. Scientific processing can piece together that history, in the same way the glacier core samples have given us background on the composition of the Earth’s atmosphere over time. Additionally, the face of the Moon bears the scars, the astroblemes, of aeons of impacts, and can serve as a chronometer of impact objects in the Earth’s neighborhood for as long as we’ve had the Moon. So there are valid scientific reasons, with direct impact on terrestrial life, for having equipment on the Moon. Having ready access to the Moon means that the scientists are going to want to set up shop and do research in situ. These are all datasets that can contribute significantly to the understanding we are developing of Earth. Other areas of scientific interest are explored in the report by the Space Studies Board of the National Academies, “The Scientific Context for Exploration of the Moon”.
A longtime favorite in the scientific community is to have radio astronomy facilities on the far side of the Moon. The Moon would provide a shield against the radio pollution coming from Earth, creating the ultimate quiet zone for research. This quietude is spoiled by specular reflection of terrestrial signals off the small bodies in the solar system, but at a level of a whisper compared with the shouting from Earth. Some are concerned that facilities at EML2 (basically right above where the telescopes would be, though the halo orbit could be quite large), could more materially affect the noise environment. An alternative might be to position pole-sitting solar sails above the Lunar poles to provide communication links into the perpetually-shadowed “everdark” craters. And if that’s not enough, NASA has identified a large number of things to do on the Moon to keep their scientists busy.
|As more and more activities are undertaken on the Moon, the number of caretakers of the equipment is going to grow.|
The products that come from the Moon will start out as very low-value-added goods, with little processing required before getting shipped up to the processing and production freeflyer facilities in cislunar space. Oxygen is one, radiation cladding another, and as we add equipment to the stockpile on the Moon we can start creeping up the value chain. One example is low-quality solar cells, produced from the abundant silicates in the soil. Extruded metal structural elements could be developed for use on the Moon, as well as in cislunar space and even beyond for things like solar power satellites in GEO,or the construction of Mars-bound craft at EML1.
Later, as increasingly sophisticated capabilities accrue on the Lunar surface, production methods will become more sophisticated, such as breaking down the processing remnants from regolith, likely through some combination of pyrolitic and electrophoretic methods, and storing the results. Having stockpiles of vacuum-processed ultra-pure source elements (hydrogen, oxygen, carbon, titanium, etc.), and 3D printing technology may bring us one step closer to the concept of “replicators”.
The environment of the Moon also creates its own unique laboratory that will be exploited in unusual ways. It has been suggested that cutting-edge nanotechnology research be moved to the Moon, providing a natural quarantine for the inevitable “oops” moment. The same holds true for the nastiest of biological research endeavors. Google Lunar X PRIZE competitor Moon Express has announced that they will include a telescope on their rover, the first of likely many telescopic facilities that will be set up on the Moon. Another competitor, Astrobotic Technology, is actively seeking payloads, and has published a price list.
The Moon can also serve as a celestial timekeeper. Many cultures around the world use the Lunar calendar, so it is not inconceivable that at some point someone builds a Solar Cathedral that marks the beginning of each Lunar month.
As more and more activities are undertaken on the Moon, the number of caretakers of the equipment is going to grow. The earliest persons spending time on the Moon are likely to be the engineers who repair the robots and scientists doing field work for calibration and verification purposes. As the numbers increase, more support personnel are going to be needed. Someone’s going to build a still, and expect plants to be very popular pets. Regolith will be added to the growing medium early on, and those plants that provide foodstuffs in addition to oxygen will be particularly favored.
Eventually some of those foodstuffs are going to be exported to cislunar space: to facilities at EML1 for starters, but expect demand eventually for Lunar foodstuffs from Earth. There is likely also to be demand on Earth for raw Lunar regolith, in bulk, for use in gardens, greenhouses, and other applications.
Any process that uses vacuum—and there are many—can find a home on the Moon. Nearly 39,000,000 square kilometers are available, of a quality far superior to that which can be generally provided on Earth. To preserve that vacuum at that level of quality, industry is going to have to figure out some best practices very quickly. It was estimated that each of the Apollo landings effectively doubled the ambient Lunar atmosphere. That speaks more to the almost complete absence of atmosphere rather than to the pollution-generating aspects of the Lunar Excursion Modules, but the point is important nonetheless. It might be wise then to consider putting outgassing operations in deep craters so that they can help serve as a sort of catchment for those gases. This would be particularly effective in the everdark craters of the poles.
|We’re seeing an increasing shift from viewing space as the domain of scientists and engineers alone, to a view of space as a place to conduct growing levels of economic activities to pursue future prosperity.|
In his 1965 book The Case for Going to the Moon, Neil Ruzic polled scientists and researchers in academia and industry. When queried about what kinds of processes might be done better or easier on the Moon, results included, for those in the vacuum industry: vacuum cast alloys, vacuum welds, electron optical systems, optical components, pharmaceuticals and biologicals, industrial chemicals, and energy conversion materials and devices. He also notes the advantages that levitation melting can provide, sidestepping the issue of crucible contamination of the product.
One example of a product that would benefit from vacuum is the production of anhydrous glass. Its mechanical properties have long been suspected of being exceptional. However, its optical properties generally haven’t been considered. It may well be that an early niche on the Moon is the production of superior optical components for export to whomever wants the particular properties offered by Moonglass.
The author also points out that most if not all of the products produced on the Moon will not be for export to Earth. They will be destined primarily for use on the Moon: spare parts to fix the myriad robots, useful objects for the habitats like furniture, and new tools specific to the Lunar environment. Nevertheless, the creation of a transport network from Earth to LEO, LEO to EML1, and EML1 to a variety of destinations including the Moon, will mean that there will be the opportunity for exports, and someone is going to take advantage. Bags of raw regolith for “Moon Gardens” back on Earth. The cislunar entrepreneur producing vacuum globes may decide to add a line of regolith globes to their offerings, a unique variant of the “snow globe” so popular Earthside. Lunar handicrafts, like jewelry made of thin-sections mounted on polarized LEDs, might fetch a stiff premium, and there will always be markets for vicestuffs like moonshine and “lunajuana”.
As the infrastructure develops, increasingly sophisticated and higher value-added products can be developed. New design aesthetics can be explored. Eventually there will be tourists: those who do not have a specific task on the Moon. Except for a few scattered exceptions, the facilities will be unlikely to accommodate the additional life-support strain that tourists would entail. Nevertheless, their tickets help pay the rent, so ways to accommodate them will be found. Once the tourists start showing up, you’ll start seeing things like “rego-boarding” the craters, which should be encouraged as the extreme sports crowd will help drive advances in Moonsuit technology. They’ll have other needs and desires to be met as well, which is the foundation of business opportunity. Many of these have been explored over the years in the pages of the Moon Miners’ Manifesto.
The above should not be viewed as a roadmap, but rather an exploration of the myriad ways that exist to create value in cislunar space. What finally does happen will be driven more by necessity than desire. Business grows by responding to needs.
What should be clear is that economic development is not easy. It depends on complex webs of inter-relationships nurturing one another to grow the whole. It also requires an openness to pursuing things in a new way, even if they are perceived as disruptive to existing markets. Potent forces are always marshaled to resist changes to the status quo, but if humanity desires long-term prosperity it must continually re-evaluate what it is doing, and must secure access to increasing amounts of resources, both energy and material. Those resources exist in abundance off-world. We can pursue them, or continue trying to reallocate the effectively fixed amount of obtainable resources available on Earth, pursuing increasingly marginal supplies.
We’re seeing an increasing shift from viewing space as the domain of scientists and engineers alone, to a view of space as a place to conduct growing levels of economic activities to pursue future prosperity. Also slowly coming into view is the realization is that this is one industry with exceedingly high barriers to entry in which we have a clear commercial competitive advantage. The priority should be on growing that industry as a specialization in which the United States excels. The Moon Society will further explore this field with their track at this year’s International Space Development Conference in Washington, D.C., which is entitled “The CisLunar EconoSphere”. Speakers interested in participating are encouraged to contact the National Space Society.
It starts with assured access to orbit by several suppliers, and suborbital researchers using parabolic flights to warm up for eventual facilities on orbit. Cubesats and Nanosats can then provide design experience for future experimenters. Bigelow Aerospace modules can be leased to research consortiums for private research. Fuel depots can gas up vehicles for the next step out. This technology is not beyond our grasp, but the government cannot provide it unto the American citizenry. The American citizenry must make it happen, through their industry, initiative, and through investing in the technology and infrastructure to make it happen. We can let it wither on the vine, as we have with so many other industries, or we can make it happen and the entire world will benefit, as they have to date. The choice is entirely ours.
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