A bit late to the party here, but here’s an alternative proposal to shielding:
I disagree with the statement
it’s going to take the form of a super-narrow pinprick of kinetic energy directed on a single point
0.9 c is not ultra-relativistic, the Lorentz factor at this speed is a mere 2.3, so the kinetic energy of an incoming particles is on the same order of magnitude of its rest mass. This means that relativistic beaming is going to be fairly weak.
Since the kinetic energy far outstrips the chemical binding energy of the dust grain, we can expect it to instantly disintegrate into a particle shower upon first contact with the shield. So why not place the shield hundreds of kilometers ahead of the ship and let the inverse-square law do the rest? Most of the particle shower will simply miss the ship. Multiple, thinner shields would be even better at diffusing the particle shower while taking less damage themselves.
I imagine there will only be some minor damage to the shield since most energy still lies within the particle shower if you made the shield thin enough, and you wouldn’t even need advanced nanotechnology to repair, just fill the hole in the shield with ANY material. And since we’re moving at 0.9 c, you’d need to make the shield at most a few hundred meters wide to prevent dust sneaking in between the shield and the ship.
Furthermore, if the ship itself already uses a magnetic field to protect itself against charged particle radiation, a soap bubble would suffice as a shield as it would be enough to vaporize and ionize the dust grain. Either way, I think there is enormous mass savings possible here.
A bit late to the party here, but here’s an alternative proposal to shielding:
I disagree with the statement
0.9 c is not ultra-relativistic, the Lorentz factor at this speed is a mere 2.3, so the kinetic energy of an incoming particles is on the same order of magnitude of its rest mass. This means that relativistic beaming is going to be fairly weak.
Since the kinetic energy far outstrips the chemical binding energy of the dust grain, we can expect it to instantly disintegrate into a particle shower upon first contact with the shield. So why not place the shield hundreds of kilometers ahead of the ship and let the inverse-square law do the rest? Most of the particle shower will simply miss the ship. Multiple, thinner shields would be even better at diffusing the particle shower while taking less damage themselves.
I imagine there will only be some minor damage to the shield since most energy still lies within the particle shower if you made the shield thin enough, and you wouldn’t even need advanced nanotechnology to repair, just fill the hole in the shield with ANY material. And since we’re moving at 0.9 c, you’d need to make the shield at most a few hundred meters wide to prevent dust sneaking in between the shield and the ship.
Furthermore, if the ship itself already uses a magnetic field to protect itself against charged particle radiation, a soap bubble would suffice as a shield as it would be enough to vaporize and ionize the dust grain. Either way, I think there is enormous mass savings possible here.
Very good point!