Posts: 933
From: Belgium
Registered: Jul 2003

posted 10-19-2018 03:56 PM               

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How all those satellites, probes, instruments on planets, space junk are followed?

I can't imagine that every object have its own "following crew" of people, sitting there the whole day to see how things are going. So, how do they do that?

Posts: 4437
From: Sierra Vista, Arizona
Registered: Nov 1999

posted 10-19-2018 08:34 PM               

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In many instances objects are cataloged from launch. Additionally ground and space based sensors deployed as part of several nations' space based situational awareness systems detect and obtain empheris data on secondary debris from staging or impacts, which is compiled into a catalog of objects.

Computers do most of the work correlating detected tracks with their originating source.

Posts: 1463
From: Cape Canaveral, FL
Registered: Mar 2010

posted 10-20-2018 10:18 AM               

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Junk is done differently than spacecraft. Radar and optics are used to track junk. Once junk is found, it is tracked for a short time while in view of a particular sensor to provide enough information to resolve it orbital parameters. Then tracking is occasionally revisited to make sure it is still in the same orbit, which can be done with different sensors around the globe.

For science spacecraft, there are multiple control rooms around the country at NASA centers, contractors, research centers and universities. They contact their particular spacecraft using shared tracking stations or satellites. Each communication session is preplanned when spacecraft are in view of a particular tracking site. Some control centers handle multiple spacecraft.

Military spacecraft also have multiple control centers around the country and tracking stations around the world. So do commercial satellites.

Satellites in high or GSO orbits can remain in constant contact with their ground station. Low orbiters only have contact when they are in view of tracking station.

Some people use tracking station and ground station interchangeably. I prefer to use tracking station for transient and temporary contacts. Like those that would be used for a launch and as a spacecraft changes orbits. A ground station would be for those that just receive data from a spacecraft or control the payload on spacecraft.