I agree. Sounds like the plan is to have the signals from each probe add up coherently, which means the laser pulses need to be coherent with each other. The wa

I agree. Sounds like the plan is to have the signals from each probe add up coherently, which means the laser pulses need to be coherent with each other. The wavelength of optical light is 100s of nanometers, so that is the level of precision required spatially, relative to the much much larger probe spacing that they quote. This (plus the required temporal coherence) is probably not possible without the probes actively locking their lasers to each other, but now each probe needs the optics to send and detect the optical signal from at least its nearest neighbors. I can't say if this is impossible given the weight restrictions, but it sounds rough.