How far can you go up?

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therocketjohn

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If you fly up, and keep going up, and keep going up, at what altitude should you stop saying you are going up?

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origin

Guest
therocketjohn":wcudychq said:
If you fly up, and keep going up, and keep going up, at what altitude should you stop saying you are going up?

This just sounds like semantics to me. I would say probably once you are beyond the earths gravity, if I was pressed to answer.

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MeteorWayne

Guest
Indeed, if you are referring to going up from the earth' surface, as long as you are moving at least 11.2 km/sec (~ 25.000 mph), you can keep going up forever.

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therocketjohn

Guest
What if you are a spaceship getting closer to the South Pole because of an orbit, but have no plans to enter the atmosphere near the South Pole. In that case, are you going South? How about after you get over the South Pole?

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MeteorWayne

Guest
Ah, but you said going up. An orbit is not going up, it's going sideways, staying at the same altitude (for a circular orbit), or repeating vatying altitudes (for an elliptical one). That's not going up anymore.

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aphh

Guest
This question is both interesting and very theoretical, because it would be next to impossible to fly straight up for a very long time.

If you took off from the equator, earth's rotation would give you momentum sideways, that would have to be corrected. This would take up propellant, that you would otherwise use to go straight up.

On the other hand, if you took off from the poles, your launch platform, the Earth, would still be moving sideways at over 30 km/s on a curved path around the Sun. Again a launch from poles would make you going sideways aswell.

It is impossible to maintain straight course in space for a very long time. Any straight course would turn into elliptical once your fuel ran out, which would happen very soon. Maintaining a straight line would mean fighting the gravity wells of planets and sun, and there is no way to do that. Anything that has been sent away in the vicinity of our Sun will eventually return, unless another body of gravity takes a hold of the object.

Hence all paths in space are curved one way or another. It could be said, that there are no straight lines in space, other than line of sight. And even LOS may be curved due to gravity.

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MeteorWayne

Guest
True, but the way I look at it, even if the path is curved, as long as you are heading away from the surface that you launched from (altitude/disnce increasing) you are still going "up" from the surface of the earth.

http://heavens-above.com/solar-escape.a ... t=0&tz=CET

The current leader is Voyager 1 at just over 109 AU; 109 times further from the erath that we are from the sun. That's over 15 light hours away.

That's 16,316,340,560 kilometers or 10,138,503,987 miles. Now that's "UP" !

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aphh

Guest
MeteorWayne":21p5snce said:
That's 16,316,340,560 kilometers or 10,138,503,987 miles. Now that's "UP" !

That is very "UP", but do you know if Voyager is still going to return one day? Has this been estimated, meaning, will Voyager meet some other body of gravity on it's journey besides our Sun?

Because I think that if Voyager does not meet another star or some other source of gravity on it's way, it will eventually return...

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MeteorWayne

Guest
No, all 5 Spacecraft listed on that site are leaving the solar system and will never return.

Their velocity far exceeds the gravitational attraction of the solar system.

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aphh

Guest
MeteorWayne":3r4smi7p said:
No, all 5 Spacecraft listed on that site are leaving the solar system and will never return.

Their velocity far exceeds the gravitational attraction of the solar system.

I find that hard to believe. Their velocity is constantly decreasing, because they have no additional boost, and Sun is still affecting them slightly and pulling them back. Velocity keeps decreasing, until one day the velocity becomes negative. That is the point when the craft starts it's long journey back home.

Even if they leaved our solar system for now, I think they would still be on a extremely eccentric orbit and would return perhaps thousands of years from now, unless another star started pulling them away from our star, that is. Basically they would act like comets.

Perhaps some other star's gravity has been calculated in, meaning a star like Proxima Centauri, or some other, might start to pull these crafts away from our Sun.

C

CommonMan

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MeteorWayne":22byx2sf said:
No, all 5 Spacecraft listed on that site are leaving the solar system and will never return.

Their velocity far exceeds the gravitational attraction of the solar system.

Is any of them still sending data or pictures back?

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MeteorWayne

Guest
Sorry if you find it hard to believe. Please look up the concept of escape velocity. They are going fast enough that the decreasing gravity of the sun (as they get further away) will never be able to pull them back. That's why that page is labeled "Spacecraft escaping the Solar System".

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aphh

Guest
MeteorWayne":w8hgu42e said:
Sorry if you find it hard to believe. Please look up the concept of escape velocity. They are going fast enough that the decreasing gravity of the sun (as they get further away) will never be able to pull them back. That's why that page is labeled "Spacecraft escaping the Solar System".

I still want to maintain, that comets also regularly leave our solar system, but keep returning back to our solar system, unless there is some other source of gravity that nudges the orbit away from our solar system, like Oort cloud or something else.

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MeteorWayne

Guest
CommonMan":3edqdw7i said:
Is any of them still sending data or pictures back?

Pioneer 10 and 11 have expired; they have no more power.

Voyager 1 and 2 are still funtioning on a limited basis, but I don't believe they have enough power left for imaging.

New Horizons is on it's way to Pluto, so is hibernating on it's way. It will take plenty of pictures of the Plutonian system when it gets there in 2,264 days

http://pluto.jhuapl.edu/mission/whereis_nh.php

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MeteorWayne

Guest
aphh":1oh3ggbo said:
I still want to maintain, that comets also regularly leave our solar system, but keep returning back to our solar system, unless there is some other source of gravity that nudges the orbit away from our solar system, like Oort cloud or something else.

Again, you are wrong. Comets don't leave the solar system, or they wouldn't come back (a very small percentage never do return, and do indeed leave the solar syatem). They go very very far away from the sun, (out of the "inner" solar system) but do not have enough speed to escape the sun, so they return. These 5 craft, on the other hand, have more than enough speed to escape the grasp of the sun.

Oh will they ever return, no they'll never return, and their fate will be unlearned...They will fly forever from the solar system, they're the craft that will never return, they're the craft that will never return.....
(with apologies to the Kingston Trio...I know Yevaud will get it)

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aphh

Guest
MeteorWayne":3e7v2axl said:
Again, you are wrong. Comets don't leave the solar system, or they wouldn't come back (a very small percentage never do return, and do indeed leave the solar syatem). They go very very far away from the sun, (out of the "inner" solar system) but do not have enough speed to escape the sun, so they return. These 5 craft, on the other hand, have more than enough speed to escape the grasp of the sun.

Oh will they ever return, no they'll never return, and their fate will be unlearned...They will fly forever from the solar system, they're the craft that will never return, they're the craft that will never return.....
(with apologies to the Kingston Trio...I know Yevaud will get it)

Okay, I believe you. But as you mentioned, the point remains moot if there is no way we could know about the fate of these crafts. They serve no purpose to us.

Whether they exist or not is irrelevant then. They demonstrate that it is possible to go ever higher, but that itself gives us no additional value.

O

origin

Guest
MeteorWayne":21pypot3 said:
Oh will they ever return, no they'll never return, and their fate will be unlearned...They will fly forever from the solar system, they're the craft that will never return, they're the craft that will never return.....
(with apologies to the Kingston Trio...I know Yevaud will get it)

Unfortuanately, I am so ancient that I 'get it'.

Y

yevaud

Guest
MeteorWayne":3e6hxwdv said:
they're the craft that will never return, they're the craft that will never return.....
(with apologies to the Kingston Trio...I know Yevaud will get it)

If the MBTA were in charge of NASA, they not only would never return, they'd run late, be overcrowded, and several of them would just...disappear, never to be found again.

Thanks for the reference, Wayne. Muchly appreciated!

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MeteorWayne

Guest
aphh: Sigh, you don't know much about the history of spacecraft, do you?

The subject of this thread is not what value they have to us. It's how far can you go up. So I only mentioned them to answer the question of the original poster.

Besides, the Pioneers and Voyagers have messages from we humans to whoever might find them in millions or billions of years if they ever do. They are the first things we ever sent out into interstellar space. I think that's important. Sorry if it doesn't impress you enough.

As I said, Voyager 1 and 2 are still functioning and are investigating the edge of the heliosphere, where the influence of the sun interacts with the galactic environment. I consider that VERY useful. We are leaning plenty from them still, even in their aged and weakened state. It's the first time we've ever been there.

New Horizons will be visiting Pluto and it's 3 moons. I consider that VERY useful. It's also the first time we've ever been there.

I don't see how you could call any of them irrelevant, if your eyes are open.

Wayne

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MeteorWayne

Guest
Figured you could use a smile Yev; it's good to get out of FS and wash off the slime once in a while

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aphh

Guest
MeteorWayne":htqvb97w said:
I don't see how you could call any of them irrelevant, if your eyes are open.

Wayne

I admit I was pulling your leg a bit. But what I think I was able to bring to the table was that there are no straight lines in space.

Yes, you go up even if you leaved solar system, not on a straight line, but on a curved path. Only the curve of the path now has constantly larger radius. Otherwise you would return.

All of the probes will still be kind of circling our solar system, only with a ever increasing radius. Unless some other body of gravity takes hold of them, as mentioned.

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