View Full Version : Errr, Why Does the Moon Orbit the Eath ?
Seems like an easy question to answer, after all this Moon is just out there.
But if you do the math, the Sun 'pulls' on the Moon twice as much as our Earth.
Remember that the 'relative orbitital planes' of the Moon and the Earth are almost parallel and perpendicular to the magnetic axis of the Sun (or Earth).
So there are times when the Moon is moving directly towards the Sun and times when it is powering away.
Mr James R, states the solution is simple.
"This is an easy one. The Moon orbits the Earth because the Earth's gravity attracts the Moon."
and
"Yes, but the Sun's gravity also attracts the Earth. Both the moon and the Earth are in orbit around the Sun. This is fairly basic physics."
(both quotes drawn from the / Should we get more Moderators?/ thread in the Open Government stream.
If it is so simple, I think I may be able to understand an explanation, if there is one.
Is there an explanation ???????????
The Earth and the Moon are both orbiting the sun. If the Sun only exerted it's infulence on the Earth, the Earth's path would curve but the Mon's would not curve in the same way... resulting in the orbit being disturbed.
If you do the math, both the Earth and the Moon experience the same acceleration due to the Sun. This results in the Earth and Moon both following the same path around the Sun. The added complexity is that the Moon and Earth are also a system of orbiting bodies... but the math still works out.
You can't look only at force. Acceleration is far more important.
"times when it is powering away"
It is never 'powering away'. It is in a mostly circular orbit around the Earth.
"Remember that the 'relative orbitital planes' of the Moon and the Earth are almost parallel and perpendicular to the magnetic axis of the Sun (or Earth)."
What does this have to do with anything?
Any more questions?
Fraggle Rocker
04-26-04, 09:43 PM
The Earth and the Moon form a system which revolves around the Sun. The Earth-Moon system rotates about its center of gravity. Since the Earth is roughly 500 times as massive as the Moon (mass is proportional to the cube of radius assuming they have the same density), the system's center of gravity is so close to the Earth's own center of gravity that it's actually inside the Earth. But if you had precise enough instruments and the right place to watch from, you could see the Earth wobbling slightly in relation to its own C of G.
Good rhetoric, but sophism IMO.
Orbits are determined by the vector, tangential velocity..... this implies direction, which is all important in where a body travels, unless it is subverted by an unbalanced force.
We know that objects placed at L1 to Earth are in both Sun orbit and Earth orbit. The Moon is much closer that L1, the Moon is not ever in a Sun orbit.
Math, where is it?
blackholesun
04-26-04, 10:35 PM
Math:
http://lhs.lexingtonma.org/Teachers/Trainor/emsys/emsys.htm
BTW the moon is in the sun's orbit. Just because it circles the Earth doesn't mean it isn't orbiting the sun either.
Edit - More math:
http://www.ams.org/new-in-math/cover/orbits1.html
blackholesun
04-26-04, 10:47 PM
Let's put it this way. The system is working because we see it working. Our math for may years has been able to accurately predict these movements as we can also accurately send probes to the furthest reaches of the solar system calculating their trajectories. If your math isn't explaining the planetary orbits correctly but Newton's laws and (more accurately) GR do than what does that say about your theory? That the universe is wrong and should be following YOUR rules? Should we call you God or something?
>> . The system is working because we see it working.
Ha Ha..... my math shows why what we see is.
What I am asking here is established opinion.... all I read is sophistry.
blackholesun
04-26-04, 11:10 PM
Ha Ha..... my math shows why what we see is.
Um so does Newton and GR. It HAS been.
What I am asking here is established opinion.... all I read is sophistry.
The links I posted are established theory with a lot of evidence to back it up. Really, what HAVE you predicted that GR and Newton haven't? And more importantly what observable evidence that GR and Newton accurately model does YOUR model discredit? Because so far you haven't really proven yourself on ANYTHING. And yet we're still accurately predicting planetary movement and sending probes to planets without you. Hmmm....makes you think. lol
>> Um so does Newton and GR
well at least we have got that far..... now put up the math !
transio
04-26-04, 11:27 PM
Zarkov,
All I see is trolling. The earth and the moon treated as closed system follow a predictable path around the Sun. How that closed system acts inside itself is separate from how it interacts with external systems. When you try to apply the Sun's forces to the Moon part of the Earth-Moon system, you're doing redundant math. You can't apply the same forces twice! Well, maybe in YOUR physics, you can, but not in what the general public accepts as Physics! Who did you say is the sophist again? ;)
blackholesun
04-26-04, 11:31 PM
I did. LOOK AT THE LINKS!!!!!! They deal with Newton.
Here are some more for GR:
http://www.fourmilab.ch/gravitation/orbits/
http://csep10.phys.utk.edu/astr161/lect/
http://www.fesg.tu-muenchen.de/bv/seiten-e/forschung/lunar.html
Why do I post links? Because its a pain to post math otherwise.
Just read Zarkov. Jeez.
>> I did. LOOK AT THE LINKS!!!!!! They deal with Newton
Useless, Lagrangian points and theoretical orbits.... not related to Moon, Earth and the Sun.
Not one of those links address the WHY???????
blackholesun
04-27-04, 12:19 AM
WHY what?!
The first link especially is very informative about the earth moon system.
You wanted orbital math I gave you orbital math. I assume you're chosing to ignoring those links because they don't agree with YOUR theory.
Useless, Lagrangian points and theoretical orbits.
OOOOOOOOOOR maybe its your theory that is useless.
transio
04-27-04, 12:37 AM
Apparently, Zarkov believes that any explanation he doesn't understand is a sophism? :D
blackholesun
04-27-04, 12:42 AM
Given his past posts yes hehe.
transio
04-27-04, 12:42 AM
The bottom line is that if you break the moon out from the earth-moon system, it is still affected by the sun's gravity in an apparent fashion, as can is evidenced by its path around the Sun (a sinusoidal ellipse). The sinusoid is the result of the Earth's gravity. If you eliminate the Earth altogether, you're left with an Ellipse (although without the Earth to hold it down, the moon will shoot off into space like shot from a sling).
If you get it, you get it. If you don't, stick with Lagrange. :D
>> You wanted orbital math I gave you orbital math
I came, I saw, and I left, empty handed :(
>> The sinusoid is the result of the Earth's gravity.
OK, then apply this to the moons of Jupiter.... That is all gobblygook.
curioucity
04-27-04, 04:53 AM
By the way, is it possible for a satellite to orbit a planet in a planeperpendicular to the planet's orbital plane? I mean like the moon going around the pole, equator, other pole, equator again etc.... or is it already a case of some satellites?
2inquisitive
04-27-04, 05:16 AM
Yes, polar orbits by satellites are quite common. Polar orbits are usually employed
by satellites used to map a planets' surface. The planet or moon will rotate inside
the orbit so the entire surface can be mapped.
John Connellan
04-27-04, 07:06 AM
Its an orbit within an orbit Zarkov. Surely u must realise that is possible?!
Stryder
04-27-04, 08:07 AM
http://chatsoba.sprawl-vr.com/images/chaosp.gif
Now my image/diagram isn't particular brilliant, I'm not exactly going to town on dressing it up either but the reason why I created it was to try and give you a clue at something you should perhaps look at to get a better understanding of the relationship of mass in conjuction to different bodies.
The diagram was actually used in an explaination of chaotic algorythms in James Gliecks book 'Chaos'.
Take three weights of different value, they are all to be a weight used as a pendulum, however rather than having three different pendulums you string them all together, so three seperate pendulums are now made to kind of be one. (as seen in the image)
Now you will find that if you swing the pendulum it will react different based upon weight positions and string length, but it should give you an idea of what takes precidence in relationship based upon weight and position.
(You could theoretically have it like the image where the large weight comes first followed by the medium one then right at the end the smallest weight, and you could infact change the smallest weight and medium weight around if experimenting.)
The reason for the weights being setup like this is to give the same kind of relationship the sun would have with the earth and then the moon.
(Although the relationship is inaccurate for many reasons, one of them being that the moons orbit alters slightly based upon a straight alignment in theory, everytime there is an eclipse [solar or lunar] there will be an increased alteration in the orbit)
You should notice a few things about it that might give you a reason to understand why you might be overlooking something, of course I'm not going to tell you what otherwise their would be no point doing the experiment would there?
John Connellan
04-27-04, 09:09 AM
Very nice way of explaining it Stryder! Since the strings act the same way gravity would :)
RawThinkTank
04-27-04, 09:45 AM
Why doesn’t the moon just fall into sun as it approaches in the direction of sun while it orbits the earth or at least it should incline towards it ?
Stryder
04-27-04, 10:33 AM
Why doesn’t the moon just fall into sun as it approaches in the direction of sun while it orbits the earth or at least it should incline towards it ?
Well thats the suggestion towards orbital paths (decays and longation), however as I believe is mentioned their is a LaGrange point between the planet and it's satellite, and the basis here is both the earth and the moon have their velocities while orbiting the sun, the moon has it's own orbital path around the earth that alters as it deals with the tilt of the planetary poles.
(in fact this is shown in both tidal changes and even polar alterations due to molten magma movements.)
one of the many places to find information on Lagrange:
http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Lagrange.html
James R
04-27-04, 11:53 AM
Why doesn’t the moon just fall into sun as it approaches in the direction of sun while it orbits the earth or at least it should incline towards it ?
Because the Earth's gravitational attraction and the existing orbit velocity of the moon around the Sun prevent it from doing that.
>> Because the Earth's gravitational attraction and the existing orbit velocity of the moon around the Sun prevent it from doing that.
By fall into the Sun, I mean form a true Sun orbit, and quite an elliptical one it would be!!!!!!........ Please show some mathematical logic.
All this arm waving really does no justice to a reallly important question.
Zarkov,
You still seem to be completely ignoring acceleration. Yes, at one point the Moon's velocity is toward the Sun. At the same time though the Moon is being accelerated toward the Earth by gravity. This causes the velocity vector to rotate away from the sun.
What of this do you disagree with?
>> At the same time though the Moon is being accelerated toward the Earth by gravity.
Yep but only half (according to Newton) as strong as the Sun!!!!!!
Basically Newton and Mr E's efforts are incorrect.
Can't you see that.
The Moons of Jupiter are in an even worst theoretical situation, and yet there is no GREAT preturbations in either moon's orbits....
The proof is in the math..... and there basically is none.
Yeah, and the Earth is also being accelerated toward the sun BY THE SAME AMOUNT, which makes the relative motion between the moon and earth ZERO due to the sun.
Where do you disagree?
The proof is in the math..... and there basically is none.
The math has been shown to you.
>> The math has been shown to you.
if so show me again, as I must have overlooked it.
>> Persol: You still seem to be completely ignoring acceleration
>> You still seem to be completely ignoring acceleration
The direction is changing for the Moon, therefore the vector is varying...
PS, you seem to like acceleration, show a formula that uses this as a criteria for planetary motion, please.
:)
About as basic as you can get...
F = Gm1m2/r^2
a=F/m1
dv=dt*a
where m1 is the sun
The direction is changing for the Moon, therefore the vector is varying...
The direction is ALSO changing for the Earth... and by the same amount. You said you've done the math. If so this is your result. The above equations show very quickly that the acceleration due to the Sun is the same for both the Moon and the Earth.
If it is so simple, I think I may be able to understand an explanation
You'd think so, wouldn't you?
Unfortunately, history says otherwise.
PS, you seem to like acceleration, show a formula that uses this as a criteria for planetary motion, please.
:)
Have you heard of Newton's second law?: F = ma
Open any undergraduate book on mechanics, you will find there the solution to planetary motion.
>> The direction is ALSO changing for the Earth... and by the same amount.
Sorry, please show this mathematically, the Earth has a constant change of direction, normal to a radius to the SUN
The Moon has a constant change of direction normal to the radius to the EARTH.
These are entirely different.
Lots of know-alls here of no substance.
I can't believe I'm actually doing this... knowing that you are just a troll
msun=mass of sun
mearth=mass of earth
mmoon=mass of moon
g=gravitation constant
rsun=distance between sun and earth=distance between sun and moon
rmoon=distance between earth and moon
Fsunearth = G*msun*mearth/rsun^2
Fsunmoon = G*msun*mmoon/rsun^2
acceleration of earth due to sun=Fsunearth/mearth
=G*msun/rsun^2
acceleration of moon due to sun=Fsunmoon/mmoon
=G*msun/rsun^2
You'll notice that the acceleration of the Earth and the Moon due to the Sun are both the same. This means that no relative motion is generated between the Earth and the Moon because of the Sun.
And this answers your request for:
>> The direction is ALSO changing for the Earth... and by the same amount.
Sorry, please show this mathematically, the Earth has a constant change of direction, normal to a radius to the SUN
This problem has been simulated in hundreds of programs you can download off the net and is simulationed by hundreds of thousands of students a year. This is one of the most basic problems having to do with gravity. Trust us, it works for the earth, sun, moon system quite nicely.
>> Fsunearth = G*msun*mearth/rsun^2
Fsunmoon = G*msun*mmoon/rsun^2
You are treating both as satellites of the Sun.... this assumption is invalid, making your calculations invalid.
It is obvious from observation that the Moon is NOT undergoing the SAME motion as the Earth.
>> >> This means that no relative motion is generated between the Earth and the Moon because of the Sun.
This is true, but it is not the answer to the question.....
All relative motion of the Moon is due entirely to the Earth.
You are treating both as satellites of the Sun.... this assumption is invalid, making your calculations invalid.
No.. I'm not. That equation is to calculate the force between two objects. THIS IS THE SAME EQUATION WHICH YOU SAID DIDN'T WORK. The fact is, the Earth feels a larger force because it is bigger. However the acceleration is the same as the moon because if F=ma.
>> >> This means that no relative motion is generated between the Earth and the Moon because of the Sun.
This is true, but it is not the answer to the question.....
All relative motion of the Moon is due entirely to the Earth.Actually, it is the answer. I showed that the there is no relative acceleration between the Earth and the Moon due to the Sun... and hence no relative motion between teh earth and moon due to the sun. It agrees with your statement that the Moon's movement is due to the Earth.
You asked for the math, I showed it to you. It is to calculate the force and acceleration caused by gravity between two objects. The above equations show that the acceleration due to the sun is the same for both the Earth and the Moon. This results in no relative movement due to the Sun.
So what you are saying is
Because both the Earth and the Moon are travelling around the Sun, the position of their point masses is stabolised to the same degree by their orbital motion.
Thus the extra motion the Moon has around the Earth is because of the force between the Earth and the Moon.
Is this your view?
James R
04-28-04, 01:54 AM
Zarkov:
By fall into the Sun, I mean form a true Sun orbit, and quite an elliptical one it would be!!!!!!........ Please show some mathematical logic.
The moon orbits the sun in almost a perfect circle, perturbed slightly by its co-orbit with the Earth.
>> At the same time though the Moon is being accelerated toward the Earth by gravity.
Yep but only half (according to Newton) as strong as the Sun!!!!!!
Both the moon and the Earth are in free fall relative to the sun.
Basically Newton and Mr E's efforts are incorrect.
I'm sorry, but you are wrong.
The Moons of Jupiter are in an even worst theoretical situation, and yet there is no GREAT preturbations in either moon's orbits....
The moons of Jupiter are in the same situation.
The proof is in the math..... and there basically is none.
You didn't look very hard, did you?
Sorry, please show this mathematically, the Earth has a constant change of direction, normal to a radius to the SUN
Can't do that, because it isn't true. It seems you are wrong again.
The Moon has a constant change of direction normal to the radius to the EARTH.
No it doesn't.
Lots of know-alls here of no substance.
So it seems.
You are treating both as satellites of the Sun.... this assumption is invalid, making your calculations invalid.
The moon and the Earth are both satellites of the sun. You are wrong yet again.
It is obvious from observation that the Moon is NOT undergoing the SAME motion as the Earth.
Yes.
All relative motion of the Moon is due entirely to the Earth.
Relative to what? Please be specific.
So what you are saying is
Because both the Earth and the Moon are travelling around the Sun, the position of their point masses is stabolised to the same degree by their orbital motion.
What do you mean by "stabolised"?
Thus the extra motion the Moon has around the Earth is because of the force between the Earth and the Moon.
Is this your view?
That's part of the explanation. The Earth's gravity certainly affects the Moon's motion.
>> What do you mean by "stabolised"?
Ok, the force between the Earth or Moon and the Sun is the ?? same which is countered (stabolised) by a tangential velocity,,,, that allows the Earth and Moon to orbit the Sun. This only assures that the tangential velocity of the Earth is the same as the 'corrected' (in Earth orbit direction) Moon's velocity.
Next, why then does the Moon orbit the Earth ?
>> The moon orbits the sun in almost a perfect circle, perturbed slightly by its co-orbit with the Earth.
This I doubt, it must follow in the same ellipse as the Earth, and on top of that it alternately travels faster and slower than the Earth, and both powers away from the Sun, and towards it, as it orbits the Earth.
All this reminds me of Ptomoly's cosmology of epicycles within epicycles.
Please explain.
James R
04-28-04, 03:32 AM
Zarkov:
Ok, the force between the Earth or Moon and the Sun is the ?? same
No. The force on the sun's gravity on the Earth is greater than the force of the sun's gravity on the Moon. The acceleration is approximately the same for the Earth and Sun, because they are at approximately the same distance from the Sun, and acceleration is force divided by mass.
Next, why then does the Moon orbit the Earth ?
Because the Earth's gravity pulls on the Moon.
>> The moon orbits the sun in almost a perfect circle, perturbed slightly by its co-orbit with the Earth.
This I doubt, it must follow in the same ellipse as the Earth, and on top of that it alternately travels faster and slower than the Earth, and both powers away from the Sun, and towards it, as it orbits the Earth.
"Powers" is the wrong word, but other than that you are correct.
All this reminds me of Ptomoly's cosmology of epicycles within epicycles.
Please explain.
Yes, there is a similarity, if you want to think of it like that.
The problem with the model you are putting forward is that such a bipolar interaction of the Sun and the Earth with the Moon, would quickly lead to quite an eccentric orbit for the Moon, IMO
This is not seen, instead the Moon's orbit is quite circular and moving away from Earth.
The problem with the model you are putting forward is that such a bipolar interaction of the Sun and the Earth with the Moon, would quickly lead to quite an eccentric orbit for the Moon, IMO
In your opinion...
Can you show your derivation of such an orbit, using Newtonian mechanics and gravity?
Stryder
04-28-04, 07:07 AM
This post isn't an entry to try and aid explaining it, but I just wanted to mention to Persol that although he wasn't too happy about attempting the Maths, it was worth a try as others might benefit from it.
>> Can you show your derivation of such an orbit, using Newtonian mechanics and gravity?
We both agree that the greater orbit of both bodies, is similar and counters the Sun's gravity (inertial movement) only if both bodies were actually in the same orbit.
Because there is a "non inertial" component that is harmonic (caused by the Earth), natural precession will accentuate this trying to bring the Moon back to an inertial Sun orbit, IMO.
Because in a static sense the Sun 'attracts' the Moon twice as strong as the Earth does. Sun gravity to Moon = 2 X Earth gravity to Moon.
blackholesun
04-28-04, 03:19 PM
Because in a static sense the Sun 'attracts' the Moon twice as strong as the Earth does. Sun gravity to Moon = 2 X Earth gravity to Moon.
That doesn't matter Zarkov. Graviational influence is an inverse square law. The moon is much closer to the Earth then the Sun is to the Moon and Earth.
Here is another good link to someone that knows his stuff, given that you aren't listening to anyone whos knows their stuff on this board.
http://www.badastronomy.com/bad/misc/planets.html
Can you show your derivation of such an orbit, using Newtonian mechanics and gravity?I take it that you can not do this. Others however have done this, and do it on a daily basis... and it has been demonstrated correct.
Because there is a "non inertial" component that is harmonic (caused by the Earth), natural precession will accentuate this trying to bring the Moon back to an inertial Sun orbit, IMO.Once again, in your opinion. If you actually do the math though you will see that this is not the case.
Because in a static sense the Sun 'attracts' the Moon twice as strong as the Earth does. Sun gravity to Moon = 2 X Earth gravity to Moon.ONCE AGAIN, the force doesn't matter.... the acceleration does. The acceleration due to the sun is almost exactly the same.
Thus the extra motion the Moon has around the Earth is because of the force between the Earth and the Moon.
Is this your view?The motion of the Moon relative to the Earth is due to the acceleration due to the gravity between the Moon and the Earth.
Janus58
04-28-04, 06:32 PM
>> Can you show your derivation of such an orbit, using Newtonian mechanics and gravity?
We both agree that the greater orbit of both bodies, is similar and counters the Sun's gravity (inertial movement) only if both bodies were actually in the same orbit.
Because there is a "non inertial" component that is harmonic (caused by the Earth), natural precession will accentuate this trying to bring the Moon back to an inertial Sun orbit, IMO.
Because in a static sense the Sun 'attracts' the Moon twice as strong as the Earth does. Sun gravity to Moon = 2 X Earth gravity to Moon.
But we are not dealing with a static system but a dynamic one. The Earth and Moon both orbit the Sun in nearly identical orbits. To find the force of separation the Sun exerts on the pair due to the fact that the orbits are not exactly identical, we must examine the difference between the two orbits.
Generally, the Moon moves 384000 km closer to and further away from the Sun than the Earth. Thus the difference in force it feels would be due to this difference in distance I.E. the difference between G* 2e30 * 7.35e22/(1.496e11)² and G* 2e30 * 7.35e22/(1.496e11 - 3.84e8)²
This difference is the magnitude of the resultant force trying to pull the Earth and moon apart.
Comparing this force to the force of gravity exerted on the Moon by the Earth and we find that it is 100 times smaller than the latter. Enough to "stretch out" the Moon's orbit around the Earth a little along the line joining it to the Sun, but way short of that needed to pull the Moon away from the Earth.
>> Because in a static sense the Sun 'attracts' the Moon twice as strong as the Earth does. Sun gravity to Moon = 2 X Earth gravity to Moon.
That doesn't matter Zarkov. Graviational influence is an inverse square law. The moon is much closer to the Earth then the Sun is to the Moon and Earth. >>>>
Whatever. Blackholesun,... the original assertion I presented is correct, even though as you said, the Moon is closer to the earth. I am afraid the Sun is too big to imagine.
>>> Enough to "stretch out" the Moon's orbit around the Earth a little along the line joining it to the Sun
Yep certainly
>> ONCE AGAIN, the force doesn't matter.... the acceleration does.
and
>> The motion of the Moon relative to the Earth is due to the acceleration due to the gravity between the Moon and the Earth.
And the force is due to gravity.... mmmh make up your mind Persol.
>> Generally, the Moon moves 384000 km closer to and further away from the Sun than the Earth. Thus the difference in force it feels would be due to this difference in distance I.E. the difference between G* 2e30 * 7.35e22/(1.496e11)² and G* 2e30 * 7.35e22/(1.496e11 - 3.84e8)²
This difference is the magnitude of the resultant force trying to pull the Earth and moon apart. >>>>>
this thought has some merit.
James R
04-28-04, 10:47 PM
Yes, so compare the force in the last post, trying to pull the Earth and Moon apart, to the force trying to pull them together, namely:
G * 6e24 * 7.35e22/(3.84e8)<sup>2</sup>
and tell me which is bigger.
RawThinkTank
04-29-04, 10:07 AM
Even though humans have no Idea what gravity is and how it works U can just go ahead without tackling the real problem and Answer this :
At what height will a moon’s artificial satellite’s orbit will become inclined towards earth from moon and how much?
Please explain in theorotical details.
2inquisitive
04-29-04, 10:28 AM
Even though humans have no Idea what gravity is and how it works U can just go ahead without tackling the real problem and Answer this :
At what height will a moon’s artificial satellite’s orbit will become inclined towards earth from moon ?
24001 miles. Did I win something?
From my calculations L1-Moon-Earth = 71,880 km
L2-Moon-Earth = 114,821 km.
So an artificial satellite of the Moon, will be in Earth and Moon orbit at 71,880 km from the Moon and on the radial to Earth.
Is this the question you wanted answered ?
RawThinkTank
05-01-04, 09:00 AM
Question : can we get a satallite orbiting moon such that as it comes near earth the height of the its orbit from moon will increase dramatically, Is this ever done before ? And yes will the satellite change its mind instead and start orbiting earth instead ?
Janus58
05-01-04, 01:03 PM
Question : can we get a satallite orbiting moon such that as it comes near earth the height of the its orbit from moon will increase dramatically, Is this ever done before ? And yes will the satellite change its mind instead and start orbiting earth instead ?
Any Lunar satellite (with the exception of any placed at Lagrange points) with an Lunar altitude greater than 66000 km (as measured from the center of the moon) will no longer orbit the Moon but will begin to orbit the Earth instead. 66000 km is the radius of the Moon's gravitational sphere of influence.
If you want to have a satellite which moves from Moon to Earth orbit, you just need to place it in an eccentric orbit that starts with a periapis of less than 66000 km and has an apapis of greater than 66000 km. l
Has it been done before? Yes. During the Apollo missions, the craft were placed on a trajectory that caused them to swing around the far side of the Moon on a close approach, and unless altered by firing the engines, would whip them back up to 66000 km placing them into a return orbit of the Earth.
RawThinkTank
05-02-04, 08:10 AM
Janus58
Was that because of earths gravity or can the same be done to any planet with out a moon or other massive object ?
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