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Author Topic:   How did a new satellites get in the right position?
techristian
Member (Idle past 567 days)
Posts: 60
Joined: 04-03-2002


Message 1 of 35 (427387)
10-11-2007 10:25 AM


Such as the Moon in relation to the Earth or the Earth in relation to the Sun? 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?

Oh yes, and stay in orbit for MILLIONS OF YEARS.

Dan

http://teachmedrums.com

Edited by techristian, : addition


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Message 2 of 35 (427414)
10-11-2007 11:41 AM


Thread moved here from the Proposed New Topics forum.
    
macaroniandcheese 
Suspended Member (Idle past 393 days)
Posts: 4258
Joined: 05-24-2004


Message 3 of 35 (427415)
10-11-2007 11:42 AM
Reply to: Message 1 by techristian
10-11-2007 10:25 AM


as far as i know, our orbit is declining. i know the moon's is.
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Rahvin
Member (Idle past 136 days)
Posts: 3943
Joined: 07-01-2005


Message 4 of 35 (427421)
10-11-2007 12:02 PM
Reply to: Message 1 by techristian
10-11-2007 10:25 AM



Such as the Moon in relation to the Earth or the Earth in relation to the Sun? 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?

Oh yes, and stay in orbit for MILLIONS OF YEARS.

Dan

http://teachmedrums.com

It's actually really simple.

An orbit can only remain stable if the orbiting body is moving at the right speed at the right distance. Too fast, and the body will fly away. Too close, and the body will fall into whatever it is orbiting.

The simple answer is that those bodies that happened to be the correct distance away at the correct speed are the ones remaining in the solar system - that is, they are the objects that did not fly away or fall into the sun (or other nearby bodies). Those bodies attracted the smaller particles in their immediate area and grew to the planets, asteroids, and comets that remain today.

The moon is essentially the same case. The current model of the origin of our moon is that it was created as the result of a large collision with Earth. The majority of the debris would have fallen back to Earth over years. Some happened to be in a relatively stable orbit (the moon is actually moving a few centimeters away from the Earth each year, as I recall) with the Earth, and this debris accreted over many years into the moon. The moon does not fall into the sun because it's basically in the same stable orbit as the Earth.

Hopefully this should explain it to you. It's not as if these satellites were suddenly poofed into existence and placed specifically in their orbits. It's literally an inevitability that the matter which happens to be moving at the right speed at the right distance will be all that remains after the remaining particles are either attracted to a stable body or thrown out of the system.


Every time a fundy breaks the laws of thermodynamics, Schroedinger probably kills his cat.
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EighteenDelta
Inactive Member


Message 5 of 35 (427422)
10-11-2007 12:03 PM


Our moon is slowly escaping the earths gravity, at about 3.8 cm every year. Currently the moon is about 4.527 ± 0.01 billion years old, but hasn't always been as far away or as slow in revolution.

As far as the question of how it got there, when the impact of Theia (or sometimes called Orpheus) ejected large amounts of the earths crust off, the materials were either close enough to be recaptured by the earths gravity or too far away. Of the materials too far away to be recaptured, the materials that had a high enough velocity, were carried away, the mass that remained in that band that wasn't far enough away or close enough, eventually was pulled together by gravity to form the moon. So the question you ask is misleading, the moon wasn't 'put' into orbit, it was 'built' in orbit.

Mars for example has two 'moons' that are captured asteroids, Phobos and Deimos. Mars has a weaker gravity though owing to its smaller mass.

A really good information source with computer simulations to help you understand the process,

http://www.psrd.hawaii.edu/Dec98/OriginEarthMoon.html

or

http://www.xtec.es/recursos/astronom/moon/camerone.htm

-x

Edited by EighteenDelta, : No reason given.

Edited by EighteenDelta, : added gifs

Edited by EighteenDelta, : Removed gifs, too large and unsightly


"Debate is an art form. It is about the winning of arguments. It is not about the discovery of truth. There are certain rules and procedures to debate that really have nothing to do with establishing fact — which creationists have mastered. Some of those rules are: never say anything positive about your own position because it can be attacked, but chip away at what appear to be the weaknesses in your opponent's position. They are good at that. I don't think I could beat the creationists at debate. I can tie them. But in courtrooms they are terrible, because in courtrooms you cannot give speeches. In a courtroom you have to answer direct questions about the positive status of your belief. We destroyed them in Arkansas. On the second day of the two-week trial we had our victory party!"
-Stephen Jay Gould
  
jar
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Member Rating: 1.6


Message 6 of 35 (427424)
10-11-2007 12:10 PM
Reply to: Message 1 by techristian
10-11-2007 10:25 AM


Easy answer is...
How did a new satellites get in the right position?

Well there is no "right" position, but the answer to why they are where they are is over time.

The satellite must mysteriously set itself up so that it is neither pulled back by gravity nor let loose into space.

Utter nonsense. A satellite is where it happens to be due to very normal well understood models.

It must have that perfect balance between just enough gravity but not too much gravity.

Huh? That sounds like the kind of nonsense Biblical Christians spout. The amount of gravity is a function of the mass of the object.

How did the satellites get to that perfect spot in the first place?

Well, again, there is no perfect spot in the first place. That is simply silly. Just look at our own little solar system and you find satellites all over the place.

Oh yes, and stay in orbit for MILLIONS OF YEARS.

Billions even. They do it by falling.

Just curious but have you even had beginning introduction to science yet?


Aslan is not a Tame Lion
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LinearAq
Member (Idle past 1141 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


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Message 8 of 35 (427434)
10-11-2007 12:53 PM


Forum Guidelines Reminder
Please, let's keep the discussion civil and positive.


--Percy
EvC Forum Director

    
Dr Adequate
Member
Posts: 12837
Joined: 07-20-2006
Member Rating: 2.2


Message 9 of 35 (427436)
10-11-2007 1:05 PM
Reply to: Message 1 by techristian
10-11-2007 10:25 AM


The satellite must mysteriously set itself up so that it is neither pulled back by gravity nor let loose into space.

It is being pulled back by gravity, which is why it's not let loose into space.

It must have that perfect balance between just enough gravity but not too much gravity.

"Must", you say? Did it not occur to you that before you announced what "must" be true about gravity, you should have studied the theory of gravity?

Its orbit is a "balance" (so to speak) between its velocity and its gravitational attraction to the earth. Now, orbits are stable. That is to say, a change in the position or velocity or mass of the satelite would result in a change in its orbit, not in it stopping orbiting and crashing to earth or flying off into space.

If some sort of "perfect balance" of cosmic fine-tuning was required, as you seem to think, then we'd have futzed the solar system by landing spaceships on the moon and suchlike exploits.

Oh yes, and stay in orbit for MILLIONS OF YEARS.

Because as orbits are stable, it would take a miracle to knock it out of its orbit.

---

You can see some of the math, including a proof of the stability of orbits, here.

Edited by Dr Adequate, : No reason given.

Edited by Dr Adequate, : No reason given.


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LinearAq
Member (Idle past 1141 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.


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Dr Adequate
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Posts: 12837
Joined: 07-20-2006
Member Rating: 2.2


Message 11 of 35 (427443)
10-11-2007 1:53 PM
Reply to: Message 10 by LinearAq
10-11-2007 1:43 PM


Actually, our group did just that by hitting it with another satellite...oops.

Huh?

But OK, let's be pedantic, the moon could be knocked into the Earth or out of the solar system by colliding with something else very massive.

Also, man-made satellites have issues like drag and gravitational variance that cause them to lose their proper orbital characteristics.

Yes, yes, and those aren't the satellites he's asking about, is he?

I'm trying to keep this simple.

Edited by Dr Adequate, : No reason given.


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jar
Member
Posts: 24775
From: Texas!!
Joined: 04-20-2004
Member Rating: 1.6


Message 12 of 35 (427444)
10-11-2007 1:56 PM
Reply to: Message 10 by LinearAq
10-11-2007 1:43 PM


And the hits keep rolling.
Actually, our group did just that by hitting it with another satellite...oops.

Isn't that also true of our moon? Just hit one satellite with another satellite and we are set to spoon in June.


Aslan is not a Tame Lion
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truthlover
Member (Idle past 524 days)
Posts: 1548
From: Selmer, TN
Joined: 02-12-2003


Message 13 of 35 (427445)
10-11-2007 1:58 PM
Reply to: Message 7 by LinearAq
10-11-2007 12:42 PM


Re: Not such a mystery
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.

Absolutely awesome. I live in a [relatively large] house with two other families, and I have six children. There are 14 people under the age of 18 in our house. I love opportunities to play with their minds.

So the next time I'm jump roping on the front porch, I can tell them that I'm not exercising, I'm attempting to maintain orbit.

If I remember correctly, I'll have to get to 22,000 miles of elevation to maintain geosynchronous orbit and land back on my front porch rather than someplace dangerous or far from home. It will take a few years, I think, to work up to that high of a jump :P. Besides, I don't want to maintain orbit, but return to earth, so I'm going to have to figure out how high to go and how much atmospheric drag to account for. I know my basic orbiting speed is close to 800 MPH, but I'll have to get that exact, too.

Or, maybe I can just get it right the way I would catching a baseball, intuitively with practice.

Maybe I better get back to work and stop wasting my time and everyone else's :D.

My kids will love that discussion, though. I'll bet the teenagers will keep it going for hours and actually go look up information on orbits.

Edited by truthlover, : Fixed my quote box


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LinearAq
Member (Idle past 1141 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.


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iceage 
Suspended Member (Idle past 2380 days)
Posts: 1024
From: Pacific Northwest
Joined: 09-08-2003


Message 15 of 35 (427450)
10-11-2007 2:06 PM
Reply to: Message 1 by techristian
10-11-2007 10:25 AM


Balance of Forces
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.

hi Techristian.

No mystery or magic really. The same mystery on how a boat finds that perfect balance between just enough buoyancy and not too much much buoyancy - a balance of forces on the freebody.

For an orbiting satellites the body will find that perfect orbit based on the velocity and mass of the satellite.

techristian writes:

Oh yes, and stay in orbit for MILLIONS OF YEARS.

Billions actually. The moon is receding, but at a slow pace in human terms (a few inches per year) because of the relatively small energy loss due to tides and deformations.

Edited by iceage, : No reason given.


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