Why aren't moored helium balloons hoovering a few kilometers over many cities as a competing alternative to expensive satellite launches? They could provide services with local advantage such as: high powered radio communication, precision navigation, live traffic observation, micro meteorology and more which takes advantage of the low altitude and local adaptions.
Some benefits I can think of:
unlimited access to cheap electric power through the ground cable, which could constantly power payload and even rotors to achieve extra altitude and control (an electric chopper in a leash),
reusability and therefor much lower cost,
no space graded equipment needed and therefor much lower cost again,
serviceability of payload and therefor higher reliability,
high degree of adaptation to specific local and current demands.
What is it that makes moored balloons apparently incapably to exist as a competitor with commercial (and military) geostationary satellites, GPS, LEO-satellites? Where's the deadly flaw?
In particular: SOFIA is an IR telescope on a Bo747 which is used at 12 km altitude in order to get over the clouds and most of the IR distorting atmosphere. Could moored balloons with similar payload capacity reach as high? "Telescope installation weight: 17 tons"