How to deal with expanding spectrum of telecommunication networks threatening VLBI?

New plans from telecommunication enterprises foresee the demand of wide sub-band allocations in the range of 1-100 GHz during the upcoming World Radio Conferences, which go beyond of the known expansion of spectrum use by 5G and large satellite constellations (starlink, OneWeb).

More than 50,000 satellites have been planned to be launched in the next decade by telecommunications industry to provide global connectivity, but satellite downlink signals can affect VGOS receivers. Furthermore there are indications that recent agreements among national administrations and satellite companies to coordinate protection zones around radio telescopes and VGOS stations, avoiding downlink satellite transmissions, have been rejected.

Installation of normal cell-phone base stations on communication satellites is also under discussion to connect normal smartphones to satellites to provide global connectivity. Concerning the conducted power levels of cell-phone base stations would have an impact on any radio astronomy observation. CRAF studies show that coordination zones of up to 100km radius would be required to continue with undisturbed VLBI observations. This demonstrates that the future of VLBI is at risk, if no actions are taken to protect VLBI-sites.

Another troubling clue comes from the contention of a big part (6425-7125 MHz) of the so called mid-band by international mobile telecommunication (IMT), 5G and RLAN (Wi-Fi) services in many European Countries. This would degrade sensitivity and accuracy of VGOS measurements in this band. In addition RA community is going to loose the long observed Methanol spectral line at 6650-6675.2 MHz, despite this line is protected by ITU-R Footnote 5.149. National licensing processes are necessary to protect radio astronomy facilities in this band.

Important achievements in increasing sensibility of scientific communities on the importance of geodetic VLBI and VGOS activities have been reached, but still urgent initiatives and strategies are necessary to gain proper protection of VGOS bands before they will be fully crowded by signal of telecommunications services. The situation raises the question what should be done?