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Scratching the Surface: The Ethics of Mining Helium-3
Tony Milligan
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INTERNATIONAL ACADEMY OF ASTRONAUTICS
8th IAA SYMPOSIUM ON THE FUTURE OF SPACEEXPLORATION: TOWARDS THE STARS Torino, Italy, July 3-5, 2013

SCRATCHING THE SURFACE: THE ETHICS OF HELIUM-3 EXTRACTION
Tony Milligan
Department of Philosophy, University of Aberdeen,
t.milligan@abdn.ac.uk
ABSTRACT
Terrestrial mining is ethically problematic by virtue of its directly destructive impact and by virtue of itscontribution to both the depletion of fossil fuels and (through the use of the latter) to the raising of C0
2
levels inthe atmosphere. Extraction of helium-3 (
3
He) from the lunar regolith would share two of these same problems, i.e.resource depletion (which I will suggest is the
soft problem
of lunar mining) and destructive impact (which I willsuggest is the
hard problem
). In response to the
hard problem
, in spite of the fact that the Moon is a lifeless place,I will argue that we do nonetheless have reasons for lunar protection. Firstly, it is a culturally-significant object;
secondly, familiar appeals to planetary ‘integrity’ (notably by Holmes Rolston) may be supported by appeal to a‘last
-
man argument’; finally (and following Hannah Arendt) l
iving in places which we value is integral to our humanity and this should shape and inform our move beyond the Earth. However, none of these considerationwill yield sufficient grounds for ruling out
all
mining under
all
circumstances and for
all
purposes. Different justificatory narratives may then be told for and against any particular proposal. Even so, it is difficult to envisagewhat kind of narrative could be used to justify destructive mining on an extensive scale other than the familiar narratives which are already used to justify space exploration as such, i.e. those concerning terrestrial advantage; aduty to extend life (or human life); and a naturalistic appeal to a human longing to explore. I will suggest that thelatter is by far the least convincing justification. A tendency to expand into new areas is a species trait and not astandard character trait of individual humans. As such, the expression of this trait is not a requirement for humanwell-being. What this leaves us with is, on the one hand, the terrestrial advantage of a cleaner form of nuclear energy and, on the other, a duty to extend life (or human life) which might be served by the lure of this uniquesource. However, with regard to terrestrial benefits all is not so simple as it might seem. And, as for the duty toextent human life, while the duty is perhaps both real and noteworthy, it can only be what Kant referred to as animperfect duty, i.e. a duty which may be fulfilled in several different ways. As a result, only if the other plausibleways of fulfilling this duty were blocked off or, more ethically problematic, should extensive and destructive
3
Hemining be regarded as the default option.
Keywords:
mining, integrity, duty, lunar protection.
INTRODUCTION
What follows is a provisional consideration of the ethics of Helium-3 (
3
He) mining, a scratching of the surfaceof this issue in an attempt to show that something deeper and more comprehensive may perhaps be said (andought to be said). This light isotope has repeatedly been cast in the role of an energy saviour for an overcrowdedand under-resourced world with the promise that nuclear fusion, based upon the Deuterium-
3
He reaction, will
become one of humanity’s primary sources of energy or, more modestly, that it will replace
nuclear fission (Lewis1997; Santarius et al. 2006). If we can mine or capture even relatively modest amounts of
3
He off-world, we may be able to shift to safer and cleaner systems of nuclear power based upon the least radioactive forms of fusiontechnology. We may be able to do so while sustaining standards of living and we may even be in a position tothink a little more seriously about building fusion-based propulsion systems which are capable of reaching nearbystars (Spencer 1966; Gilster 2004; Zubrin 1999).


VIII IAA Symposium on The Future of Space Exploration
2
1.

THE LUNAR OPTION
Setting aside the point that fusion technology has yet to become economic (and assuming that at some point itmay do so) what makes this otherwise attractive picture of our near future problematic is the proposed source.From a purely logistical point of view, the Moon is the best candidate for
3
He mining. The gas giants at the outer edges of the solar system do have far richer reserves but they are a long distance away. If
3
He capture is to happenanytime soon, say in the next half century or so (the usual time-frame for the beginnings of a shift to fusion power) it may have to take place much closer to home. Discounting Mercury and Venus (because they are too hotto work on) and Mars (because it is too atmospherically-protected to have built-up significant
3
He reserves) thereare only two serious candidate sources: asteroids and the Moon. But while asteroids may be good for a one-hitoption, until we are able to park them in orbit, successive returns will be impractical. This is likely to push thecosts of mining through the roof. It stands in the way of operational stability and the establishment of infrastructure. Added to which, the concentration of
3
He within asteroid regolith is probably less than within lunar regolith. Asteroids are gravitationally weaker than the Moon and do not retain ejected material nearly so well. Asa result, they (again probably) have far less
mature
regolith. (These are familiar and plausible claims which standin need of empirical verification.)Given that concentrations of
3
He, wherever found, tend to be low (i.e. measured in parts per billion) and that ittakes an extremely long time for them to build up to significant levels, and given the substantial financial outlaysthat will be required for start-up costs, the processing of the most accessible concentrations of the most matureregolith is, from a strictly mining standpoint, the default option. Enthusiasts for
3
He mining (which includes at
least some figures within all of the world’s leading space a
gencies) seem to be entirely correct about this matter.Lunar
3
He is also, in the absence of an extensive off-world economy the only resource which
might
allow the
initial stages of lunar settlement to ‘pay its own way’ or to do so at least in part, depend
ing upon the cost of extraction and return-to-Earth technologies. As a consequence, the first major ethical challenge for lunar protection may well turn out to the issue of
3
He mining. It is, for example, closer to becoming an immediateethical issue than the question of lunar property rights because, until there is an economically viable reason for going to the Moon and staying there, property rights will remain merely token, they will be rights at a distance.
2.

DESTRUCTIVENESS OF PROCESS
Terrestrial mining is ethically problematic by virtue of its directly destructive impact and by virtue of itscontribution to the depletion of fossil fuels and the raising of C0
2

levels in the Earth’s atmosphere. Extraction of
3
He from the lunar regolith would share two of these same problems. Significant amounts of mature regolithwould have to be processed in order to extract even a small amount of this isotope. Extraction would therefore bedestructive, or at least intrusive to the point of re-shaping areas of the lunar landscape. It would also involve theremoval of an important, and effectively non-renewable, resource. Weighing-up these difficulties I will suggestthat the
hard problem
of
3
He mining concerns lunar damage and that, considered on its own, the problem of resource depletion need not be intractable and may be considered the
soft problem
of
3
He mining. Although futuregenerations do have reasonable entitlements which we cannot flout, lunar mining of
3
He, if linked to further access i.e. to making the further reaches of the solar system accessible for
3
He capture, could allow us to leave far
more than ‘as much and as good’ for future generations. (Here, as a matter of convenience, I use the classic
Lockean formulation with regard to the correct usage of natural resources however I am not wedded to it.)But just how destructive would the process of
3
He mining be? The option which is generally under consideration is the systematic extraction, crushing and heating of regolith to around 700 °C in order to releasevarious gasses, including
3
He which could then be stored for later use in a fusion reactor. How much of the lunar surface would be affected is still something of an unknown. In part, it would depend upon the local compositionof the regolith itself. Of course, we have lunar return samples to work from and they suggest an averageconcentration of about 4 parts of
3
He per billion (ppb) of regolith. But in some areas the figure is significantlyhigher, rising to 15 ppb partly because finer grains in some areas happen to expose more surface area per volume
and hence have a higher capture ratio. There is also the lumpiness of the Moon’s magnetic field to consider. The
Solar wind which seeds the Moon with
3
He is deflected in an uneaven manner.To add to our uncertainties, these figures only take account of strongly-bound
3
He. Weakly-bound
3
He,especially in high lunar latitudes, may be significantly more abundant

(Slyuta et al. 2007). (And this could openup the possibility of ethically-unproblematic capture technologies with minimal surface disruption.) What is alsolikely to shape the pattern of mining is the varying depth of the regolith. The deepest regolith is correlated withreduced
3
He concentrations. And because of this, going deep to restrict the area which is mined might not be the

VIII IAA Symposium on The Future of Space Exploration
3
easiest economic option. Assuming a concentration of 4 ppb and a regolith density of around 2g/cm
3
, it wouldrequire at least 250,000 tonnes of regolith to be processed in order to obtain 1kg of
3
He.

How much of an areawould have to be stripped in order to do so would depend upon how deep the mining would reach. Robert Zubrin(1999: 88) has suggested stripping an area of 1km square to a depth of 10 cm which could take us into roughly theright territory (0.8 kg of
3
He). However, it seems implausibly minimal for an actual mining operation as opposedto some less intrusive form of activity such as an expansive archaeological dig. Santarius, Kulcinski and Miley(2006) have suggested instead that we mine to about 3 meters deep using a bucket-wheel excavator. This wouldtake us to the depths at which the
3
He concentration starts to fall off. In a perfect world this might yield around24kg of
3
He over an excavation area of 1km square. To mine as much as a tonne of
3
He it would then take an areaof more than 6km square.However, for
3
He to become a serious player in the terrestrial energy mix it would have to at least match theexisting contribution of nuclear fission (which supplies roughly 6% or thereabouts of our energy worldwide and11% or thereabouts of energy production in the OECD countries). That might require as much as 40 tonnes of
3
He per year mined over an area of as much as 40 square km. Over several decades mining on this scale couldstart to eat up significant portions of the lunar surface. Admittedly, the data needs to be refined in all sorts of ways but these rough and ready figures convey something of the magnitude of destruction that could be involved in any process of extensive He
3
extraction, i.e. extraction geared to meet the aspirations outlined at the start of this paper, just so long as it was carried out by any familiar form of intrusive/destructive mining technique. It may also be prudent to acknowledge that limited mining concessions, geared initially to planetary protection and to therestriction of impact, could follow the familiar terrestrial pattern by operating as a beachhead for wider exploitation. If lunar protection is a genuine ethical requirement then, given the possible impact of He-3 mining,we have legitimate reasons for ethical concern.
3.

REASONS FOR LUNAR PROTECTION
I will now suggest that we do have reasons to regard lunar protection as a genuine ethical requirement
. Morespecifically, we have contributory reasons for doing so, reasons which may sometimes be overridden butnever silenced (Dancy 2004:15). However, as a concessionary point,
the independence of the final
reason
that I will offer may be open to question. Firstly, the Moon is a culturally-significant object. Given this, we shouldno more treat it as a
mere
resource (as a giant mine or quarry) than we should treat Stonehenge or the pyramids asa convenient source of building materials. This is another way of making sense of the idea (already enshrined inspace law) that the Moon is part of the
‘common heritage of mankind’. It may, of course, be pointed out that the
Moon is not a human artifact whereas structures such as Stonehenge and the pyramids are. And this no doubtrestricts the
ways
in which the Moon can realistically be viewed as culturally significant but not the fact that it hassuch significance. Moreover, this does not seem to be dependent upon how the present generation, or any particular generation of humans, happens to feel about the Moon.After all, it is plausible to say that if we, on our travels, were to encounter the culturally-significant objects of alien beings (even if we could not understand
why
they were significant and even if there no longer happened to be any of the alien beings around) this would still be a reason to treat such objects in a special manner. (Althoughthis presupposes a larger story about what can count as a reason and why it can do so.) Similarly, not only do
we
have reasons not to damage Stonehenge by virtue of its cultural-historic significance for
other
humans, butintelligent visitors from other worlds (if any such beings happened to exist) who encountered this region of spaceafter the demise of humanity, would also have reasons to avoid damage to Stonehenge just as long as they were ina position to recognize the significance that Stonehenge once had for the (now defunct) humans. These commentsoutline a familiar
‘indirect duties’ approach towards the assignment of moral considerability: a special importance
can be assigned to objects and structures without any appeal to their inherent value but by appeal to the fact thatthey are or have been important to other beings towards whom we continue to have duties of respect and care. Weshould care about the objects because we care about (or respect) those other beings.
Secondly, familiar appeals to planetary ‘integrity’ (notably those made by Holmes Rolston) may turn out to be
defensible, in which case we can go further than the indirect-duties approach and actually make a claim of intrinsic lunar value (Rolston 1986). Attempts have been made to argue, by fell swoop, that intrinsic value accrues
only
to sentient or, more restrictively, rational beings (Smith 2009). But we cannot make this move withoutdisturbing exclusions and without the risk of turning our attitude towards sentience, or rationality, into a peculiar kind of fetish, one which not only restricts attributions of value but also divorces them from our actual (and