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#21
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NASA proposes artificial magnetic field to make Mars a secondhome
On 3/10/2017 2:21 AM, Rodney Pont wrote:
On Fri, 10 Mar 2017 01:51:59 -0500, Yousuf Khan wrote: Isn't this the ideal application of that magnetic scoop to collect particles and an ion drive to keep it in position? Even an ion drive will eventually run out of propellant. Then either you go up to refuel the ion drive, or just make it a disposable spacecraft, and when one runs out of fuel, you replace it with another one. Wasteful. That's why I suggested the scoop, to collect more propellant. I'm sure I've seen a proposed spacecraft with a huge magnetic scoop collecting particles to fuel the ion drive. The propellant ions used are not just any old ions, such as hydrogen ions, they are usually more massive ions like Xenon. More mass produces more thrust. https://en.wikipedia.org/wiki/Ion_thruster However, I wonder if a large enough magnetic ring can be used like an ion thruster, only using the solar wind particles, rather than Xenon? Not only could they use the magnetic field to divert the solar winds away from the planet, they could also use it as thrust to keep the orbit stable at the L1 point. Yousuf Khan |
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NASA proposes artificial magnetic field to make Mars a second home
Dear Yousuf Khan:
On Friday, March 10, 2017 at 6:24:53 AM UTC-7, Yousuf Khan wrote: .... However, I wonder if a large enough magnetic ring can be used like an ion thruster, only using the solar wind particles, rather than Xenon? Where does it get its power from? Won't be solar panels... Not only could they use the magnetic field to divert the solar winds away from the planet, they could also use it as thrust to keep the orbit stable at the L1 point. .... which is not where you really want this half-baked system. The particles this "magnetic shield" is to protect you from, are not moving at c. And Mars is still whipping around at a good clip. The "wake" this system produces will fall behind Mars, not *around* Mars. You'd need to "drive" the object a little forward of the stability point. David A. Smith |
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NASA proposes artificial magnetic field to make Mars a secondhome
On 3/10/2017 9:37 AM, dlzc wrote:
Dear Yousuf Khan: On Friday, March 10, 2017 at 6:24:53 AM UTC-7, Yousuf Khan wrote: ... However, I wonder if a large enough magnetic ring can be used like an ion thruster, only using the solar wind particles, rather than Xenon? Where does it get its power from? Won't be solar panels... And why not? Just scale up the number of solar panels to the required level to get to 1 or 2 Tesla. Not only could they use the magnetic field to divert the solar winds away from the planet, they could also use it as thrust to keep the orbit stable at the L1 point. ... which is not where you really want this half-baked system. The particles this "magnetic shield" is to protect you from, are not moving at c. And Mars is still whipping around at a good clip. The "wake" this system produces will fall behind Mars, not *around* Mars. You'd need to "drive" the object a little forward of the stability point. The solar winds aren't travelling at c, they're only going between 300 - 750 km/s. https://en.wikipedia.org/wiki/Solar_wind Yousuf Khan |
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NASA proposes artificial magnetic field to make Mars a second home
In sci.astro message , Wed, 8 Mar 2017
08:16:28, S Ergio posted: On 3/8/2017 6:42 AM, Yousuf Khan wrote: http://www.zdnet.com/article/nasa-pr...agnetic-field- to-make-mars-a-second-home/ Green proposes that by placing a magnetic dipole shield at the Mars L1 Lagrange Point, a man-made magnetosphere sphere would cradle the entire planet. Sort of. The dipole would shield the dayside of the atmosphere of Mars from the solar wind. By the way, in the past, at least some respected authors called L1 "L2" and L2 "L1". The proposal is not by Green; it is by Green /et al/. how far away is Mars L1 Lagrange Point from Mars ? about 141,000,000 miles. Very wrong. how does magnetic field strength decline with distance ? 1/d^2 ? For that, you need a monopole source. Point-dipole fields go as d^-3. so you need a magnet of at least 2*10^16 telsa ? ? The field strength at the magnet is of itself not important. It is the dipole moment which creates the far field. Referees should not have accepted http://www.hou.usra.edu/meetings/V2050/pdf/8250.pdf as it is, on those grounds. why not just put it on the surface ? by the way, you will have to water cool it too. Because that is a different, and not useful, idea; superconductors were discovered about 11 decades ago. Use currently-available high- temperature superconductors or better, and cool by shades as will be done for JWST; allow the magnet to cool by radiation into the rest of the Universe. extra credit questions; 1. how much water is needed to cool magnet that generates a 1 T field 100,000 miles away. (how is this water stored?) None; why 100,000 miles, as according to you L1 is at 141,000,000 miles. (in a zero-litre container). 2. how much electricity in megawatts is required to run magnet, then to pump water. None. But energy will be needed to create the dipole moment initially. 3. what % of partials will be deflected away and outside a 100 mile zone on the surface around the magnet? (assume 98% speed of light) Wrong question. 4. What type of partials will be hardly by magnet ? Parse failure. Try writing in your native language. While Green admits the idea is somewhat "fanciful," this dude works at NASA ??? Why not? NASA must have canteen staff, toilet cleaners, and PR people. But the esteemed originators should not be criticised for the failure of /hoi polloi/ to understand their published proposal, and perhaps to read it. The proposal is to deflect the solar wind, without adding energy to it. Therefore, the wind will press the magnet outwards; the magnet must be a little inwards from L1, because of that and of radiation pressure. -- (c) John Stockton, Surrey, UK. Turnpike v6.05 MIME. Merlyn Web Site - FAQish topics, acronyms, & links. |
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NASA proposes artificial magnetic field to make Mars a second home
Dear Yousuf Khan:
On Saturday, March 11, 2017 at 1:58:40 PM UTC-7, Yousuf Khan wrote: On 3/10/2017 9:37 AM, dlzc wrote: .... Where does it get its power from? Won't be solar panels... And why not? Just scale up the number of solar panels to the required level to get to 1 or 2 Tesla. Don't need intense, if you can get big. ... which is not where you really want this half-baked system. The particles this "magnetic shield" is to protect you from, are not moving at c. And Mars is still whipping around at a good clip. The "wake" this system produces will fall behind Mars, not *around* Mars. You'd need to "drive" the object a little forward of the stability point. The solar winds aren't travelling at c, they're only going between 300 - 750 km/s. https://en.wikipedia.org/wiki/Solar_wind So the "shield" will have to be WAY forward. About 43 minutes forward: https://plus.google.com/+JonathanLan...ts/h4HBjVDkS74 David A. Smith |
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NASA proposes artificial magnetic field to make Mars a secondhome
On 3/11/2017 3:54 PM, Dr J R Stockton wrote:
In sci.astro message , Wed, 8 Mar 2017 08:16:28, S Ergio posted: On 3/8/2017 6:42 AM, Yousuf Khan wrote: http://www.zdnet.com/article/nasa-pr...agnetic-field- to-make-mars-a-second-home/ Green proposes that by placing a magnetic dipole shield at the Mars L1 Lagrange Point, a man-made magnetosphere sphere would cradle the entire planet. Sort of. The dipole would shield the dayside of the atmosphere of Mars from the solar wind. By the way, in the past, at least some respected authors called L1 "L2" and L2 "L1". The proposal is not by Green; it is by Green /et al/. how far away is Mars L1 Lagrange Point from Mars ? about 141,000,000 miles. Very wrong. how does magnetic field strength decline with distance ? 1/d^2 ? For that, you need a monopole source. Point-dipole fields go as d^-3. no, the fields vary as d^n where n is between 2 and 4, and n is also a function of d, and orentation of the field. so you need a magnet of at least 2*10^16 telsa ? ? The field strength at the magnet is of itself not important. It is the dipole moment which creates the far field. field strength is *the key* design requirement, it drives the rest of the design. Referees should not have accepted http://www.hou.usra.edu/meetings/V2050/pdf/8250.pdf as it is, on those grounds. why not just put it on the surface ? by the way, you will have to water cool it too. Because that is a different, and not useful, idea; superconductors were discovered about 11 decades ago. Use currently-available high- temperature superconductors or better, cooling is to lower copper coil losses, high temp superconducters are not yet reliable for this, unless you have a url to a 1 T magnet using one... I think it gets down to watts, if 100 W it probably could be done, if 2000, probably not. and cool by shades as will be done for JWST; allow the magnet to cool by radiation into the rest of the Universe. but all that is limited by # Watts used, and if it is in sunlight, which it is. extra credit questions; 1. how much water is needed to cool magnet that generates a 1 T field 100,000 miles away. (how is this water stored?) None; why 100,000 miles, as according to you L1 is at 141,000,000 miles. (in a zero-litre container). you evade the question, how much heat is generated by the super-cooling refrigeration unit for a 1 T field at 100,000 miles ? ( leave "T at 100,000 miles" as a variable) How many Watts does will the refrigeration unit take to keep the unit cool? how many solar panels ? how much storage capacity is needed ? How much refrigeration fluid is lost each year ? (NASA has supercooled stuff in flight, limited life time due to fluid loss) 2. how much electricity in megawatts is required to run magnet, then to pump water. None. But energy will be needed to create the dipole moment initially. not so, see above, [Im sure NASA has info on this, effecient supercooling refegeration, not sure about application to a magnet, but they probably have a study on it] 3. what % of partials will be deflected away and outside a 100 mile zone on the surface around the magnet? (assume 98% speed of light) Wrong question. yep, wrong question to you, as you do not have any answer. 4. What type of partials will be hardly by magnet ? Parse failure. Try writing in your native language. you engrlish teacher ? this is physics group. While Green admits the idea is somewhat "fanciful," this dude works at NASA ??? Why not? NASA must have canteen staff, toilet cleaners, and PR people. But the esteemed originators should not be criticised for the failure of /hoi polloi/ to understand their published proposal, and perhaps to read it. need more engineering before reclassifying from pipe dream to possable. The proposal is to deflect the solar wind, without adding energy to it. Therefore, the wind will press the magnet outwards; the magnet must be a little inwards from L1, because of that and of radiation pressure. which directly goes to what the field strength should be, . |
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NASA proposes artificial magnetic field to make Mars a secondhome
On 3/11/2017 9:09 PM, dlzc wrote:
Dear Yousuf Khan: On Saturday, March 11, 2017 at 1:58:40 PM UTC-7, Yousuf Khan wrote: On 3/10/2017 9:37 AM, dlzc wrote: ... Where does it get its power from? Won't be solar panels... And why not? Just scale up the number of solar panels to the required level to get to 1 or 2 Tesla. Don't need intense, if you can get big. So either way, i.e. intense or big, how does that preclude using solar panels? ... which is not where you really want this half-baked system. The particles this "magnetic shield" is to protect you from, are not moving at c. And Mars is still whipping around at a good clip. The "wake" this system produces will fall behind Mars, not *around* Mars. You'd need to "drive" the object a little forward of the stability point. The solar winds aren't travelling at c, they're only going between 300 - 750 km/s. https://en.wikipedia.org/wiki/Solar_wind So the "shield" will have to be WAY forward. About 43 minutes forward: https://plus.google.com/+JonathanLan...ts/h4HBjVDkS74 43 minutes is the distance of the L1 away from Mars as far as the local solar wind speed is considered. Or 3.5 light-seconds as far as the solar light is concerned. Yousuf Khan |
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NASA proposes artificial magnetic field to make Mars a second home
Dear Yousuf Khan:
On Sunday, March 12, 2017 at 10:13:05 PM UTC-7, Yousuf Khan wrote: On 3/11/2017 9:09 PM, dlzc wrote: .... Dear Yousuf Khan: On Saturday, March 11, 2017 at 1:58:40 PM UTC-7, Yousuf Khan wrote: On 3/10/2017 9:37 AM, dlzc wrote: ... Where does it get its power from? Won't be solar panels... And why not? Just scale up the number of solar panels to the required level to get to 1 or 2 Tesla. Don't need intense, if you can get big. So either way, i.e. intense or big, how does that preclude using solar panels? Easier to do big, with lower light intensity, and fewer "expensive" materials. ... which is not where you really want this half-baked system. The particles this "magnetic shield" is to protect you from, are not moving at c. And Mars is still whipping around at a good clip. The "wake" this system produces will fall behind Mars, not *around* Mars. You'd need to "drive" the object a little forward of the stability point. The solar winds aren't travelling at c, they're only going between 300 - 750 km/s. https://en.wikipedia.org/wiki/Solar_wind So the "shield" will have to be WAY forward. About 43 minutes forward: https://plus.google.com/+JonathanLan...ts/h4HBjVDkS74 43 minutes is the distance of the L1 away from Mars as far as the local solar wind speed is considered. Or 3.5 light-seconds as far as the solar light is concerned. The magnetic field does not stop light, only charged particles. So solar wind speed, is what needs to be figured in. David A. Smith |
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NASA proposes artificial magnetic field to make Mars a secondhome
On 3/13/2017 10:14 AM, dlzc wrote:
Dear Yousuf Khan: On Sunday, March 12, 2017 at 10:13:05 PM UTC-7, Yousuf Khan wrote: So either way, i.e. intense or big, how does that preclude using solar panels? Easier to do big, with lower light intensity, and fewer "expensive" materials. So go big. They'll figure out the best way to approach it. So the "shield" will have to be WAY forward. About 43 minutes forward: https://plus.google.com/+JonathanLan...ts/h4HBjVDkS74 43 minutes is the distance of the L1 away from Mars as far as the local solar wind speed is considered. Or 3.5 light-seconds as far as the solar light is concerned. The magnetic field does not stop light, only charged particles. So solar wind speed, is what needs to be figured in. David A. Smith The article you linked to is from 2011, and it's about a totally different issue. It's about an early warning system for solar winds, so putting a satellite at the L1 would encounter the solar wind 43 minutes before Mars itself does. But due to the higher speed of light, which gets to Mars in 3.5 seconds, you have 43 minutes - 3.5 seconds of early warning about it. The issue here is not about early warning, but about redirecting the solar winds completely from Mars. So early warning really has no bearing on anything here, except that if the parameters of the magnetic shield need to be adjusted, you have about 7 seconds of turn around time to react from Mars. Yousuf Khan |
#30
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NASA proposes artificial magnetic field to make Mars a second home
Dear Yousuf Khan:
On Wednesday, March 15, 2017 at 8:41:45 PM UTC-7, Yousuf Khan wrote: On 3/13/2017 10:14 AM, dlzc wrote: On Sunday, March 12, 2017 at 10:13:05 PM UTC-7, Yousuf Khan wrote: So either way, i.e. intense or big, how does that preclude using solar panels? Easier to do big, with lower light intensity, and fewer "expensive" materials. So go big. They'll figure out the best way to approach it. You have a lot of faith in "them". So the "shield" will have to be WAY forward. About 43 minutes forward: https://plus.google.com/+JonathanLan...ts/h4HBjVDkS74 43 minutes is the distance of the L1 away from Mars as far as the local solar wind speed is considered. Or 3.5 light-seconds as far as the solar light is concerned. The magnetic field does not stop light, only charged particles. So solar wind speed, is what needs to be figured in. The article you linked to is from 2011, and it's about a totally different issue. It's about an early warning system for solar winds, so putting a satellite at the L1 would encounter the solar wind 43 minutes before Mars itself does. But due to the higher speed of light, which gets to Mars in 3.5 seconds, you have 43 minutes - 3.5 seconds of early warning about it. The issue here is not about early warning, but about redirecting the solar winds completely from Mars. So early warning really has no bearing on anything here, except that if the parameters of the magnetic shield need to be adjusted, you have about 7 seconds of turn around time to react from Mars. The solar wind takes 43 minutes to reach the orbit of Mars. So a "shadow" in solar wind created by an object at the L1 point, crosses Mars orbit 61,920 km BEHIND Mars. Mars is only 7000 km in diameter. David A. Smith |
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