Our interstellar space craft is traveling 1/2 c = 150,000 kilometers per second, and is about to enter an area of space with lots of one cubic millimeter particles. At this speed they have enough kinetic energy for one of them to total the manned space craft. We have 33 robot space craft about 1500 kilometers ahead of the manned craft which can detect slightly larger particles, which can be vaporized with 13 laser canons (500 to 1000 kilometers ahead of the manned space craft) a few micro seconds before they hit our manned craft, but the radars can't detect one cubic millimeter particles, except at very short range. How can we design to save our space craft? We have several other systems which protect from smaller than one cubic millimeter particles, but the one cubic millimeter particles have the kinetic energy of an H bomb when they hit anything due to the relative speed of about 1/2 c. It appears we were imprudent to go that fast. Design a system that can save the space craft without magic. 330 robot space craft, perhaps? Something else is possibly more cost effective and safer as a disabled/malfunctioned robot space craft (or laser cannon kinetic energy) could total the manned space craft. Nearly all the particles that are a threat are within plus or minus one degree of arc from straight ahead of the space craft at 1500 kilometers ahead where we need to find all of them within a few hundred micro seconds.
In case you didn't do the arithmetic, the 1/2 c is already marginal or worse: After the radar pulse reflects off the several cubic millimeter particle it takes up to 100 microsecond to reach the radar receiver antenna, another microsecond to get though the stages of the receiver and calculate the aiming instruction for the laser canons; another microsecond to get though the data link transmitter stages and be radiated by the data link antenna, another 100 micro seconds to travel at c to the closer laser cannons, another ten microsecond to aim and fire the laser cannon; another 100 micro seconds for the laser beam to reach the one cubic millimeter particle; another ten micro second for the plasma to spread out sufficiently that it is no longer a serious threat to the manned space craft. Possibly some of those microsecond delays can be reduced, but others are over optimistic. We are all ready using coded pulses so we can transmit a million radar pulses per second, and receive them at multiple radar receivers up to 10,000 micro seconds later, with only rare multiple range results. The laser canons can fire at occasional false targets, but they need to avoid shooting at the manned space craft, the robot space craft and the other laser canons so one micro second computing time may be very optimistic. Our technology isn't there yet, but is it within grasp? Please suggest alternative ways to save the manned space craft, refute, or embellish the problem. Neil