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| "Slide show" comparing an illumination model of the lunar north pole region, made using a three-dimensional printer and LRO laser altimetry by Howard Fink of New York University, with standard representations of LOLA data and one LROC WAC mosaic [Howard Fink/NYU/NASA/GSFC/ASU]. |
Paul D. Spudis
Smithsonian Air & Space
Of all the wonders depicted in science fiction books and movies, one of the most intriguing is the machine that makes anything
that you need or desire. Merely enter a detailed plan, or push the
button for items programmed into the machine – dials twirl, the machine
hums and out pops what you requested. Technology gives us Aladdin’s
Lamp. A handy device that will find many uses.
We’re not quite there yet but crude versions of such imagined
machines already exist. These machines are called “rapid prototype”
generators or three-dimensional printers.
They take digitized information about the dimensions and shape of an
object and use that data to control a fabricator that re-creates the
object using a variety of different materials. Typically, these
machines use easy to mold plastics and epoxy resins but in principle,
any material could be used to create virtually any object.
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| 3-D printers contribute to the advancement our understanding of lunar morphology, as LRO fills long-neglected gaps in lunar morphology. Malapert Massif (85.9°S, 0.42°E). From an 80 meter resolution image of the South Pole region of the Moon built from a 20 meter original supplied by the LRO/LOLA science team [Howard Fink/NYU]. |
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| For comparison nearly the same area modeled by laser altimetry (LOLA) above, Malapert from the LROC Wide Angle Camera (WAC) RDR 100 meter Global Mosaic [NASA/GSFC/Arizona State University]. |
What’s the relevance of this technology to spaceflight and to the Moon? One of the key objects of lunar return is to learn how to use the material and energy resources of the Moon
to create new capabilities. To date, we have focused our attention on
simple raw materials like bulk regolith (soil) and the water found at
the poles. It makes sense to initially limit our resource utilization
ambitions to simple materials that are both useful and relatively
massive, which currently have those killer transportation costs when
delivered from Earth. Bulk regolith has many different uses, such as shielding (e.g., rocket exhaust blast berms) as well as raw material for simple surface structures.
However, once we are on the Moon and have met the basic necessities
of life, we can begin to experiment with making and using more complex
products. In effect, the inhabitants of the Moon will begin to create
more complicated parts and items from what they find around them, just
outside their door. The techniques of three-dimensional printing will
allow us to discover what makes life off-planet easier and more
productive. We will experiment by using the local materials to maintain
and repair equipment, build new structures, and finally begin
off-planet manufacturing.
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| To illustrate the obliquity of the view angle and the problem posed in gathering information about the tantalizing but permanently shadowed regions of the Moon, Shackleton crater, with the Moon's South Pole on its rim (upper left) together with Malapert Massif on the horizon, seen with Earth as a back drop. HDTV still from Japan's Kaguya orbiter released November 2007 [JAXA/NHK/SELENE]. |
During the early stages of lunar habitation, material and equipment
will be brought from Earth. With continued use, particularly in the
harsh lunar surface environment, breakdowns will occur. Although
initially we will use spare parts from Earth, for simple uncomplicated
structures that are needed quickly, a three-dimensional printer can make
substitute parts using local resource materials found near the
outpost. Most existing 3-D printers on Earth use plastics and related materials
(which are complex carbon-based compounds, mostly derived from
petroleum) but some processing has used concrete, which can be made on
the Moon from sieved regolith and water. In addition, we also know that
regolith can be fused into ceramic using microwaves,
so rapid prototyping activities on the Moon may eventually find that
partially melting particulate matter into glass is another way to create
useful objects.
The lunar surface is a good source of material and energy useful in creating a wide variety of objects. I mentioned simple ceramics and aggregates, but additionally, a variety of metals (including iron, aluminum and titanium) are available on the Moon. Silicon for making electronic components and solar cells is abundant on the Moon. Designs for robotic rovers
that literally fuse the in-place upper surface of the lunar regolith
into electricity-producing solar cells have already been imagined and
prototyped. We can outsource solar energy jobs to the Moon!
These technical developments lead to mind-boggling possibilities. Back in the 1940s, the mathematician John von Neumann imagined what he called “self-replicating automata,”
small machines that could process information to reproduce themselves
at exponential rates. Interestingly, von Neumann himself thought of the
idea of using such automata in space, where both energy and materials
are (quite literally) unlimited. A machine that contains the
information and the ability to reproduce itself may ultimately be the
tool humanity needs to “conquer” space. Hordes of reproducing robots
could prepare a planet for colonization as well as providing safe havens
and habitats.
We can experiment on the Moon with self-replicating machines because
it contains the necessary material and energy resources. Of course, in
the near-term, we will simply use this new technology to create spare
parts and perhaps simple objects that we find serve our immediate and
utilitarian needs. But things like this have a habit of evolving far
beyond their initial envisioned use, and often in directions that we do
not expect; we are not smart enough to imagine what we don’t know. The
technology of three-dimensional printing will make the habitation of the
Moon – our nearest neighbor in space – easier and more productive.
Even now, creative former NASA workers have found a way to make this technology pay off. In the future, perhaps their talents could be applied to making the Moon a second home to humanity.
Originally published October 24, 2011 at his Smithsonian Air & Space blog The Once and Future Moon,
Dr. Spudis is a Senior Staff Scientist at the Lunar and Planetary Institute in Houston. The opinions expressed are those of the author and
are better informed than average.
Lunar Pioneer, LLP
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