Space-Based Power Station

Status
Not open for further replies.
A

alonzofyfe

Guest
Orbiting Power Plant Proposal<br /><br />Let us assume that somebody wanted to build a 10MW power station in space.<br /><br />This power station will not be used to ship power to Earth. Rather, it's intended use is to beam power to a number of government and privately owned space stations and large satellites. These entities wish to outsource the expense of electricity production.<br /><br />I would like to ask: What would you do to construct such a power plant? Would it even be worth doing?
 
T

thereiwas

Guest
I would not want to be on the receiving end of one of these beams. With the angles between vehicles constantly changing the active beam steering would have to be awfully careful. And you would not want to fly thru the beam, or have any satellites pass thru it - they would be fried. In fact the beam may actually be applying thrust.<br /><br />It might be cheaper to push ahead with the development of Bussard's inertial confinement fusion machine.
 
J

j05h

Guest
<i>> I would not want to be on the receiving end of one of these beams.</i><br /><br />Proposed orbit-Earth SPS have a power density about twice normal sunlight. Normal spacecraft shielding should protect crew fine - the main issue might be hull heating. SPS was never planned to be a tight beam. Maintaining a properly shaped kilometer-scale rectenna is going to be a challenge, but not insurmountable. <br /><br />The above assumes typical "O'Neill" SPS. One more modern concept involves circuit based digital transmitters. This type of antenna, if I understand it right, could re-shape it's beams and customize beam-spot characteristics on the fly. This would allow a stationary transmitter to service multiple receivers. Perhaps lasers or charged-plasma beaming (or magnetic,etc) will eventually work, but for now microwaves are probably the best choice simply because of the development that has already happened. <br /><br />One option for high-power SPS (whether microwave or laser) is to have a receiving station separate from crew stations. Power is received at a safe distance (which is tricky w/ microwaves because of side lobes) and delivered to crew craft as charged flywheels or ISRUed fuel cells (waste to methane or similar). <br /><br />With either a high or low power-density scheme, some of the infrastructure could be in separate orbits. Collectors could be in GEO with relays in MEO or similar.<br /><br /><i>> It might be cheaper to push ahead with the development of Bussard's inertial confinement fusion machine.</i><br /><br />I described Polywell to my electrical engineer friend the other day and it totally blew him away. The best part about it is that the technology to do it seems to be lab-level. It's ready to go - and unlike tokamaks and cold fusion, it seems to point to practical, clean break-even. <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
 
J

jimfromnsf

Guest
Tracking recieving stations in LEO would be problematic
 
A

azorean5000

Guest
Perhabs it can be done, who knows? <div class="Discussion_UserSignature"> </div>
 
N

nexium

Guest
The length of the beam = thousands to millions of kilometers is one of the possible show stoppers. This requires a very large antenna for microwave or even millimeter waves.<br />Lasers at present are rarely even one percent efficient, except laser diodes which are a fraction of a watt each and expensive.<br />10 megawatts transmitted by a 10,000 square meter antenna produces a beam which averages one kilowatt per square meter = 1/10 watt per square centimeter which is the maximum allowable leakage from microwave ovens = not very dangerous. The beam will diverge at least slightly over long distances, so perhaps a square kilometer of rectenna is needed at the receiving end, or about that large a stearable mirror or photovoltac array for receiving 10 megawatts of laser energy.<br />My guess is only modest improvements in steering and guidance are needed to keep the beam centered on the rectenna or mirror. Neil
 
A

alonzofyfe

Guest
Thank you for your input. It has been most useful.<br /><br />So, let us then say that this system is going to be used over shorter distances. If a powerstation is built in space, most customers would probably have reason to establish their operations nearby anyway.<br /><br />It would provide for ease in communicating (and trading with) other stations and allow for some measure of safety (mutual support) in an emergency.<br /><br />The satellites will have to provide their own power.<br /><br />So, let us assume a set of stations built just beyond geosynchronous orbit. (1) A power station. (2) A satellite maintenance facility (that hauls communications and other geosynchronous satellites in for refit before sending them out again), (3) A refining system that accepts asteroid material and turns it in to something useful, (4) Some amenities and entertainment for crew, (5) a space ship repair and maintenance facility, and (6) a visitor/tourist/crew quarters "residential" station, <br /><br />For the stations beyond geosynchronous orbit, one of the products provided is a "radiation box" - a room in the center of the station with walls, ceiling, and floor packed with 1 meter of asteroid rubble.<br /><br />I am not talking about huge systems here. I am talking about small systems. Assume that the asteroid processor can only manufacture a standard 2-story house size box with walls 1 meter thick once per year.<br /><br />So, now, what are the limitations? What are the better options?<br /><br />
 
N

nyarlathotep

Guest
<i>"This power station will not be used to ship power to Earth. Rather, it's intended use is to beam power to a number of government and privately owned space stations and large satellites. These entities wish to outsource the expense of electricity production.<br /><br />I would like to ask: What would you do to construct such a power plant? Would it even be worth doing?"</i><br /><br />It's not particularly economic. Ignoring the transmitting station, you need very large rectennas on the smaller satellites if you want any sort of transmission efficiency. These will mass tens of tonnes and make the whole ordeal remarkably pointless. <br /><br />edit: Just read nexiums post which covers the same ground. Lasers just aren't worth considering. Diode lasers aren't particularly efficient and the power conversion gear (either photovoltaic or thermal) will mass pretty much the same as an equivalent set of solar panels anyway.
 
M

MeteorWayne

Guest
"So, let us then say that this system is going to be used over shorter distances. If a powerstation is built in space, most customers would probably have reason to establish their operations nearby anyway. "<br /><br />And that's a big problem.<br /><br />With low earth orbit, "nearby" is a very temporary thing unless you spend fuel to maintain that position.<br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
K

kelvinzero

Guest
If the satellites were able to store power for a short duration (I guess about 45 minutes if in low orbit and reverse direction) or use it immediately eg for thrust then this problem could become a benefit. One power satellite could service a large area. Alternatively instead of one large power satelite there could be a number of smaller ones, though I guess that eats into the advantage.
 
M

MeteorWayne

Guest
You don't mean for the satellite to reverse direction, do you?<br /><br />LEO is about a 90 minute orbit in one direction.<br />Changing it even slightly requires large amounts of energy. Reversing it is impossible, since when the speed became zero it would plummet to earth under the influence of gravity. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
A

annodomini2

Guest
Reversing is not impossible, just requires lots of energy as changing orbit and over time rotating the orbit. <div class="Discussion_UserSignature"> </div>
 
M

MeteorWayne

Guest
What he appears to be suggesting IS impossible, reversing during the same orbit. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
T

thereiwas

Guest
You could do it in one "orbit", with a tremendous expenditure of fuel and time:<br /><br />1. Boost prograde into a <i>very</i> elongated Molinya-type orbit.<br />2. On the way back boost like crazy crosswise until the return vector is on the opposite side of the planet. Possibly use the moon to tack on.<br /><br />Seems like a lot of trouble, but not impossible. The whole idea of one central power station in orbit feeding a bunch of other satellites seems like a non-starter to me anyway. So much simpler and more reliable to put solar panels on each one.
 
M

MeteorWayne

Guest
Yep, you are correct it could be done. But if you can carry enough fuel to do it, why do you need solar power <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
A

alonzofyfe

Guest
Please, let me clarify a couple of points.<br /><br />I am actually not talking about a system in low earth orbit. Rather, what I am wondering about is a system just beyond geosynchronous orbit.<br /><br />Also, I do not know where the idea of reversing an orbit came from. I looked for an ambiguity in my post that could be interpreted in such a way, but could not find one.<br /><br />As I understand it, a station just beyond geosynchronous orbit would travel more slowly compared to satellites in geosynchronous orbit. So, geosynchronous satellites will be constant passing 'below' the station.<br /><br />This would give the maintenance station an opportunity to perform maintenance as the satellite passes by.<br /><br />If somebody thought that I was asking about a repair facility that zipped along from satellite to satellite in low earth orbit performing maintenance . . . no, that is not what I had in mind at all. Geosynchronous satellites are all in going in the same direction at the same speed, and all lined up one after the other, right? No course corrections are required.<br /><br />It seems that it would still be cost effective for the satellites to maintain their own power (through photovoltaic cells), though a maintenance team could replace those panels as required.
 
M

MeteorWayne

Guest
It wasn't you who suggested a reversing LEO orbit, it was Kelvin_Zero.<br /><br />Sorry if I confused you.<br /><br />Wayne <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
K

kelvinzero

Guest
Sigh.. why do I only get discussion when people think I have said something so silly that discussion is pointless. Sorry, I worded it badly.<br /><br />Permanently moving in a retrograde orbit.<br /><br />A bit more expensive to launch. Satellites would have to store power for 45 minutes or use it immediately.
 
N

nexium

Guest
Even in low earth orbit, the customers can be in essentually the same orbit about one kilometer away. This requires very little energy to maintain and even less, if the group is just beyond GEO stationary altitude. A one kilometer long beam needs a much smaller antenna and rectenna, but the high power density beam may damage a customer, if the rectenna is positioned wrong. Reasonably each member of the group produces their minimum power needs and the beams provide additional power as desired. One kilometer spacing would be much safer from a marginal nuclear power plant tha leaked lots of radiation.<br /> It might be practical to tether the group members together with a slight spin to insure predictable spacing, roll, yaw and pitch. Neil
 
N

nexium

Guest
The laser diodes look more attractive in this application, even if you need 100 million diodes to produce 10 megawatts. Also consider mirrors which suppliment the energy from the sun of the solar panels of a group member when positioned properly. A laser or mirror beam could also suppliment the power of a working satellite briefly while it is close to the power station. Sometimes a brief shot of power can partially restore batteries which are near the end of their useful life. Neil
 
I

inventorwannabe

Guest
I believe the best thing to do is to use the energy to split water to oxygen and hydrogen. This can then be sold to moonfarers and anyone who is intressted in interplanetary journeys. This will definetly make you a buck or maybe even a vaultload! :)<br /><br />The problem is of course where to get the water initially. Now consider what a kg of water costs to ship to LEO and then consider how much you could charge for the splitted water + your expenses for the powerstation... The energy is free!<br /><br />Seems to be a rocker to me! I'll sign at once for this kind of a mission. The next thought that gets in my mind is that if we control a comet - then another cost will vanish for a very long time filling even a bigger vault :). <br /><br />This vault can then be used to catch an metal rich asteroid, dig it through and make it into an decent size space station with shipyards, laboratories, hotels and - whatever you want! Keep it spinnig to provide at least 0.5G's at the radius of the living quarters and with the poles pointing one at the earth and the other one towards the Sun. The pole towards the sun is where you build your new powerstation. Of course with whatever parts that are usable from the old one... Unless further investigations show that the need for propellants is so big that one station isn't enough. The comet we catched earlier is now nearby this pole behind an artificial shade to prevent it from dissintegratin into space.<br /><br />Enterprises that seeks room at the station will have to pay for the excavations and services needed to fulfill their needs - and the will be many willing to do so. <br /><br />Now, the things we need that is not in place yet.<br /><br />1. A model that lets us slow down a comet in a controlled way with the goal of get it rested at one of the lagrande points... Or for that matter where ever we want it to rest. There is certainly some periods of the comet track that is more rewarding to slow down or speed up than others. It's all about
 
N

neilsox

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I believe the best thing to do is to use the energy to split water to oxygen and hydrogen. This can then be sold to moonfarers and anyone who is intressted in interplanetary journeys. This will definetly make you a buck or maybe even a vaultload! :) The problem is of course where to get the water initially. Now consider what a kg of water costs to ship to LEO and then consider how much you could charge for the splitted water + your expenses for the powerstation... The energy is free! Seems to be a rocker to me! I'll sign at once for this kind of a mission. The next thought that gets in my mind is that if we control a comet - then another cost will vanish for a very long time filling even a bigger vault :). This vault can then be used to catch an metal rich asteroid, dig it through and make it into an decent size space station with shipyards, laboratories, hotels and - whatever you want! Keep it spinnig to provide at least 0.5G's at the radius of the living quarters and with the poles pointing one at the earth and the other one towards the Sun. The pole towards the sun is where you build your new powerstation. Of course with whatever parts that are usable from the old one... Unless further investigations show that the need for propellants is so big that one station isn't enough. The comet we catched earlier is now nearby this pole behind an artificial shade to prevent it from dissintegratin into space. Enterprises that seeks room at the station will have to pay for the excavations and services needed to fulfill their needs - and the will be many willing to do so. Now, the things we need that is not in place yet. 1. A model that lets us slow down a comet in a controlled way with the goal of get it rested at one of the lagrande points... Or for that matter where ever we want it to rest. There is certainly some periods of the comet track that is more rewarding to slow down or speed up than others. It's all about <br />Posted by InventorWannabe</DIV><br />The water used to make hydrogen can have many types of impurities, and extracting energy from the hydrogen typically produces water of high purity, so that is a big plus where water is very expensive as in space. Splitting the water into hydrogen takes about twice as much energy as the hydrogen will produce, but alternatives are also inefficient, and often the oxygen is useful.</p><p>I think we know how to control comets, but&nbsp;comets are fast, so catching a comet takes lots of&nbsp;time and energy. Moving even a 1000 ton comet takes a lot of energy, and bigger comets may distroy a city if a navigational error is made.</p><p>Building cities in space is urgent, but presently too costly, and payback is puny compared to&nbsp;the enourmos construction cost. We can test some of the concepts with hydrogen and/or&nbsp;hot air balloons. Earth likely has only enough helium for one large floating city. Luckily hydrogen has negligible fire hazard above about 10,000 meters altitude.&nbsp;&nbsp; Neil</p>
 
C

Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> If somebody thought that I was asking about a repair facility that zipped along from satellite to satellite in low earth orbit performing maintenance . . . no, that is not what I had in mind at all. Geosynchronous satellites are all in going in the same direction at the same speed, and all lined up one after the other, right? No course corrections are required.<br /> Posted by AlonzoFyfe</DIV></p><p>&nbsp;</p><p>It is no different than LEO.&nbsp; Still would have to "zip" down to the satellite (i.e change orbits and rendezvous) and then&nbsp; "zip" back up and rendezvous with the facility.&nbsp; Since each spacecraft is not 'exactly" at GSO (both in altitude and inclination), there still is a lot of manevering required.&nbsp;</p><p>&nbsp;Also depending on the amount of time a 'repair" would take might mean it could take days to get back to the facility, unless the transfer vehicle has large amounts of propellant. &nbsp; </p>
 
D

DrRocket

Guest
<p>What problem are you trying to solve ?</p><p>Unless you have some process in mind that is much more efficient than the solar cells normally used for power of earth satellites, then you are not only going to incur the cost associated with having basically the same area of solar cells required for the individual satellites but also the losses of transmission, plus the weight of the transmitting and receiving antennae.&nbsp; The large receiving antennae being discussed will be a challenge in themselves.&nbsp; Large membrane structures in a vacuum can get into unstable "flapping" modes so you have to take care of that aspect of the design as well.</p><p>The tranmitting antennas are going to be fairly complicated as well, since I presume that you would be serving many satellites simultaneously.&nbsp; What do you have in mind, some sort of&nbsp;steerable phased array arrangement ?</p><p>This sounds like a very compllicated solution in search of a problem.&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
Status
Not open for further replies.

Latest posts