Power satellites

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pmn1

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http://www.spacedaily.com/news/oped-05zza.html<br /><br />100-150MW from a 100 ton satellite seems quite good particularly if you can do it in one go....<br /><br /><font color="orange">The Mega-Module Path To Space Exploration Or: How To Use An HLV<br /><br />An engineering concept shows NASA's new heavy lift and crew launch vehicles. View size compared to Apollo, shuttle. Credit: NASA. <br />by John K. Strickland, Jr.<br />Houston TX (SPX) Oct 06, 2005<br />Ever since the abrupt demise of the Saturn V rocket system at the end of the Apollo era, engineers and space advocates have dreamed of what they could do with a booster of similar capacity.<br />The recent correct decision by Griffin and his team to go for the largest available booster which can be created at a reasonable cost, will now allow us to make big plans for the first time in 35 years. This article focuses on how to exploit the wide variety of large payloads which an truly large HLV makes possible.<br /><br />Replacing the shuttle orbiter and external tank with a second stage based on the ET itself will provide greatly increased flexibility and capability. The only capability lost is that of returning large payloads, and this capability has been used only a few times to advantage.<br /><br />The extreme annual cost of maintaining the shuttle system could have paid for duplicating these payloads many times over. The ability to launch payloads of 100 or more tons with a payload shroud diameter of over 27 feet far outweighs that loss. Using a "hammerhead" type shroud could allow payloads of at least 30 feet across.<br /><br />There are several obvious reasons for wanting a large booster, (beyond just the ability to launch a bigger payload), such as avoiding multiple launches and the massive complications and delays that would accompany them.<br /><br />However, one kind of multiple launch system deserves a second look. Most of the potential problems</font> <div class="Discussion_UserSignature"> </div>
 
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spacester

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Well done, Mr. Strickland!<br /><br />That's what we've been talking about.<br /><br />It is no longer a matter of *hoping* that if we build it (HLLV) they (payloads) will come. There is a space infrastructure to be built, and the first step is propellant depots, the bigger the better.<br /><br />If a consortium of companies that all had solid business plans for heavy payloads got together, they could finance the development of a HLLV. That is one way for the "private sector" to achieve CATS with little to no help from federal tax dollars.<br /><br />I did a post on exactly that concept, except looking at power sats alone to provide the payloads to finance the development of a BDB HLLV, several years ago. I'm gonna see if I can dig it up. The conclusion was that it could be done, but that the scale of the project to "supply 100% of USA's energy needs" was too big even for this wild-eyed optimist.<br /><br />Still, power sats could provide a large chunk of the financial pull to develop CATS, and that's worth considering.<br /><br />I'm not so sure that SPS is a better prospect than SSP though. Lol, SPS is "Solar Power Satellites", beaming power to Earth receivers. SSP is "Space Solar Power", generating power in space and using it in space.<br /> <div class="Discussion_UserSignature"> </div>
 
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barrykirk

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Solar Power sats is the killer app for space.<br /><br />Considering that people are just beginning to realize that global warming causes real problems and energy production is one of the biggest contributors to global warming. We need an alternative power source.<br /><br />Fusion would be it, but it will take too long.<br /><br />Fission would be it, but people are scared of fission. Unreasonably so, but that is the way it is.<br /><br />Ground solar has too many problems.<br /><br />1) Low solar density.<br />2) Night time<br />3) Weather<br />4) Cost of the land<br /><br />Solar Power sats have their own set of problems , mostly high launch costs.... But if the launch costs become low enough, than Solar Power Sats can be very competitive with ground based solar.<br /><br />If the launch costs get really low, than solar power sats can compete with more convential power sources.<br /><br />
 
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nexium

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I'm not sure that solar power satelites are competitive with coal fired electric plants on Earth's surface, even if the launch cost is very low. The rectennas are also costly and have issues.<br />Why put the fuel cashe in low Earth orbit? If the recovery time is brief and known the fuel can be sent ahead such that the manned craft can rondevous part way to Mars at low speed. After the fuel is transfered the rest of the way to Mars can be faster. The empty tank will be in solar orbit or high Earth orbit for future use as a habitat etc. The manned craft to Mars can fine tune the empty tank orbit before detaching from the empty tank. Neil
 
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najab

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I don't get how this is related to the topic of Solar Power Satellites?
 
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nexium

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The second part of my post relates to paragrapgh 6 of the pmn1 post (in orange)<br />A power satellite that delivers a few megawatts to the grid cannot be cost effective. At 1/2 gigawatt, the numbers are mind boggling. Let's start with a steerable flat solar array, 3 kilometers by 4 kilometers = 12 square kilometers in geo synchronous orbit. The cells are connected in series-parallel to produce 5 million volts at no load: 3 million volts at maximum power transfer. Solar input is about 16 gigawatts, so we can expect 3 gigawatts delivered to the far end of the umbilical cord 10 kilometers from the solar array. The DC current is 1000 amps at 3 million volts. To get zero amps, in an emergency, we need to turn the solar array 90 degrees, so the sunlight does not fall on the photovoltaic panels (takes several minutes) or detonate a ton or so of explosives to vaporize a hundred meters of the umbilical cord. I don't think we know how to build a switch that will reliably and quickly turn off three gigawatts of DCpower.<br />We may occasionally need to interrupt power to untangle the umbilical cord. The one kilometer plus antenna tracks Earth while the solar array tracks the sun, and we need to avoid either blocking the other, so I think umbilical cord is the best solution. More in next post. Neil
 
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nexium

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I like traveling wave amplifiers as they can be modulated with broadband data which can be received over half the solar system and half of Earth's surface from the microwave beam leakage. Last I heard, they need about 100,000 volts, so we will operate 30 of them in series to produce 1.5 gigawatts of microwave energy. 30 separate feed horns for a 1 kilometer dish antenna may be best to avoid problems with the 3 million volts DC.<br />I think a very large array of dipoles is cost competitive, but I have no details, except lots of driven dipoles are necessary as a few cannot handle 1.4 gigawatts. We lost 7% getting the RF from the 30 traveling wave amplifiers (more if they can't be designed for 1000 amps input) to the driven dipoles or feed horns. Some heat is produced converting the rf to the microwave beam and at least a small amount of energy goes in wrong directions, so 1.3 gigawatts in the beam = very optimistic.<br />1.2 gigawatts illuminates the rectenna, perhaps divided between 3 rectenas hundreds of kilometers apart. The rectenna does not intercept all of the energy, so 0.1 gigawatts heats the people, cows, ground and whatever else is under the rectenna. We need additional utilization of the several square kilometers (purchased for a billion dollars)<br />Unless the standing wave ratio of the rectenna is 1.000, we can expect 0.1 gigawatts to be reflected back into space. Unless the rectenna covers ten square kilometers, we can expect 0.1 gigawatts to miss the rectenna by a small amount. <br />The ten billion? dipoles are heated by the RF, so we are down to 0.8 gigawatts. The diodes will lose another 0.1 gigawatts = very optimistic. The diode outputs and inverters can be in a series parallel to minimize wiring losses and complications with the series-parallel output arrangement of the hundred thousand? inverters. Perhaps three series strings of inverters phase shifted 120 degrees apart can put the 1/2 gigawatt at 1/2 million volts onto the grid to avoid losing
 
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josh_simonson

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If you put the power-sats at L1 instead of GEO, then they'd provide energy and reduce the amount of heat the earth receives from the sun at the same time. It's certainly cheaper to spread a few hundred square km of mylar at L1 than reduce carbon emissions. Kyoto has already cost $100bn, but only reduced warming by 1/1000th of a degree by 2050. http://www.junkscience.com/MSU_Temps/Kyoto_Count_Up.htm
 
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nexium

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Hi josh: The junk science link did not mention power satellites. My guess is junkscience is correct about Kyoto being ineffective. Generally solar satelites in neither geo orbit nor L1 shade the Earth significantly. It is however possible to fly a sunshade called a statite, but it needs to be bigger than a few hundred square kilometers to cool Earth significantly. It may be important to cool Earth, but it is far more important to free ourselves from Arab oil. Neil
 
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nexium

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Are you sure you want L1? L whatever wobbles due to the moon circling Earth, such that the shadow of the shade will miss Earth during part of each month, unless station keeping energy is used. This is less energy than reqired by a satite at 150,000 kilometers, but the closer shade cools lots more, for the same shade size.<br />I think laser beams can produce a spot size of about one square kilometer from the closer distance: 100 square kilometer at 1,500,000 kilometers, but the optics required are huge (and of extreme precision) especially if you want to send one million megawatts = 1000 gigawatts. The sunshade will be undesirable when the next ice age begins. Neil
 
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josh_simonson

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I was thinking that having it at L1 would allow it to always shade the earth. Perhaps closer orbits would be more effective, even if the shade is only between the earth and sun for less than half the time. <br /><br />I believe less than 1% of sunlight would have to be deflected to counteract the couple degrees of warming we're supposed to get over the next century. Perhaps judicious use of that shade could help change the climate of deserts or cool the hurricane spawning parts of the atlantic as well.<br /><br />To market it, call the thing a 'sunlight denial system' that can be used to sanction the enemies of the free world. <img src="/images/icons/wink.gif" />
 
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barrykirk

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The problem with a "sunlight denial" system is that it would target civilian farmers more than the military of an annoying state.
 
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josh_simonson

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I was mostly tounge-in-cheek for that last bit about 'sun denial'.
 
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bobvanx

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<blockquote><font class="small">In reply to:</font><hr /><p>I'm not sure that solar power satelites are competitive with coal fired electric plants on Earth's surface,<p><hr /></p></p></blockquote><br /><br />Ralph Nansen shows, in his book "Sun Power," how the basic fact of continuing to supply fuel in an inflationary economy to a coal-fired plant over a 40-year period ends with a cost of 70c per kWHr. A satellite system ends with a cost of 2c per kWHr.<br /><br />A satellite system is all about the capital cost. A coal fire system gets to spread costs out over a long time, pushing them into the future.<br /><br />Finally, a rectenna can be placed on marginal land. Coal mines are huge. The land denuded by coal mining is larger than the land area needed for rectennas.
 
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vogon13

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Simpson's did it.<br /><br /><img src="/images/icons/wink.gif" /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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nexium

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Let's try some arithmetic on a 200 megawatt rectenna on an abandoned strip mine in West Virginia. Typically the land has many short, but steep slopes, but the rectenna needs to be approximately flat, so the structure to hold the 100 billion dipoles is perhaps as costly as 4 square kilometers of no frills bleachers for a sports event. If the dipoles cost ten cents each (optimistic) including materials, instalation and testing = 10 billion dollars. Let's assume 20 billion dollars total including a high tension power line to carry the 200 megawatts 50 kilometers to the nearest mid size city. That is $100 per watt = $100,000 per kilowatt for 100,000 hours = one dollar per kilowatt hour, so the rectenna is a large part of the total cost, if it can be built that cheaply and operate with little mantainance for 100,000 hours = 4167 days = 11.4 years, unless I made an arithmetic error.<br />It appears the rectenna cost is more than the total value of the electricity even if the land costs one million dollars, including real estate taxes for 11.4 years. Better: 50 years of operation may be practical for another billion dollars in mantainance costs.<br />Mantainance costs for the GEO orbit solar power satellite, may be enormous to keep it reliable for 50 years, even with very cheap access to space. Neil
 
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tukong

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I have been interested in SPS since I met Dr. O'Neil in 1981 and spoke with Dr. Glaser several times. It seems that you are making the argument that SPSs are an unworkable technology with current engineering and materials. Am I wrong on this? Do you think that a viable and realistic operation model can be designed with current understanding or maybe some extra research? The gentlemen form MITI seem to think it is possible and their designs are interesting. I spoke with Boris Gubonov who designed the Energia (IPO) for the Soviets about HLLV capacities using Fuzzy Boundaries concepts for GEO and Lunar injection. Neil Armstrong, in 1995, pointed out to me, that the most difficult part of the problem was political in nature. 10 years, later there might be a political solution, but it hinges on engineering after all. I am truly interested in find a viable SPS operational solution, but listening to the ‘preachers’ talking to their flock only provides food for the believers. I need a realistic “Devil’s Advocate” to bring the problems out, so that solutions can be found. As the say, “The Devil is in the details.” If this technology could be agreed as viable, I am of the belief that it could be initiated in a very short time frame given the proper political, financial, environmental and social climates. It appears that some of the more astute financial pundits of the world, believe a $300 billion project could be funded without government revenue. Given financial comparison models of the Iraq action and Katrina to date and projected total cost to benefits, the political climate my be ready to support such an effort IF it is plausible and viable from and engineering standpoint. So, I am very interested in your opinion. Can it be made to work?
 
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nexium

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Unless the military has much advanced technology the cost would be thousands of times the cost of a coal fired electric plant. Optimistic projections for a space elevator might bring the price down to 100 times a coal fired plant. Cheap super conductors are needed to make a 20 gigawatt beam practical. Neil
 
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rjoshb

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Wouln't it be easier to put these on a planetray body such as the moon rather than floating them in space?
 
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barrykirk

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Most of the proponents of power sats are talking about putting them in geo synch orbit for several reasons.<br /><br />1) It's stationary over the ground. Your ground based antenna is pointed at the time of construction and never moved. The moon rises and sets and goes through all sorts of complicated motions.<br /><br />2) Geosynch is a lot closer than the moon.<br /><br />3) Geosynch is guarenteed 23 hour 50 plus minutes of direct overhead sunlight per day. The moon doesn't have very many spots that have that much sunlight.<br /><br />4) Geosynch is a lot closer to the earth than the moon. The beam doesn't have to be focuse as tightly.<br /><br />5) If using earth manufactured cells, the cost of transport to geo synch is a lot cheaper than to the moon. If using moon manufactured cells, they will be too expensive to use for powering the earth.<br /><br />6) The cost of the support structures is a lot lower in geo-synch orbit than on the lunar surface. Zero G is a lot lower than 1/6 G.
 
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mikeemmert

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They're not going to build solar power satellites according to Peter Glasser's original design. Nobody's interested.<br /><br />I think it was kind of a strawman design anyway, mostly designed to elicit ideas. These have not been forthcoming.<br /><br />The major problems I see are 1) the orbital debris problem with it's exponential increase in space junk, leading the geosychronous design to render that orbit useless for any purpose in about 30 years, and 2) magnetically induced currents in the miles and miles of conductors. That's less of a problem at GEO but there are still solar flares and CME's.<br /><br />Nobody has delved into shorter wavelenth power beams. Transmission windows through the atmosphere occur above 1 cm, narrow windows down to 1 mm, at 10.6 microns (infrared) and several are available at shorter wavelenths like 3.3, 2.2, and 1.1 micron. And of course there are visible wavelengths. Shorter wavelengths focus more easily.<br /><br />The orbital debris problem might be solvable with LEO orbits sweeping the debris away. Polar sun-synchronous walking orbits along the day-night terminator would have the large solar panels slicing sideways through the highly tenuous upper atmosphere. That would neccesitate a network of secondary transmission satellites transferring power to each other.<br /><br />Maybe the induction problem could be solved by using beams on board the satellite itself, possibly transmitted with optic fibers.<br /><br />Yeah, it's pretty speculative. Come on, people, this is the Space.com message board! You're all using pseudonyms except me, and I don't mind at least trying to come up with new ideas to revive this moribund project. Let's get creative!<br /><br />
 
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nexium

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Hi mikeemmert: I think your analysis is correct, except I believe investors will appear when cheap access to space appears. I have a varriation on your polar sun-sychronous walking orbits. Are you thinking semi-polar as there appears to be little point in over Antarctica nor Northern Greenland. I've been guessing altitude 10,000 miles for the sun sychronous orbit altitude. I think the solar panels would never be shaded if the satelites stayed over the sunshine terminator, which is a plus. The beam could reach rectennas just before the peak demand in early evening, and continue for several hours if an other rectenna did not have greater need. At this time of day the beam would be least disruptive to existing powerplant economics. The shorter beam length means the transmitting antenna can be smaller and/or be less accurate and a beam aiming error can be corrected quicker.<br />The rectennas can also be smaller, if the public will tolerate one watt per square cm =10,000 watts per square meter = 10,000 megawatts per square kilometer. A guard band is needed around each rectenna and there will be hot spots up to ten times that powerful, but the hot spots are fast moving, so fatalities will be rare, even if the beam falls on a dense population instead of a rectenna. A person wearing a foil lined hat will be safer. I don't think you need any secondary transmission satellites, unless you want to energize rectennas many hours away from the peak demand period.<br />The solar panels and the transmitting antenna will however hit the least space debris, I think, if they are at noon instead of the sunshine terminator. Demand however is typically much lower at noon, especially if there is lots of competing surface solar power. If the transmiting antenna is at the center of the back of the giant solar panel, I think there are no blocking problems for the solar sychronous satellite, but there is for the GEO sychronous satellite.<br />At fractions of a millimeter, each rectenna will have
 
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