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How long could a man-made earth satellite stay up?



 
 
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  #1  
Old January 20th 07, 05:18 PM posted to sci.astro.amateur
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Posts: 11
Default How long could a man-made earth satellite stay up?

Musing....

The earth is many orders of magnitude older than the time humans - or
even mammals - have been here.

And who knows what the future may bring.

As far as I can tell, any thought that we are not the first to inhabit
this planet belong in the realm of science fiction - but we may not
last, and there could therefore be other sentients after us.

If we wished to leave a notice that we'd been here, the best place
might be in orbit; by the time another sentient form reached that
level, they might be able to decipher and understand whatever we
decided to leave.

Low orbits decay - I assume higher ones do as well, just more slowly.
Could we place a satellite such that it would still be up there, say,
a million years from now? How about 100 million years?
  #2  
Old January 20th 07, 06:06 PM posted to sci.astro.amateur
Chris L Peterson
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Posts: 10,007
Default How long could a man-made earth satellite stay up?

On Sat, 20 Jan 2007 16:18:02 GMT, wrote:

Musing....

The earth is many orders of magnitude older than the time humans - or
even mammals - have been here.

And who knows what the future may bring.

As far as I can tell, any thought that we are not the first to inhabit
this planet belong in the realm of science fiction - but we may not
last, and there could therefore be other sentients after us.

If we wished to leave a notice that we'd been here, the best place
might be in orbit; by the time another sentient form reached that
level, they might be able to decipher and understand whatever we
decided to leave.

Low orbits decay - I assume higher ones do as well, just more slowly.
Could we place a satellite such that it would still be up there, say,
a million years from now? How about 100 million years?


Once you get a few thousand miles up, the orbital decay rate is
negligible. Objects that high can remain in orbit for millions of years.
The problem is that on those sorts of time scales, the probability of a
collision becomes high (either with other manmade objects, or with
meteoroids). I think anything we put up would be pretty beat up in a few
thousand years.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
  #4  
Old January 20th 07, 08:04 PM posted to sci.astro.amateur
Shawn
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Posts: 125
Default How long could a man-made earth satellite stay up?

wrote:
Musing....

The earth is many orders of magnitude older than the time humans - or
even mammals - have been here.

And who knows what the future may bring.

As far as I can tell, any thought that we are not the first to inhabit
this planet belong in the realm of science fiction - but we may not
last, and there could therefore be other sentients after us.

If we wished to leave a notice that we'd been here, the best place
might be in orbit; by the time another sentient form reached that
level, they might be able to decipher and understand whatever we
decided to leave.

Low orbits decay - I assume higher ones do as well, just more slowly.
Could we place a satellite such that it would still be up there, say,
a million years from now? How about 100 million years?


Cool idea. One of the Earth/Moon Lagrange points, L4 or L5, ahead of or
behind the Moon along its orbit around Earth might be a good choice. It
would be someplace some future astronomer might look for captured
asteroids in Earth orbit. Such an extraterrestrial time capsule would
be more likely to be found, and stay in orbit. Also, that high up it
would less likely to get nailed by some other satellite crossing its path.



Shawn
  #5  
Old January 20th 07, 09:02 PM posted to sci.astro.amateur
Starlord
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Posts: 1,908
Default How long could a man-made earth satellite stay up?

The 2nd object put into earth orbit back in 1959 is still up there going
around the earth.


--
There are those who believe that life here, began out there, far across the
universe, with tribes of humans, who may have been the forefathers of the
Egyptians, or the Toltecs, or the Mayans. Some believe that they may yet be
brothers of man, who even now fight to survive, somewhere beyond the
heavens.


The Lone Sidewalk Astronomer of Rosamond
Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html


"Shawn" wrote in message
...
wrote:
Musing....

The earth is many orders of magnitude older than the time humans - or
even mammals - have been here.

And who knows what the future may bring.

As far as I can tell, any thought that we are not the first to inhabit
this planet belong in the realm of science fiction - but we may not
last, and there could therefore be other sentients after us.

If we wished to leave a notice that we'd been here, the best place
might be in orbit; by the time another sentient form reached that
level, they might be able to decipher and understand whatever we
decided to leave.

Low orbits decay - I assume higher ones do as well, just more slowly.
Could we place a satellite such that it would still be up there, say,
a million years from now? How about 100 million years?


Cool idea. One of the Earth/Moon Lagrange points, L4 or L5, ahead of or
behind the Moon along its orbit around Earth might be a good choice. It
would be someplace some future astronomer might look for captured
asteroids in Earth orbit. Such an extraterrestrial time capsule would be
more likely to be found, and stay in orbit. Also, that high up it would
less likely to get nailed by some other satellite crossing its path.



Shawn



  #6  
Old January 20th 07, 10:40 PM posted to sci.astro.amateur
L.A.T.
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Posts: 78
Default How long could a man-made earth satellite stay up?


"Starlord" wrote in message
. ..
The 2nd object put into earth orbit back in 1959 is still up there going
around the earth.

For heaven's sake, don't tell the Chinese about it!


  #7  
Old January 20th 07, 11:00 PM posted to sci.astro.amateur
Starlord
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Posts: 1,908
Default How long could a man-made earth satellite stay up?

I'm sure they know about it, but while not running, it is still in orbit and
has been tracked.


--
There are those who believe that life here, began out there, far across the
universe, with tribes of humans, who may have been the forefathers of the
Egyptians, or the Toltecs, or the Mayans. Some believe that they may yet be
brothers of man, who even now fight to survive, somewhere beyond the
heavens.


The Lone Sidewalk Astronomer of Rosamond
Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html


"L.A.T." wrote in message
...

"Starlord" wrote in message
. ..
The 2nd object put into earth orbit back in 1959 is still up there going
around the earth.

For heaven's sake, don't tell the Chinese about it!



  #8  
Old January 20th 07, 11:26 PM posted to sci.astro.amateur
Chris L Peterson
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Posts: 10,007
Default How long could a man-made earth satellite stay up?

On Sat, 20 Jan 2007 12:04:14 -0700, Shawn
wrote:

Cool idea. One of the Earth/Moon Lagrange points, L4 or L5, ahead of or
behind the Moon along its orbit around Earth might be a good choice. It
would be someplace some future astronomer might look for captured
asteroids in Earth orbit. Such an extraterrestrial time capsule would
be more likely to be found, and stay in orbit. Also, that high up it
would less likely to get nailed by some other satellite crossing its path.


I believe the masses of the Earth and Moon are sufficiently close to one
another that, with perturbations from the Sun, the Earth-Moon L4 and L5
points aren't terribly stable over long periods. Also, their tendency to
accumulate other bodies might make them an unsafe place to park for
millions of years. A simple high Earth orbit is probably cleaner,
although even there I doubt something would survive millions of years
without being hit by something major, being perturbed by something
major, or simply being sandblasted to death by space dust. The inner
Solar System has quite a lot of debris in it.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
  #9  
Old January 20th 07, 11:27 PM posted to sci.astro.amateur
Chris L Peterson
external usenet poster
 
Posts: 10,007
Default How long could a man-made earth satellite stay up?

On Sat, 20 Jan 2007 14:00:17 -0800, "Starlord"
wrote:

I'm sure they know about it, but while not running, it is still in orbit and
has been tracked.


I think he was worrying- tongue in cheek- about them turning it into a
debris cloud for practice. (Been following the news the last few days?)

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
  #10  
Old January 21st 07, 12:32 AM posted to sci.astro.amateur
Rick Evans[_1_]
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Posts: 54
Default How long could a man-made earth satellite stay up?

wrote in message ...
Musing....

The earth is many orders of magnitude older than the time humans - or
even mammals - have been here.

And who knows what the future may bring.

As far as I can tell, any thought that we are not the first to inhabit
this planet belong in the realm of science fiction - but we may not
last, and there could therefore be other sentients after us.

If we wished to leave a notice that we'd been here, the best place
might be in orbit

Only in the mind of a space buff. Why would a future sentient
look into space for a sign of previous life on Earth?

Numerous notices of previous ancients have been found
on earth in the form of hundred million year old fossils.

I suspect a million years from now some posthuman
archeologist will have no problem stumbling over one
of our many land fills. I doubt he'll confuse a golf
ball or empty Disani bottle for a geological formation.

--

Rick Evans
---------------------------------------------------------------
Lon -71° 04' 35.3"
Lat +42° 11' 06.7"
---------------------------------------------------------------
Webcam Astroimaging
http://mysite.verizon.net/hiltonevan...troimaging.htm


 




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