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Close Sun-orbiting mirrors for beamed propulsion and space solar power.



 
 
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  #11  
Old June 18th 17, 12:22 AM posted to sci.space.policy,sci.optics,sci.physics
benj
external usenet poster
 
Posts: 5
Default Close Sun-orbiting mirrors for beamed propulsion and space solarpower.

On 6/17/2017 10:48 AM, Sегgi о wrote:

The Parker probe will use a refrigeration system to lower the
temperature of the components of the spacecraft from 1,400 C to room
temperature. This is about the same temperature drop as the
temperature drop from the Sun’s surface to the maximum temperature of
our high temperature ceramics. So it should be possible to do this
temperature drop on the surface of the Sun using our highest
temperature ceramics.


the major constraint is; the limited amount of heat can the probe get
rid of by radiate it out into cold space on the back side. This is only
a few hundred watts. (do the calculation)
[hint http://hyperphysics.phy-astr.gsu.edu...mo/stefan.html ]

this means the solar shield *must be* a wideband optical and heat reflector


Don't you know that directing energy back into the sun could overload it
and cause it to explode? This is science.
  #12  
Old June 20th 17, 06:31 PM posted to rec.arts.sf.science,sci.space.policy,sci.optics,sci.physics,sci.military.naval
Robert Clark[_5_]
external usenet poster
 
Posts: 245
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

"Robert Clark" wrote in message news ================================================== =====================
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.

But could we put the mirror actually on the surface of the Sun? The Sun puts
out 3.86X10^26 watts of power,
http://m.wolframalpha.com/input/?i=s...nosity&x=0&y=0.

Given its 700,000 km radius, this amounts to over 60 terawatts per sq. km.
This is 3 times the total energy usage of humans on Earth from all sources.

Could we have a station on the Sun’s surface that would persist long term?
The Sun’s surface is at about 5,500 C. The highest temperature ceramic we
have is at about 4,000 C:

Rediscovered ceramic Hafnium Carbide can withstand temperatures three times
hotter than lava at 4050 celsius and could help enable hypersonic planes.
brian wang | September 17, 2014
https://www.nextbigfuture.com/2014/0...m-carbine.html

However, there are cases such as with rocket engine combustion chambers
where the operating temperature is well above the melting point of the
material composing the engine. The reason this is possible is that in order
for a material to undergo a phase change from solid to liquid not only does
it have to be at the melting point but a sufficient quantity of heat known
as the heat of fusion has to be supplied to it.

So with high performance rocket engines such as the SSME’s a cooling
techniques known as regenerative cooling is used that circulates cool fuel
around the engine to draw off adequate heat to prevent melting from
occurring.

However, with rocket engines this cooling fuel is burned or dispensed with
after being used for the cooling. So this wouldn’t work for a power station
existing long term on the surface of the Sun. You would need something like
a refrigeration system.

The Parker probe will use a refrigeration system to lower the temperature of
the components of the spacecraft from 1,400 C to room temperature. This is
about the same temperature drop as the temperature drop from the Sun’s
surface to the maximum temperature of our high temperature ceramics. So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.

Still, we might not want the extra difficulty of landing on the Sun. If we
make the distance to the Sun of our beaming station about 1/3rd that of the
Parker probe we would be at 10 terawatts per sq. km. Two of these would
provide the entire energy requirements for the entire human population, and
the surrounding temperatures wouldn’t be so extreme.

Bob Clark

---
================================================== ===================

Just saw this mentioned in the comments to an article on the Parker Solar
Probe on Centauri-dreams.org:

April 6, 2017
Solar Surfing
Robert Youngquist
NASA Kennedy Space Center
Quote:
Description
We propose to develop a novel high temperature coating that will reflect up
to 99.9 % of the Sun’s total irradiance, roughly a factor of 80 times better
than the current state-of-the-art. This will be accomplished by leveraging
off of our low temperature coating, currently being developed under NIAC
funding. We will modify our existing models to determine an optimal high
temperature solar reflector, predict its performance, and construct a
prototype version of this coating. This prototype will be sent to our
partner at the Johns Hopkins Applied Physics Laboratory where it will be
tested in an 11 times solar simulator. The results of this modeling/testing
will be used to design a mission to the Sun, where we hope to come to within
one solar radius of the Sun’s surface, 8 times closer than the closest
distance planned for the upcoming Solar Probe Plus. This project will
substantially advance the current capabilities of solar thermal protection
systems, not only potentially allowing “Solar Surfing”, but allowing better
thermal control of a future mission to Mercury.
https://www.nasa.gov/directorates/sp.../Solar_Surfing

At a solar radius of 700,000 km away from the Sun, based on the light
intensity going inversely by the square of the distance, and with 1,360
watts per sq. meter (in space) at the Earth’s distance, or 1.36 gigawatts
per sq. km., I estimate this should give 60 terawatts per sq. km. at only a
solar radius away from the Sun.

But in the post above, I had estimated that fully *on* the Sun’s surface we
could collect 60 terawatts per sq. km. of power. Anyone have an explanation
of this discrepancy?

In any case if this research team succeeds in producing this ultra high
reflective, high temperature material, then a mirror smaller than a
kilometer across a solar radius away from the Sun could collect enough
energy for the total energy usage for the entire human population of the
Earth.

Also, interesting is 16 solar collectors a kilometer across could provide a
petawatt of power. But these are power levels long about dreamed in science
fiction for doing beamed propulsion of large-scale, *manned* spacecraft on
relativistic, interstellar flights.

Bob Clark


----------------------------------------------------------------------------------------------------------------------------------
Finally, nanotechnology can now fulfill its potential to revolutionize
21st-century technology, from the space elevator, to private, orbital
launchers, to 'flying cars'.
This crowdfunding campaign is to prove it:

Nanotech: from air to space.
https://www.indiegogo.com/projects/n...ce/x/13319568/
----------------------------------------------------------------------------------------------------------------------------------

  #13  
Old June 21st 17, 02:10 PM posted to rec.arts.sf.science,sci.space.policy,sci.optics,sci.physics,sci.military.naval
Robert Clark[_5_]
external usenet poster
 
Posts: 245
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

"Sегgi о" wrote in message news ================================================== ======================
On 6/20/2017 12:31 PM, Robert Clark wrote:
"Robert Clark" wrote in message news
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.



The Parker probe will use a refrigeration system to lower the temperature
of
the components of the spacecraft from 1,400 C to room temperature. This is
about the same temperature drop as the temperature drop from the Sun’s
surface to the maximum temperature of our high temperature ceramics. So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.


refrigeration wont work. if reflectivity is 99.9% you still ave to move
how many terrawatts(?) from front to back of the spacecraft, AND radiate
that out to cold space on the backside ??

also Gamma rays are going to cook it, +fry electonics.
what are the gamma ray radiation levels close to the sun ?

---
================================================== ======================

Look at it in terms of how much needs to be radiated per unit area. This
research project expects to reflect 99.9% of the light energy away:

April 6, 2017
Solar Surfing
Robert Youngquist
NASA Kennedy Space Center
Quote:
Description
We propose to develop a novel high temperature coating that will reflect up
to 99.9 % of the Sun’s total irradiance, roughly a factor of 80 times better
than the current state-of-the-art. This will be accomplished by leveraging
off of our low temperature coating, currently being developed under NIAC
funding. We will modify our existing models to determine an optimal high
temperature solar reflector, predict its performance, and construct a
prototype version of this coating. This prototype will be sent to our
partner at the Johns Hopkins Applied Physics Laboratory where it will be
tested in an 11 times solar simulator. The results of this modeling/testing
will be used to design a mission to the Sun, where we hope to come to within
one solar radius of the Sun’s surface, 8 times closer than the closest
distance planned for the upcoming Solar Probe Plus. This project will
substantially advance the current capabilities of solar thermal protection
systems, not only potentially allowing “Solar Surfing”, but allowing better
thermal control of a future mission to Mercury.
https://www.nasa.gov/directorates/sp.../Solar_Surfing

At that distance, the solar radiance is 60 megawatts per square meter. So
1/1,000 of this would have to be radiated away, this is 60,000 watts. That
is not a lot over a square meter.

Bob Clark

----------------------------------------------------------------------------------------------------------------------------------
Finally, nanotechnology can now fulfill its potential to revolutionize
21st-century technology, from the space elevator, to private, orbital
launchers, to 'flying cars'.
This crowdfunding campaign is to prove it:

Nanotech: from air to space.
https://www.indiegogo.com/projects/n...ce/x/13319568/
----------------------------------------------------------------------------------------------------------------------------------

  #14  
Old June 21st 17, 02:49 PM posted to rec.arts.sf.science,sci.space.policy,sci.optics,sci.physics,sci.military.naval
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

"Robert Clark" wrote:

"S??gi ?" wrote in message news ================================================= =======================
On 6/20/2017 12:31 PM, Robert Clark wrote:
"Robert Clark" wrote in message news
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.



The Parker probe will use a refrigeration system to lower the temperature
of
the components of the spacecraft from 1,400 C to room temperature. This is
about the same temperature drop as the temperature drop from the Suns
surface to the maximum temperature of our high temperature ceramics. So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.


refrigeration wont work. if reflectivity is 99.9% you still ave to move
how many terrawatts(?) from front to back of the spacecraft, AND radiate
that out to cold space on the backside ??


He wasn't speculating, Bob. That is what the Parker Probe is going to
do.


also Gamma rays are going to cook it, +fry electonics.
what are the gamma ray radiation levels close to the sun ?


If you don't know the gamma ray levels, how can you say gamma will
cook it?

The gamma ray flux outside the surface of the Sun is essentially zero.
It all gets converted to visible photons from 170,000 years of
collisions inside the Sun on its way to the surface.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
  #15  
Old June 21st 17, 03:33 PM posted to sci.space.policy,sci.optics,sci.physics
Sегgi о
external usenet poster
 
Posts: 4
Default Close Sun-orbiting mirrors for beamed propulsion and space solarpower.

On 6/21/2017 8:10 AM, Robert Clark wrote:
"Sегgi о" wrote in message news ================================================== ======================
On 6/20/2017 12:31 PM, Robert Clark wrote:
"Robert Clark" wrote in message news
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.



The Parker probe will use a refrigeration system to lower the
temperature of
the components of the spacecraft from 1,400 C to room temperature.
This is
about the same temperature drop as the temperature drop from the Sun’s
surface to the maximum temperature of our high temperature ceramics.
So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.


refrigeration wont work. if reflectivity is 99.9% you still ave to move
how many terrawatts(?) from front to back of the spacecraft, AND radiate
that out to cold space on the backside ??

also Gamma rays are going to cook it, +fry electonics.
what are the gamma ray radiation levels close to the sun ?


================================================== ======================

Look at it in terms of how much needs to be radiated per unit area. This
research project expects to reflect 99.9% of the light energy away:

April 6, 2017
Solar Surfing
Robert Youngquist
NASA Kennedy Space Center
Quote:
Description
We propose to develop a novel high temperature coating that will reflect up
to 99.9 % of the Sun’s total irradiance, roughly a factor of 80 times
better
than the current state-of-the-art. This will be accomplished by leveraging
off of our low temperature coating, currently being developed under NIAC
funding. We will modify our existing models to determine an optimal high
temperature solar reflector, predict its performance, and construct a
prototype version of this coating. This prototype will be sent to our
partner at the Johns Hopkins Applied Physics Laboratory where it will be
tested in an 11 times solar simulator. The results of this modeling/testing
will be used to design a mission to the Sun, where we hope to come to
Quote:
within
one solar radius of the Sun’s surface, 8 times closer than the closest
distance planned for the upcoming Solar Probe Plus. This project will
substantially advance the current capabilities of solar thermal protection
systems, not only potentially allowing “Solar Surfing”, but allowing better
thermal control of a future mission to Mercury.

https://www.nasa.gov/directorates/sp.../Solar_Surfing


At that distance, the solar radiance is 60 megawatts per square meter.
So 1/1,000 of this would have to be radiated away, this is 60,000 watts.
That is not a lot over a square meter.


I think you can figure out the temperature rise from that, 60,000 watts
out of a sq meter (too busy right now) to cold space, could be glowing red.

but that mirror is not real yet, 80 times is huge. and I think Gamma
rays will be a larger factor.
  #16  
Old June 21st 17, 03:39 PM posted to sci.space.policy,sci.optics,sci.physics
Sегgi о
external usenet poster
 
Posts: 4
Default Close Sun-orbiting mirrors for beamed propulsion and space solarpower.

On 6/21/2017 8:49 AM, Fred J. McCall wrote:
"Robert Clark" wrote:

"S??gi ?" wrote in message news ================================================== ======================
On 6/20/2017 12:31 PM, Robert Clark wrote:
"Robert Clark" wrote in message news
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.



The Parker probe will use a refrigeration system to lower the temperature
of
the components of the spacecraft from 1,400 C to room temperature. This is
about the same temperature drop as the temperature drop from the Sun’s
surface to the maximum temperature of our high temperature ceramics. So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.


refrigeration wont work. if reflectivity is 99.9% you still ave to move
how many terrawatts(?) from front to back of the spacecraft, AND radiate
that out to cold space on the backside ??


He wasn't speculating, Bob. That is what the Parker Probe is going to
do.


also Gamma rays are going to cook it, +fry electonics.
what are the gamma ray radiation levels close to the sun ?


If you don't know the gamma ray levels, how can you say gamma will
cook it?

The gamma ray flux outside the surface of the Sun is essentially zero.
It all gets converted to visible photons from 170,000 years of
collisions inside the Sun on its way to the surface.



that wiki is out of context.
it seems zero if you compare it to levels within the sun.

another radiation issue - our south atlantic anomoly cooks electronics
in low orbit sattilites, (earth), an area of trapped radioactive
particals from the sun.

It would be nice if NASA would publish the engeneering aspects of this
and the sun probe, very interesting areas
  #17  
Old June 21st 17, 10:27 PM posted to sci.space.policy,sci.optics,sci.physics
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

S??gi ? wrote:

On 6/21/2017 8:49 AM, Fred J. McCall wrote:
"Robert Clark" wrote:

"S??gi ?" wrote in message news ================================================== ======================
On 6/20/2017 12:31 PM, Robert Clark wrote:
"Robert Clark" wrote in message news
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.


The Parker probe will use a refrigeration system to lower the temperature
of
the components of the spacecraft from 1,400 C to room temperature. This is
about the same temperature drop as the temperature drop from the Suns
surface to the maximum temperature of our high temperature ceramics. So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.

refrigeration wont work. if reflectivity is 99.9% you still ave to move
how many terrawatts(?) from front to back of the spacecraft, AND radiate
that out to cold space on the backside ??


He wasn't speculating, Bob. That is what the Parker Probe is going to
do.


also Gamma rays are going to cook it, +fry electonics.
what are the gamma ray radiation levels close to the sun ?


If you don't know the gamma ray levels, how can you say gamma will
cook it?

The gamma ray flux outside the surface of the Sun is essentially zero.
It all gets converted to visible photons from 170,000 years of
collisions inside the Sun on its way to the surface.


that wiki is out of context.
it seems zero if you compare it to levels within the sun.


Zero. Remember, we're just talking gamma here.


another radiation issue - our south atlantic anomoly cooks electronics
in low orbit sattilites, (earth), an area of trapped radioactive
particals from the sun.


Not gamma.


--
"Insisting on perfect safety is for people who don't have the balls to
live in the real world."
-- Mary Shafer, NASA Dryden
  #18  
Old June 22nd 17, 03:59 PM posted to rec.arts.sf.science,sci.space.policy,sci.optics,sci.physics,sci.military.naval
Robert Clark[_5_]
external usenet poster
 
Posts: 245
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

"Sегgi о" wrote in message news ================================================== =====================
On 6/20/2017 12:31 PM, Robert Clark wrote:
"Robert Clark" wrote in message news
At the distance of the Parker probe, a 1 km sq. mirror could collect a
terawatt of power for beamed propulsion or space solar power beamed to
Earth.

The Parker probe will use a refrigeration system to lower the temperature
of
the components of the spacecraft from 1,400 C to room temperature. This is
about the same temperature drop as the temperature drop from the Sun’s
surface to the maximum temperature of our high temperature ceramics. So it
should be possible to do this temperature drop on the surface of the Sun
using our highest temperature ceramics.


refrigeration wont work. if reflectivity is 99.9% you still ave to move
how many terrawatts(?) from front to back of the spacecraft, AND radiate
that out to cold space on the backside ??

also Gamma rays are going to cook it, +fry electonics.
what are the gamma ray radiation levels close to the sun ?

---
================================================== =====================

This page describes the Parker Solar Probe's cooling system:

Cool Power
Posted on 06/21/2017 09:00:23
http://parkersolarprobe.jhuapl.edu/N...p?articleID=30

Also, I've found NASA scientists are very helpful in responding to questions
from the public if you have more questions on the topic. Contact info for
the Parker Probe scientists is available he

May 26, 2017
MEDIA ADVISORY M17-061
NASA to Make Announcement About First Mission to Touch Sun.
https://www.nasa.gov/press-release/n...n-to-touch-sun


Bob Clark

----------------------------------------------------------------------------------------------------------------------------------
Finally, nanotechnology can now fulfill its potential to revolutionize
21st-century technology, from the space elevator, to private, orbital
launchers, to 'flying cars'.
This crowdfunding campaign is to prove it:

Nanotech: from air to space.
https://www.indiegogo.com/projects/n...ce/x/13319568/
----------------------------------------------------------------------------------------------------------------------------------

  #19  
Old June 23rd 17, 04:42 PM posted to sci.space.policy
[email protected]
external usenet poster
 
Posts: 75
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

On Thursday, June 1, 2017 at 2:30:12 PM UTC-4, Robert Clark wrote:
NASA just announced a solar probe to travel quite close to the Sun, about
3.7 million miles from the solar surface:



I was thinking about beamed energy for Earth to-orbit power. The concept is to alter the goals of photon power. Photon inertia is not the only modality. A powerful laser can make an ion trail. And at the same time power a Magneto-hydrodynamic motor. Simple high flux density solar cells would power the magnets for the motor. Of course the flight path has to stay in the ion trail. The most efficient flight path is likely straight up.

Begging the question as to why the laser does not exactly target the center of the MHD motor.. And it does lose ion fuel with altitude, making a nonlinear launch path scenario.

Light source powered MHDs are quite viable. Fuel ions need only be present for free.
  #20  
Old June 23rd 17, 05:46 PM posted to rec.arts.sf.science,sci.space.policy,sci.optics,sci.physics,sci.military.naval
Robert Clark[_5_]
external usenet poster
 
Posts: 245
Default Close Sun-orbiting mirrors for beamed propulsion and space solar power.

" wrote in message
...

================================================== =================
On Tuesday, June 20, 2017 at 10:31:48 AM UTC-7, Robert Clark wrote:

At a solar radius of 700,000 km away from the Sun, based on the light
intensity going inversely by the square of the distance, and with 1,360
watts per sq. meter (in space) at the Earth’s distance, or 1.36 gigawatts
per sq. km., I estimate this should give 60 terawatts per sq. km. at only
a
solar radius away from the Sun.

But in the post above, I had estimated that fully *on* the Sun’s surface
we
could collect 60 terawatts per sq. km. of power. Anyone have an
explanation
of this discrepancy?


I'm not going to go through the math for you, but think about how much of
the Sun your hypothetical power-collector can "see" from a radius away as
opposed to "on the surface" (which I take to mean just above the
photosphere).

Also, how do you plan to keep it there? It can't orbit, and it can't
float. I'm pretty sure radiation/solar wind pressure won't cut it.

In any case if this research team succeeds in producing this ultra high
reflective, high temperature material, then a mirror smaller than a
kilometer across a solar radius away from the Sun could collect enough
energy for the total energy usage for the entire human population of the
Earth.


I still want to know how the refrigeration system is going to get rid of
the heat. At the photosphere's surface the radiator is going to "see" the
corona no matter how the photosphere is shaded from it.

At a radius out it will "see" much colder interplanetary space.

Mark L. Fergerson

---
================================================== =================

The suggestion that close in to the surface at a solar radius away this will
limit the amount of the Sun's surface it can see is a good one. But if this
was the issue we would expect the solar radiance would be reduced even
further below what was available directly on the surface, not equal to it.

About the solar collector remaining on the surface, it may be that it's
unnecessary anyway if you can get the same amount of power a solar radius
away. But still there is solar outward gas pressure that might allow it to
float there especially for a large area, but lightweight, solar mirror.

The corona is quite hot at millions of degrees but is quite diffuse which
will limit the amount of heat it will transmit to spacecraft. Also since the
temperature of the corona is variable with altitude we might be able to
place it at an altitude to limit the heating.

Bob Clark


----------------------------------------------------------------------------------------------------------------------------------
Finally, nanotechnology can now fulfill its potential to revolutionize
21st-century technology, from the space elevator, to private, orbital
launchers, to 'flying cars'.
This crowdfunding campaign is to prove it:

Nanotech: from air to space.
https://www.indiegogo.com/projects/n...ce/x/13319568/
----------------------------------------------------------------------------------------------------------------------------------

 




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