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Author Topic:   How did a new satellites get in the right position?
LinearAq
Member (Idle past 4697 days)
Posts: 598
From: Pocomoke City, MD
Joined: 11-03-2004


Message 7 of 35 (427432)
10-11-2007 12:42 PM
Reply to: Message 1 by techristian
10-11-2007 10:25 AM


Not such a mystery
techristian writes:
The satellite must mysteriously set itself up so that it is neither pulled back by gravity nor let loose into space. It must have that perfect balance between just enough gravity but not too much gravity. How did the satellites get to that perfect spot in the first place?
Actually, if you jump up into the air you are in orbit around the center of the earth. Unfortunately, the perigee (lowest point) of your orbit is not far enough away from the center of the Earth to prevent you from impacting with the surface of the Earth.
Getting an object into orbit is not that big a deal. Just give it enough velocity perpendicular to a line between it and the center of the Earth and it will achieve orbit. Now putting it in an orbit that you want it to maintain is substantially more difficult. A geostationary satellite would have to be moving at a speed of 3.1 km/s (6935 mph)in the direction of the earths rotation (west to east) at an altitude of 35,600 km (22,121 mi). (ABE) The geostationary orbit is always over the Equator.
You can get geosynchronous orbits that fly over the same longitude by ensuring the west-to-east component of the velocity is 3.1 km/s. The latitude would cycle between two extremes in each orbit. The altitude of that satellite would depend on the orbit inclination which would affect the total velocity.
Edited by LinearAq, : correcting information

This message is a reply to:
 Message 1 by techristian, posted 10-11-2007 10:25 AM techristian has not replied

Replies to this message:
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LinearAq
Member (Idle past 4697 days)
Posts: 598
From: Pocomoke City, MD
Joined: 11-03-2004


Message 10 of 35 (427440)
10-11-2007 1:43 PM
Reply to: Message 9 by Dr Adequate
10-11-2007 1:05 PM


techristian writes:
Oh yes, and stay in orbit for MILLIONS OF YEARS.
Dr Adequate answers: Because as orbits are stable, it would take a miracle to knock it out of its orbit.
Actually, our group did just that by hitting it with another satellite...oops.
Also, man-made satellites have issues like drag and gravitational variance that cause them to lose their proper orbital characteristics. Enough "fuel" is provided to correct the orbits for the length of the mission (actually 3X the mission length) with enough left over to send them to reentry or into a "parking" orbit that is out of the way.
Without this correction some of the LEO's (Low Earth Orbiters) could have an uncontrolled reentry.

This message is a reply to:
 Message 9 by Dr Adequate, posted 10-11-2007 1:05 PM Dr Adequate has replied

Replies to this message:
 Message 11 by Dr Adequate, posted 10-11-2007 1:53 PM LinearAq has replied
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LinearAq
Member (Idle past 4697 days)
Posts: 598
From: Pocomoke City, MD
Joined: 11-03-2004


Message 14 of 35 (427446)
10-11-2007 2:03 PM
Reply to: Message 11 by Dr Adequate
10-11-2007 1:53 PM


Dr Adequate writes:
Yes, yes, and those aren't the satellites he's asking about, is he?
He said new satellites and not new moons or planets so I assumed he was talking about man-made ones. Do you think he was asking the question because he is so blindingly ignorant of gravity that he thought he could trip someone up?
All you need is the right velocity and proximity to a large enough mass relative to your own and, bang, you've established an orbit.
I fail to see why this would be something that requires an omnipotent being to accomplish.
Frankly, I thought he wanted to learn something about orbital dynamics.

This message is a reply to:
 Message 11 by Dr Adequate, posted 10-11-2007 1:53 PM Dr Adequate has replied

Replies to this message:
 Message 17 by Dr Adequate, posted 10-11-2007 2:09 PM LinearAq has not replied
 Message 19 by Taz, posted 10-11-2007 2:18 PM LinearAq has not replied

  
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