[Jolly Roger]

Brian H wrote: Right now, H3 is unobtainium. A wee detour to mine the Moon still has to be completed. 😆

I think you mean He3, as H3 is tritium, and though somewhat rare, is not as unobtainable as He3. I do understand that He3 is not currently obtainable. But when it does become obtainable, it will then be possible to downsize the FF reactor shielding. As that will be a few years from now, perhaps the electrical components will have been downsized as well. Then small applications, such as cars, might become possible.

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So, the P-He3 reaction would require 1/6 the shielding, reducing the weight and size of the reactor. That doesn’t do anything for the capacitors or decelerators.

Maybe we can put these FF’s in planes, trucks and buses (and RV’s), but so far, not cars, PC’s or wristwatches.

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JoeL wrote: The main Space Fountain (and related concepts) stumbling block that hasn’t been addressed is that whatever reduction in weight {that} is experienced by the structure will be experienced as a downwards force on whatever turns the pellets around.

You seem to be assuming that the entire weight of the structure is supported by the top deflector station. That will not be the case. “Lifting Stations” will be positioned at regular intervals up the pellet stream. These will be pellet decelerators, and momentum will be transferred from the pellet stream to the lifting stations. A section of vacuum tube will be suspended from the lifting station above it. Each lifting station will only be responsible for lifting the weight of the section of vacuum tube between itself and the one below it.

Sections of vacuum tube will be loosely connected in some sort of sealed sliding arrangement that allows a little relative movement of lifting stations and tube sections.

Other structures, such as walls, elevators, etc. will be attached to lifting stations.

… a vertical underground shaft deep enough to effect a manageable rate of change in momentum would probably penetrate into the earth’s mantle.

You seem to be assuming that the base decelerator has to be linear. Current designs assume that the pellet path can be bent 90 degrees.

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Brian H wrote:

…

Yes, this is all “riding the stream”.

I wonder also what the pellet speed* is, and what the aerodynamic phenomena around the “stream” would be like. Sounds pretty drastic. Sure mess up any birds (or planes**) flying into it! Also be interesting to see what would happen during a severe thunderstorm, or even a tornado, in the vicinity.

*At escape velocity, wouldn’t the pellets burn up due to friction, both leaving and entering the atmosphere?

**Or satellites. A directed version of this would make a super satellite-smasher. Or ABM or AA defense.

I respectfully suggest that you read the Wikipedia article

http://en.wikipedia.org/wiki/Space_fountain

Its source material may contain more particulars about calculations of the pellet stream mass, velocity, etc. Severe weather scenarios may also have been discussed in the source material. I do not know.

As I understand it, the pellet stream would be encased in a vacuum tube for the lower 100 kilometers or so. Air in the tube would be removed to reduce friction with the pellets.

Birds and planes would have to crash through the tower superstructure and would be pretty messed up before they even hit the pellet stream.

The Space Fountain is based on “rail gun” weapon technology. Research into anti-aircraft, ABM and anti-satellite applications may be applicable to the SF and vice versa.

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Brian H wrote: Did I miss it? How does one get access to the suspended station with the Fountain? Ride the stream?

Yes, you did miss it.

If the support streams are sufficiently over-powered … the fountain can also be used to support … ELEVATORS or walls along its length… ”

The most obvious use for such a super-high structure would of course be as an orbital launch tower; line the outer walls with electromagnetic accelerators and shoot a payload up the side.

Either take an internal elevator, or stop the external payload at the top. If you don’t mind the exercise, you could also take the stairs. It’s only 40 KILOMETERS!

Yes, this is all “riding the stream”.

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Rezwan wrote: Yes, 50 does seem like a conveniently rounded number that coincides with the “end of oil”. …

With the price of crude oil due to break $100/bl any day now, $200 and $300/bl in a few years is quite possible. The end of cheap oil is in site. There is a larger supply of expensive oil, but it is doubtful that production can keep up with demand at any price.

Economical replacement of oil 50 years from now will be about 45 years too late!

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This is a good question, but one better asked in the Technology section than here in the Fundraising section. [Note: moved by admin]

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Glenn Millam wrote: http://www.cnn.com/2007/TECH/space/08/24/universe.hole.ap/index.html

Here is another version of basically the same story.

http://news.aol.com/story/ar/_a/astronomers-find-huge-hole-in-universe/20070825162909990001

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annodomini2 wrote: Interesting idea, would like to know the efficiency of such a system and obviously cost will be a determining factor.

Sorry, I don’t know anything more about it than what is in the article.

I do like the Rodriguez Ring. It seems to be the most efficient design they have so far.

… Ivan Rodriguez … built a resonator from a … hollow steel tube bent to form a ring … .

In cylinder-shaped resonators, sound waves bounce against the ends of the cylinder. But when heat is applied to Rodriguez

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texaslabrat wrote: Seeding the “desolate zone” of the ocean with iron is probably the most cost-effective way of removing CO2 from the atmosphere…recent experiments show a fixation rate of 300,000:1 CO2-to-Fe. … There’s at least one company who plans to make a business model out of exactly this process.

Please provide links to sources of this information.

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Transmute wrote: Why not just use the DPFs to propel a very larger ship with water tank shielding and enough space for artificial gravity?

Water is heavy. We need to keep the mass down, as the higher the mass the lower the acceleration applied to the ship by the engines. Though we will have some water shielding to protect the crew from neutrons, a much lighter magnetic bubble (such as M2P2) will deflect the charged particles of the solar wind. If the bubble is large enough (many miles) the solar wind can propel the craft.

Artificial gravity can be generated aboard a small craft by revolving the crew’s quarters on a counterweighted tether with a radius of at least 730 feet. See SpinCalc
http://www.artificial-gravity.com/sw/SpinCalc/SpinCalc.htm

… a DPF … does not have much thrust, … a DPF could not “take off” from anything larger then an asteroid.

A DPF does not throughput very much mass and is therefore not good for a rocket engine directly, but it could function as the power source for a High Power Helicon (HPH) plasma thruster, VASIMR or M2P2.

High Power Helicon
http://www.ess.washington.edu/Space/HPH/

Note that a VASIMR and M2P2 may not be able to function at the same time, but a VASIMR may be able to be configured to function as an M2P2.

One suggested application of the HPH is the MagBeam in which it is used as a “plasma cannon” aimed at a M2P2-equipped craft to push it to a higher orbit. The “cannon” platform would have to be substantially more massive than the craft to be pushed.

(Personal speculation – could the polarity/frequency of the MagBeam beam/field be adjusted to create a “tractor beam”?)

MagBeam
http://www.ess.washington.edu/space/magbeam/

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Glenn Millam wrote: … why couldn’t you also use a DPF power plant solely for generating a magnetic “force-field” for shielding the spacecraft from radiation, [similar] to the way Earth’s magnetic field shields us?

The “force field” you speak of is the Mini-Magnetospheric Plasma Propulsion (M2P2), which can provide both shielding and propulsion.

http://www.ess.washington.edu/Space/M2P2/

Also, here is a “parent” page on Advanced Electric Propulsion that has links to the M2P2 and related devices such as a plasma thruster.

http://www.ess.washington.edu/Space/propulsion.html

… why not have another for rotating the living quarter to provide artificial gravity…?

The living quarters can be rotated on a magnetic bearing (no friction), so after initial spin-up, maintaining rotation will need minimal energy. It will not require a dedicated power supply. It can be tapped off the shield or main propulsion reactor.

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Sequestering CO2 in trees is somewhat temporary storage in that the gas will be released again when the wood rots. Still, it is better than doing nothing.

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Sequestering CO2 instead of reducing it sounds like a variation on “closing the barn door after the horses are gone”.

Also, spending $2 Billion to make $25 Million sounds like a plan a politician would come up with. Al Gore would love it!

[Jolly Roger]

Continued…

…. the Space Fountain … can literally be built from the ground up. The ground station and the deflector station … would both be fully constructed on the ground, and the station placed on top of the ground station with their accelerators aligned. Then [as] the fountain is powered up slowly, the force of the pellet stream eventually lifts the station… The process can be suspended at any altitude … indefinitely, allowing for calibrations, maintenance, new construction, and so on.

If the support streams are sufficiently over-powered … the fountain can also be used to support … elevators or walls along its length… electromagnetic accelerators/decelerators can be built vertically along the stream as the fountain is slowly built up, drawing upon the force of the pellets passing through magnetic fields for support. [As] the wall sections (and any internal structure they themselves may support) are held aloft by the internal stream passing through them, they are under no extraordinary structural stress…

Thus Space Fountains can be used to create truly gigantic structures and towers as well as used merely to hold a space station aloft. And, unlike a Space Elevator, it would not require any extraordinarily expensive materials to hold together; modern-day alloys and composite materials would do just nicely.

The most obvious use for such a super-high structure would of course be as an orbital launch tower; line the outer walls with electromagnetic accelerators and shoot a payload up the side. A fountain tower about 40 kilometers high would be sufficient to launch passenger-carrying vessels to orbit…

A fountain tower could also be used as a super-sized arcology, research facility, industrial center, or more as a fountain 100 kilometers high and 100 meters wide at its base would have about 7.85 … cubic kilometers of volume…

Space Fountains would … have to be demonstrated on a “small” scale, first used in building kilometer-high transceiver towers and such for radio and television broadcasts. The technology can then be scaled up to support super-highrises, and then finally a true Space Fountain…

Though their initial construction costs may seem exorbitant, [Space Fountains] will quickly pay for themselves not just by making orbital travel cheaper and easier but by making space-based economies truly viable for the first time in history. They are just too good an investment for future generations to ignore.

But … within our lifetimes … [because of] long-standing conservatism …. exotic concepts such as the elevator and fountain could prove to be a very hard sell.

However … the advantages may be well worth the investment. After all, just as many who saw the first steam engines never thought they would transform a continent, so too are most people today unaware that the opening of the solar system to mankind is just a single railroad track away.

A “small”, relatively inexpensive, 40 kilometer Space Fountain could be built with existing materials and technology. Its power requirements could be supplied by Focus Fusion reactors. Their helium ion exhaust may even provide the “pellets” required to keep the tower aloft.

One possible site for this Space Fountain would be the Oklahoma Spaceport (formerly the Clinton-Sherman Airpark) near Burns Flat [there’s a mental picture! 😉 ], Oklahoma. It is located central to the contiguous United States and North America, and has much of the infrastructure needed for a space facility.

This could really open up space in a big way.

http://en.wikipedia.org/wiki/Space_fountain

http://en.wikipedia.org/wiki/Oklahoma_Spaceport

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