Author Topic: Solar Power Satellites  (Read 24667 times)

Offline Asteroza

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Re: Solar Power Satellites
« Reply #80 on: 06/09/2017 01:22 AM »
IN THE INTERESTS OF PUBLIC DISCLOSURE:

CASSIOPeiA – Constant Aperture, Solid State, Integrated, Orbital Phased Array



I think I get the design, but is the helix central axis actively pointed at the sun, or are you willing to take the off-angle power efficiency loss to utilize passive pointing? Like Mankin's SPS-ALPHA, unless you have a lot of good orientation/beaming pictures, people will have trouble visualizing the arrangement and usage. If passive, would you also be using an upward tether mass to gravity gradient stabilize the nadir pointing of the phased array, or will you also be using active means to roll the helix to improve pointing at specific ground targets?

Ideally (at GSO), the helix axis is normal to the ecliptic. A dielectric mirror inclined at 45 degrees allows a CPV chip to be mounted on the same substrate as the electronics (with radiation shielding provided by the secondary  Kohler concentrator), and may be integrated with the triple-antenna arrangement which generates the steerable cardioid pattern. Thermal management is by simple heat spreading by the conductive layers within the substrate.

The comparison here is with a standard square planar array (having side D, no rear reflector/absorber) having the same number of RF elements, power and spacing. The side-view RF aperture of the array equals its solar collecting area, and is given by 2*D^2/pi

The RF surface intensity animation is modelled for a slightly larger array, as it rotates through 360 degrees of orbit (as seen from Earth), continuously and directly facing the sun (one physical rotation/year).

As can be seen, from a mass distribution POV, the design is rotationally symmetric (so no GG stabilisation). Attitude and maneuvering control is still required, though a means of using passive sunlight pressure to aid sun-pointing is being investigated.


My RF literacy is not great, so I need to check something here. The three dipole antennas of a single transmission module all control of the beam such that you can transmit in any desired radial direction around an axis normal to the module "plate", correct? What does the radiation pattern look like in the other 2 axis (aka normal to the plate)?

Your original helix image shows what appear to be transmit plate squares hanging off the PV vanes like sub-fins, with all the plates aligned to make a single virtual flat plate that shares the same normal axis as the individual plates.

So, is the actual primary beam direction coming from the virtual flat plate normal axis ideally, or does it come from the side of the virtual plate? I guess I am asking if the correct ground orientation is a visually blocking plate like the upper left view of the helix model picture, or the mostly see through view of the lower left.

I get the feeling the helix design is more different between an SSO type and a GEO/GSO type, due to the pointing needs of the structure if the 45 degree mirror is fixed.

Offline SICA Design

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Re: Solar Power Satellites
« Reply #81 on: 06/12/2017 09:01 AM »
...The three dipole antennas of a single transmission module all control of the beam such that you can transmit in any desired radial direction around an axis normal to the module "plate", correct? What does the radiation pattern look like in the other 2 axis (aka normal to the plate)?

If you take the polar radiation pattern of an ideal vertical half-wave dipole, it is omnidirectional in azimuth (360 degrees), and like a figure 8 on its side (or infinity symbol) in elevation. CASSIOPeiA has an equivalent high-gain beaming capability: 360 degrees azimuth and +/-55 degrees in elevation. This capability arises through the combination of each element able to steer a cardioid pattern (in azimuth), and the distribution of these elements across a helical surface having constant aperture from any side view.

I've superimposed the ideal dipole pattern (in grey) and results from a small model CASSIOPeiA on the same polar plots. The peak intensity drops by half at +/- 55 degrees elevation. The azimuth plot includes beam sweeps at both 0 and 55 degrees elevation*.

Quote
Your original helix image shows what appear to be transmit plate squares hanging off the PV vanes like sub-fins, with all the plates aligned to make a single virtual flat plate that shares the same normal axis as the individual plates.

So, is the actual primary beam direction coming from the virtual flat plate normal axis ideally, or does it come from the side of the virtual plate? I guess I am asking if the correct ground orientation is a visually blocking plate like the upper left view of the helix model picture, or the mostly see through view of the lower left.

The "transmit plate squares" are actually the polymer Fresnel lenses (transparent to microwaves). The diagram shows how the actual triple dipoles (one RF element) can be integrated with the concentrating photovoltaic  (CPV) optics without shadowing.

The relationship between CPV and RF elements is not always 1:1, but follows the sine of the angle each layer makes with the sun. At middle layers, this angle is 90 degrees, hence full coverage by CPV optics, at outer layers the angle (and hence CPV coverage) approaches zero. RF element coverage, however, is essentially uniform across the array, with (at-most) half-wavelength separation to neighbouring elements to avoid grating lobes.

Quote
I get the feeling the helix design is more different between an SSO type and a GEO/GSO type, due to the pointing needs of the structure if the 45 degree mirror is fixed.

The helix design remains the same, however the concentrating optics may differ (such as using compound parabolic concentration - CPC) to allow a wider solar acceptance angle (*at the expense of optical concentration) - this will likely be the case for the stratospheric version where roll/yaw angles may be harder to maintain.

[*Edits for clarification]
« Last Edit: 06/12/2017 12:48 PM by SICA Design »

Offline Asteroza

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Re: Solar Power Satellites
« Reply #82 on: 06/13/2017 02:02 AM »
...The three dipole antennas of a single transmission module all control of the beam such that you can transmit in any desired radial direction around an axis normal to the module "plate", correct? What does the radiation pattern look like in the other 2 axis (aka normal to the plate)?

If you take the polar radiation pattern of an ideal vertical half-wave dipole, it is omnidirectional in azimuth (360 degrees), and like a figure 8 on its side (or infinity symbol) in elevation. CASSIOPeiA has an equivalent high-gain beaming capability: 360 degrees azimuth and +/-55 degrees in elevation. This capability arises through the combination of each element able to steer a cardioid pattern (in azimuth), and the distribution of these elements across a helical surface having constant aperture from any side view.

I've superimposed the ideal dipole pattern (in grey) and results from a small model CASSIOPeiA on the same polar plots. The peak intensity drops by half at +/- 55 degrees elevation. The azimuth plot includes beam sweeps at both 0 and 55 degrees elevation*.

Quote
Your original helix image shows what appear to be transmit plate squares hanging off the PV vanes like sub-fins, with all the plates aligned to make a single virtual flat plate that shares the same normal axis as the individual plates.

So, is the actual primary beam direction coming from the virtual flat plate normal axis ideally, or does it come from the side of the virtual plate? I guess I am asking if the correct ground orientation is a visually blocking plate like the upper left view of the helix model picture, or the mostly see through view of the lower left.

The "transmit plate squares" are actually the polymer Fresnel lenses (transparent to microwaves). The diagram shows how the actual triple dipoles (one RF element) can be integrated with the concentrating photovoltaic  (CPV) optics without shadowing.

The relationship between CPV and RF elements is not always 1:1, but follows the sine of the angle each layer makes with the sun. At middle layers, this angle is 90 degrees, hence full coverage by CPV optics, at outer layers the angle (and hence CPV coverage) approaches zero. RF element coverage, however, is essentially uniform across the array, with (at-most) half-wavelength separation to neighbouring elements to avoid grating lobes.

Quote
I get the feeling the helix design is more different between an SSO type and a GEO/GSO type, due to the pointing needs of the structure if the 45 degree mirror is fixed.

The helix design remains the same, however the concentrating optics may differ (such as using compound parabolic concentration - CPC) to allow a wider solar acceptance angle (*at the expense of optical concentration) - this will likely be the case for the stratospheric version where roll/yaw angles may be harder to maintain.

[*Edits for clarification]

Now it's starting to make sense! So if I understand correctly now, the dipoles are on the vanes (and normal to the vane), thus the beam covers 360 about the helix axis, and the virtual antenna provides some steering about the "face" of the antenna to track a ground target. So for GSO, the helix axis is normal to the ecliptic, and depending on the fresnel lens panels and and 45 degree mirrors, there might be some shadowing but usually not.

Couldn't you cheat a bit with the 45 degree mirror by changing to a half fresnel lens focusing to a spot just above the CPV cell, and place a much smaller 45 degree mirror there for the final turn?

However for the SSO case, if the helix axis is aligned to the ecliptic to allow easy ground tracking, would you essentially have fresnel lens sheets above the CPV that are coplanar to the vane?

Offline SICA Design

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Re: Solar Power Satellites
« Reply #83 on: 06/15/2017 12:38 PM »
Now it's starting to make sense! So if I understand correctly now, the dipoles are on the vanes (and normal to the vane), thus the beam covers 360 about the helix axis, and the virtual antenna provides some steering about the "face" of the antenna to track a ground target. So for GSO, the helix axis is normal to the ecliptic, and depending on the fresnel lens panels and and 45 degree mirrors, there might be some shadowing but usually not.

The centre-feed points of the triple dipoles are located on the substrate (shown horizontal - this could be what you mean by "vanes"), spaced one-quarter wavelength apart from each other (12.9mm for 5.8GHz). These can fit around the concentrating optics where necessary, as shown in the diagram.

Yes, the beam can steer 360 degrees about the helix axis, which is typically at 90 degrees (normal) to the ecliptic plane. It can also steer +/-55 degrees with respect to this plane, only a fraction of which would be required from ~5 Earth radii distance (36,000 km, GSO).

There should be no self shadowing by the lenses; each directly faces the Sun, with no overlap from the Sun's viewpoint. There will be some area-fill efficiency losses due to the thin substrate and lens edges.

"virtual antenna"??

Quote
Couldn't you cheat a bit with the 45 degree mirror by changing to a half fresnel lens focusing to a spot just above the CPV cell, and place a much smaller 45 degree mirror there for the final turn?

The concentrating optics are non imaging, but the "focal point" has to be fixed with respect to the Kohler concentrator and CPV for even illumination across its surface.

Quote
However for the SSO case, if the helix axis is aligned to the ecliptic to allow easy ground tracking, would you essentially have fresnel lens sheets above the CPV that are coplanar to the vane?

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

You are correct that the 45 degrees planar mirror angle could differ for each of the offset orbits, should the helix axis not remain normal to the Sun-line (the latter being my preference). Alternatively the optics could change to a compound parabolic concentrator configuration (lower concentration, but wider solar acceptance angle). The CPC would also comprise a dielectric reflector to avoid interference with the microwaves.
« Last Edit: 06/15/2017 12:43 PM by SICA Design »

Offline Asteroza

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Re: Solar Power Satellites
« Reply #84 on: 06/19/2017 12:00 AM »

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Offline SICA Design

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Re: Solar Power Satellites
« Reply #85 on: 06/19/2017 11:55 AM »

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Starting small, a station-keeping pseudo-satellite in the stratosphere gives many of the same advantages as geostationary - i.e. its always visible over a fixed point on Earth throughout 24 hours. The disadvantage is that the stratosphere is still subject to the day/night cycle, whereas Earth's shadow is mostly avoided by a satellite at GSO/GEO (exception is daily outages of a few ten's of minutes around the spring and autumn equinox).

This particular set of 3-hour sun-synchronous orbits is a compromise; it allows satellites approximately 1/5 the mass to feasibly be deployed as a single payload (given future ITS-scale heavy-lift), without complex on-orbit construction. Modelling has shown that a rectenna situated at latitudes north of 45 degrees can switch between satellites to maintain >23 hours power output (i.e. predictable, near-baseload power which repeats daily throughout the year, including mid-winter where the "red" satellite still skips over Earth's shadow, as shown).

What hasn't been proven yet is that this should also be possible simultaneously for a second rectenna (at similar latitude) half-way around the globe.

Without 5 satellites, the rectenna utlisation is much less.

I've previously looked at Molniya for the HESPeruS SPS - it was the most feasible orbit for a solid-state satellite (no moving/rotating parts) given the beam steer limitations of a phased array. It had much reduced mass (and requires less delta-vee), but still had to be very large to focus a beam from 40,000km to northern latitudes only.

CASSIOPeiA doesn't have these beam-steer limitations! It is a new arrangement of phased array able to steer a beam through 360 degrees azimuth and +/-55 degrees elevation, suitable for any orbit (hence the patent application for a Constant Aperture, Solid State, Integrated, Orbital Phased Array).
« Last Edit: 06/19/2017 11:58 AM by SICA Design »

Offline Asteroza

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Re: Solar Power Satellites
« Reply #86 on: 06/19/2017 11:05 PM »

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Starting small, a station-keeping pseudo-satellite in the stratosphere gives many of the same advantages as geostationary - i.e. its always visible over a fixed point on Earth throughout 24 hours. The disadvantage is that the stratosphere is still subject to the day/night cycle, whereas Earth's shadow is mostly avoided by a satellite at GSO/GEO (exception is daily outages of a few ten's of minutes around the spring and autumn equinox).

This particular set of 3-hour sun-synchronous orbits is a compromise; it allows satellites approximately 1/5 the mass to feasibly be deployed as a single payload (given future ITS-scale heavy-lift), without complex on-orbit construction. Modelling has shown that a rectenna situated at latitudes north of 45 degrees can switch between satellites to maintain >23 hours power output (i.e. predictable, near-baseload power which repeats daily throughout the year, including mid-winter where the "red" satellite still skips over Earth's shadow, as shown).

What hasn't been proven yet is that this should also be possible simultaneously for a second rectenna (at similar latitude) half-way around the globe.

Without 5 satellites, the rectenna utlisation is much less.

I've previously looked at Molniya for the HESPeruS SPS - it was the most feasible orbit for a solid-state satellite (no moving/rotating parts) given the beam steer limitations of a phased array. It had much reduced mass (and requires less delta-vee), but still had to be very large to focus a beam from 40,000km to northern latitudes only.

CASSIOPeiA doesn't have these beam-steer limitations! It is a new arrangement of phased array able to steer a beam through 360 degrees azimuth and +/-55 degrees elevation, suitable for any orbit (hence the patent application for a Constant Aperture, Solid State, Integrated, Orbital Phased Array).

For a multisite requirement, would you favor 3 tundra orbits with 2-3 sats each to provide high latitude global coverage (something like the QZSS layout, but with three figure 8 footprints)?

Offline SICA Design

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Re: Solar Power Satellites
« Reply #87 on: 06/20/2017 10:24 AM »

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Starting small, a station-keeping pseudo-satellite in the stratosphere gives many of the same advantages as geostationary - i.e. its always visible over a fixed point on Earth throughout 24 hours. The disadvantage is that the stratosphere is still subject to the day/night cycle, whereas Earth's shadow is mostly avoided by a satellite at GSO/GEO (exception is daily outages of a few ten's of minutes around the spring and autumn equinox).

This particular set of 3-hour sun-synchronous orbits is a compromise; it allows satellites approximately 1/5 the mass to feasibly be deployed as a single payload (given future ITS-scale heavy-lift), without complex on-orbit construction. Modelling has shown that a rectenna situated at latitudes north of 45 degrees can switch between satellites to maintain >23 hours power output (i.e. predictable, near-baseload power which repeats daily throughout the year, including mid-winter where the "red" satellite still skips over Earth's shadow, as shown).

What hasn't been proven yet is that this should also be possible simultaneously for a second rectenna (at similar latitude) half-way around the globe.

Without 5 satellites, the rectenna utlisation is much less.

I've previously looked at Molniya for the HESPeruS SPS - it was the most feasible orbit for a solid-state satellite (no moving/rotating parts) given the beam steer limitations of a phased array. It had much reduced mass (and requires less delta-vee), but still had to be very large to focus a beam from 40,000km to northern latitudes only.

CASSIOPeiA doesn't have these beam-steer limitations! It is a new arrangement of phased array able to steer a beam through 360 degrees azimuth and +/-55 degrees elevation, suitable for any orbit (hence the patent application for a Constant Aperture, Solid State, Integrated, Orbital Phased Array).

For a multisite requirement, would you favor 3 tundra orbits with 2-3 sats each to provide high latitude global coverage (something like the QZSS layout, but with three figure 8 footprints)?

Yes, it would also work in Tundra and other similar 24 hour orbits, but both the transmitter (CASSIOPeiA) and rectenna sizes would need to grow to accommodate the greater apogee (wrt GEO), yet still deliver 50W/m^2 mean, 230W/m^2 safe peak beam intensity at the intended site.

Offline Robotbeat

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Re: Solar Power Satellites
« Reply #88 on: 06/20/2017 12:51 PM »
That's really low.

I've often thought that if SBSP will ever be worthwhile, they have to up the beam intensity to greater than sunlight to reduce the footprint.
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Offline SICA Design

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Re: Solar Power Satellites
« Reply #89 on: 06/20/2017 12:54 PM »
Split recent earth vs. space solar posts into separate thread:
Earth Solar vs. Solar Power Satellites
Gongora / Other-Mods - do you know what's happened to this thread (Earth Solar vs. Solar Power Satellites)?

Offline SICA Design

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Re: Solar Power Satellites
« Reply #90 on: 06/20/2017 01:04 PM »
That's really low.

I've often thought that if SBSP will ever be worthwhile, they have to up the beam intensity to greater than sunlight to reduce the footprint.

It's an environmentally acceptable level (NASA/other research - no impact to wildlife passing through the beam, safe for passenger carrying aircraft), far greater (x10 typical) mean power/area than any terrestrial solar farm.

It also offers reassurance that an SPS can't be turned into a space weapon - physical law dictates the peak beam intensity given transmitter aperture (e.g. 1.43km diameter, *projected area being equal to the solar collector), frequency (5.8 GHz is optimum available, >>10GHz is severely attenuated by atmosphere) and distance (e.g. 36,000 km GEO).

[Edit: Clarified RF aperture = Solar Collector area, for the CASSIOPeiA concept, hence peak intensity also limited by the available power, 1365 W/m^2, and the CPV efficiency, 30% - 45%] 
« Last Edit: 06/27/2017 04:03 PM by SICA Design »

Offline QuantumG

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Re: Solar Power Satellites
« Reply #91 on: 06/20/2017 11:16 PM »
That's really low.

I've often thought that if SBSP will ever be worthwhile, they have to up the beam intensity to greater than sunlight to reduce the footprint.

There are SBSP schemes that basically just try to solve the Sun-at-night problem of terrestrial solar. The dumbest being the space-mirrors idea.
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Re: Solar Power Satellites
« Reply #92 on: 06/21/2017 12:46 AM »
Split recent earth vs. space solar posts into separate thread:
Earth Solar vs. Solar Power Satellites
Gongora / Other-Mods - do you know what's happened to this thread (Earth Solar vs. Solar Power Satellites)?

Investigating this ... it may not be back, it got kind of snarky.  But usually a PM is the way to go when wondering these sorts of things.
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Offline QuantumG

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Re: Solar Power Satellites
« Reply #93 on: 06/21/2017 01:02 AM »
Investigating this ... it may not be back, it got kind of snarky.  But usually a PM is the way to go when wondering these sorts of things.

Seeing as we're talking about it... I don't really care if the thread comes back, but I will report-to-mod all attempts to bring that snarkiness back here.
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Offline Nilof

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Re: Solar Power Satellites
« Reply #94 on: 07/08/2017 06:32 PM »
Personally I don't think I agree with low power beam designs. A beam with a spot size of ~10 meters and an average intensity of 100 solar constants is much more useful, since you can have them power vehicles such as boats or aircraft which pay more per kW of energy since they can not feasibly be connected to the grid. High power density SSP's are still less of an issue than concentrated solar thermal farms as far as birds or aircraft go. You could even put receivers on tethered high-altitude balloons if you're really that worried.

I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.
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Offline Asteroza

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Re: Solar Power Satellites
« Reply #95 on: 07/09/2017 11:40 PM »
Personally I don't think I agree with low power beam designs. A beam with a spot size of ~10 meters and an average intensity of 100 solar constants is much more useful, since you can have them power vehicles such as boats or aircraft which pay more per kW of energy since they can not feasibly be connected to the grid. High power density SSP's are still less of an issue than concentrated solar thermal farms as far as birds or aircraft go. You could even put receivers on tethered high-altitude balloons if you're really that worried.

I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.

Certainly an economic case can be made for large vehicles and fixed remote sites that require small receivers as early customers for bootstrapping. Notably, military forward bases and small islands, both of which pay through the nose for power, and both have little land reservable for large rectennas. Though that then pushes into laser territory due to the physics of it all, which is fine by me as a laser system allows launcher upgrades that accelerate bootstrapping. I have a dislike about having to weaken system designs for political purposes, but infrastructure projects by their nature are political in nature, so you're damned if do, damned if you don't.

Offline QuantumG

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Re: Solar Power Satellites
« Reply #96 on: 07/09/2017 11:55 PM »
I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.

Well, it's obviously not just batteries... even if you had 12 hour days you'd need over double the generation capacity (as the batteries have losses) and typically more than that... and as I keep saying, the real win of space solar power is for the people living in space. Neither energy farms, nor space projects are good investments. If your goal is to make money, go make a Facebook game or whatever.

If you want people living and working in space, selling sunlight is a pretty good business for them.

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Re: Solar Power Satellites
« Reply #97 on: 07/10/2017 11:54 AM »
I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.

Well, it's obviously not just batteries... even if you had 12 hour days you'd need over double the generation capacity (as the batteries have losses) and typically more than that... and as I keep saying, the real win of space solar power is for the people living in space. Neither energy farms, nor space projects are good investments. If your goal is to make money, go make a Facebook game or whatever.

If you want people living and working in space, selling sunlight is a pretty good business for them.
Beaming power by laser to lunar rovers and outposts could well be first use. For rovers even a few 100watts is all that is needed every few hours to operate through lunar night. Radio telescopes would also need power for lunar night.


Online TrevorMonty

Re: Solar Power Satellites
« Reply #98 on: 01/03/2018 03:26 AM »


http://www.minesnewsroom.com/news/lange-studying-feasibility-space-based-solar-power

“The two markets that everyone is interested in as far as space-based solar power is advanced deployment of military units and remote mining operations,” Lange said. 

You can also add space mining operations to that list, especially lunar mines.