A method of optical communication between a transceiver on earth and a communication satellite in an orbit above the earth , the method comprising - transmitting information encoded in an uplink beam (Lu) from the transceiver to the communication satellite , wherein the uplink beam (Lu) travels through an atmosphere there between, wherein a wavefront (Wu) of the uplink beam (Lu) is distorted as a result of its propagation through the atmosphere ; - wherein the transceiver comprises a wavefront sensor to measure a reference distortion (Wr') of a wavefront (Wr) of a reference beam (Lr), wherein the reference distortion (Wr') is caused by the reference beam (Lr) propagating through the atmosphere ; - wherein the transceiver comprises adaptive optics to pre-correct a wavefront (Wu) of the uplink beam (Lu) prior to its transmission based on the measured reference distortion (Wr'); - wherein the pre-correction at least partially negates the measured wavefront distortion caused by travel through the atmosphere to improve the wavefront (Wu) of the uplink beam (Lu) arriving at the communication satellite after propagating through the atmosphere ; - wherein the reference beam (Lr) originates from a guidestar satellite formed by a separate man-made object which, at least at the moment of sending the reference beam (Lr) used for the pre-correction, is disposed at a distance (D) from the communication satellite so that the reference beam (Lr) travels through the same part of the atmosphere as the uplink beam (Lu); - wherein the distance (D) between the communication satellite and the guidestar satellite is at least equal to a velocity (Vc) of the communication satellite divided by a roundtrip time (T) that it takes the reference beam (Lr) to travel from the guidestar satellite to the transceiver and the corresponding uplink beam (Lu) to travel from the transceiver back to the communication satellite . - transmitting information encoded in an uplink beam (Lu) from the transceiver to the communication satellite , wherein the uplink beam (Lu) travels through an atmosphere there between, wherein a wavefront (Wu) of the uplink beam (Lu) is distorted as a result of its propagation through the atmosphere ; - wherein the transceiver comprises a wavefront sensor to measure a reference distortion (Wr') of a wavefront (Wr) of a reference beam (Lr), wherein the reference distortion (Wr') is caused by the reference beam (Lr) propagating through the atmosphere ; - wherein the transceiver comprises adaptive optics to pre-correct a wavefront (Wu) of the uplink beam (Lu) prior to its transmission based on the measured reference distortion (Wr'); - wherein the pre-correction at least partially negates the measured wavefront distortion caused by travel through the atmosphere to improve the wavefront (Wu) of the uplink beam (Lu) arriving at the communication satellite after propagating through the atmosphere ; - wherein the reference beam (Lr) originates from a guidestar satellite formed by a separate man-made object which, at least at the moment of sending the reference beam (Lr) used for the pre-correction, is disposed at a distance (D) from the communication satellite so that the reference beam (Lr) travels through the same part of the atmosphere as the uplink beam (Lu); - wherein the distance (D) between the communication satellite and the guidestar satellite is at least equal to a velocity (Vc) of the communication satellite divided by a roundtrip time (T) that it takes the reference beam (Lr) to travel from the guidestar satellite to the transceiver and the corresponding uplink beam (Lu) to travel from the transceiver back to the communication satellite . <EOS>