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Sand in space



 
 
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  #1  
Old June 4th 11, 03:55 PM posted to sci.astro
Litus Arare
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Posts: 18
Default Sand in space

If I were launched into space and was able to achieve an independent orbit
far away from the earth's gravitational field, and released some grains of
sand, would the solar wind blow them away?
  #2  
Old June 4th 11, 04:19 PM posted to sci.astro
Yousuf Khan[_2_]
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Posts: 1,692
Default Sand in space

On 06/04/2011 10:55 AM, Litus Arare wrote:
If I were launched into space and was able to achieve an independent orbit
far away from the earth's gravitational field, and released some grains of
sand, would the solar wind blow them away?


No, not enough surface area. More likely that the grains of sand would
actually start coming together under their own mutual self-gravitation.
In fact that's how the Solar System first formed, dust and gas fell
together.

Yousuf Khan
  #3  
Old June 4th 11, 05:04 PM posted to sci.astro
Mike Dworetsky
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Posts: 715
Default Sand in space

Litus Arare wrote:
If I were launched into space and was able to achieve an independent
orbit far away from the earth's gravitational field, and released
some grains of sand, would the solar wind blow them away?


This depends on their size. Actual sand (as in beach sand) would be too
heavy and the main effect would be the "Poynting-Robertson Effect" which is
essentially due to solar radiation pressure being slightly aberrated
(appearing to be from slightly in front of a radial line to the Sun), so
these grains would stay in orbit but slowly spiral into the Sun (or to the
distance at which they would vaporise). Sand-sized particles would stay in
orbit for a long time; smaller particles would spiral in more rapidly.

Very small particles, such as comet tail dust and (perhaps) cigarette smoke,
would indeed be blown out by radiation pressure. The "break-point" where
the two effects balance is around size 0.5 micrometre, depending on
properties.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

  #4  
Old June 5th 11, 02:33 AM posted to sci.astro
Brad Guth[_3_]
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Posts: 15,175
Default Sand in space

On Jun 4, 7:55*am, "Litus Arare" wrote:
If I were launched into space and was able to achieve an independent orbit
far away from the earth's gravitational field, and released some grains of
sand, would the solar wind blow them away?


Do carbon buckyballs count as sand?

Perhaps little bits of atomic carbon could be expected to move along
with the solar wind, such as the tonnes of helium that's blown away
from Earth and is extracted from our gravity pool by the solar wind.

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Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet”
  #5  
Old June 5th 11, 07:53 PM posted to sci.astro
Dr J R Stockton[_114_]
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Posts: 4
Default Sand in space

In sci.astro message , Sat, 4 Jun 2011
11:19:22, Yousuf Khan posted:

On 06/04/2011 10:55 AM, Litus Arare wrote:
If I were launched into space and was able to achieve an independent orbit
far away from the earth's gravitational field, and released some grains of
sand, would the solar wind blow them away?


No, not enough surface area. More likely that the grains of sand would
actually start coming together under their own mutual self-gravitation.
In fact that's how the Solar System first formed, dust and gas fell
together.



The solar wind is irrelevant.

According to Wikipedia, the Solar Wind amounts to 6.7 billion tons per
hour - about 2 million tons per second - at a speed of 400-750 km/s.
But the Sun emits 4 million tons of photons per second, at 300,000 km/s.

The light therefore has about a thousand times as much momentum as the
wind.

At Earth's distance, not orbiting, the light pressure will balance a
sail of 1.6 gm / sq m, equivalent to ordinary paper 2 um thick. Grains
in circular orbit will apparently not feel the Sun's gravity, and can be
pushed out into an elliptical orbit.

Since the solar pushes on the grains will be virtually parallel, the
minute gravitational force might, eventually, cause clumping. More
likely, you will get something like a junior version of the meteor
trails left by comets.

--
(c) John Stockton, near London.
Web http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, and links.
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  #6  
Old June 6th 11, 07:50 AM posted to sci.astro
Mike Dworetsky
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Posts: 715
Default Sand in space

Mike Dworetsky wrote:
Litus Arare wrote:
If I were launched into space and was able to achieve an independent
orbit far away from the earth's gravitational field, and released
some grains of sand, would the solar wind blow them away?


This depends on their size. Actual sand (as in beach sand) would be
too heavy and the main effect would be the "Poynting-Robertson
Effect" which is essentially due to solar radiation pressure being
slightly aberrated (appearing to be from slightly in front of a
radial line to the Sun), so these grains would stay in orbit but
slowly spiral into the Sun (or to the distance at which they would
vaporise). Sand-sized particles would stay in orbit for a long time;
smaller particles would spiral in more rapidly.
Very small particles, such as comet tail dust and (perhaps) cigarette
smoke, would indeed be blown out by radiation pressure. The
"break-point" where the two effects balance is around size 0.5
micrometre, depending on properties.


The original question was about the effects of the solar wind (not about
radiation pressure). The best way to see this question as a natural
experiment is to examine comet tails. The dust tail of a comet is driven by
the solar radiation pressure. They look amorphous and reflect sunlight
(they have the same spectrum as the Sun). Gas tails are driven by the solar
wind, and inhomogeneities and irregular emissions from the cometary body
cause the gas tails to develop clumps and structure, and occasionally you
can see disconnection events as clouds of atoms from the comet are pinched
off and blown away.

So the solar wind does not affect the movement of sand grains (not much,
anyways).

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

  #7  
Old June 6th 11, 10:05 PM posted to sci.astro
Brad Guth[_3_]
external usenet poster
 
Posts: 15,175
Default Sand in space

On Jun 5, 11:50*pm, "Mike Dworetsky"
wrote:
Mike Dworetsky wrote:
Litus Arare wrote:
If I were launched into space and was able to achieve an independent
orbit far away from the earth's gravitational field, and released
some grains of sand, would the solar wind blow them away?


This depends on their size. *Actual sand (as in beach sand) would be
too heavy and the main effect would be the "Poynting-Robertson
Effect" which is essentially due to solar radiation pressure being
slightly aberrated (appearing to be from slightly in front of a
radial line to the Sun), so these grains would stay in orbit but
slowly spiral into the Sun (or to the distance at which they would
vaporise). *Sand-sized particles would stay in orbit for a long time;
smaller particles would spiral in more rapidly.
Very small particles, such as comet tail dust and (perhaps) cigarette
smoke, would indeed be blown out by radiation pressure. *The
"break-point" where the two effects balance is around size 0.5
micrometre, depending on properties.


The original question was about the effects of the solar wind (not about
radiation pressure). *The best way to see this question as a natural
experiment is to examine comet tails. *The dust tail of a comet is driven by
the solar radiation pressure. *They look amorphous and reflect sunlight
(they have the same spectrum as the Sun). *Gas tails are driven by the solar
wind, and inhomogeneities and irregular emissions from the cometary body
cause the gas tails to develop clumps and structure, and occasionally you
can see disconnection events as clouds of atoms from the comet are pinched
off and blown away.

So the solar wind does not affect the movement of sand grains (not much,
anyways).

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)


How about the solar wind moving those icy carbon buckyballs, a C60
(Buckminsterfullerene) of 1 nm diameter, that's only worth as little
as 1.205e-24 kg each (plus whatever else they might contain, such as
h2o or 4He)?

http://translate.google.com/#
Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet”
 




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