Helium‑3 from the lunar surface for nuclear fusion?

Since 1969, the return of a human mis­sion to the Moon has nev­er seemed so close. Although sci­entif­ic interest con­tin­ued to flour­ish, space pro­grammes had for many dec­ades aban­doned it in favour of the Inter­na­tion­al Space Sta­tion and mis­sions to explore the sol­ar sys­tem. Dom­in­ated by the grow­ing com­pet­i­tion between the United States and China, the return to the Moon is now motiv­ated by a desire to study and pos­sibly exploit resources that can be found there.

Of these, helium‑3 rep­res­ents the most sig­ni­fic­ant poten­tial in the field of energy. This non-radio­act­ive iso­tope is an ideal fuel for the oper­a­tion of a fusion react­or; it con­sists of fus­ing helium‑3 with deu­teri­um, with the advant­age of not pro­du­cing neut­rons. Whilst it is still in its exper­i­ment­al stages, the abil­ity to con­tain such energy in the reactor’s con­tain­ment cham­ber could make it a viable energy source.

In Septem­ber 2021 US com­pany, Com­mon­wealth Fusion Sys­tems based in Mas­sachu­setts, announced the cre­ation of a 20 Tesla mag­net­ic field using a high-tem­per­at­ure super­con­duct­ing elec­tro­mag­net, which con­sti­tutes a remark­able advance. From this per­spect­ive, the extrac­tion of helium‑3 on the Moon could facil­it­ate the devel­op­ment of this break­through technology.

As early as 1988, a NASA report on helium‑3 men­tioned the poten­tial of this iso­tope for use in a nuc­le­ar fusion react­or¹. The­or­et­ic­ally, it offers sev­er­al advant­ages com­pared to cur­rent nuc­le­ar power as an abund­ant, low-car­bon energy and no nuc­le­ar waste tech­nique. On paper, its advant­ages make it a com­pet­it­ive resource, while this iso­tope is use­ful for oth­er applic­a­tions includ­ing cryo­gen­ics, quantum com­puters and MRI lung ima­ging. Also, the Moon is its main reservoir.

For bil­lions of years, the action of sol­ar wind has released high-energy particles, includ­ing helium‑3, which has accu­mu­lated on the Moon in the absence of an atmo­sphere. A renew­able resource by defin­i­tion, the iso­tope is reg­u­larly depos­ited on the Moon’s sur­face under the con­stant activ­ity of the Sun. How­ever, as Ian Craw­ford shows, the notion of the abund­ance of this resource must be weighed up: the highest con­cen­tra­tion observed in meas­ure­ments car­ried out on samples is 10 parts per bil­lion (ppb), depend­ing on the mass, for an aver­age con­cen­tra­tion of 4 ppb in the rego­lith lay­er².

As a pre­requis­ite for the install­a­tion of a human base, many states (India, Rus­sia, China, United Arab Emir­ates, etc.) are pre­par­ing new lun­ar mis­sions in the com­ing years. By far, the Artemis pro­gramme, sup­por­ted by NASA, is the most suc­cess­ful at this stage for this planned return. Along­side the United States, many coun­tries such as Aus­tralia, Brazil, Italy, Japan, and Lux­em­bourg have joined this ambi­tious pro­ject. China, togeth­er with Rus­sia, is also con­sid­er­ing the estab­lish­ment of a lun­ar base. How­ever, the spe­cific­a­tions for such an under­tak­ing remain incom­plete for the time being, both in terms of the fin­an­cial resources and the tech­nic­al arrange­ments to reach the tar­get set for 2030.

Clearly, a per­man­ent install­a­tion requires the con­struc­tion and main­ten­ance of infra­struc­ture through the use of loc­ally avail­able resources and the intens­ive use of robots. In this regard, the Aus­trali­an com­pany Luyten is look­ing to deploy 3D print­ing tech­no­logy to provide on-site con­struc­tion solu­tions³. In oth­er words, the aim is to imple­ment an arti­fi­cial lun­ar eco­sys­tem to facil­it­ate travel to Earth. To achieve this ambi­tion, the French incub­at­or Tech­TheMoon, based in Toulouse, is the first in the world ded­ic­ated to devel­op­ing a per­man­ent set­tle­ment on the Moon⁴. Des­pite this emu­la­tion, the estab­lish­ment of a human colony remains a dis­tant pro­spect. A recent NASA audit report points to cumu­lat­ive delays in the Artemis pro­gramme, par­tic­u­larly in the devel­op­ment and test­ing of the lun­ar mod­ule, which de facto post­pones the mis­sion bey­ond 2024⁵.

China has demon­strated a met­eor­ic rise in its space activ­it­ies head­ing towards the moon – both eco­nom­ic­ally and tech­no­lo­gic­ally. As a fun­da­ment­al step in the devel­op­ment of its space pro­gramme, China sent its first probe into orbit around the Moon in 2007. Since then, the Chang’e 4 (2018) and Chang’e 5 (2020) mis­sions have made sig­ni­fic­ant pro­gress in the know­ledge and study of data on the topo­graphy and com­pos­i­tion of the soil. One of the object­ives of these trips is to determ­ine the exact amount of helium‑3 present. To this end, the Beijing Research Insti­tute of Urani­um Geo­logy (BRIUG) is meas­ur­ing the con­tent of helium‑3 in the lun­ar soil, eval­u­at­ing its extrac­tion para­met­ers, and study­ing the ground fix­a­tion of this iso­tope. These advances also reflect Beijing’s over­all strategy to con­trol ter­restri­al min­er­als and metals and their use.

Over­all, oth­er coun­tries are fund­ing pro­grammes to ana­lyse the lun­ar soil, such as the future mis­sion of the first Emir­ati rover sched­uled for 2022⁶. With the help of the Japan­ese com­pany Ispace’s lun­ar lander, the ‘Rashid’ rover will study its geo­lo­gic­al com­pos­i­tion and prop­er­ties. These mis­sions will undoubtedly help to assess its min­ing potential.

Sci­entif­ic mis­sions are bound to con­tin­ue over the next dec­ade to con­tin­ue sur­vey­ing rego­lith­ic rocks in new lun­ar ter­rit­or­ies. This is an invalu­able piece of sci­entif­ic inform­a­tion that reflects one of the found­a­tions of the human space explor­a­tion; based on the pos­sib­il­ity of exploit­ing extra­ter­restri­al resources that appear to be unlim­ited. In any case, the devel­op­ment of an extra-ter­restri­al min­ing industry entails invest­ment and infra­struc­ture con­straints such that the deploy­ment of exist­ing renew­able resources on Earth would remain less costly. In fact, the energy cost of lun­ar helium‑3 – from extrac­tion to use in a nuc­le­ar fusion react­or – would make it at most a rather mar­gin­al con­tri­bu­tion to our long-term energy needs.

While exist­ing tech­no­lo­gic­al and fin­an­cial bar­ri­ers ostens­ibly hinder the launch of such a ven­ture out­side the Earth sys­tem⁷, sus­tained research and devel­op­ment policies in sev­er­al coun­tries are in this sense a way of keep­ing the pos­sib­il­ity open. All in all, this feas­ib­il­ity could be unrav­elled when a tech­no­lo­gic­al threshold is crossed that cor­rel­ates with its eco­nom­ic prof­it­ab­il­ity. Finally, cur­rent inter­na­tion­al treat­ies do not provide a polit­ic­al and leg­al frame­work for min­ing activ­it­ies on the Moon. In the mean­time, thought must be giv­en to the status of the celes­ti­al object, which could ulti­mately be like that of Ant­arc­tica, by becom­ing a neut­ral space ded­ic­ated to science.