Retrorefltors are very useful. They are hard to beat for covert comms.
   Unfortunately, optical ones are limited by weather. Much more
   versatile,  if possibly less covert, are radio types. Ultra lights the
   size of the Echo are now easily deployed via inflatable and UV
   regidification.

   On Sun, Dec 30, 2018, 6:19 PM grarpamp <[1]grarpamp@gmail.com wrote:

     On 12/30/18, jim bell <[2]jdb10987@yahoo.com> wrote:
     >
     [3]https://www.zmescience.com/research/technology/quantum-internet-p
     ossible-26122018/
     The useful part is this...
     “Our experiment used the passive retro-reflectors mounted on the
     satellites"
     Which means you can abuse said reflectors for
     your own fun experiments, permissionless style.
     [4]http://iopscience.iop.org/article/10.1088/2058-9565/aaefd4/meta

References

   1. mailto:grarpamp@gmail.com
   2. mailto:jdb10987@yahoo.com
   3. https://www.zmescience.com/research/technology/quantum-internet-possible-26122018/
   4. http://iopscience.iop.org/article/10.1088/2058-9565/aaefd4/meta