It all depends on how sensitive your receiver is…
also very important also is the antenna(s).
with radio astronomy, which are weak signals, there are very large reflector elements.
No. It’s not and never was. Just as a matter of transmitted power the signals would be indistinguishable from random noise before you got much farther than Mars.
Galaxy Quest. Star Trek (direct parody) used as model for distant civilization. Actors, treated as heros, transported to help in war of survival. A very funny, genial movie ensues.
What do you mean by the antenna and large reflector?
Like a TV satellite dish. The dish is the reflector. The antenna is the round thing that hangs in front of it, because that’s where the dish focuses the radio waves.
Iridium uses a very complex packet routing system which can bounce packets between satellites. Globalstar at least does not; their satellites are little more than so-called “bent pipes”. You send a packet from the ground, and any satellites in range pick up the signal, amplify it, perform a frequency shift, and transmit it back to the nearest ground station. Despite the name they are not particularly global–if you are over the ocean you are out of luck because there is no ground station for the packet to go to. There are even regions on land which do not have coverage. I don’t know about Orbcomm.
Incidentally, it’s possible to use Iridium while in orbit. One or two cubesats have done it so far and my next one may also use it. Licensing is the main issue.
You would need very large dish to pick up any thing the distance to Mars.The bigger the dish the more it reflects.
That’s the idea, yes.
Or an array.
There was an episode of Futurama in which an alien civilization 1,000 light-years from Earth is obsessed with the Ally McBeal TV show.
The idea turned up in Carl Sagan’s Contact as well (the ETs send back the first TV signal they received from Earth: a broadcast of the 1936 Berlin Olympics).