Lunarpedia - User contributions [en]

Talk:Variable-specific-impulse magnetoplasma rocket (VASIMR)

2008-08-11T16:39:39Z

Lazarus:

How do we reconcile this article with [[VASIMR]] on Exoplatz? - [[User:Jarogers2001|Jarogers2001]] 14:42, 11 August 2008 (UTC)

NASA chief: ISS tests for super plasma space drive

Nuclear-powered Mars ships on drawing board

By Lewis Page

Published Wednesday 6th August 2008 12:31 GMT

In non-Mars-lander NASA news, it has been reported that the space agency will soon set out concrete plans to test a revolutionary new drive system aboard the International Space Station. The propulsion tech in question is a plasma engine known as Variable Specific Impulse Magnetoplasma Rocket (VASIMR).

According to Flight International, NASA supremo Michael Griffin says that his agency is "at the end stages of agreeing a co-operative agreement for NASA to test the VASIMR engine on station".

The plasma drive is intended to work by using electric power to blast hydrogen reaction mass from its rocket nozzles at a much greater velocity than normal chemically-fuelled rockets can achieve. This means that the carrying spacecraft gets a lot more acceleration or deceleration from a given amount of fuel, and so can potentially make interplanetary journeys in much shorter times. Another potential application seen for VASIMR is maintenance of the space station's orbit, without the need to burn off colossal amounts of chemical rocket fuel.

VASIMR is the brainchild of Franklin Chang-Díaz, MIT plasma physicist and former NASA astronaut with seven Shuttle flights and 1600 hours in space. Chang-Díaz nowadays heads up the Ad Astra Rocket Company, dedicated to bringing plasma drives to market. He believes that VASIMR - or some kind of more fuel-efficient propulsion, anyway - must be developed, or travel beyond Earth orbit will never become a serious activity.

In the near future, for lower-thrust applications at Earth orbit or closer to the sun, plasma drives could draw their power from solar panels - the mainstream means of electricity generation in spacecraft today. The proposed ISS orbit-maintenance plan would be on this model. But more ambitious uses for the electric rockets, such as carrying humans on fast interplanetary journeys*, would require higher output, probably from onboard nuclear powerplants. Here's a YouTube concept vid of a triple-VASIMR nuclear Mars ship in action:

http://www.youtube.com/watch?v=Zj53rVWK5z0

This last might not be politically simple, however. Spacecraft with small nuclear reactors or radioisotope batteries - mostly spy satellites needing the juice for radar scanning - have been launched for decades, but whenever the use of nuclear power in space isn't kept secret it tends to draw a lot of technofear protest.

That's all for the further-off future, though, where humanity is beginning to operate seriously beyond Earth orbit. For now, it'll be a big step for VASIMR just to get aboard the ISS. ®

Category:Energy

2007-12-19T19:41:49Z

Lazarus: Space Based Solar Power, a Matter of National Security

Space Based Solar Power

The DOD National Security Space Office (NSSO) has published a feasibility study on Space Based Solar Power (SBSP). It says that advances in photovoltaics, electronics, robotics and space-based construction, coupled with the increasing importance of energy security and climate change, now make SBSP a serious option. Kilometre-sized solar panel arrays, probably in geostationary orbit (GEO), would gather sunlight and then transmit the electrical power to Earth via laser or microwave beams. A kilometre-wide band at GEO receives a solar flux in one year of about 212 terawatt-years, comparable to the energy in all known recoverable conventional oil reserves (250 TW-yrs). The report recommends the US government should invest $10bn over the next decade to build a test satellite to beam down 5 to 10 MWe. This would be large enough to provide proof-of-concept and would also have great value for military logistics by delivering power flexibly to remote locations. The biggest challenge in building a full system would then be how to launch so much mass into orbit, even if most came from the Moon.

[http://www.newscientist.com/article/dn12774.html]

[http://www.space-frontier.org/Presentations/SBSPInterimAssesment0.1.pdf]

Large scale excavations using HE beams.

2007-12-19T18:05:12Z

Lazarus:

Large scale excavations on the moon will be undertaken at some point. High Energy Beam Weapons, now coming online with the US Military, will make it much easier to create the vast underground spaces needed for a large society to grow and evolve. The following article shows the current state of these devices.

----

Beam weapons almost ready for battle

Directed energy could revolutionize warfare, expert says

By Leonard David Senior space writer

Updated: 12:10 p.m. ET Jan. 11, 2006

LOS ALAMOS, N.M. - There is a new breed of weaponry fast approaching — and at the speed of light, no less. They are labeled "directed-energy weapons," and they may well signal a revolution in military hardware — perhaps more so than the atomic bomb.

Directed-energy weapons take the form of lasers, high-powered microwaves and particle beams. Their adoption for ground, air, sea, and space warfare depends not only on using the electromagnetic spectrum, but also upon favorable political and budgetary wavelengths too.

That’s the outlook of J. Douglas Beason, author of the recently published book "The E-Bomb: How America’s New Directed Energy Weapons Will Change the Way Wars Will Be Fought in the Future." Beason previously served on the White House staff working for the president’s science adviser under both the Bush and Clinton administrations.

After more than two decades of research, the United States is on the verge of deploying a new generation of weapons that discharge beams of energy, such as the Airborne Laser and the Active Denial System, as well as the Tactical High Energy Laser, or THEL.

"History has shown that, without investment in high technology, fighting the next war will be done using the 'last war' type of technique," Beason told Space.com. Putting money into basic and long-range research is critical, Beason said, adding: "You can’t always schedule breakthroughs."

A leading expert in directed-energy research for 26 years, Beason is also director of threat reduction here at the Los Alamos National Laboratory. However, he noted that he was expressing his own views rather than the policy of the laboratory, the Defense Department or the Energy Department.

Ripe for transformation?

Though considerable work has been done in lasers, high-power microwaves and other directed-energy technologies, weaponization is still an ongoing process.

For example, work is continuing in the military’s Airborne Laser program. It utilizes a megawatt-class, high-energy chemical oxygen iodine laser toted skyward aboard a modified Boeing 747-400 aircraft. Purpose of the program is to enable the detection, tracking and destruction of ballistic missiles in the boost phase, or powered part of their flight.

Similarly, testing of the U.S. Army’s Tactical High Energy Laser in White Sands, N.M., has shown the ability of heating high-flying rocket warheads, blasting them with enough energy to make them self-detonate. THEL uses a high-energy, deuterium fluoride chemical laser. A mobile THEL also demonstrated the ability to kill multiple mortar rounds.

Then there’s Active Denial Technology — a non-lethal way to use millimeter-wave electromagnetic energy to stop, deter and turn back an advancing adversary. This technology, supported by the U.S. Marines, uses a beam of millimeter waves to heat a foe’s skin, causing severe pain without damage, and making the adversary flee the scene.

Beason also pointed to new exciting research areas underway at the Los Alamos National Laboratory: Free-electron laser work with the Navy and a new type of directed energy that operates in the terahertz region.

Niche for new technology

While progress in directed-energy is appreciable, Beason sees two upfront problems in moving the technology forward. One issue has to do with "convincing the warfighter that there’s a niche for this new type of weapon," and the other relates to making sure these new systems are not viewed as a panacea to solve all problems. "They are only another tool," he said.

Looming even larger is the role of those who acquire new weapons. "The U.S. could put ourselves in a very disastrous position if we allow our acquisition officials to be non-technically competent," Beason explained.

Over the decades, Beason said that the field of directed-energy has had its share of "snake-oil salesmen", as well as those advocates who overpromised. "It wasn’t ready for prime time."

At present, directed-energy systems "are barely limping along with enough money just to prove that they can work," Beason pointed out. Meanwhile, huge slugs of money are being put into legacy-type systems to keep them going.

"It’s a matter of priority," Beason said. The time is now to identify high-payoff, directed-energy projects for the smallest amounts of money, he said.

Unknown unknowns

In Beason’s view, Active Denial Technology, the Airborne Laser program and the THEL project, as well as supporting technologies such as relay mirrors, are all works in progress that give reason for added support and priority funding.

"I truly believe that as the Airborne Laser goes, so goes the rest of the nation’s directed-energy programs. Right now, it’s working on the margin. I believe that there are still ‘unknown unknowns’ out there that are going to occur in science and technology. We think we have the physics defined. We think we have the engineering defined. But something always goes wrong … and we’re working too close at the margin," Beason said.

Stepwise demonstration programs that spotlight directed-energy weapon systems are needed, Beason noted. Such in-the-field displays could show off greater beam distance-to-target runs, mobility of hardware, ease-of-operation, battlefield utility and other attributes.

Directed-energy technologies can offer a range of applications, from botching up an enemy’s electronics to performing "dial-up" destructive strikes at the speed of light with little or no collateral damage.

Beason said he has a blue-sky idea of his own, which he tags "the voice from heaven." By tuning the resonance of a laser onto Earth’s ionosphere, you can create audible frequencies. Like some boom box in the sky, the laser-produced voice could bellow from above down to the target below: "Put down your weapons."

Relay mirrors

Regarding use of directed-energy space weapons, Beason advised that "we’ll eventually see it."

However, present-day systems are far too messy. Most high-powered chemical lasers — in the megawatt-class — require onboard fuels and oxidizers to crank out the amount of energy useful for strategic applications. Stability of such a laser system rooted in space is also wanting.

On the other hand, Beason said he expected to see the rise of more efficient lasers — especially solid-state laser systems. "What breakthroughs are needed … I’m not sure. Eventually, I think it’s going to happen, but it is going to be a generation after the battlefield lasers."

Shooting beams "through space" is another matter, Beason quickly added. Space-based relay mirrors — even high-altitude airships equipped with relay mirrors — can direct ground-based or air-based laser beams nearly around the world, he said.

"So you’re using space … exploiting it. But you are going through space to attack anywhere on Earth," Beason said.

History lesson

Late last year, speaking before the Heritage Foundation in Washington, Beason told his audience that laser energy, the power sources and beam control, as well as knowledge about how laser beams interact with Earth’s atmosphere, are quite mature technologies that are ready for the shift into front-line warfare status.

"The good news is that directed energy exists. Directed energy is being tested, and within a few years directed energy is going to be deployed upon the battlefield," Beason reported. "But the bad news is that acquisition policies right now in this nation are one more gear toward evolutionary practices rather than revolutionary practices."

"Visionaries win wars … and not bureaucrats. We’ve seen this through history," Beason observed.

[[category:Civil Engineering]]

Large scale excavations using HE beams.

2007-12-19T18:04:00Z

Lazarus: Beam weapons almost ready

Category:Main: Large Scale Excavations

2007-12-19T17:53:32Z

Lazarus: High Energy Beam Weapons pave the way for lunar underground cities.

Zero to 76,000 mph in a Second

2007-12-19T17:37:02Z

Lazarus: Z Machine accelerates a plate from zero to 76,000 mph in a second

Zero to 76,000 mph in a Second
By Leonard David LiveScience Senior Writer: 07 June 2005

Scientists at the Sandia National Labs in Albuquerque, New Mexico have accelerated a small plate from zero to 76,000 mph in less than a second. The speed of the thrust was a new record for Sandia’s "Z Machine" – not only the fastest gun in the West, but in the world too.

The Z Machine is now able to propel small plates at 34 kilometers a second, faster than the 30 kilometers per second that Earth travels through space in its orbit about the Sun. That’s 50 times faster than a rifle bullet, and three times the velocity needed to escape Earth’s gravitational field.

The ultra-tiny aluminum plates, just 850 microns thick, are accelerated at 1010 g. One g is the force of Earth’s gravity. Doing so without vaporizing the plates was possible because of the finer control now achievable of the magnetic field pulse that drives the flight.

Z’s hurled plates strike a target after traveling only five millimeters, or less than a quarter-inch. The impact generates a shock wave -- in some cases, reaching 15 million times atmospheric pressure -- that passes through the target material. The waves are so powerful that they turn solids into liquids, liquids into gases, and gases into plasmas in the same way that heat melts ice to water or boils water into steam.

One purpose of these very rapid flights is to help understand the extreme conditions found within the interiors of giant planets in our solar system. By creating states of matter extremely difficult to achieve on Earth, the flyer plates provide hard data to astrophysicists speculating on the structure and even the formation of planets like Jupiter and Saturn.

Didier Saumon, an astrophysicist at Los Alamos National Laboratory, noted that the internal structures of Jupiter and Saturn are composed mostly of hydrogen. So knowing its equation of state -- how hydrogen and its isotopes behave at pressures from one to 50 million atmospheres -- is highly relevant to how scientists infer the interior properties of these planets.

An upgrade of the Z Machine is planned for next year and is expected to achieve higher plate velocities

An electrical storm lights up the surface of the Z machine, an accelerator built to simulate what happens during a nuclear explosion. The electrical discharges result from powerful electric fields that the experiment produces.

Housed at Sandia National Laboratories, the Z machine attracted a lot of attention eight years ago when its energy output more than quadrupled – raising hopes that the reactions in the Z could provide a new source of clean, abundant power. To help further progress towards this end, the machine is getting a $61.7 million upgrade, officials announced recently.

The Z uses a short burst of intense electricity – only a few 10 billionths of a second long – that forces an ionized gas to implode. The process is called a z-pinch because the pulse creates a magnetic field that squeezes particles in the vertical direction, which math books usually label as the "z-axis."

At the center of the z-pinch, in the space of a small soup can, gas particles race at each other at a million miles an hour. The collisions result in X-rays and extremely high temperatures.

Last year, when physicists placed a capsule of deuterium, or heavy hydrogen, at the focus of the z-pinch, they detected neutrons flying out from the implosion site – a signal that fusion reactions were taking place, as they do in the sun.

If researchers can learn to tame these fusion reactions, the setup can rely on a seemingly endless supply of deuterium fuel in seawater.

[[category:Rocketry]]

Zero to 76,000 mph in a Second

2007-12-19T17:31:45Z

Lazarus: Sandia Labs has accelerated a small plate from zero to 76,000 mph in less than a second.

Zero to 76,000 mph in a Second

By Leonard David LiveScience Senior Writer: 07 June 2005

Scientists at the Sandia National Labs in Albuquerque, New Mexico have accelerated a small plate from zero to 76,000 mph in less than a second. The speed of the thrust was a new record for Sandia’s "Z Machine" – not only the fastest gun in the West, but in the world too.

The Z Machine is now able to propel small plates at 34 kilometers a second, faster than the 30 kilometers per second that Earth travels through space in its orbit about the Sun. That’s 50 times faster than a rifle bullet, and three times the velocity needed to escape Earth’s gravitational field.

The ultra-tiny aluminum plates, just 850 microns thick, are accelerated at 1010 g. One g is the force of Earth’s gravity. Doing so without vaporizing the plates was possible because of the finer control now achievable of the magnetic field pulse that drives the flight.

Z’s hurled plates strike a target after traveling only five millimeters, or less than a quarter-inch. The impact generates a shock wave -- in some cases, reaching 15 million times atmospheric pressure -- that passes through the target material. The waves are so powerful that they turn solids into liquids, liquids into gases, and gases into plasmas in the same way that heat melts ice to water or boils water into steam.

One purpose of these very rapid flights is to help understand the extreme conditions found within the interiors of giant planets in our solar system. By creating states of matter extremely difficult to achieve on Earth, the flyer plates provide hard data to astrophysicists speculating on the structure and even the formation of planets like Jupiter and Saturn.

Didier Saumon, an astrophysicist at Los Alamos National Laboratory, noted that the internal structures of Jupiter and Saturn are composed mostly of hydrogen. So knowing its equation of state -- how hydrogen and its isotopes behave at pressures from one to 50 million atmospheres -- is highly relevant to how scientists infer the interior properties of these planets.

An upgrade of the Z Machine is planned for next year and is expected to achieve higher plate velocities

An electrical storm lights up the surface of the Z machine, an accelerator built to simulate what happens during a nuclear explosion. The electrical discharges result from powerful electric fields that the experiment produces.

Housed at Sandia National Laboratories, the Z machine attracted a lot of attention eight years ago when its energy output more than quadrupled – raising hopes that the reactions in the Z could provide a new source of clean, abundant power. To help further progress towards this end, the machine is getting a $61.7 million upgrade, officials announced recently.

The Z uses a short burst of intense electricity – only a few 10 billionths of a second long – that forces an ionized gas to implode. The process is called a z-pinch because the pulse creates a magnetic field that squeezes particles in the vertical direction, which math books usually label as the "z-axis."

At the center of the z-pinch, in the space of a small soup can, gas particles race at each other at a million miles an hour. The collisions result in X-rays and extremely high temperatures.

Last year, when physicists placed a capsule of deuterium, or heavy hydrogen, at the focus of the z-pinch, they detected neutrons flying out from the implosion site – a signal that fusion reactions were taking place, as they do in the sun.

If researchers can learn to tame these fusion reactions, the setup can rely on a seemingly endless supply of deuterium fuel in seawater.

[[category:Rocketry]]

Variable-specific-impulse magnetoplasma rocket (VASIMR)

2007-12-19T17:24:30Z

Lazarus: Magnetoplasma rockets will take us from Earth orbit to anywhere in the solar system

This rocket is expected to enable long-term human exploration of outer space.

Lyndon B. Johnson Space Center, Houston, Texas

Johnson Space Center has been leading the development of a high-power, electrothermal plasma rocket — the variable-specific-impulse magnetoplasma rocket (VASIMR) — that is capable of exhaust modulation at constant power. An electrodeless design enables the rocket to operate at power densities much greater than those of more conventional magnetoplasma or ion engines. An aspect of the engine design that affords a capability to achieve both high and variable specific impulse (Isp) places the VASIMR far ahead of anything available today. Inasmuch as this rocket can utilize hydrogen as its propellant, it can be operated at relatively low cost.

The design of the VASIMR is so original that a prototype is being developed in collaboration with the Department of Energy and with the Oak Ridge National Laboratory and its Center for Manufacturing Technology. The VASIMR is expected to be commercially useful for boosting communication satellites and other Earth-orbiting spacecraft to higher orbits, retrieving and servicing spacecraft in high orbits around the Earth, and boosting high-payload robotic spacecraft on very fast missions to other planets. Similarly, the VASIMR should make it possible for robotic spacecraft to travel quickly to the outer reaches of the Solar system and begin probing interstellar space. By far, the greatest potential of the VASIMR is expected to lie in its ability to significantly reduce the trip times for human missions to Mars and beyond. This reduction in times is expected to enable long-term exploration of outer space by humans — something that conventional rocket designs now preclude.

Because the VASIMR uses plasma to produce thrust, it is related to several previously developed thrusters; namely, the ion engine, the stationary plasma thruster (SPT) (also known as the Hall thruster), and the magnetoplasmadynamic (MPD) thruster [also known as the Lorentz-force accelerator (LFA)]. However, the VASIMR differs considerably from these other thrusters in that it lacks electrodes (a lack that enables the VASIMR to operate at much greater power densities) and has an inherent capability to achieve high and variable Isp. Both the ion engine and the SPT are electrostatic in nature and can only accelerate ions present in plasmas by means of either (1) externally applied electric fields (i.e., applied by an external grid as on an ion engine) or (2) axial charge nonuniformity as in the SPT. These ion-acceleration features, in turn, result in accelerated exhaust beams that must be neutralized by electron sources strategically located at the outlets before the exhaust streams leave the engines.

In the LFA, acceleration is not electrostatic but electromagnetic. A radial electric current flowing from a central cathode interacts with a self-generated azimuthal magnetic field to produce acceleration. Although LFAs can operate at power levels higher than those of either the ion engine or the SPT and do not require charge neutralization, their performances are still limited by the erosion of their electrodes.

An MPD plasma injector includes a cathode in contact with the plasma. Although the plasma at the location of contact is relatively cold, the cathode becomes eroded and the plasma becomes contaminated with cathode material (typically tungsten). The erosion and contamination can contribute to premature failure and to increased loss of energy through radiation from the contaminants in the plasma. An equal limitation on performance is exerted by nonionized propellant in a high-power amplifier cavity that is part of the MPD; the reason for this limitation is that neutral atoms and molecules in this region lead to charge-exchange losses, which, in turn reduce the overall efficiency of the engine and increase the unwanted heat load on the first wall (the liner) of the MPD thruster.

The design of the VASIMR avoids the aforementioned limiting features. The VASIMR contains three major magnetic cells — the forward, central, and aft cells. A plasma is injected into these cells, then heated, then expanded in a magnetic nozzle. (The magnetic configuration is of a type known as an asymmetric mirror.) The forward cell handles the main injection of propellant gas and an ionization system; the central cell serves as an amplifier to further heat the plasma to desired magnetic-nozzle-input conditions; and the aft cell acts as a hybrid two-stage magnetic nozzle that converts the thermal energy of the fluid into directed flow while protecting the nozzle walls and allowing efficient detachment of the plasma from the magnetic field. During operation of the VASIMR, a neutral gas (typically, hydrogen) is injected into the forward cell, where it is ionized. The resulting plasma is then heated in the central cell, to the desired temperature and density, by use of radio-frequency excitation and ion cyclotron resonance. Once heated, the plasma is magnetically and gas-dynamically exhausted by the aft cell to provide modulated thrust. Contamination is virtually eliminated and premature failures of components are unlikely.

The VASIMR offers numerous advantages over the prior art:

· Its unique electrodeless design provides not only high thrust at maximum power but also highly efficient ion-cyclotron-resonance heating, and high efficiency of the VASIMR regarded as a helicon plasma source.

· Because the VASIMR operates at relatively high voltage and low current, its mass is relatively low. This means that a one-ship human mission will not depend on a high-energy, complex rendezvous near Earth to achieve escape velocity. Instead, a rapid interplanetary transfer will be achieved with an adaptable exhaust, which will provide optimal acceleration throughout the mission.

· The residual magnetic field of the engine and the hydrogen propellant will be effective as a shield against radiation.

· Because of its continuous acceleration, the VASIMR will be able to produce a small amount of artificial gravitation, thereby reducing the physiological deconditioning produced by weightlessness.

· The variability of thrust and Isp at constant power will afford a wide range of capabilities to abort.

· Because hydrogen is the most abundant element in the universe, the supply of hydrogen could likely be regenerated in situ.

· The VASIMR is flexible and adaptable to both fast transfers of humans and slower high-payload robotic missions; hence, there would be no need to develop separate propulsion systems for missions of each type, and costs would be held down accordingly.

Long-range benefits could be derived from the continued development of the VASIMR. The VASIMR can be expected to pave the way for fusion-driven plasma rockets. In addition, because the VASIMR is a high-Isp rocket, the VASIMR concept can be expected to lead to lower initial mass in low Earth orbit, relative to nuclear, thermal, and/or chemical rockets.

This work was done by Franklin R. Chang-Díaz of Johnson Space Center.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, Johnson Space Center, (281) 483-0837. Refer to MSC-23041.

[[category:Rocketry]]

Magnetoplasma

2007-10-26T16:01:44Z

Lazarus: Magnetoplasma thruster is the key to long-term human exploration of space

Variable-Specific-Impulse Magnetoplasma Rocket

==='''This rocket is expected to enable long-term human exploration of outer space.'''===
Lyndon B. Johnson Space Center, Houston, Texas

Johnson Space Center has been leading the development of a high-power, electrothermal plasma rocket — the variable-specific-impulse magnetoplasma rocket (VASIMR) — that is capable of exhaust modulation at constant power. An electrodeless design enables the rocket to operate at power densities much greater than those of more conventional magnetoplasma or ion engines. An aspect of the engine design that affords a capability to achieve both high and variable specific impulse (Isp) places the VASIMR far ahead of anything available today. Inasmuch as this rocket can utilize hydrogen as its propellant, it can be operated at relatively low cost.

The design of the VASIMR is so original that a prototype is being developed in collaboration with the Department of Energy and with the Oak Ridge National Laboratory and its Center for Manufacturing Technology. The VASIMR is expected to be commercially useful for boosting communication satellites and other Earth-orbiting spacecraft to higher orbits, retrieving and servicing spacecraft in high orbits around the Earth, and boosting high-payload robotic spacecraft on very fast missions to other planets. Similarly, the VASIMR should make it possible for robotic spacecraft to travel quickly to the outer reaches of the Solar system and begin probing interstellar space. By far, the greatest potential of the VASIMR is expected to lie in its ability to significantly reduce the trip times for human missions to Mars and beyond. This reduction in times is expected to enable long-term exploration of outer space by humans — something that conventional rocket designs now preclude.

Because the VASIMR uses plasma to produce thrust, it is related to several previously developed thrusters; namely, the ion engine, the stationary plasma thruster (SPT) (also known as the Hall thruster), and the magnetoplasmadynamic (MPD) thruster [also known as the Lorentz-force accelerator (LFA)]. However, the VASIMR differs considerably from these other thrusters in that it lacks electrodes (a lack that enables the VASIMR to operate at much greater power densities) and has an inherent capability to achieve high and variable Isp. Both the ion engine and the SPT are electrostatic in nature and can only accelerate ions present in plasmas by means of either (1) externally applied electric fields (i.e., applied by an external grid as on an ion engine) or (2) axial charge nonuniformity as in the SPT. These ion-acceleration features, in turn, result in accelerated exhaust beams that must be neutralized by electron sources strategically located at the outlets before the exhaust streams leave the engines.

In the LFA, acceleration is not electrostatic but electromagnetic. A radial electric current flowing from a central cathode interacts with a self-generated azimuthal magnetic field to produce acceleration. Although LFAs can operate at power levels higher than those of either the ion engine or the SPT and do not require charge neutralization, their performances are still limited by the erosion of their electrodes.

An MPD plasma injector includes a cathode in contact with the plasma. Although the plasma at the location of contact is relatively cold, the cathode becomes eroded and the plasma becomes contaminated with cathode material (typically tungsten). The erosion and contamination can contribute to premature failure and to increased loss of energy through radiation from the contaminants in the plasma. An equal limitation on performance is exerted by nonionized propellant in a high-power amplifier cavity that is part of the MPD; the reason for this limitation is that neutral atoms and molecules in this region lead to charge-exchange losses, which, in turn reduce the overall efficiency of the engine and increase the unwanted heat load on the first wall (the liner) of the MPD thruster.

The design of the VASIMR avoids the aforementioned limiting features. The VASIMR contains three major magnetic cells — the forward, central, and aft cells. A plasma is injected into these cells, then heated, then expanded in a magnetic nozzle. (The magnetic configuration is of a type known as an asymmetric mirror.) The forward cell handles the main injection of propellant gas and an ionization system; the central cell serves as an amplifier to further heat the plasma to desired magnetic-nozzle-input conditions; and the aft cell acts as a hybrid two-stage magnetic nozzle that converts the thermal energy of the fluid into directed flow while protecting the nozzle walls and allowing efficient detachment of the plasma from the magnetic field. During operation of the VASIMR, a neutral gas (typically, hydrogen) is injected into the forward cell, where it is ionized. The resulting plasma is then heated in the central cell, to the desired temperature and density, by use of radio-frequency excitation and ion cyclotron resonance. Once heated, the plasma is magnetically and gas-dynamically exhausted by the aft cell to provide modulated thrust. Contamination is virtually eliminated and premature failures of components are unlikely.

The VASIMR offers numerous advantages over the prior art:

* Its unique electrodeless design provides not only high thrust at maximum power but also highly efficient ion-cyclotron-resonance heating, and high efficiency of the VASIMR regarded as a helicon plasma source.

* Because the VASIMR operates at relatively high voltage and low current, its mass is relatively low. This means that a one-ship human mission will not depend on a high-energy, complex rendezvous near Earth to achieve escape velocity. Instead, a rapid interplanetary transfer will be achieved with an adaptable exhaust, which will provide optimal acceleration throughout the mission.

* The residual magnetic field of the engine and the hydrogen propellant will be effective as a shield against radiation.

* Because of its continuous acceleration, the VASIMR will be able to produce a small amount of artificial gravitation, thereby reducing the physiological deconditioning produced by weightlessness.

* The variability of thrust and Isp at constant power will afford a wide range of capabilities to abort.

* Because hydrogen is the most abundant element in the universe, the supply of hydrogen could likely be regenerated in situ.

* The VASIMR is flexible and adaptable to both fast transfers of humans and slower high-payload robotic missions; hence, there would be no need to develop separate propulsion systems for missions of each type, and costs would be held down accordingly.

Long-range benefits could be derived from the continued development of the VASIMR. The VASIMR can be expected to pave the way for fusion-driven plasma rockets. In addition, because the VASIMR is a high-Isp rocket, the VASIMR concept can be expected to lead to lower initial mass in low Earth orbit, relative to nuclear, thermal, and/or chemical rockets.

This work was done by Franklin R. Chang-Díaz of Johnson Space Center.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, Johnson Space Center, (281) 483-0837. Refer to MSC-23041.

==='''Record Set for Hottest Temperature on Earth: 3.6 Billion Degrees in Lab'''===
LiveScience.com; Feb 2006

Scientists have produced superheated gas exceeding temperatures of 2 billion degrees Kelvin, or 3.6 billion degrees Fahrenheit.

This is hotter than the interior of our Sun, which is about 15 million degrees Kelvin, and also hotter than any previous temperature ever achieved on Earth, they say.

They don't know how they did it.

The feat was accomplished in the Z machine at Sandia National Laboratories.

"At first, we were disbelieving," said project leader Chris Deeney. "We repeated the experiment many times to make sure we had a true result."

Thermonuclear explosions are estimated to reach only tens to hundreds of millions of degrees Kelvin; other nuclear fusion experiments have achieved temperatures of about 500 million degrees Kelvin, said a spokesperson at the lab.

The achievement was detailed in the Feb. 24 issue of the journal Physical Review Letters.

The Z machine is the largest X-ray generator in the world. It’s designed to test materials under extreme temperatures and pressures. It works by releasing 20 million amps of electricity into a vertical array of very fine tungsten wires. The wires dissolve into a cloud of charged particles, a superheated gas called plasma.

A very strong magnetic field compresses the plasma into the thickness of a pencil lead. This causes the plasma to release energy in the form of X-rays, but the X-rays are usually only several million degrees.

Sandia researchers still aren’t sure how the machine achieved the new record. Part of it is probably due to the replacement of the tungsten steel wires with slightly thicker steel wires, which allow the plasma ions to travel faster and thus achieve higher temperatures.

One thing that puzzles scientists is that the high temperature was achieved after the plasma’s ions should have been losing energy and cooling. Also, when the high temperature was achieved, the Z machine was releasing more energy than was originally put in, something that usually occurs only in nuclear reactions.

Sandia consultant Malcolm Haines theorizes that some unknown energy source is involved, which is providing the machine with an extra jolt of energy just as the plasma ions are beginning to slow down.

Sandia National Laboratories is located by Albuquerque New Mexico and is part of the U.S.

==='''Zero to 76,000 mph in a Second'''===
By Leonard David LiveScience Senior Writer: 07 June 2005

Scientists at the Sandia National Labs in Albuquerque, New Mexico have accelerated a small plate from zero to 76,000 mph in less than a second. The speed of the thrust was a new record for Sandia’s "Z Machine" – not only the fastest gun in the West, but in the world too.

The Z Machine is now able to propel small plates at 34 kilometers a second, faster than the 30 kilometers per second that Earth travels through space in its orbit about the Sun. That’s 50 times faster than a rifle bullet, and three times the velocity needed to escape Earth’s gravitational field.

The ultra-tiny aluminum plates, just 850 microns thick, are accelerated at 1010 g. One g is the force of Earth’s gravity. Doing so without vaporizing the plates was possible because of the finer control now achievable of the magnetic field pulse that drives the flight.

Z’s hurled plates strike a target after traveling only five millimeters, or less than a quarter-inch. The impact generates a shock wave -- in some cases, reaching 15 million times atmospheric pressure -- that passes through the target material. The waves are so powerful that they turn solids into liquids, liquids into gases, and gases into plasmas in the same way that heat melts ice to water or boils water into steam.

One purpose of these very rapid flights is to help understand the extreme conditions found within the interiors of giant planets in our solar system. By creating states of matter extremely difficult to achieve on Earth, the flyer plates provide hard data to astrophysicists speculating on the structure and even the formation of planets like Jupiter and Saturn.

Didier Saumon, an astrophysicist at Los Alamos National Laboratory, noted that the internal structures of Jupiter and Saturn are composed mostly of hydrogen. So knowing its equation of state -- how hydrogen and its isotopes behave at pressures from one to 50 million atmospheres -- is highly relevant to how scientists infer the interior properties of these planets.

An upgrade of the Z Machine is planned for next year and is expected to achieve higher plate velocities.

An electrical storm lights up the surface of the Z machine, an accelerator built to simulate what happens during a nuclear explosion. The electrical discharges result from powerful electric fields that the experiment produces.

Housed at Sandia National Laboratories, the Z machine attracted a lot of attention eight years ago when its energy output more than quadrupled – raising hopes that the reactions in the Z could provide a new source of clean, abundant power. To help further progress towards this end, the machine is getting a $61.7 million upgrade, officials announced recently.

The Z uses a short burst of intense electricity – only a few 10 billionths of a second long – that forces an ionized gas to implode. The process is called a z-pinch because the pulse creates a magnetic field that squeezes particles in the vertical direction, which math books usually label as the "z-axis."

At the center of the z-pinch, in the space of a small soup can, gas particles race at each other at a million miles an hour. The collisions result in X-rays and extremely high temperatures.

Last year, when physicists placed a capsule of deuterium, or heavy hydrogen, at the focus of the z-pinch, they detected neutrons flying out from the implosion site – a signal that fusion reactions were taking place, as they do in the sun.

If researchers can learn to tame these fusion reactions, the setup can rely on a seemingly endless supply of deuterium fuel in seawater.

List of Propulsion Systems

2007-10-26T15:49:58Z

Lazarus: /* Earth Moon Transfer */

{{Bootstrap}}

==Moon launched==
[[LOX-Aluminium]] -- derived from lunar oxygen and mined aluminium 
[[LOX-Hydrogen]] -- derived from polar ice 
[[Maglev]] launcher -- a la Gerard O'Neill and/or Heinlein 
[[Ring launch]] or [[line launch]] 

==Earth launched==
Conventional Chemical -- (links to Astronautix might be useful here) 
[[SCRAMJet]] 
[[Space Elevator]] 
[[Tether]] 
[[Inverted-aerobraking]] 
[[Momentum from GTO]] 

==Earth Moon Transfer==
[[Nuclear]] -- [[Orion]]. 
[[Magnetoplasma]] 
[[Ion]] 
[[Tether]]

[[Category:Space Transport]]
[[Category:Components]]
[[Category:Hardware Plans]]

Evolution's Child

2007-06-12T15:18:35Z

Lazarus: Science collides with religion in the late 21st century

In a century filled with strife, the dogs of war are gathering once again. By 2092, climate change has devastated the planet and even thinned by incessant bloodshed, famine, and disease, Earth’s population exceeds 13 billion. Food and water are in short supply, refugee’s number in the hundreds of millions, and lawlessness abounds. Humanity is in turmoil.
Religious zealots have seized upon this despair, claiming it is God’s punishment for man’s misdeeds. Within the North American Federation, Christian theocracy has displaced democracy plunging once proud America into the 21st century’s version of the Dark Ages. On the other side of the planet, the Islamic Brotherhood controls territory from Indonesia, across Asia and the Middle East and well onto the African continent, India the only holdout. Even China, the leading space faring nation on Earth, allies with the Brotherhood, providing them with science and technology for a price. Only within the European Union is there still a semblance of peace between Christians and Muslims but it has become increasingly strained. The nations of the world align along sectarian lines as global violence escalates.
In sharp contrast, the Republic of Luna is a technocratic society where information flows freely and nothing is secret, a place governed by humanism and the laws of science. Out of necessity, life on an airless world burrows deep underground and to stay alive, Lunarians unlock nature’s deepest secrets, gaining mastery over the genetic foundations of life itself. In doing so, they become the first true extraterrestrial race.
Back on Earth, when the scope of the Lunarians meddling in evolution is revealed, they are loudly denounced as abominations. Prince Ahmed Mohammed Al Zarqowi, Caliph of the Islamic Brotherhood, believes he can use this prejudice to attack Luna with impunity and create mankind’s first multi-planet empire. To the Caliph this is simply the next step in a plan to bring an unbelieving world under Islamic Law, unleashing forces intent on destroying the Republic before it is even fifty years old.
Lazarus Sheffield is a Senior Analyst within the Department of Homeland Security. When he learns of the Brotherhood’s plan, he becomes the highest ranking Federation officer to ever defect. Thus begins an adventure like no other, the fate of Earth hanging in the balance.

List of Books

2007-06-12T15:16:30Z

Lazarus:

{{Bootstrap}}

[[The High Frontier]], Third Edition
by [[Gerard K. O'Neill]] (2000) (ISBN 0962237906) 
http://ssi.org/?page_id=12

[[NASA TM-2004-212743]] - "Reinventing the Solar Power Satellite" and "Peak Power Markets
for Satellite Solar Power" from the Houston IAF Congress.
Author: "[[Geoffrey A. Landis]]"

[[Apollo 13: Lost Moon]].
by Jim Lovell. Pocket, 1995. (ISBN 0671534645) 

[[Category:Hardware Plans]]
[[Category:History]]

[[Atlas of the Moon]], Revised Edition
by [[Antonin Rukl]] (2004) (ISBN 1931559074) 

[[Evolution's Child, Republic of Luna]], Fiction
by [[Charles Lee Lesher]] (2007) (ISBN 097772350X)

List of Books

2007-06-12T15:15:14Z

Lazarus:

{{Bootstrap}}

[[The High Frontier]], Third Edition
by [[Gerard K. O'Neill]] (2000) (ISBN 0962237906) 
http://ssi.org/?page_id=12

[[NASA TM-2004-212743]] - "Reinventing the Solar Power Satellite" and "Peak Power Markets
for Satellite Solar Power" from the Houston IAF Congress.
Author: "[[Geoffrey A. Landis]]"

[[Apollo 13: Lost Moon]].
by Jim Lovell. Pocket, 1995. (ISBN 0671534645) 

[[Category:Hardware Plans]]
[[Category:History]]

[[Atlas of the Moon]], Revised Edition
by [[Antonin Rukl]] (2004) (ISBN 1931559074) 

[[Evolution's Child]], Science Fiction
by [[Charles Lee Lesher]] (2007) (ISBN 097772350X)

Talk:Fiction on Lunarpedia

2007-06-12T15:05:45Z

Lazarus:

'''Are we active or passive?'''

The Lunarpedia community must decide if it wants to be active or passive. If we want to aggressively promote the idea of returning to the Moon to stay, we need to get a very large number of people in effective action on this idea.

A purely technical Lunarpedia will help technical people to be in action. It will not help non-technical people.

To reach non-technical people we must reach out. We must go were they live and feed them what they eat.

The story category is an experiment in reaching out to a much larger number of people. We need to keep it, at least long enough to find out if the experiment is going to succeed or fail.

--[[User:Jriley|Jriley]] 05:22, 10 March 2007 (PST)

----

It's not about being active or passive, and it's not technical versus non technical. Plain and simple, Lunarpedia is intended to be '''fact''' based. We're in the process of setting up a related wiki for fiction, but it wont be only lunar fiction. Should be up and running soon.

--[[User:Mdelaney|MikeD]] 13:33, 10 March 2007 (GMT)

Not a problem. Just need to get ideas out and discussed.

We do need to get a clear purpose or mission statement on Lunarpedia that makes this clear. I have started a category to work out such ideas but I have not searched out The Moon Society's mission statement yet.

Thanks,

--[[User:Jriley|Jriley]] 07:43, 10 March 2007 (PST)

----

Hah!

I've been searching for that since 2000, haven't found it yet.

Lunarpedia was started mainly as a tool for encouraging growth, collaboration on projects, and very importantly, inter society relations by way of highlighting the commonalities in their goals instead of the differences.

We just put up a Mars wiki, that's almost ready to go public. The science fiction wiki will be aimed more towards budding authors than towards librarians. But the science part of the stories must be currently feasibl or at least look like it will be in the next few years.

Getting people to read and write about space stuff is important. I truly wish the Star Trek people had done a 21st century series complete with weightlessnes and space sickness and all the stuff we'll have to deal with for the first 50 - 100 years.

[[User:Mdelaney|MikeD]] 18:07, 10 Mar 2007 (GMT)

----

----
'''Hard Science Fiction'''

The type of fiction you are describing is called hard science fiction. It was invented by Jules Vern, but I am afraid it is quite out of fashion now. The limit on adult themes also makes these stories very retro. Stories of this type were the cutting-edge between about 1930 and 1960.

We can certainly move the stories themselves. The problem will be the useful support pages like "People on the Moon" and "Archetecture as Mole Hills". I am certain that these make a real contribution to people envisioning what a lunar settlement will be like.

In developing my Purposes pages I have found myself being so eclectic that I argue both sides of an arguement.

Thanks,

--[[User:Jriley|Jriley]] 10:40, 10 March 2007 (PST)

----

The great thing about running 2 MediaWiki sites is that they can easily augment each other. The People On the Moon article can remain story oriented on the fiction wiki, but can also be linked to from Lunarpedia as a valuable source of ideas and discussion. Vis a vis, the article can also link to Lunarpedia articles as sources of information. One can be fact and one can be fiction. Both can be integrated via MediaWiki interlinks and will build on each other. This approach allows a full spectrum of information using separate specialized sources which can be "tied together" in a sense.

If all goes well, this will allow an exchange of ideas and encourage collaboration between the SpaceWiki user communities and their respective advocacy groups. [[User:Jarogers2001|Jarogers2001]] 12:28, 10 March 2007 (PST)

----

Fiction has a place in an encyclopedia if it's the best way to show the reader what an article is about. In that context, I would expect fiction pieces to be very short, just a vignette that illustrates a particular point within a much larger article.

There is a strong downside risk. If someone came the Lunarpedia expecting to find information about the moon and ran into a bunch of fan fiction instead of solid facts, that would be the last time he'd ever visit. At the same time, this is the last place one would look to find fan fiction set on the moon.

-- Greg

== Imagination is the backbone of commitment ==

Good science fiction is the imagination of the human race. We depend upon it to light up the darkness and open the debate about what is possible and what is not. I am not talking about Mars Attack, which I loved, but serious fiction set in the near future about the people and societies who will develop from lunar colonies can be very beneficial to current discussions.
Lazarus

Talk:Fiction on Lunarpedia

2007-06-12T15:01:44Z

Lazarus: Imagination is the backbone of commitment