Does the signal go through the entire earth? Does it curve and travel around the earth? How come the earth isn’t blocking out the signal? I just can’t wrap my head around it. Same thing with satelites that transmit our internet. There can’t be thousands of satelites in a perfect formation that covers every angle, so how does it work?
PRIMARILY interested in the first scenario, how does the ISS transfer signals to USA if the earth’s mass is between USA and the satelite?
In: 5
The two ISS sections can communicate via geostationary satellites back to their mission command centers. The Russian section can communicate using the Russian Luch satellites, while the US section uses the US TDRSS (Tracking and Data Relay Satellite System). Each of these satellite systems can relay messages among their own satellites to and from the mission command center.
>There can’t be thousands of satelites in a perfect formation that covers every angle, so how does it work?
There absolutely are; the GPS and GLONASS systems are big networks of satellites (GPS has 32, GLONASS has 26) that cover basically the whole globe, so that there are always going to be a few satellites in “view” at any time. Satellite internet providers have their own networks of satellites that can provide near global coverage for their clients. There are a total of around 5500 satellites currently operating all around the world for various agencies/companies/countries (nearly 3000 belong to the US or US-based companies alone); this is plenty of satellites to provide many different networks with near complete global coverage.
Imagine you have 2 people who are communicating and for whatever reason they’re around a corner, and no matter how hard they yell they can’t hear each other.
They could wait until they both move close enough to where they have direct line of sight (or close enough to where they can hear each other.) Or they can pass their message to someone else and have them transmit it to the other party (this is what the ISS does.)
Rather than waiting for a direct signal with US, it’ll send the signal to some country who it currently can transmit to, and have them pass it on. Typically done with satellites, though can be done through ground stations also.
You only need 3 satellites to form a perfect geostationary orbit, the more you add the shorter the distance between them and faster the transmission rate.
There are radio stations connected around the world.
It transmits to Australia. From there to the US by cable.
About satellites, they are in near perfect formation, but the farther away less satellites are needed to cover the entire surface. There are only 31 GPS satellites covering the entire planet. For Internet, they need to be closer, so there are more, but their orbits are calculated so when one is out of range, there will be another one.
One last note about satellites and internet: most of the Internet traffic goes through submarine cables. Satellites are like a last option if where you are doesn’t have any infrastructure and can’t be reached by any cabled Internet. The distance the signal must travel to and from a satellite would make your connection very very slow.
There are base stations scattered around the world which can receive a signal from the ISS and then can relay that signal to any desired location not just the USA the station after all is the International Space Station.
> There can’t be thousands of satelites in a perfect formation that covers every angle, so how does it work?
You don’t need thousands but yeah, that’s exactly how it works.
https://www.nasa.gov/feature/goddard/2020/space-communications-7-things-you-need-to-know
https://www.nasa.gov/directorates/heo/scan/services/networks/tdrs_main
https://en.wikipedia.org/wiki/Ground_segment and https://en.wikipedia.org/wiki/Ground_station
If you want to get a message from point A to point B, you can send it to point C (and any number in between) which will relay the message. Radio needs line of sight to work. It’s like note passing in a classroom. You can’t reach your friend on the other side of the room, but you can pass it to someone in reach, who can pass it to someone else they can reach. Something as simple as writing who you want it to get to should be enough for each person to decide which way to pass it.
If you think of your ground route like the classroom, a station that can transmit to space could be like a window where you could hold up a big note for someone outside the window to see. They know to look at the window (point their receiver to the transmitter). Then as they move past that window, your notes will go to another window.
The satellites for relay could be like other people outside the windows watching and who can copy the sign and show it. What matters is that the information is effectively the same.
You can bounce radio signals off of the magnetosphere in specific conditions, but that’s not what’s going on here. There’s just a network of satellites in place, so if you can’t make a direct connection, you can relay it through satellites. We also have antennas all over the Earth that are connected through the internet, but not quite enough for complete coverage.
Latest Answers