Just found this new idea for SBSP, instead of the traditional GSO and microwave antenna and ground rectenna. You have LEO orbiting mirrors always in the orbit of the dusk/dawn of Earth, essentially always facing the Sun in a polar orbit riding along the edge of the Earth's shadow. The mirrors reflect sunlight onto the solar panels of already existing, and future, solar farms. Extending their power production 3 hours later in the evening and 3 hours earlier in the morning. Very interesting, I'm curious what temperature affects it'll have adding the sunlight but I don't see any show stoppers or even serious problems with it.
Brooks
http://jxcrystals.com/publications/Mirrors_in_Dawn_Dusk_Orbit_AIAA_Tech_Conf_Final_2013.pdf
"There are two problems limiting solar electric power. The amount of sunlight is limited and there is no sunlight during peak demand in the evening hours. Herein, we note that these problems can be addressed by placing light weight mirror (heliostat) satellite constellations in sun synchronous dawn to dusk low earth orbits in
space at an altitude of 1000 km [1]. These satellites can deflect sunbeams dawn to an array of solar power stations distributed near major population centers around the earth. These solar PV or trough CSP earth stations are already being built. If we assume that there can be 40 such stations generating 5 GW each ten years from now, then the solar energy available to these ground sites can be increased from an average of 7 kWh per sq m per day without thespace mirrors to 12 kWh per sq m per day with the space mirrors. The additional 5 kWh per sq m per day will be provided in the early morning and evening hours. See Fig. 1. The additional solar energy can reduce the cost of
solar electricity at the ground sites to less than 6 cents per kWh."
> but I don't see any show stoppers or even serious problems with it.
Regards,
Mike Combs
From: spacesettlers@yahoogroups.com [mailto:spacesettlers@yahoogroups.com] On Behalf Of brooksn
Sent: Wednesday, July 10, 2013 7:38 AM
To: spacesettlers@yahoogroups.com
Subject: [spacesettlers] A different kind of SBSP
Just found this new idea for SBSP, instead of the traditional GSO and microwave antenna and ground rectenna. You have LEO orbiting mirrors always in the orbit of the dusk/dawn of Earth, essentially always facing the Sun in a polar orbit riding along the edge of the Earth's shadow. The mirrors reflect sunlight onto the solar panels of already existing, and future, solar farms. Extending their power production 3 hours later in the evening and 3 hours earlier in the morning. Very interesting, I'm curious what temperature affects it'll have adding the sunlight but I don't see any show stoppers or even serious problems with it.
Brooks
Agreed, and this doesn't have to replace SBSP via the usual method, it just dramatically augments what we already have and will have on the ground since evening energy use is a very big downfall to ground based solar power. Plus it makes space based power production an immediate reality that will make any further work on any future GSO platform more palatable politically.
Brooks
--- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> You have LEO orbiting mirrors always in the orbit of the dusk/dawn of Earth, essentially always facing the Sun in a polar orbit riding along the edge of the Earth's shadow.
http://www.freemars.org/jeff/speed/
--- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
> --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > You have LEO orbiting mirrors always in the orbit of the dusk/dawn of Earth, essentially always facing the Sun in a polar orbit riding along the edge of the Earth's shadow.
> They'd be catching quite a breeze. Even at 1,000 km above sea level, the average wind-speed broadside to the mirrors would be 7.35 km/s:
> http://www.freemars.org/jeff/speed/
> --- In spacesettlers@yahoogroups.com 13316, wrote:
> 500 km/s.
We're at 3 times the altitude of the ISS and at the higher altitude you get less atmospheric density. I believe each mirror is twice the size of the ISS and the thin material used is similar to that used by a japanese solar sail spacecraft.
Brooks
--- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> We're at 3 times the altitude of the ISS
> the thin material used is similar to that used by a japanese solar sail spacecraft.
Perhaps it would be better not to be in orbit at all, and simply sail at stationary latitudes. The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
--- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
>
> --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > We're at 3 times the altitude of the ISS
>
> ...Which has a greater sectional density and, despite that, still needs to be boosted periodically.
http://www.braeunig.us/space/atmos.htm
> > the thin material used is similar to that used by a japanese solar sail spacecraft.
>
> Perhaps it would be better not to be in orbit at all, and simply sail at stationary latitudes. The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
Wait, not in orbit so in the air from an airplane or balloon? Why would the wing blow it sunward and cosmosward at those times?
Brooks
Wouldn't you be going slower at the higher altitude?
--- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> --- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
> > --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > > We're at 3 times the altitude of the ISS
> > ...Which has a greater sectional density and, despite that, still needs to be boosted periodically.
> The ISS is at 420 km on average, with an atmospheric density around 2.75 E-12, while at 1000 km the atmospheric density is 5.46 E-15, so I believe that's about 1,000 times less atmosphere.
> you will be traveling faster at the higher altitude
No. The opposite is the case. See the link I posted for you which shows orbital speeds at various altitudes:
http://www.freemars.org/jeff/speed/
> > > the thin material used is similar to that used by a japanese solar sail spacecraft.
> > Perhaps it would be better not to be in orbit at all, and simply sail at stationary latitudes.
> not in orbit so in the air from an airplane or balloon?
...No, solar sailing at or above the altitude of the ISS, stationary with respect to the Sun-Earth system.
> > The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
> Why would the wing blow it sunward and cosmosward at those times?
...Because the earth spins (and its atmosphere with it), and does so counterclockwise from the perspective of a viewer from above the north pole, and because the sail mirrors wouldn't be moving with respect to the sun and the earth. Standing on the surface of the earth, you are traveling strait toward the sun at 6AM, and directly away from the sun at 6PM.
> > > > We're at 3 times the altitude of the ISS
> > > ...Which has a greater sectional density and, despite that, still needs to be boosted periodically.
> > The ISS is at 420 km on average, with an atmospheric density around 2.75 E-12, while at 1000 km the atmospheric density is 5.46 E-15, so I believe that's about 1,000 times less atmosphere.
>
> The sectional densities of these sail mirrors might be on the order of one millionth that of the ISS. That would leave you with about 1,000 times as much drag per mass.
>
> > you will be traveling faster at the higher altitude
>
> No. The opposite is the case. See the link I posted for you which shows orbital speeds at various altitudes:
> http://www.freemars.org/jeff/speed/
You are correct on altitude and speed.
The website you posted was very helpful in making the case as well, according to it the equatorial bulge has the biggest affect on satellites in orbits between 500 and 40,000 km. Our mirror sat will be at 1000 km. Below 500, where ISS is, the atmospheric drag is the predominant force in perturbing orbits. Also the website mentions the 'lifetime' of different orbits and puts the ISS in 'years' and a 1000 km orbit in 'millenia'.
> > > > the thin material used is similar to that used by a japanese solar sail spacecraft.
> > > Perhaps it would be better not to be in orbit at all, and simply sail at stationary latitudes.
> > not in orbit so in the air from an airplane or balloon?
>
> ...No, solar sailing at or above the altitude of the ISS, stationary with respect to the Sun-Earth system.
Solar sailing, so using the pressure from the sun to keep you aloft without being in orbit? I wouldn't think there'd be enough pressure to counter the gravity. The only other stationary positions in regards to the Sun-Earth system I know of are the Lagrange points.
> > > The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
> > Why would the wing blow it sunward and cosmosward at those times?
>
> ...Because the earth spins (and its atmosphere with it), and does so counterclockwise from the perspective of a viewer from above the north pole, and because the sail mirrors wouldn't be moving with respect to the sun and the earth. Standing on the surface of the earth, you are traveling strait toward the sun at 6AM, and directly away from the sun at 6PM.
Ah, I get that, but you were describing a non orbiting satellite stationary to the Sun-Earth system, so I was seeing it as a constant dawn for the sat or constant dusk. If you mean a polar orbit that has a constant L configuration with the Sun Earth system, that's what the proposal currently is and yes I would see, what minimal atmospheric drag affects the orbit, would push them as you describe.
Brooks
--- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > > > The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
> > > Why would the wing blow it sunward and cosmosward at those times?
> > ...Because the earth spins
> you were describing a non orbiting satellite stationary to the Sun-Earth system
--- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
>
> --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > > > > The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
> > > > Why would the wing blow it sunward and cosmosward at those times?
> > > ...Because the earth spins
> > you were describing a non orbiting satellite stationary to the Sun-Earth system
>
> Yes. That's why the average speed of the wind hitting the sail-mirror is 538 m/s at an altitude of 1,000 km above the equator. The sail-mirror is stationary, but the earth is spinning.
Brooks
From: brooksn
> I wouldn't think there'd be enough pressure to counter the gravity.
That would all depend on the mass per square area.
I know there's been a proposal to speed up the terraforming of Mars using an enormous halo mirror to concentrate and reflect additional sunlight onto the nighttime side of Mars. At first I thought the mirrors were rotating to resist the Martian gravity (essentially in orbit), and thought they had foolishly neglected to consider that such an enormous mirror ring would gyroscopically maintain orientation relative to the stars and hence would fail to track the sun as Mars orbits. But I later came to realize that the proposed mirrors were not rotating, but were statites, a bit behind Mars relative to the sun, with gravity from Mars exactly balanced by the solar pressure.
So I suppose such a scheme would work. To which I would only say that if Zubrin is right, and we should leave O'Neill habitats out of our thinking because space mirrors a few miles across would get us into "engineering absurdities", then any researcher proposing mirrors bigger than worlds should get kicked out of the conference.
Regards,
Mike Combs
> That would all depend on the mass per square area.
Regards,
Mike Combs
From: spacesettlers@yahoogroups.com [mailto:spacesettlers@yahoogroups.com] On Behalf Of Combs, Mike
Sent: Monday, July 15, 2013 10:32 AM
To: spacesettlers@yahoogroups.com
Subject: RE: [spacesettlers] Re: A different kind of SBSP
From: brooksn
> Solar sailing, so using the pressure from the sun to keep you aloft without being in orbit?
> I wouldn't think there'd be enough pressure to counter the gravity.
That would all depend on the mass per square area.
I know there's been a proposal to speed up the terraforming of Mars using an enormous halo mirror to concentrate and reflect additional sunlight onto the nighttime side of Mars. At first I thought the mirrors were rotating to resist the Martian gravity (essentially in orbit), and thought they had foolishly neglected to consider that such an enormous mirror ring would gyroscopically maintain orientation relative to the stars and hence would fail to track the sun as Mars orbits. But I later came to realize that the proposed mirrors were not rotating, but were statites, a bit behind Mars relative to the sun, with gravity from Mars exactly balanced by the solar pressure.
So I suppose such a scheme would work. To which I would only say that if Zubrin is right, and we should leave O'Neill habitats out of our thinking because space mirrors a few miles across would get us into "engineering absurdities", then any researcher proposing mirrors bigger than worlds should get kicked out of the conference.
Regards,
Mike Combs
--- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> --- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
> > --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > > > > > The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
> > > > > Why would the wing blow it sunward and cosmosward at those times?
> > > > ...Because the earth spins
> > > you were describing a non orbiting satellite stationary to the Sun-Earth system
> > Yes. That's why the average speed of the wind hitting the sail-mirror is 538 m/s at an altitude of 1,000 km above the equator. The sail-mirror is stationary, but the earth is spinning.
> I don't think there is enough force from the limited air molecules to provide enough lift to counter the gravity of the Earth.
--- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
>
> --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > --- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
> > > --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> > > > > > > The wind would still blow the sails sunward at the 6AM side of the planet, and cosmosward at the 6PM side of the planet.
> > > > > > Why would the wing blow it sunward and cosmosward at those times?
> > > > > ...Because the earth spins
> > > > you were describing a non orbiting satellite stationary to the Sun-Earth system
> > > Yes. That's why the average speed of the wind hitting the sail-mirror is 538 m/s at an altitude of 1,000 km above the equator. The sail-mirror is stationary, but the earth is spinning.
> > I don't think there is enough force from the limited air molecules to provide enough lift to counter the gravity of the Earth.
>
> It's a solar sail. The force-stream it rides to stay in position comes from the sun. The 538 m/s average-speed wind blowing on it is unhelpful.
Brooks