04-21-2016, 08:23 PM
That is the clever part. They would (in theory) be able to work together to send coordinated messages back to us, which would be received by the same phased-array emitters that provided the thrust to send them there, only working in reverse. Luke Campbell has pointed out the sort of remarkable things a phased-array emitter-detector system could achieve; this is one of them.
Note, however that none of this technology is available today, and will need several decades of development to make it suitable for interstellar missions. And the same technology that could receive faint messages from a swarm of tiny sails four light-years away would also make a bloody good telescope, probably producing much better information by directly imaging the star (and planets) than by receiving data from a swarm of tinfoil spacecraft cannoning through the system at a significant fraction of light speed.
Note, however that none of this technology is available today, and will need several decades of development to make it suitable for interstellar missions. And the same technology that could receive faint messages from a swarm of tiny sails four light-years away would also make a bloody good telescope, probably producing much better information by directly imaging the star (and planets) than by receiving data from a swarm of tinfoil spacecraft cannoning through the system at a significant fraction of light speed.