A free space optical communications network comprising: a constellation of relay nodes in serial optical communication to form an optical path , wherein the relay nodes are configured to wavelength-multiplex a plurality of wavelength-dependent optical bent pipe channels into and out of the optical path, wherein the relay nodes include optical add-drop multiplexers being configured to add the bent pipe channels to, to drop the bent pipe channels from, or to pass the bent pipe channels along the optical path in dependence on a respective wavelength of each of the bent pipe channels, wherein the optical path is bidirectional, and wherein some of the bent pipe channels carry data in a first direction, and others of the bent pipe channels carry data in a second, opposite direction, wherein a first relay node (SAT1) of the constellation is configured to receive data by an uplink at a specific wavelength (λ3) and add an optical bent pipe channel into the optical path at said specific wavelength (λ3), wherein the free space optical communications network is configured such that the uplinked data is sent a pre-configured number of hops along the optical path in a pre-assigned direction, via the added optical bent pipe channel, to a second relay node (SAT3) of the constellation , and such that the pre-assigned direction is one of the first direction or the second direction based on the specific wavelength (λ3); and wherein the second relay node (SAT3) is configured to drop the added optical bent pipe channel having the specific wavelength (λ3) and send the uplinked data by a downlink at the specific wavelength (A3). a constellation of relay nodes in serial optical communication to form an optical path , wherein the relay nodes are configured to wavelength-multiplex a plurality of wavelength-dependent optical bent pipe channels into and out of the optical path, wherein the relay nodes include optical add-drop multiplexers being configured to add the bent pipe channels to, to drop the bent pipe channels from, or to pass the bent pipe channels along the optical path in dependence on a respective wavelength of each of the bent pipe channels, wherein the optical path is bidirectional, and wherein some of the bent pipe channels carry data in a first direction, and others of the bent pipe channels carry data in a second, opposite direction, wherein a first relay node (SAT1) of the constellation is configured to receive data by an uplink at a specific wavelength (λ3) and add an optical bent pipe channel into the optical path at said specific wavelength (λ3), wherein the free space optical communications network is configured such that the uplinked data is sent a pre-configured number of hops along the optical path in a pre-assigned direction, via the added optical bent pipe channel, to a second relay node (SAT3) of the constellation , and such that the pre-assigned direction is one of the first direction or the second direction based on the specific wavelength (λ3); and wherein the second relay node (SAT3) is configured to drop the added optical bent pipe channel having the specific wavelength (λ3) and send the uplinked data by a downlink at the specific wavelength (A3). <EOS>