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*To*: curtismanges@netscape.net*Subject*: Re: starship-design: Hitching a Ride on a Magnetic Bubble*From*: STAR1SHIP@aol.com*Date*: Sun, 8 Oct 2000 01:12:47 EDT*CC*: starship-design@lists.uoregon.edu*Reply-To*: STAR1SHIP@aol.com*Sender*: owner-starship-design@lists.uoregon.edu

In a message dated 10/5/00 10:24:13 AM Pacific Daylight Time, curtismanges@netscape.net writes: > Hi! > I thought you'd be interested in this story from Science@NASA: > > NASA-funded scientists are experimenting with miniature magnetospheres as > an innovative means of space transportation. If the group succeeds, > next-generation spacecraft may come equipped with fuel-efficient magnetic > bubbles that speed their occupants from planet to planet and ward off the > worst solar flares. > http://science.nasa.gov/headlines/y2000/ast04oct_1.htm?friend > (or > <A HREF="http://science.nasa.gov/headlines/y2000/ast04oct_1.htm?friend"> > Hitching a Ride on a Magnetic Bubble </A>.) Hi Curtis, Partial quote from link "The solar wind's force per unit area decreases as the square of the distance from the Sun. Doubling the distance, for instance, decreases the solar wind pressure by a factor of four. "The solar wind is weaker far from the Sun, but the bubble is bigger, too (precisely because the solar wind pressure is lower)," he continued. "It so happens that the cross section of the bubble increases by the same factor that the solar wind pressure declines. The two effects completely cancel." It seems amazing, but the propulsive thrust of an M2P2-powered craft remains the same whether the spacecraft is near the Sun or in the outer reaches of the solar system. " end partial quote ----- I would have to examine the math. On the surface It seems to violate the laws of conservation of momentum. P=mv, so the momentum of the push force must equal the momentum of the accelerating object. I do not see how the bubble getting bigger cancels the inverse square law that determines the push force in relation to the acclerating object bubble field size. In other words, I am not convinced the area exposed to the solar wind by increased bubble size is an equal size inverse square function as claimed. Bubble size may indeed have some linear effect, but not to the exponential extent claimed. Do you have any more math data on the subject? It seems clear to me using the powering energy of the sun being it light, electro or magnetectic field providing the energy. The inverse square law limits the practicality as the observed sun grows dimmer and smaller wrt to the bubble. For the conservation of energy or momentum to balance on both sides of the equation, an added energy source would be in order. Energy added to the bubble from internally aboard the craft may be required to cancel the remainder of the inverse square function. If so, that energy must come from an increased mass aboard the ship which puts you back to square one and a decrease in velocity as P remains equal to mv. Until I am shown the error of my ways I will stick to action/reaction engines blowing exhaust out the back as they are practical for star journeys. Solar power just fizzles out any signifigant distance from the sun. Tom

**Follow-Ups**:**Re: starship-design: Hitching a Ride on a Magnetic Bubble***From:*Steve VanDevender <stevev@efn.org>

**Re: starship-design: Hitching a Ride on a Magnetic Bubble***From:*curtismanges@netscape.net (Curtis Manges)

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