[BRIEF NOTE] And more on lunar helium-3

[rfmcdonald]

The most regular Neil Reynolds article in the Globe and Mail, "Many moons to go: the promise of lunar mining" prompted james_nicoll, when he came across it, to give it the tag "die lunar helium 3 die." That may be, but when I read it in print I was more taken aback by his opening comments on Titan.

For $1-billion, Canada convened a summer weekend session of assorted world leaders who, as they left, produced an ambivalent communiqué of improbable historic importance. For $3.2-billion (U.S.), or a week’s worth of such summitry, several of these same countries paid for the U.S.-European Cassini space mission to Saturn, a 3.5-billion kilometre, seven-year voyage that has revealed the secrets of Saturn’s strange orange moon, Titan. It turns out that Titan is awash in liquid hydrocarbons: in oil. Indeed, it rains liquid hydrocarbons – and, in the moon’s light gravity, each drop floats down from the clouds at roughly the speed that large snowflakes fall to Earth.

With only one-fifth of this moon radar-scanned so far, scientists calculate that dozens of lunar lakes each hold more oil and gas than all of Earth’s proven oil and gas reserves – and that Titan’s equatorial sand dunes hold hundreds of times more coal than all of Earth’s proven coal reserves. Titan is a vast reservoir of hydrocarbons. Talk about Peak Oil.

I don't think that he was serious about Titan's hydrocarbons being a potential source of energy, because if he was, as a commenter at James' blog pointed out, the physics would be impossible.

On the broader issue, can it *possibly* be energy-effective to ship petroleum an average of 9 AU from Titan to Earth orbit? The difference in orbital velocities is 20km/s, and that rotational energy has to come from somewhere.

Ah, unless I've dropped a 0 somewhere, I think it can't be. Gasoline has an energy content of 44 Mj/kg, and the difference in kinetic energy is ~400 Mj/kg (1 kg x (20,000 m/s)^2).

Reynolds is much more interested in the Moon's helium-3.

Our own moon is a mere 384,000 kilometres away, four days by shuttle – less time than it takes to truck grapes from California to Toronto. China, for one, now appears to understand the strategic importance of Earth’s moon: Chinese geochemist Ouyang Ziyuan, director of China’s Lunar Exploration Program, says that a principal goal of China’s space program is the mining of Helium-3, a non-radioactive isotope scarce on Earth but relatively plentiful on the moon.

By some calculations (including China’s), a four-ton shuttle load of lunar Helium-3 per week would theoretically provide enough safe nuclear-fusion energy to meet the needs of the entire world. (The only practical Earth source for Helium-3 is apparently obsolete nuclear warheads.) Russian scientists have advanced similar analysis – suggesting that lunar mining could be under way by 2020, provided governments invested $6-billion in up-front funding.

Only Americans – 12 of them – have walked on the moon. U.S. astronaut Harrison Schmitt, a geologist, was the last – in 1972. Mr. Schmitt champions lunar mining of Helium-3 and puts the up-front cost at $15-billion, or (he says) roughly the cost of building the Trans-Alaska Pipeline.

I myself have noted in the past that (1, 2), apart from being so expensive to separate from the lunar soil as to be uneconomic--stripmining the Moon's surface is expensive--commercial nuclear fusion is decades away and, in any case, helium-3 fusion is even more difficult than the regular nuclear fusion that (I reiterate) is decades away. Helium-3, as autopope noted in the comments to post #2, is best understood as a desperate pseudoeconomic rationale to make the case that space colonization is economically sensible and doesn't need to be driven largely by the sentiment "Isn't it cool?"