The ITU Radiocommunication Assembly considering a)that there are requirements to use spacecraft for conducting very long baseline interferometry (VLBI); b)that space VLBI observations usually require wideband data transmission in the space-to-Earth direction;c)that space VLBI systems require precision uplink and corresponding downlink phase reference signals which need to be protected from interference;d)that there may be a potential for mutual interference when space VLBI systems are operated in the same frequency bands used by other space research systems.
ITU-R QUESTION 202-1/7-1997 history
1997ITU-R QUESTION 202-1/7-1997 Protection criteria and frequency sharing between space very long baseline interferometry and other space research systems