Monday, February 18, 2013

Dump The Asteroids

Dump The Asteroids

          The recent asteroid flyby and Chelyabinsk meteor fireball (together with a small fireball over the San Francisco Bay area) got me to thinking: dammit, planet Earth is in a shooting gallery! Remember Tunguska, a century ago? Or how about Chicxulub, 65 million years ago? This has got to stop!

          Fortunately there are methods to change an incoming asteroid's trajectory, given enough time. My favorite method is the gravity tug. It weighs tons, has solar panels, ion drives, and plenty of propellant. It moves next to the offending asteroid; it hovers motionless relative to it, using ion thrust; its gravitational pull gradually accelerates the flying mountain. Given enough time, this allows you to manipulate the asteroid's orbit.

          Given enough time; which requires full mapping of near-Earth objects. That is an existing NASA mission, underfunded at present.

          Once you find the asteroid and send a gravity tug, you could simply deflect the asteroid into a safer orbit; but I think that's just putting off the problem. Flying mountains in near-Earth orbit are a public menace! So I say; let's clear out near-Earth orbit! Sweep it clean of solid matter other than Earth. So either dump those asteroids into the Sun, or mine them to oblivion. The first way is for worthless rock-heaps; the latter way sounds more profitable for solid metal-type asteroids (which by the way are also the most dangerous if they hit Earth). The carbonaceous chondrites might also be somewhat profitable, perhaps as a source of carbon for human space colonists.

          But where to mine that asteroid? Not LEO; it was already too near to Earth! L5? Kind of far to go, and not much there. And how do you mine a mountain in zero gee? Some companies imagine developing zero-gee mining techniques; but all are theoretical; we have little zero-gee experience, and none of that for rough work like mining. We'd have to start from scratch. For instance, wheels and treads need at least a little gee, and ground to push against. So do legs.

          Using present technologies, we have to dump the asteroid onto solid ground if we wish to profit from mining it. Not onto Earth, of course; that would be precisely the cosmic catastrophe that the whole operation is ostensibly about preventing! (Its real purpose is, of course, extracting all that nickel-iron to sell at a profit, or organics to feed to the local work-force.) So where to dump the flying mountain?

          Where but the Moon? I propose that we target the Sea of Moscow; the best flat terrain on Farside. I suggest a "tangential trajectory lunar capture": that is, that the gravity tug manipulate the asteroid to a trajectory eventually tangential to the Moon's. It finds itself a short distance from the Lunar surface, moving in the same direction as the Moon and at minimal relative velocity; so relative to the Moon, it slows to a near-halt... and then falls down!

          Thus we dump the mountain onto the Sea of Moscow. Since the asteroid is briefly at minimal velocity, relative to the Moon, this should minimize  the energy of its impact. It'll still be a cosmic catastrophe, of course, but a planned cosmic catastrophe, as small a one as possible, and on the far side of the Moon. The Moon's already a cosmic shooting range!

          After the dust and debris settles, and the moonquakes stop, send in the mining equipment. Telepresence robots, mostly; the world's best spacesuit. The human operators may be on Earth, or orbiting Luna, or on Lunar Nearside. In 1/6th gee, wheels work differently, but they still work. Ditto treads and scoops. And ditto legs. Moon dust is a complication; but at least dropped things fall down (unlike zero-gee work). I say that moon-dumping the asteroids, then mining them using near-standard techniques, is a lot cheaper than reinventing all of mining, processing, fabrication - and walking - for zero-gee. 

          Telepresence robots work best if their humans operators are nearby relative to lightspeed; thus Lunar orbit or on Luna. I wouldn't recommend colonizing Farside, if we're going to drop lots of mountains onto it. So we colonize Nearside and they work telepresently. Lunar living sounds a lot like life in a mining town; tough, dangerous, unhealthy, and incredibly profitable.

          And like mining everywhere, Lunar mining is as environmentally destructive as Hell. But the Moon already looks like Hell; dumping some more asteroids on it, at minimal velocity, is relatively mild.

          Or so I argue to my daughter Hannah! For she and I are in a political dispute; shall we change the appearance of the Moon, or not? She is a Preservationist, I am a Developer. I suggested this project to her this afternoon, and she was horrified. Dumping asteroids onto the Moon?! That's a cosmic catastrophe! But one that's on the Moon, not Earth, I replied. She pressed, and I conceded Farside. She worried about dust and debris; so in this email I propose a minimum-energy collision. But what about Moonquakes? So I admitted Nearside for any human operators. Perhaps Earthside telepresence, or Lunar orbit, will do for most of the work.

          I also argued that dumping dino-killer-sized mountains onto the Moon is a lot more environmentally friendly  - for Earth at least - than letting them hit Earth and cause another mass extinction! So let’s save the Earth! I suggested that if we, as the human race, manage to prevent at least one asteroidal mass extinction, then we would in effect pay our blood debt back to the ecosphere. We could save more than we have killed; thus we could be of value to the planet. Apex species plus planetary guardian is a stable ecological niche. Doing well by doing good!

          But I also admitted frankly to her that she, as a Preservationist, should scoff at my Developer rationalizations; for the real motive for the entire moon-dumping program is profit! Trillions of dollars worth of iron and nickel in them thar flying mountains. And gold. And platinum. And rare earths; element not easily found on Earth because they condensed`on a different orbit in the solar nebula. You see a heap of interplanetary rubble and dirt; I see money, money, money!

          Let's face it; profit or not, saving the Earth or not, this'll dump filthy dirt all over the nice clean Moon! The whole operation will make a huge mess; utterly un-Preservationist. But the profit motive is involved; therefore the Developers will inevitably defeat the Preservationists, and in the process prevent mass extinctions for many hundreds of millions of years.

          So dump those asteroids. Dump 'em on the Moon.

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