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Alternative to Rockets
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#32
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Alternative to Rockets
In sci.space.science Olli Wilkman wrote:
The website describes the technology thus: "The back side of the craft is a large, highly polished parabolic mirror that is designed to capture the laser beam projected at it from the ground. The mirror focuses the beam, rapidly heating the air to 5 ^^^^^^^^^^^^^^^ TIMES the temperature of the sun, creating a blast wave out the back that pushes the vehicle upward. As the beam is rapidly pulsed, the vehicle is continuously propelled forward, on its way to orbit." This seems to imply that no propellant is used as such, Except air. How's this supposed to reach orbit? |
#34
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Alternative to Rockets
"George Kinley" wrote in message ...
Are there any way for rockets to fly in space , other then throwing mass out in one direction and moving in other Yes there is. |
#35
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Alternative to Rockets
Sander Vesik wrote:
Strictly speaking, the solar sail too throws mass (photons) out in one direction and moves in the other direction. Where the mass being thrown out comes from is not too important. I'm sure someone else will also point this out but photons are massless. A solar sail basically redirects the momentum vector of some of the incident photons. In order for momentum to be conserved the solar sail must acquire the vector difference. |
#36
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Alternative to Rockets
Jim Logajan wrote:
Sander Vesik wrote: Strictly speaking, the solar sail too throws mass (photons) out in one direction and moves in the other direction. Where the mass being thrown out comes from is not too important. I'm sure someone else will also point this out but photons are massless. A solar sail basically redirects the momentum vector of some of the incident photons. In order for momentum to be conserved the solar sail must acquire the vector difference. On another point, the sail itself may have low mass, but something is going to have to hold it open and taught. Richard |
#37
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Alternative to Rockets
In article ,
Sander Vesik wrote: In sci.space.tech Mark Foskey wrote: George Kinley wrote: Are there any way for rockets to fly in space , other then throwing mass out in one direction and moving in other If they don't work that way, then we don't call them rockets. One other possibility is a solar sail that uses the pressure of sunlight, but such a sail would have very low thrust. Strictly speaking, the solar sail too throws mass (photons) out in one direction and moves in the other direction. Where the mass being thrown out comes from is not too important. It also catches things, which is something that most rockets don't do. -- "Suppose you were an idiot... And suppose you were a member of Congress... But I repeat myself." - Mark Twain |
#38
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Alternative to Rockets
Richard Lamb wrote:
Jim Logajan wrote: Sander Vesik wrote: Strictly speaking, the solar sail too throws mass (photons) out in one direction and moves in the other direction. Where the mass being thrown out comes from is not too important. I'm sure someone else will also point this out but photons are massless. A solar sail basically redirects the momentum vector of some of the incident photons. In order for momentum to be conserved the solar sail must acquire the vector difference. On another point, the sail itself may have low mass, but something is going to have to hold it open and taught. Radiation pressure plus the solar wind will balloon it out no problem. Two immediate problems come to mind, 1) Steering in general. How do you tack? If you water sail, what will pulling on the sheets (lines, for the rest of you) mean in the context of a solar sail? Where do you set your feet to do the pullng? 2) The curved solar sail - huge area - will have a focus or caustics. Where do you put the ship? If it crosses the sweet spot (or the sweet spot crosses it - billowing in solar storms) the ship is literal toast. -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) "Quis custodiet ipsos custodes?" The Net! |
#39
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Alternative to Rockets
In article ,
Richard Lamb wrote: Jim Logajan wrote: Sander Vesik wrote: Strictly speaking, the solar sail too throws mass (photons) out in one direction and moves in the other direction. Where the mass being thrown out comes from is not too important. I'm sure someone else will also point this out but photons are massless. A solar sail basically redirects the momentum vector of some of the incident photons. In order for momentum to be conserved the solar sail must acquire the vector difference. On another point, the sail itself may have low mass, but something is going to have to hold it open and taught. Richard Possibly centrifugal forces. My favorite design involves unrolling sails like windowshades from a rotating craft. -- "The average person, during a single day, deposits in his or her underwear an amount of fecal bacteria equal to the weight of a quarter of a peanut." -- Dr. Robert Buckman, Human Wildlife, p119. |
#40
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Alternative to Rockets
"George Kinley" wrote:
Are there any way for rockets to fly in space , other then throwing mass out in one direction and moving in other At last - a segue to announce my goofy new interstellar travel system! One can pull masses together rather than throwing them apart! The idea is to use a lot of specially designed "chains" that are strung between star systems - each end of each chain is anchored to some asteroid or small planet. It will take some time to create all the links "the old fashioned way": basically shoot a spool into space and let it unwind. The scheme is called HTML (Hyper Thread Movement Links) that define the WWW (Wanking Wide Web - cause it spans the galaxy with a LOT of links). Anyway, to travel to another system a special vehicle called the HTTP (Hyper Thread Transport Packet) is pulled along the wire. Basically the far anchor is minutely pulled closer while the HTTP moves forward. The HTTP doesn't actually touch the "chains". The "chain" is actually an alternating link of steel and glass segments. The HTTP contains an electromagnet. As it passes the halfway point of a glass segment it turns on the electromagnet - and gets pulled toward the next closer steel segment. As it comes to the steel segment it shuts off the electromagnet and coasts on to the next glass segment, at which time it repeats the same cycle. As the HTTP vehicle speeds up, the on-off frequency must increase. The mechanism to keep things in sync is called the TCP (Transport Control Pull). TCP uses visual sensing (via the luminiferous ether) to view the chain links as its feedback mechanism. So TCP typically runs over the ether. The scheme has a few minor flaws, though. But I may yet get DARPA funding.... ;-) |
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