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This article aims to highlight the impact for ground based astronomicalobservations in different windows of the electromagnetic spectrum coming fromthe deployment of fleets of telecommunications satellites. A particularattention is given to the problem of crowding of circumterrestrial space bymedium/small size orbiting objects. Depending on their altitude and surfacereflectivity, their contribution to the sky brightness is not negligible forprofessional ground based observations. With the huge amount of about 50,000new artificial satellites for telecommunications planned to be launched inMedium and Low Earth Orbit, the mean density of artificial objects will be of>1 satellite for square sky degree; this will inevitably harm professionalastronomical images leaving trails on them. Only one of these project,Starlink@SpaceX's, authorized by US Federal Communication Commission, plans todeploy about 42,000 not geostationary satellites, which will shine in sky aftersunset and before sun dawn. Satellites will be observed in deep field imagesand particularly negative for scientific large area images used to search forNear Earth Objects, predicting and, eventually, avoiding possible impactevents. Serious concerns are also common to other wavelengths eligible forground based investigation, in particular for radio-astronomy, whose detectorsare already saturated by the ubiquitous irradiation of satellites communicationfrom Space stations as well as from the ground. The risk of running into the"Kessler syndrome" is also noteworthy. Understanding the risk for astronomicalcommunity, a set of actions are proposed in this paper to mitigate and containthe most dangerous effects arising from such changes in the population of smallsatellites. A dedicate strategy for urgent intervention to safeguard andprotect each astronomical band observable from the ground is outlined.

Concerns about ground based astronomical observations: a step to safeguard the astronomical sky