by Sam Wilkinson
You may have heard of the hyper-startup Planetary Resources, a company which aims to “expand Earth’s natural resource base” by developing (and eventually using) the technology to mine asteroids in the Solar System. They also have a lot of money, with investors such as Larry Page (Co-founder of Google) and James Cameron (Writer of Rambo: First Blood Part II). But what if they’re thinking a bit too small? There’s an exoplanet called 55 Cancri e which orbits the star 55 Cancri A ~41 light-years away from Earth. What makes 55 Cancri e interesting is that it weighs about 8.63 times the mass of the Earth and there is a good chance that about third of that mass is diamond. That’s a lot of diamond. Let’s be optimistic and assume for the moment that 55 Cancri e does in fact contain 2.88 times the mass of the Earth on diamond. What would happen if Planetary Resources really turned on the afterburner and tried to mine 55 Cancri e?
One slight problem is that at the moment very little is known about the geochemistry/geophysics of carbon-rich planets like 55 Cancri e (Earth is “oxygen-rich”), though I’m sure the promise of INFINITY DIAMOND would make the necessary research happen. Let’s just assume that the mining professionals can figure out how to mine diamond from 55 Cancri e anyway (probably with lasers or something). The problem then becomes transport. 41 light-years doesn’t sound too bad, does it? Voyager 1, which recently left our Solar System, is 18,812,796,028 km away from Earth and is going really quite fast (~17km per second relative to the Sun). While it is one of humanity’s crowning achievements in space exploration, Voyager 1 is only 0.00198 light-years from Earth (and that took 36 years!). It would therefore take 20707 years for a spacecraft travelling at the same speed as Voyager 1 to get to 55 Cancri e from Earth. Even Helios 2, a West German/NASA probe which currently holds the record for the highest speed attained by a man-made object, 67km per second, would still take 5254 years at it’s max speed to reach 55 Cancri e. It should also be noted that while Voyager 1 and Helios 2 are reasonably heavy, the equipment required for a substantial mining program would be orders of magnitude heavier.
The fact is that conventional propulsion technologies currently available to us just don’t cut it. But there’s another problem. Even if we can develop the technology fast enough to get there within a few decades (i.e. figure out how to travel close to the speed of light), we develop an arch-nemesis: Hydrogen gas. Why? Well, there’s the extremely low density cloud of hydrogen in Interstellar space that we would need to travel through. The issue is that when you travel at near the speed of light, that thin cloud of hydrogen is essentially turned into a death ray. According to William Edelstein of the Johns Hopkins University School of Medicine in Baltimore, if a spacecraft were to travel at 99.999998 percent the speed of light, the hydrogen atoms would seem to have an energy of 7 Teraelectronvolts, the same energy as protons in the Large Hadron Collider at Cern running at full tilt. This would expose the crew to over 10000 sieverts of radiation every second, given that the lethal dose of radiation for a human is 8 sieverts, you’re going to have a bad time. Even a robotic mining crew would struggle, the electronics would be very quickly fried and the structure of the ship would disintegrate well before the ship arrived at 55 Cancri e.
“The issue is that when you travel at near the speed of light, that thin cloud of hydrogen is essentially turned into a death ray”
There’s an obvious solution to the death ray problem, we’re going to have to go faster than light! There are two options for this, both of which are highly theoretical at the moment. I’m not going to go into too much detail, because there’s a lot of complex physics/maths and not a whole lot of consensus. The first method involves creating a “Traversable Wormhole” (essentially a gate between two locations) between somewhere near Earth and somewhere near 55 Cancri e. Since you can travel at fairly vanilla speeds through the wormhole, Hydrogen death-rays aren’t a problem, but you can still travel somewhere far away very quickly. The second method uses something called an “Alcubierre Drive” which distorts space-time around you in order to get to a location faster than light travelling in normal, garden-variety spacetime. While it is somewhat mathematically consistent with current physical theories, it requires weird things like Negative Energy Density, so might not be feasible to build one! Because of these considerations, I’m going to say that a Traversable Wormhole will be our best bet. These will enable us to get to 55 Cancri e extremely quickly (<41 years).
It would be prudent to open up the wormhole portal thing reasonable far away from Earth, we’ll use 35,786km because that’s the same height as a Geosynchronous orbit and I can calculate how much it costs to to get our mining equipment up there! Using the SpaceX Falcon Heavy launch system, currently the world’s most powerful rocket, it costs $130 million to get 21.2 tonnes up to that altitude. I don’t know much about mining equipment, so I just found the most expensive looking Drill I could. I know it probably won’t be the right kind of thing, but I’m going to use it’s mass as a benchmark for the weight for the fancy laser-using robotic miners we’re going to deploy to 55 Cancri e. Fortunately, the expensive looking drill weighs 20.4 tonnes, so we’ll say each Robo-Miner thing costs $130 million to get to 55 Cancri e (assuming the wormhole was already there or something). We’re also going to want to bring some transportation equipment to send the diamonds back to Earth! Since there likely aren’t any people on 55 Cancri e, we can probably put one of the wormhole entrances on the surface of 55 Cancri e (and figure out some way to slow down our equipment when it passes through the wormhole from Geostationary Transfer orbit). I’m going to use the specs of the SpaceX Dragon as a benchmark for what the specifications of our diamond return vehicle will be like (we’d need a souped up heatshield though!). A SpaceX dragon weighs 4.2 tonnes and can return to Earth with 3.13 tonnes of extra cargo, so if we use some fancy folding system we can assume that we can launch 5 diamond return vehicles on one SpaceX Falcon Heavy. Since R&D/Construction/Running costs are notoriously hard to estimate, let’s assume that the cost will be in the same order of magnitude as the Apollo program (I’ve excluded the cost of the launch vehicles, because we’re going to get them from SpaceX): $15.2 billion. I’m going to sum up our costs below:
Startup Costs: 20 Robo-Miners x $130 million each for launch = $2.6 billion. Total Estimated Costs = $2.6 billion + $15.2 billion = $17.8 billion (This does not take into account the cost of the Diamond Return Vehicle launches).
Cost of each Diamond Return Vehicle: $130 million for each launch/5 Vehicles = $26 million.
Current estimated price of 1 Tonne of Diamond: $60 million for 0.01192 kilograms. Therefore 1 Tonne of Diamond is currently worth $83892 million.
Cost to return 1 Tonne of Diamond: Each Diamond Return Vehicle costs $26 million and can return 3.13 Tonnes of Diamond. Therefore 1 Tonne costs $8.3 million.
Profit on each Tonne of Diamond: $83892 million – $8.2 million = ~$84.9 billion.
As you can see from the above, this would be very profitable! Keep in mind the effect INFINITY DIAMOND would have on the price of diamond (Economists, help me out!) It would give the miners of 55 Cancri e essentially a monopoly in the diamond industry though, and each capsule returning to Earth would make ~$265.7 billion in profit with the diamond prices of today! This would likely make the extremely high R&D costs much easier to stomach!