There are a few phases to getting a satellite “online”:
– it is installed on the top of the rocket and we do checks with electrical signals to make sure it’s all looking ok
– launch – all done by the rocket, we don’t get any data back during this bit
– separation, it is pushed away from the rocket and it on its own – we start getting data at that point
– it does something called “LEOP” manuevours: Launch and Early Operations Phase – these are planned activities to make sure it gets to where it needs to be safely and checks that we do to make sure everything is working.
The checks are electrical signals, so we switch something on and see if that unit responds.
To “talk” to the spacecraft (and for it to send the data back) it has a big antenna and that is pointed at a ground station – a really big dish on Earth. We decide in advance which ground station we will use, so we know to look out for the stuff coming in.
DId you know – Jodrell Bank near Manchester was were Sputnik was detected!
Depending on where the satellite is going to changes how long it takes to get it online. Gaia went a really long way away – 150000 miles, from launch to completing all it’s checks took 8 months.
For satellites around Earth, that could look like 3 days
Pretty much what Katie said. In fact anybody can pick up the signals from satellites. There are group of people called AmSat (Amateur Radio Satellite) who use their own radio equipment to talk to satellites – anyone can do it. We once used a long wave radio to pick up signals from the International Space Station – we could hear the Russian astronauts talking to Earth! So cool. If you’re interested google AmSat UK.