satellites

[rohannson]

Hi,

I was wondering if someone could explain to me how satellites behave in the sky. Like if they go fast, change directions, blink enz.

Thanks

[Nick Matkin]

They don't stop or change direction if that's what you are asking, although perspective from the ground may make them appear to curve across the sky. As a rough guide I'd say they move at about the rate of a high altitude aircraft - maybe a little faster. So say five to 10 minutes from horizon to horizon, although in practice they are not usually visible below an elevation of about 10 degrees above the horizon.

They don't flash, although the Iridium satellites can flare once for a second or two to much brighter than Venus as they pass overhead.

The ISS is by far the brightest (apart from the Iridium flares) when approaching your observation point.

The ones you can easily see with the naked eye are only a about 100 - 200 miles up. They are 'falling' to Earth, but as they fall the Earth has curved away under them. Here is a good graphic (http://science.howstuffworks.com/question378.htm) showing a huge cannon 'firing' a satellite so you can see how they orbit.

They have fuel, but it's only used in very sort, occasional burst to adjust their orbit gradually. It does not power them like an aircraft.

Eventually, if those in a low-Earth orbit drift too low, they end up in the very thin upper atmosphere which causes them to slow down by atmospheric drag. They slow down more, etc. until they fall so fast they burn up by friction, like dust the particles that cause shooting stars.

If you want to see some on a clear night, put your location into http://www.heavens-above.com/ to see what you'll be able to see.

Hope that's not too much guff...

Nick

[rohannson]

Thanks. :o

[GoodETxSG]

I hope this helps,

This is known by some here on this Forum, I just happened to work with Satellites and Communications while working in Army Command Control Communication Computation & Intelligence AKA "C4I".

Yes indeed a few countries do have top secret satellites that have the ability to change "types" of orbits and direction on a dime. Geo-spacial Engineering has come a long way using the same maneuvering technology as some of the SSP Craft that are in service.

Space has been militarized for quite a while. Some of the satellites we see falling to earth are not because of decaying orbits or end of life devices brought in over oceans in a controlled burn. There are "Hunter Killer Satellites" that track "enemy" reconnaissance & weapons platform satellites as well as these platforms/satellites that have detection and evasion capabilities to evade the "Hunter Killer Satellites" and surface to space weapons.

As far as the ISS and normal communications satellites they behave in the normal geosynchronous, geostationary, geo-polar (etc...) orbits that we are accustomed to seeing in the night sky as white dots moving relatively quickly in comparison to the stars in the background. The more exotic satellite platforms I am speaking of are often confused as alien craft as they appear to "zig zag" and make what look like 90 degree turns though these are usually optical illusions due to perspective.

These very expensive and important satellites are programmed to evade space debris as well as encounters with other satellites both autonomously and with the input of Geo-spacial Engineer's on the ground in various programs such as the known "Space Command's" (& related programs) of the:
This Table Is Unclassified.
Name Title
Air Force Space Command (AFSPC) - Air Force Space Command (AFSPC)
Eglin - Eglin
N/UWSS - NORAD/USSPACECOM Warfighting Support System (N/UWSS)
Naval Space Cmnd (NAVSPACECOM) - Naval Space Command (NAVSPACECOM)
US Army Space Cmnd (USARSPACE) - United States Army Space Command (USARSPACE)

Related Categories:
Name Title
Military Hqtrs & Space Commands - Military Headquarters and Space Commands

http://www.sciencelearn.org.nz/var/sciencelearn/storage/images/media/images/satellites-and-orbits9/861280-1-eng-NZ/Satellites-and-orbits.jpg

Catalog of Earth Satellite Orbits (Edit: "Disclosed/Known Orbits and terms used for decades")
Communications
Weather
GPS
Hubble
Land surveying
CryoSat-2
COSMIC/FORMOSAT
Low-Earth
Polar
Medium-Earth
Sun-synchronous
Geosynchronous
Geostationary

http://earthobservatory.nasa.gov/Features/OrbitsCatalog/

http://images.slideplayer.us/7/1641148/slides/slide_10.jpg

[Nick Matkin]

The more exotic satellite platforms I am speaking of are often confused as alien craft as they appear to "zig zag" and make what look like 90 degree turns though these are usually optical illusions due to perspective.

That's very interesting, thanks. I doubt these will appear in the heavens-above.com database!

Do they actually zigzag fast enough and at sufficiently acute angles to be able to be clearly seen doing it?

Nick

[GoodETxSG]

Yes, they change directions and velocity in unconventional ways.

They can be clearly seen depending on conditions, especially if you are away from the light pollution of city lights... If they are seen at the right angle and altitude and catch a reflection of the Sun you can catch quite a show.

This is not to say that ALL zig zagging or dancing lights are secret satellites... There are craft up there. This was just in answer to your question.

Edit: FYI... These satellite observations would not be an often occurrence but a reactionary maneuver to a perceived threat. Otherwise they blend in with the other satellite traffic or station in proximity with stars...